Food without agriculture: Food from CO2, biomass and hydrocarbons to secure humanity's food supply against global catastrophe

Full text

Published on Trends in Food Science & Technology
https://doi.org/10.1016/j.tifs.2024.104609
This version: 06/2024
Food without agriculture:
Food from CO2, biomass and hydrocarbons to secure humanity's food
supply against global catastrophe
Juan B. García MartínezA,B , Jeffray Behr A, David C. DenkenbergerA,C
Affiliations:
AAlliance to Feed the Earth in Disasters (ALLFED), Lafayette, CO, USA
BObservatorio de Riesgos Catastróficos Globales (ORCG), Towson, MD, USA
CDepartment of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand
*Corresponding author: juan@allfed.info.
Abstract
Background: The growing human population requires consistent access to nutritious and
sustainable food to thrive. To this end, non-agricultural, closed-environment food production
methods can complement agriculture while increasing the resilience of the global food system to
climate shocks, biological threats, environmental threats, trade restrictions, and even extreme
scenarios such as abrupt sunlight reduction (e.g. from a volcanic winter or nuclear winter).
Scope and approach: This review describes the existing production processes and recent
developments in non-agricultural food production, including the activities of companies carrying
out established processes and of those developing innovative production processes. The potential
of fermentation for production of single cell foods and for biosynthesis of key nutrients, and the
nonbiological synthesis of food compounds such as from CO2are reviewed in depth. The study has
a special focus on potential response to global catastrophic food shocks that disrupt agricultural
production.
Findings and conclusions: The enormous potential for food production via key non-agricultural
pathways was described and quantified. All macronutrients can be produced by both
biomanufacturing and nonbiological synthesis, independently from agriculture, even using CO2.
These technologies are capable of synthesizing all amino acids, as well as the essential fatty acids
and multiple vitamins and micronutrients of interest. Many of these pathways are relevant
industrially and resilience-wise compared to agricultural pathways due to their potential to
produce at either lower cost, improved sustainability, in more extreme conditions and
environments (e.g. outer space), or a combination of these. More research and resilience work is
urgently needed to realize their potential.

Keywords
Food without agriculture; Global catastrophic risk; Existential risk; Resilient food; Food security;
Global Catastrophic Food Failure
Highlights
●All macronutrients and many micronutrients can be produced without agriculture.
●There is potential for sourcing vast amounts of food independently from agriculture.
●Non-agricultural food production is resilient to a set of key food system risks.
●Food without agriculture can reduce global catastrophic risk and existential risk.
●Future work: pilot factories, fast construction and repurposing pilots, open designs.
Abbreviations
Abrupt Sunlight Reduction Scenario (ASRS)
Imperial Chemical Industries (ICI)
National Aeronautics and Space Administration (NASA)
Single Cell Protein (SCP)
2

Table of contents
1 Introduction 4
2 Synthesis of food without agriculture 5
3 Lignocellulosic Biomass as a Sugar Source and a Platform for Food Synthesis 9
4 Single cell proteins and oils 10
4.1 Gas fermentation 11
4.1.1 Single Cell Protein from Methane (CH4) - Natural Gas or Biogas 12
4.1.2 Single Cell Protein from CO₂ and H2 - “Air Protein” 13
4.2 Liquid fermentation 15
4.2.1 Single Cell Protein from Methanol, formate, or acetate as liquid intermediates derived from
Natural Gas, Biogas, CO2, or CO 15
4.2.2 Single Cell Protein from Lignocellulosic Biomass 16
4.2.3 Single Cell Protein from Petroleum-derived Products 16
4.2.4 Microbial Fats from Lignocellulosic Biomass 17
4.2.5 Single Cell Protein from Peat 17
4.3 Solid-state fermentation 18
4.4 Photosynthetic microorganism cultivation (SCP) 18
5 Microbial cell factories for food production 20
5.1 Biosynthesis of essential nutrients from sugars (e.g. lignocellulosic glucose) through precision
fermentation 20
5.2 Biosynthesis of food from carbon dioxide 21
5.2.1 Lipid biosynthesis from CO2 and H2 21
5.2.2 Amino acid biosynthesis from CO2 and H2 21
5.2.3 Microbial Electrosynthesis of Acetic Acid and Fatty Acids from CO2 21
6 In vitro BioTransformation (ivBT) 22
7 Chemical synthesis of food 22
7.1 Synthesis of food from hydrocarbons 23
7.1.1 Chemical Synthesis of Vitamins 23
7.1.2 Chemical Synthesis of Amino Acids 23
7.1.3 Fats from hydrocarbons or from CO2 (Paraffin oxidation process) 24
7.1.4 Glycerol from propylene 24
7.1.5 Chemical Synthesis of other Carboxylic Acids 25
7.2 Chemical synthesis of carbohydrates from carbon dioxide 25
7.2.1 Sugars from CO2 and H2 26
7.2.2 Glycerol from CO2 and water 27
8 Discussion 27
8.1 Future work on resilient food synthesis 28
8.2 Ethical considerations 31
9 Concluding remarks 32
References 34
Supplementary material - Table S1: Production capacity values 42
3

1Introduction
The current global agricultural system depends on a set of crucial conditions (institutional, abiotic,
and biotic) that act as risk factors, including trade restrictions, environmental degradation
(pollution, soil erosion), extreme weather events, changing climates, pathogens, and pests (Tzachor
et al., 2021). It also depends heavily on steady environmental conditions including sunlight,
temperature, and precipitation, all of which could be severely affected by global catastrophes
(Denkenberger et al., 2017). Among potential ways to mitigate these risks, non-agricultural food
production is underexplored.
The field of non-agricultural food production first gained traction in the 1960s-1970s. Initially,
chemical and biochemical production was proposed as an option to deal with mounting pressures
to produce enough food for a rapidly growing population (McPherson, 1966), addressing
overpopulation concerns of the time. These forecasted pressures on the food system failed to
materialize, thanks mostly to the third agricultural revolution, and in turn the idea of a burgeoning
non-agricultural food industry also failed to materialize. However, there were successes, including
large-scale production of synthetic fats from paraffin wax (García Martínez, Alvarado, et al., 2022),
microbial protein from hydrocarbons (Lackner et al., 2022), and large-scale synthesis of vitamins
and amino acids such as the chemical synthesis of methionine or the biosynthesis of lysine and
vitamin C (Drauz et al., 2007; Eggersdorfer et al., 2012). Regardless, some of these pathways which
were competitive at the time were eventually superseded by the decreasing cost of agricultural
analogues and were largely forgotten, such as agricultural fats taking synthetic fats out of the
market or cheap soy displacing microbial protein feeds.
Now, renewed interest in food without agriculture is coming from various areas. Environmental
pressures are leading foodtech companies to reinvigorate the field, finding new ways to reduce
food system CO2emissions while enabling humanity to feed more people around the world with
less water and land use than conventional agriculture. Many routes are being unearthed and
developed for food production using CO2as main feedstock, reaching towards the ideal of net-zero
CO2food production. For example, synthetic fat production has potential to fulfill humanity’s fat
demand at considerably lower CO2intensity than many conventional vegetable oils, as
demonstrated by (Davis et al., 2023) in their recent work “Food without agriculture”, inspired by a
concept originally developed in the 1940s (García Martínez, Alvarado, et al., 2022). “Air protein”,
microbial protein obtained via gas fermentation from CO2and H2, has recently seen a surge of
companies seeking to commercialize novel alternative protein and cellular agriculture food
products (García Martínez, Egbejimba, et al., 2021), based on a NASA concept from the 1960s
(Alvarado et al., 2021). Similar processes using methane are driving the construction of large-scale
factories around the world to fulfill sustainable animal feed demand (García Martínez, Pearce, et al.,
2022). Some researchers are even calling for the mass production of carbohydrates from captured
atmospheric CO2to address food sector emissions (Dinger & Platt, 2020; O’Brien et al., 2022),
which, while economically and energetically questionable, does show the potential of
nonagricultural food production for deployment on the scale of gigatonnes per year.
A latent interest in non-agricultural food production for extreme environments is also reemerging
from other fronts. Space agencies like NASA are revisiting the development of in-situ food
4

production to efficiently provide food supply in long term missions (Alvarado et al., 2021; García
Martínez, Alvarado, et al., 2021; Alvarado et al., 2023) — also fundamental for potential space
settlements (Averesch et al., 2023) — such as through NASA’s CO2Conversion Challenge and Deep
Space Food Challenge. DARPA’s Cornucopia program is pushing the development of nutritionally
complete microbial foods produced from CO2, water and electricity for military and humanitarian
missions. A related idea is applying these technologies for food supply and life support in
self-sufficient, isolated refuges (underground, underwater, or extraplanetary) conceptualized to
weather catastrophes posing an existential risk to modern civilization or possibly humanity itself
(Alvarado et al., 2021; García Martínez, Alvarado, et al., 2021; Alvarado et al., 2023).
Circling back to food security, non-agricultural food production methods have recently been
studied as a response intervention to safeguard humanity’s food supply in the most extreme
agricultural disruption scenarios (García Martínez, Alvarado, et al., 2021; García Martínez, Brown,
et al., 2021; García Martínez, Egbejimba, et al., 2021; García Martínez, Alvarado, et al., 2022; García
Martínez, Pearce, et al., 2022; Throup et al., 2022), as had been previously proposed by (Y.-H. P.
Zhang et al., 2012). They are particularly suited to Abrupt Sunlight Reduction Scenarios (ASRS),
defined by a sudden event that projects vast amounts of aerosol material (e.g. a volcanic eruption,
asteroid/comet impact, or nuclear war) that stay in the atmosphere for years, causing extensive
reductions in solar irradiation, temperature and precipitation, resulting in plummeting
agricultural yields (Pham et al., 2022).
This review pays special interest to pathways that leverage non-agricultural resources through
industrial conversion to complement traditional food sources and increase the chances that
humanity produces enough food in catastrophic scenarios in which industrial manufacturing
capacities remain. Compared to agriculture, these closed environment, modular, polycentric food
production systems minimize or even remove key risks (Tzachor et al., 2021) such as climate
variability (including sunlight dependence as long as sufficient energy can be obtained
independently from sunlight), environmental degradation and pollution, pests, pathogens, and
trade restrictions. Thus, these systems are more resilient to extreme catastrophic scenarios with
partial or total loss of agricultural function such as ASRS, extreme climate change (e.g. abrupt
change, runaway change (Richards et al., 2023), or moisture greenhouse effect), or other plant
collapse risks from potential future threats, perhaps of biotechnological nature. However, they may
be more vulnerable to certain catastrophic events than the current agricultural system, such as
those risking a collapse of electrical/industrial infrastructure (Denkenberger et al., 2017).
This article aims to characterize the enormous potential of non-agricultural food production
methods for contributing to the global food system by making it more resilient, efficient and
sustainable. The list of food production pathways presented here is comprehensive but not
exhaustive, capturing all the major pathways capable of producing the largest amounts of food
from the major pools of raw materials.
2 Synthesis of food without agriculture
Even in the harsh conditions of an ASRS, many resources that are much more resilient than crops
to changes in environmental factors would be available for food production without relying on
agriculture, by using industrial technologies (Davis et al., 2023; McPherson, 1966). A summary table
of key resources and their potential for food production is given in Table 1. It is expected that even
5

in an ASRS lignocellulosic biomass is a very widely available input for food production
(Denkenberger & Pearce, 2014; Throup et al., 2022) not significantly threatened by decomposition
rates in most cases (Winstead & Jacobson, 2022). It could make significant contributions to
people’s diets, especially regarding carbohydrates and minerals, and even proteins and some
vitamins for certain types of biomass such as leaves and forages (Siva & Anderson, 2023). Notable
quantities of plant waste, food waste and municipal waste may remain available for upcycling to
food. Fossil fuels such as natural gas, coal and petroleum can be converted into all three
macronutrients (carbohydrates, proteins and fat). Even CO2captured from factories or directly
from the atmosphere can be converted into multiple types of food, including all three
macronutrients, as shown in Fig. 1 (Davis et al., 2023).
Fig. 1. Schematic of selected pathways to synthesize food without agriculture. Material reprinted
from: Steven Davis, Kathleen Alexander, Juan Moreno-Cruz, Chaopeng Hong, Matthew Shaner, Ken
Caldeira & Ian McKay, Food without agriculture, Nature Sustainability, published 2023 by Springer
Nature (CC BY 4.0 license, no changes made). Other relevant pathways (not pictured) include the
conversion of biomass to carbohydrates through methods other than gasification (Throup et al.,
2022), the conversion of those sugars to proteins, fats, and essential micronutrients through
fermentation, or the cultivation of photosynthetic microorganisms.
6

Table 1. Resources available for industrial conversion of resources independent from agriculture to food, as well as agricultural residues.
Includes resource reserves, current production, and an approximate measure of their potential* as a resilient food.
*This potential is illustrated via estimations of the amount of food that could be produced by converting the entire global yearly production of the resource using
current technologies, if no other limitations were present. These are only meant as an indication of potential, and do not necessarily imply a recommendation to
generate or repurpose entire industrial sectors to food production as a response to catastrophic scenarios, as there may be limitations of industrial, nutritional, or
other nature; or better alternatives to be prioritized depending on the situation.
⸸References for production capacity values can be found in the supplementary table.
Resource
Global reserves
Global
production per
year
Food production potential through industrial conversion
Wood
~900 billion tonne (plant
matter, wet) ⸸
~4 billion
m3/year
(roundwood, wet)
⸸, equivalent to
~1.5 billion
tonne/year (dry)
Converting the entire global production of roundwood to sugar would
result in the equivalent of 36% of the global population’s caloric
requirement (Throup et al., 2022).
Other nutrients can be obtained, though at lower conversion
efficiencies, through various other processes, e.g. feeding pretreated
biomass to animals/fungi, or fermenting cellulosic sugar to various
nutrients.
Plant
residues
N/A
~3.4 billion tonne
(dry)⸸- might be
lower during an
agricultural
catastrophe
Converting the entire global production of plant residues to sugar
would result in the equivalent of 91% of the global population’s caloric
requirement (Throup et al., 2022).
Natural gas
188.07 trillion m3⸸
4.09 trillion m3⸸
Natural gas steam cracking processes enable its transformation to all
3 types of macronutrients (Davis et al., 2023).
Converting the entire global production of natural gas to food
through single cell protein production results in nearly 3 times the
caloric requirement of the global population, or 9 - 15 times the
protein requirement (García Martínez, Pearce, et al., 2022).
7

Petroleum
and
petroleum
products
236.3 billion tonne
petroleum ⸸
4.4 billion tonne
petroleum ⸸
Petroleum steam cracking processes enable its transformation to all 3
types of macronutrients (Davis et al., 2023).
Paraffins derived from oil could be converted into synthetic fats to
produce 8% - 17% of the global caloric requirements (García Martínez,
Alvarado, et al., 2022).
Conversion of oil-derived propylene to glycerol could produce the
equivalent of ~16% of the global caloric requirement (García Martínez,
Alvarado, et al., 2022).
Coal
1,070 billion tonne ⸸
7.6 billion tonne ⸸
Gasification processes enable the transformation of coal to all 3 types
of macronutrients (Davis et al., 2023).
Converting the entire global production of coal to food:
a) through single cell protein production results in the equivalent of
nearly 3 times the caloric requirement of the global population, or 9 -
15 times the protein requirement (García Martínez, Egbejimba, et al.,
2021).
b) through Fischer-Tropsch and paraffin oxidation, could produce 13%
of the global caloric requirement as synthetic fats (García Martínez,
Alvarado, et al., 2021).
Carbon
dioxide (CO2)
Reserves can be considered
virtually limitless if
including industrial and
atmospheric carbon
capture potential, since the
carbon in digested food
returns to the atmosphere
as CO2via respiration.
A limited amount is
available in CO2storage
facilities.
230 million
tonne (CO2
commodity
market) ⸸
Myriad routes exist for conversion of CO2to nutrients. As an example,
producing single cell protein from CO2and H2(obtained via
electrolysis), the entire global protein requirement could be covered in
6 years (García Martínez, Egbejimba, et al., 2021). However, since this
is an energy-intensive process, like most CO2conversion processes, it
would require 15-24% of the global electricity capacity (García
Martínez, Egbejimba, et al., 2021).
8

3 Lignocellulosic Biomass as a Sugar Source and a Platform for Food
Synthesis
Lignocellulosic biomass is plant dry matter such as corn stalks, wheat straw, leaves, and wood. Its
complex polymeric structure composed of cellulose, hemicellulose and lignin makes it indigestible
to humans. However, it can be treated with hot steam or biological catalysts to break down the
plant matter into simple sugars which can be safely consumed as food, used as an input for animal
feed, or upcycled to proteins and other nutrients via fermentation (Throup et al., 2022) — see also
the sections on Biosynthesis of targeted nutrients from sugars (e.g. lignocellulosic glucose),Single Cell
Protein from Lignocellulosic Biomass, and In vitro BioTransformation. The major component of this
lignocellulose-derived sugar mixture is glucose (from the degradation of cellulose), but the final
composition depends on process conditions and the choice of feedstock (Ou et al., 2021; Palà et al.,
2022).
To the best of our knowledge, no large-scale lignocellulosic sugar production enterprises have been
deployed yet. However, lignocellulosic sugar-based food ingredients have been produced and
distributed by companies Renmatix and Comet Bio , both of which possess highly efficient
1
patented technologies for the production of lignocellulosic sugar, respectively achieving 85% and
90% of the theoretical yields (Throup et al., 2022). Decentralized low-tech production is also
possible, but yields are expected to be notably lower, with some researchers proposing around 30%
nutrient extraction ratio for this production style (Siva & Anderson, 2023). In addition, the inner
bark of some trees is directly edible, and has been consumed throughout history as a famine food
(Turner & Davis, 1993).
Pulp and paper mills, sugarcane biorefineries, corn biorefineries, and breweries have the potential
to be repurposed to convert plant biomass into sugar. Doing this would come at a notably lower
cost than building new factories, because 84%, 65%, 37%, and 39% of the required equipment for
lignocellulosic sugar production is already present, respectively (Throup et al., 2022). In the event
of ASRS, if the entire global pulp mill factory capacity were rapidly repurposed for sugar
production, that would produce the equivalent of ~9% of the caloric requirements of the global
population, and the current global sugar demand could be fulfilled within 1 year after a catastrophe
if this technology was deployed en masse (Throup et al., 2022). The cost of these sugars has been
estimated at $0.43/kg of sugar mixture, being very affordable at a retail cost of $0.55-0.91 to fulfill a
person’s daily caloric requirement in ASRS conditions (Throup et al., 2022).
So far no pulp and paper mills, biorefineries, or breweries have been repurposed for producing
sugar, to the best of our knowledge. Performing a cellulosic sugar repurposing pilot could help
immensely with ASRS response (Throup et al., 2022), by proving to institutional and private
decision makers that this food provision method can be deployed to rapidly counter food
production yield losses to prevent a global catastrophic food failure. Models and estimates provide
only limited catastrophe preparedness.
1Personal communication with Loula Merkel from Comet Bio on July 2023: “we have produced several batches of
cellulosic dextrose that total around 100 kg”
9

4 Single cell proteins and oils
Fermentation technologies enable a veritable cornucopia of microbial foods to be produced from a
multitude of sources. Gas, liquid and solid fermentation can be used to produce highly nutritious
food from inedible plants, fossil fuels, industrial and agricultural byproducts, and even CO2from
the air as carbon substrates (Woern & Grossmann, 2023; Linder, 2023). These cells can be turned
into protein- and fat-rich food ingredients containing a multitude of key nutrients, known as single
cell proteins (SCP) (García Martínez, Egbejimba, et al., 2021; García Martínez, Pearce, et al., 2022;
Silverman, 2020) or single cell oils if very rich in fats. Fig. 2 shows the schematic of a model SCP
powder production process, which describes the vast majority of the processes described in this
section. Examples specific to H2feedstocks may be found in (García Martínez, Egbejimba, et al.,
2021), and for methane processes in (García Martínez, Pearce, et al., 2022).
Fig. 2. Process flows and unit operations of an aerobic SCP powder production process through gas
or liquid fermentation.
These microbial ingredients might be added to a variety of food products, including solid foods like
bread, pasta, and plant-based meats, as well as in liquid food and drinks, such as dairy analogues,
protein shakes, or broths (Southey, 2019). SCPs from agriculture-independent feedstocks have yet
to be commercialized as food, but the large global yeast products sector with a yearly production of
1.73 million tonnes (FAO & WHO, 2023) provides a very significant precedent for the viability and
consumer acceptance of microbial foods, with part of these being used as a food ingredient in
many food products or consumed directly as nutritional yeast. They can also be used as animal
feeds to circumvent consumer hesitancy, as described in Fig 3. (Linder, 2023) which shows the
many direct and indirect possibilities available for food production for humans that single cell
foods enable.
10

Fig. 3. A biocatalytic view of food production and human nutrition. (A) shows how humans lack the
metabolic ability to assimilate the most commonly occurring inorganic forms of carbon (carbon
dioxide, CO2), nitrogen (nitrogen gas, N2) and sulfur (sulfate, SO42–) in nature. (B) shows the
traditional concept for agriculture-based food production in which edible plants enable humans to
indirectly acquire inorganic carbon, nitrogen, and sulfur, and herbivores enable humans to
indirectly access nutrients in inedible plant biomass, or convert edible crops into the animal
products that consumers demand. (C) Edible microbial biomass enables humans to indirectly
acquire inorganic carbon, nitrogen, and sulfur but without an absolute requirement for
photosynthesis, and using the microbial biomass as animal feed can circumvent consumer
hesitancy. Material adapted from: Tomas Linder, Beyond Agriculture─How Microorganisms Can
Revolutionize Global Food Production, ACS Food Science & Technology, published 2023 by ACS (CC
BY 4.0 license).
4.1 Gas fermentation
There are myriad production routes to production of single cell protein (SCP) products from
gas-fermenting bacteria (Matassa et al., 2020). Four ingredients are required: 1) a carbon source, 2)
an energy source (electron donor), 3) a nitrogen source, and 4) an oxygen source (as electron
acceptor, unless the process is anaerobic) (García Martínez, Pearce, et al., 2022). As a carbon source,
one-carbon compounds (e.g methane, CO2, CO) are typically provided in the culture medium
(Woern & Grossmann, 2023) — this recent review by Woern and Grossman is of note thanks to its
in-depth technical discussion of the the challenges and opportunities of gas-based SCP
technologies. Two representative examples are discussed in this section.
11

4.1.1 Single Cell Protein from Methane (CH4) - Natural Gas or Biogas
Methylotrophic organisms enable the conversion of methane to high-protein microbial biomass to
be used as food or feed, by growing the microorganisms in bioreactors using methane as carbon
and energy source in combination with nitrogen and oxygen sources (e.g. ammonia and O2gas).
There is huge potential for methylotrophic SCP to make contributions to human food supply by
leveraging natural gas and/or renewable biogas resources, both during a global catastrophe and
during business-as-usual to enable sufficient food supply for a growing global population (García
Martínez, Pearce, et al., 2022). Equation 1 shows the reaction stoichiometry of the process when
using ammonia as a nitrogen source (Villadsen et al., 2011).
(1)
𝐶𝐻4+ 1. 453 𝑂2+ 0. 104 𝑁𝐻3 → 0. 521 𝐶𝐻1.8𝑂0.5𝑁0.2 + 0. 479 𝐶𝑂2+ 1. 687 𝐻2𝑂
The two main companies currently developing this technology are Calysta Inc. and Unibio A/S.
Calysta, in a joint venture with Adisseo, recently started production in a facility in China capable of
producing 20,000 tonnes of protein product each year with intention to scale to 100,000
eventually⸸, for fish feed uses. Unibio has partnered with Protelux, which operates a plant with an
installed capacity of 6,000 tonnes per year of methane-derived single cell protein and allegedly has
the potential to scale up to 20,000 tonnes per year⸸. For comparison, a full-scale 100,000 ton/year
plant would produce the equivalent caloric requirement of 620,000 people, or the protein
requirements of 2.6 million (García Martínez, Pearce, et al., 2022). Both Calysta and Unibio have
plans to build larger factories in other locations, and the sector has other companies working to
scale up the technology such as Circe Biotechnologie GmbH, and String Bio Pvt Ltd. Even though
methane SCP has yet to be sold for human consumption, all of the companies mentioned in this
section are working to change that, having shown interest in producing SCP for the food sector.
The next step in developing this resilient food technology is demonstrating commercial viability
for a human consumption market. Drawbacks include the large capital investment needed to build
production facilities and the associated high energy usage as well as the high nucleic acid content,
requirement of a sterile environment for production and removal of gram-negative bacteria that
may produce endotoxins (Lackner et al., 2022).
What makes SCP from methane a promising technology is that there are very large amounts of
natural gas available which can be sourced from reservoirs. In addition, stranded natural gas (e.g.
currently being flared or reinjected) and biogas could be a significant resource for methane SCP
production, considering that global protein requirements could be potentially fulfilled by SCP
obtained from these sources alone, as shown in Fig. 4 (García Martínez, Pearce, et al., 2022),
without necessarily affecting current natural gas uses. Recent models suggest SCP from methane
could fulfill the protein requirements for the entire global population within 2.5 to 4.5 years and
could be produced at an affordable wholesale cost of US$1.50-2.50 per kg (dry), costing consumers
just ~$2 (retail) to fulfill a person’s daily caloric requirement (García Martínez, Pearce, et al., 2022).
12

Fig. 4. Share of the global caloric requirements that could be fulfilled by different potential
methane sources (left) in comparison with the share of global protein requirements that could be
fulfilled using the same sources (right). Material reprinted from: Juan B. García Martínez, Joshua
M. Pearce, James Throup, Jacob Cates, Maximilian Lackner, David C. Denkenberger, Methane
Single Cell Protein: potential to secure a global protein supply against catastrophic food shocks,
Frontiers in Bioengineering and Biotechnology, published 2022 by Frontiers (CC BY 4.0 license, no
changes made).
4.1.2 Single Cell Protein from CO₂ and H2- “Air Protein”
Hydrogenotrophic microorganisms can use carbon dioxide (CO2) as a carbon source and hydrogen
(H2) as an energy source to obtain highly nutritious bulk biomass. These microbes can act as food
sources high in protein and micronutrients (especially B vitamins). H2SCP could be produced from
H2sourced from multiple sources, such as water electrolysis or gasification of solid biomass or
fuels, while the CO₂ could be obtained from industrial sources, from biomass or fuel combustion or
gasification, or directly from the atmosphere (García Martínez, Egbejimba, et al., 2021). Fig. 5 shows
a high-level overview of relevant pathways to microbial food production from CO2(Linder, 2023),
while Equation 2 shows the approximate reaction stoichiometry of the direct CO2chemosynthetic
process when using ammonia as a nitrogen source, adapted from (Ishizaki & Tanaka, 1990). The use
of widely available CO2as a carbon source means the resource base for this process is virtually
inexhaustible, but current iterations of the technology might suffer from limitations if deployed at
massive scale, such as the availability of platinum for electrolyzers or magnesium for microbial
media (García Martínez, Egbejimba, et al., 2021).
13

Fig. 5. Possible routes from CO2(atmospheric or flue gas) to edible microbial biomass. Material
reprinted from: Tomas Linder, Beyond Agriculture─How Microorganisms Can Revolutionize
Global Food Production, ACS Food Science & Technology, published 2023 by ACS (CC BY 4.0 license,
no changes made).
(2)
𝐶𝑂2+ 5. 222 𝐻2+ 1. 518 𝑂2+ 0. 186 𝑁𝐻3 → 𝐶 𝐻1.743𝑂0.462𝑁0.19 + 4. 572 𝐻2𝑂
There are multiple companies working to make single cell protein (SCP) from CO2and H2,
including Solar Foods, Air Protein (Kiverdi), NovoNutrients (OakBio), Avecom, Gas2Feed, and Deep
Branch; Solar Foods launched its demonstration facility in 2024 (160 tonne/year), the first
hydrogenotrophic SCP demonstration scale plant to the best of our knowledge. Deep Branch
projects that its first commercial production plant for CO2-derived single-cell protein will become
operational in 2027. However, to date, no company has yet demonstrated commercial viability of
this technology mainly due to high capital and operational costs (mainly high electricity
requirements).
The potential of this food source to contribute in ASRS is notable, though probably lower than
methane SCP due to higher capital costs and a considerable electricity requirement estimated at
32-37.8 kWh/kg SCP for the electrolysis process. For example, if the entire global electricity
consumption was instead used to produce SCP from CO2via electrolysis, it would produce just
14

over half of the caloric requirement of the global human population (García Martínez, Egbejimba, et
al., 2021). The retail cost for customers has been estimated at $2.60-7.40 for fulfilling a person’s
daily caloric requirement, or $0.45-1.30 to fulfill just the daily protein needs (García Martínez,
Egbejimba, et al., 2021).
4.2 Liquid fermentation
4.2.1 Single Cell Protein from Methanol, formate, or acetate as liquid intermediates derived
from Natural Gas, Biogas, CO2, or CO
In the late 1970’s, Imperial Chemical Industries (ICI) produced one of the earliest forms of creating
SCP under the brand name Pruteen™, a methanol derived protein used in animal feed. It was
produced using Methylophilus methylotrophus (Macauley-Patrick et al., 2005) in a plant capable of
achieving over 50,000 metric tonnes/year through the use of a 600 tonne, 1,500 m3airlift
fermenter (Westlake, 1986), the largest bioreactor ever built. ICI sold at a market price of 50 cents
per pound in 1992 (Weaver, 1991), which inflation-updated to 2024 USD is $2,420/tonne. This
Billingham factory cost on the order of £90 million (L. Chen, 2024), which inflation-updated and
converted to 2024 USD is approximately $430 million. ICI stopped operations decades ago due to
market hurdles (Lackner et al., 2022), and no comparable large-scale liquid fermentation SCP
factories have been built as of 2024. However, preliminary analyses for such factories have been
made using acetate (a two carbon molecule) as a carbon source, which appears viable at least when
using a coupled fermentation approach based on acetogens utilizing the carbon monoxide
contained in furnace gas (Vlaeminck et al., 2023). Formate currently appears to have lower
potential: a recent meta-analysis proposes that methanol is more advantageous than formate in
terms of protein content and carbon yields (Sakarika, Ganigué, et al., 2022); it also has no historical
precedent of large scale production, and is generally in an earlier phase of development. As an
example, Equation 3 shows the reaction stoichiometry of the process when using methanol as a
carbon and energy source, and ammonia as a nitrogen source (Villadsen et al., 2011), where
CH1.8O0.5N0.2 refers to the formula for protein-rich microbial biomass.
(3)
𝐶𝐻3𝑂𝐻 + 0. 732 𝑂2+ 0. 146 𝑁𝐻3 → 0. 732 𝐶𝐻1.8𝑂0.5𝑁0.2 + 0. 268 𝐶𝑂2+ 1. 56 𝐻2𝑂
Farmless is one company currently looking to commercialize SCP using liquid fermentation of
methanol intermediates, ideally sourced from sustainable processes based on renewable
feedstocks such as CO2or biomass, in contrast with the historical production based on fossil fuels.
Other companies such as KnipBio (current capacity 100 tonne/year⸸, for feed additives) are looking
to use biofuel plant waste products as an alternative source of methanol and ethanol for SCP
production, but this method is of lower relevance to ASRS due to limited feedstock availability in
comparison.
Overall these liquid fermentation technologies provide an alternative way of unlocking the
potential of multiple widely available feedstocks from both fossil fuels and waste products,
separate but related to gas fermentation.
15

4.2.2 Single Cell Protein from Lignocellulosic Biomass
Quorn™, the major SCP product being commercialized directly as food today, is a direct
descendant of the historical ICI industrial process for methylotrophic SCP production, with a
capacity of 50,000 tonne/year⸸. The most notable difference is that Quorn™ uses sugar as the
main feedstock rather than methanol, so it is not independent from agriculture and thus less
resilient to loss of agricultural function such as in an ASRS. Using lignocellulosic sugar as a
feedstock instead would overcome this issue, for example using Quorn’s Fusarium venenatum
fungus, torula yeast (Candida utilis), or Pekilo fungus (Paecilomyces variotii). Production costs for
these have been estimated at around 5-9 €/kg dry for a 40,000 tonne/year factory operating on
straw feedstock, with conversion rates of cellulosic sugar to SCP of 31-50% (Voutilainen et al., 2021).
Equation 4 shows the stoichiometry of the process when using glucose as a carbon and energy
source, and ammonia as a nitrogen source (Villadsen et al., 2011).
(4)
𝐶𝐻2𝑂 + 0. 394 𝑂2+ 0. 115 𝑁𝐻3 → 0. 577 𝐶𝐻1.8𝑂0.5𝑁0.2 + 0. 423 𝐶𝑂2+ 0. 65 𝐻2𝑂
One company currently working to bring this form of lignocellulose-based SCP to market is
Arbiom, with its yeast product SylPro™, planning to have a 10,000 tonne/year factory operational
by the end of 2024⸸. Many other companies such as ENOUGH, KnipBio, Hyfé, and iCell have
demonstrated the use of sugar- or starch-containing industrial waste streams as an alternative
source of sugars for SCP production — ENOUGH reports significant mycoprotein production
capacity at 10,000 tonne/year⸸— but this route is of lower relevance to ASRS due to limited
feedstock availability in comparison to the lignocellulose conversion. There also exist alternative
processes for SCP production from cellulosic biomass, such as using lactic acid (derived from
grass) instead of sugar as a carbon source (Sakarika, Delmoitié, et al., 2022).
To the best of our knowledge, SCP from cellulosic material has been commercialized for animal
feed but has not yet been sold for human consumption. However, the large global yeast market
serves as a significant precedent, since yeast products are similarly produced via liquid
fermentation, though from agricultural sugars. The Soviet Union was thought to have had a
significant lignocellulosic SCP industry for animal feed production in the 1980s (CIA, 1984).
4.2.3 Single Cell Protein from Petroleum-derived Products
SCPs derived from petroleum products, namely paraffin wax and gas oil, were the first
non-agricultural SCPs to be produced at industrial scale, as pioneered by British Petroleum during
the 1970s (Shacklady, 1970). British Petroleum’s plant had an annual SCP production capacity of up
to 100,000 tonnes of Yarrowia lipolytica SCP for animal feed, but this and other plants were
abandoned due to environmental permit issues and the high input costs (Groenewald et al., 2013).
The Soviet Union had a significant paraffin-based SCP industry, claiming to have produced 1.8
million tonnes by 1988 (Greenshields et al., 1990), which rapidly collapsed in the following years
(Roffey, 2010). Yarrowia lipolytica SCP is recognized as safe for human consumption by the
European Food Safety Authority (EFSA NDA et al., 2022), and currently produced by Skotan S.A. in
16

Poland at a rate of 600 tonnes per year (Groenewald et al., 2013) — though not from petroleum
products, but from waste glycerol.
4.2.4 Microbial Fats from Lignocellulosic Biomass
Yarrowia lipolytica is a very versatile microorganism, which can be used to produce dietary fats
including omega and essential fatty acids (H. Liu et al., 2021), which are fundamental for human
health and are often not found in sufficient quantities in the resilient foods proposed for ASRS
response (Pham et al., 2022). Lignocellulosic sugar enables cultivation of Yarrowia for fat
production independently from agricultural sugars. Another method utilizes plant fiber which
would be turned into a pulp, and then the cellulose would be digested directly by Cystobasidium
oligophagum to produce the fats (Vyas & Chhabra, 2017). The two essential fatty acids have been
synthetized at significant concentrations: Cystobasidium oligophagum JRC1 was found to contain
linoleic acid content of 24.2% of total fatty acids (Vyas & Chhabra, 2017), while modified Yarrowia
lipolytica yielded α-linolenic acid at a concentration of 28.1% of total fatty acids (H. Liu et al., 2021).
There is potential that in the event of a global catastrophe, pulp and paper mills, biorefineries, and
breweries could be quickly repurposed to convert plant biomass into key lipids by installing the
relevant equipment (Throup et al., 2022) including SCP producing bioreactors. For example, using
lignocellulosic biomass as the carbon source by first converting it to sugars (Throup et al., 2022) or
using it to grow cellulose-digesting microbes (Vyas & Chhabra, 2017) to produce lipids.
To the best of our knowledge, the methods described for production of nutritionally relevant lipids
are not currently used for food production, although Dupont used to produce a Yarrowia-derived
omega-3 rich product at scale for direct human consumption called New Harvest™ (Xie et al.,
2015). In addition, the startup Äio is looking to commercialize single cell oils made from sawdust as
substitutes for unsustainable vegetable oils (palm, coconut), with products rich in omega fatty
acids. Further research into better understanding and optimizing the bioprocess to convert
cellulosic material into microbial fat and scale up costs as well as conducting human safety trials
would help make this resilient food technology a better option for catastrophe response.
4.2.5 Single Cell Protein from Peat
Peat is a solid carbonaceous material originating from decaying organic matter, which can be
hydrolyzed into a mixture (peat hydrolysate) that some microorganisms can use as a carbon
source. This process has been demonstrated for the production of nutrient-rich biomass at
laboratory scale (Taskila et al., 2016), but to the best of our knowledge has not been commercialized
or tested for food uses, or even analyzed for economic viability, thus requiring extensive study to
characterize its resilient food potential. However, considering that there are over 4 million km2of
peatlands containing 550 billion tonnes of carbon (Harris et al., 2022) — more than all of Earth’s
forests — this method should be noted.
17

4.3 Solid-state fermentation
Solid-state fermentation, referring to fermentation processes using a solid substrate with absence
or near absence of water, has also been used for the production of potential food compounds. An
example is the saccharification of solid lignocellulosic biomass by cellulolytic enzyme-producing
fungi, which has been proven on sugarcane bagasse (Farinas, 2018). This could enable 1-step
synthesis of lignocellulosic sugar, which might serve as a source of food or an input to
fermentation processes.
A different but related idea that was proposed as potentially useful for lignocellulosic biomass
conversion in ASRS is direct digestion of woody material using cellulose digesting bacteria,
followed by flushing out the sugar produced (Denkenberger & Pearce, 2014). This would synergize
with other resilient food sources since mushrooms could feed on the lignin byproduct for this
process and ruminants could feed on what is leftover from the mushrooms (Denkenberger &
Pearce, 2014). However, this idea is speculative and no proof of concept exists as of now.
A more unorthodox example is the production of SCP on plastic substrates. Proof of concept has
been achieved by growing microorganisms on a Polyethylene terephthalate (PET) plastic substrate
using a combination of chemical and biological processing by a team exploring the feasibility of
obtaining SCP from plastic (Schaerer et al., 2022). They estimated that “If all PET waste (32 million
tonnes per year) was converted with 100% efficiency into human food, we could supply ~4% of the global
carbon consumption [of food]” (Schaerer et al., 2022).
4.4 Photosynthetic microorganism cultivation (SCP)
There exists a large diversity of microorganisms capable of fixing CO2through photosynthesis
using sunlight or other sources of light energy, some of which have considerable potential as food
sources. These organisms are similar to hydrogenotrophs in that they both use CO2as their carbon
source, meaning they are both autotrophs, but they use sunlight instead of H2as an energy source,
meaning they are photoautotrophs rather than chemotrophs. Microalgae are the most commonly
produced and already established as a food source, but other organisms proposed for SCP
production include purple phototrophic bacteria (Capson-Tojo et al., 2020).
Microalgae are single cell photosynthetic organisms which grow in water using CO2as a carbon
source. They grow naturally in aquatic environments, but can be cultivated in either closed
photobioreactors or artificial open ponds, or a hybrid of both. Closed reactors are able to control
the precise conditions (i.e. temperature, light, CO2levels) for the microalgae while providing
constant agitation to incorporate the CO2. Open ponds are a larger, and more scalable production
method, but are less efficient in terms of quality due to lower control of growing conditions (Narala
et al., 2016).
Microalgae are an excellent source of protein, fatty acids, and essential vitamins including A, B12,
D, and E (Chamorro-Cevallos, 2015). It also can grow in areas of varying pH levels and can grow
18

with minimal light exposure (Difusa et al., 2015), with even the most extreme ASRS conditions
allowing for significant open pond microalgae productivity. Microalgae have very fast growth
rates, are more efficient than plants at converting sunlight into energy, and have minimal biomass
waste (Okoro et al., 2019; Perrine et al., 2012). Microalgae’s role as a source of omega-3 fatty acids in
oceanic trophic chains is so important that (Moomaw et al., 2017) have called for “cutting out the
middle fish” by eating omega-3 rich microalgae like Nannochloropsis oculata instead of fish.
Naturally occurring spirulina (Arthrospira platensis, a type of cyanobacteria) was harvested and
consumed by the Aztecs, and still is around Lake Chad (Barone et al., 2023). Global annual
production of microalgae was 93,000 tonnes in 2010, but declined to 56,000 in 2019, with spirulina
being the only species cultivated in significant quantities (J. Cai et al., 2021). (Greene et al., 2022)
estimate that using the top 5% most suitable areas near 20 km of the coast for microalgae
cultivation could produce 587.9 megatonne/year, more than the global protein demand projected
for 2050.
However, high unit costs currently are a considerable obstacle for microalgae foods. Cost ranges
from 100 $/kg when using closed reactors to 10 $/kg using open raceway ponds (Oostlander et al.,
2020). Significant work is required to bring production costs down, most notably optimization of
cultivation processes and strain productivity (Dolganyuk et al., 2020). Most notable in this area is
the benchmarking work of (Klein & Davis, 2023) based on experimental efforts, which estimates the
minimum production costs of microalgae biomass at ~$0.70 per dry kg, and projects cost
reductions to ~$0.50/kg dry by 2030 (for a 20% dry, non-food-grade product assuming n-th plant
economics and lowest-cost methods).
The resilient food potential of microalgae under resource-constrained scenarios of catastrophe
response is probably limited to the pond production method. In terms of energy efficiency, the
photobioreactor method has considerably lower electricity-to-calories efficiency than alternative
processes such as hydrogenotroph SCP that can produce at higher than 10% efficiency (Alvarado et
al., 2021), with state of the art microalgae photobioreactor systems having 2.4% efficiency (Tzachor
et al., 2022).
19

5 Microbial cell factories for food production
Fermentation technologies not only enable the production of nutritionally-rich single cells, but also
the exploitation of microorganisms to convert renewable resources and upcycle waste products
into food products (Choi & Lee, 2023). In comparison with the previous section discussing
consumption of whole cells or their component parts, this section discusses the use of
microorganisms as cell factories for food production, in which they are used to synthesize food
compounds without being consumed themselves, or the biological compounds that enable other
food production routes such as enzymes.
These methods are at varying levels of technology and economic readiness and would require
different impulses for their development and application where appropriate. More modeling
research is needed to characterize this potential in both business as usual and catastrophe
response scenarios, by estimating production costs, scalability, and ramp-up speed. Demonstrating
scale-up and food safety are the main avenues of practical work for the development of these
methods as a resilient food technology.
5.1 Biosynthesis of essential nutrients from sugars (e.g. lignocellulosic glucose)
through precision fermentation
Microorganisms have incredible potential for synthesizing key nutrients of relevance to avoiding
malnutrition, which is particularly relevant in catastrophes that limit crop growth like ASRS.
Glucose, such as that obtained from lignocellulosic biomass, can be used to produce all 3
macronutrients, most major vitamins, and all 9 essential amino acids (Choi & Lee, 2023).
Many of these production routes are at various early stages of development, but some represent
very mature industries. For example, vitamin C biosynthesis from glucose was performed at a
scale of 140,000 tonnes/year in 2018 (Demain & Sánchez, 2019). Lysine — an essential amino acid
— is currently produced at very large scales via Corynebacterium glutamicum using glucose or
sucrose as a feedstock. Production facilities synthesize an average of 100,000 to 400,000
tonne/year, to supply a market size of 2.2 million tonnes (2016 values) (J. Liu et al., 2022), at prices
around $1.5/kg for L-Lysine HCL (Ploegmakers, 2024). Researchers are actively looking into
alternative feedstocks for lysine production that do not compete with human food sources, such as
algae-based mannitol (J. Liu et al., 2022), which is of relevance to ASRS. Progress in genetic
engineering could be relevant to enabling more favorable feedstocks (Wendisch et al., 2016).
20

5.2 Biosynthesis of food from carbon dioxide
5.2.1 Lipid biosynthesis from CO2and H2
Hydrogenotrophic bacteria can be used not only for direct consumption as SCP, but also as
platforms for the synthesis of nutrients via gas fermentation (from CO2and H2) in aerobic
bioreactors. Recent advancements in genetic engineering allow for the production of multiple
compounds relevant to industry and space exploration (Nangle & Ziesack, 2022; Dunn et al., 2023;
Averesch et al., 2023). Of note is their capacity to manufacture crucial nutrients such as
triacylglycerides with high energetic efficiency (Nangle & Ziesack, 2022). This has yet to be
commercialized as a food source, but a startups looking to do so is Circe Bioscience Inc .
2
5.2.2 Amino acid biosynthesis from CO2and H2
Hydrogenotrophic archaebacteria can be used to produce free amino acids via an anaerobic
process, using CO2as a carbon source and H2as an energy source (Taubner et al., 2023). These
amino acids may be purified and used directly as food ingredients, or polymerized into peptides or
protein macromolecules for food (Dondapati et al., 2020). Although this process has not yet been
commercialized, one startup working to leverage it for food production is Arkeon Biotechnologies.
5.2.3 Microbial Electrosynthesis of Acetic Acid and Fatty Acids from CO2
Microbial electrosynthesis refers to the use of electroactive microbes as biocatalysts in
bioelectrochemical reactors for the synthesis of compounds of interest. One such example is the
generation of carboxylic acids from CO2, although so far only short- and medium-chain fatty acids
have been synthesized from this method, which are not as nutritionally relevant as long-chain fatty
acids. (García Martínez, Egbejimba, et al., 2021) studied the potential of electrotrophs to convert
CO2and water into acetic acid — typically consumed as the main component of vinegar, with a
caloric content of 3.49 kcal/g (Greenfield & Southgate, 2003), comparable to sugars by mass. The
overall reaction for acetic acid synthesis can be described by Equation 5 (Christodoulou et al., 2017).
(5)
2𝐶𝑂2+ 6𝐻2𝑂 + 8𝑒−→ 𝐶𝐻3𝐶𝑂𝑂𝐻 + 4𝐻2𝑂 + 2𝑂2
Despite its very high energy efficiency as a calorie generation method, between ~15-20% in terms
of power to food when using carbon capture (Alvarado et al., 2023), this technology is severely
limited for the catastrophe response application, and is not recommended over alternatives.
Current forms of the technology produce compounds that do not provide key nutrients and cannot
make large caloric contributions to the diet, while hydrogenotroph SCP produces key nutrients at
comparable unit cost and energy efficiency. Production costs are also higher than other foods in
2U.S. based company, not to be confused with the Austrian company Circe Biotechnologie GmbH (see section on single
cell protein from methane)
21

this work, at $2.60-6.50/kg wholesale (García Martínez, Egbejimba, et al., 2021). Realizing the
potential of microbial electrosynthesis for resilient food production would require developing
similarly efficient methods to use it for long chain fatty acid, protein, or micronutrient synthesis.
Alternatively, the acetic acid could be used as an intermediate to grow more relevant nutrients,
including plant nutrients, using hybrid inorganic-biological systems (Hann et al., 2022; Zheng et
al., 2022), but this would greatly reduce overall energy efficiency compared to direct consumption
of microbial electrosynthesis products.
6 In vitro BioTransformation (ivBT)
In vitro BioTransformation produces biocommodities using in vitro synthetic enzymatic
biosystems, consisting of specific combinations of natural enzymes, artificial enzymes, biomimetic
or natural coenzymes, or artificial membranes or organelles. This is a third approach to food
biomanufacturing separate from enzymatic biocatalysis (e.g. enzymatic lignocellulosic sugar
synthesis, see Section 3) or the cell-based fermentation approaches described in sections 4 and 5.
ivBT is characterized by the use of artificial enzymatic pathways and artificial electron transfer
chains to overcome certain limitations of natural biological systems and achieve high product
selectivities and yields (Y.-H. P. J. Zhang et al., 2023).
The most notable potential application of ivBT for resilient food production without agriculture is
the synthesis of starch and glucose from cellulose, first described by (You et al., 2013). It has
undergone significant cost reductions in the last decade and was recently improved upon by (Xu et
al., 2023), who describe a broader novel method that allows for one-pot conversion of
lignocellulosic biomass to artificial starch and SCP. Starch has even been synthesized via ivBT from
CO2(T. Cai et al., 2021). The first industrial application of ivBT is the one-pot synthesis of the
inositol micronutrient, a high-value added food product and nutraceutical, currently performed at
10,000 tonne/year by Sichuan Bohaoda⸸. It can be synthesized via ivBT from cellulose,
independently from agriculture (Han et al., 2023).
This existing large-scale application of ivBT indicates potential for large-scale food production
applications. However, to the best of our knowledge no economic analyses describing the costs of
producing food from lignocellulosic material at scale using ivBT are available. Further process
development is needed for ivBT-based conversion of lignocellulosic material to macro- and
micronutrients, in order to reduce costs and scale up the process. Technoeconomic analyses should
be performed to compare its affordability and catastrophe response potential to comparable
options like lignocellulosic sugar production and fermentation approaches.
7 Chemical synthesis of food
Biological organisms are not strictly necessary for food production. Fundamental nutrients such
as vitamins and amino acids are routinely produced from commodity chemicals. Chemical building
blocks such as CO2, syngas, or ethylene can be converted into various types of carbohydrates (Davis
22

et al., 2023). This section focuses on the provision of food through purely nonbiological pathways,
reviewing relevant methods in which nutrients have been synthesized using chemical processes
that do not involve living organisms.
7.1 Synthesis of food from hydrocarbons
7.1.1 Chemical Synthesis of Vitamins
Industrial synthesis of vitamins is probably the most established form of nonbiological nutrient
synthesis, starting in 1934 and becoming a large sector with both significant production volume
and market value (Eggersdorfer et al., 2012). Vitamins A, B1, B5, B7, and E are currently synthesized
nonbiologically in industrial quantities from widely available petrochemicals . Vitamin B6 is
3
synthesized from common chemicals which are typically obtained from agricultural products but
can be synthesized nonbiologically as well. Vitamins C and B2 can be synthesized nonbiologically
but fermentation is the current industry standard. Vitamin A is synthesized at over 7,500
tonnes/year (Bonrath et al., 2023), B1 at 4,000 tonnes/year (Demain & Sánchez, 2019), and B6 at
2,500 tonne/year (Demain & Sánchez, 2019).
7.1.2 Chemical Synthesis of Amino Acids
There are three most common techniques for synthetic amino acids production: fermentation via
engineered microbes, enzymatic catalysis (refer to The potential of biosynthesis through microbial
conversion of lignocellulosic biomass section), and direct chemical synthesis. Methionine, glycine,
and aspartate/asparagine can be synthesized nonbiologically (Drauz et al., 2007). Amino acids
produced in this manner can be used in a free form for direct consumption, to supplement other
sources of food such as wheat to fulfill protein completeness requirements (McPherson, 1966), or
they could be polymerized into proteins (Dondapati et al., 2020).
DL-Methionine is the most massively synthesized, with a yearly global production capacity of
exceeding 1.6 million tonnes by 2020 (Neubauer & Landecker, 2021). It is produced from common
chemicals (sulphur, methanol, ammonia, propylene, sulphuric acid) and was traded at an average
price of ~$2.50/kg in Europe and China during 2022-2023 (Ploegmakers, 2024). Glycine has been
chemically synthesized in the order of over 10,000 tonne/year, from chloroacetic acid with
ammonia.
3Some common synthesis routes in industry: B1 is produced nonbiologically from petrochemicals (commonly
acrylonitrile or malononitrile). B5 is produced nonbiologically from petrochemicals (isobutyraldehyde and formaldehyde).
B7 is produced nonbiologically from petrochemicals (fumaric acid). A is produced nonbiologically from petrochemicals
(isoprenal and prenol, via isoprenol, itself derived from isobutene and formaldehyde). E is produced nonbiologically from
petrochemicals (m-cresol, acetylene, and acetone), but a new fermentation process recently took over, with an annual
output of 30,000 tonnes (Ye et al., 2022). B6 is produced chemically from ethanol and diketene (typically from acetate),
which are typically obtained from agricultural products but can be synthesized nonbiologically as well (Eggersdorfer et
al., 2012).
23

7.1.3 Fats from hydrocarbons or from CO2(Paraffin oxidation process)
A synthetic butter or oil substitute can be produced by converting n-paraffins via paraffin
oxidation which ruptures the alkanes creating “synthetic” fatty acids (García Martínez, Alvarado, et
al., 2022). These paraffins may be obtained, among other sources, as a common petroleum
processing byproduct, as a byproduct of coal liquefaction (Fischer-Tropsch process), or they may be
synthesized from chemical building blocks such as CO2or natural gas. The derived free fatty acids
may then be esterified with glycerol into triacylglycerides to form a butter-like product, which was
consumed as a food product during a fat shortage in 20th century Germany, as obtained from
Fischer-Tropsch paraffin byproducts (García Martínez, Alvarado, et al., 2022). In 1978, production of
“synthetic” fatty acids in Eastern Europe was over 500,000 tonnes (Fineberg, 1979). Due to higher
costs of synthetic fatty acids produced from petroleum compared to agrichemicals, production
rapidly declined and they are no longer manufactured (Anneken et al., 2006). However, the startup
Savor Foods has recently started production of synthetic butter substitutes from CO2with the
intent to commercialize as a food product, with a reported energy to calories efficiency of 26.5%
(Davis et al., 2023), and has already produced prototypes using paraffin derived from petroleum,
natural gas, and CO2. CO2emission accounting models indicate that the paraffin oxidation process
4
can even have lower emissions per unit of product than butter and common agricultural oils such
as Brazilian or Indonesian palm oil (Davis et al., 2023).
Models indicate that this resilient food technology could be scaled relatively rapidly to produce the
equivalent amount of food to 100% of the global fat requirements in about 2 years (García Martínez,
Alvarado, et al., 2022). Wholesale production costs have been estimated at $1.30-4.70/kg for
factories constructed using 24/7 construction, or a retail cost for customers of just $0.75-2.70 to
fulfill a person’s entire daily caloric requirement (García Martínez, Alvarado, et al., 2022). Compared
to business-as-usual, synthetic fat could become an economically competitive source of fat in the
event of an ASRS that causes agricultural fat prices to skyrocket. However, a limitation of this
process is that it only produces saturated fats (García Martínez, Alvarado, et al., 2021), which are
often recommended by dietary guidelines to be consumed as less than 10% of total energy intake
(USDA & USDHHS, 2015).
Further scale up is needed as well as resolving major uncertainties regarding production potential,
capital expenditure, food safety, transferability of labor and equipment construction (García
Martínez, Alvarado, et al., 2022).
7.1.4 Glycerol from propylene
Glycerol, also known as glycerin, is a sugar alcohol (a type of carbohydrate) with a sweet taste that
is often used as a food ingredient in baked goods (Bagnato et al., 2017). Glycerol can be chemically
synthesized from propylene, a mass produced petroleum product (Bagnato et al., 2017). Propylene
is currently produced on very large scales, but it has yet to be used widely for synthesis of
4Personal communication with Kathleen Alexander and Ian McKay of Savor in January 2024: Proof of
concept for synthetic butter production has been achieved from petroleum wax, natural gas synthetic wax,
and CO2-synthetic wax.
24

food-grade glycerol, which is now obtained from vegetable oils and fats — a more economical
route in the current market conditions.
The process can operate at a molar conversion yield of 76.5% (García Martínez, Alvarado, et al.,
2022), which in terms of mass works out to ~1.67 units of glycerol produced per unit of propylene
consumed (this is despite the unreacted propylene, because the glycerol molecule has a notably
larger mass). At this conversion rate, the global production of 150 million tonnes of propylene⸸
would allow for production of up to 251 million tonnes of glycerol, equivalent to ~16% of the global
caloric requirement. However, more research is needed to prove the potential of synthetic glycerol
as a resilient food technology, such as pilot studies and fast factory construction pilots. Equation 6
shows a simplified overall reaction for the process (García Martínez, Alvarado, et al., 2022).
(6)
𝐶3𝐻6 + 2 𝐶𝑙2 + 𝐻2𝑂 + 2 𝑁𝑎𝑂𝐻 → 𝐶3𝐻8𝑂3 + 2 𝐻𝐶𝑙 + 2 𝑁𝑎𝐶𝑙
7.1.5 Chemical Synthesis of other Carboxylic Acids
Acetic acid, citric acid, lactic acid and malic acid are organic acids with three important
characteristics in common: they are used as common food additives for their acidulant properties,
they have estimated calorie contents between 2.3-3.5 kcal/g (Greenfield & Southgate, 2003), and
they can all be synthesized nonbiologically. Acetic acid can be efficiently produced through
non-biological electrochemical methods, at an estimated electricity to calories efficiency of over
25%, based on a reaction energy consumption of 33.71 kJ/g acetate (Hann et al., 2022). Citric acid
can be produced through Bis(chloromethyl) ketone, typically derived from propylene, but this
petrochemical route is not economically competitive with biological synthesis in the current
market (Max et al., 2010). Lactic acid can also be synthesized from petrochemical resources, via
ethylene (Lebarbe, 2013). Similarly, malic acid can be synthesized from butane through maleic
anhydride (Cornils et al., 2014). Mature industries for the production of all these carboxylic acids
exist in the world today, but they generally use more economical biological methods, a situation
which an agricultural catastrophe such as an ASRS could reverse.
7.2 Chemical synthesis of carbohydrates from carbon dioxide
Glucose, glycerol and propylene glycol can be synthesized from CO2, water, and electricity using
electrochemical and thermochemical reactions (Cestellos-Blanco et al., 2022). The power-to-food
conversion efficiencies of this route are estimated at 10-21% (García Martínez, Alvarado, et al., 2021;
Kouidri & Taylor, 1970) using current technologies, although the theoretical efficiency is much
higher at 31-73% (Dinger & Platt, 2020). The challenges and opportunities of these technologies are
discussed in-depth in a recent review by (O’Brien et al., 2022).
The main inputs for these technologies, CO2, water, and electricity, are widely available and easily
accessible given the right equipment. The CO₂ can be obtained from industrial fuels or directly
from the atmosphere (García Martínez, Egbejimba, et al., 2021). Water is generally used to obtain
the H2needed for this reaction (sourced from splitting water electrolysis), but the H2can also be
25

obtained via gasification of solid fuel or steam methane reforming (García Martínez, Egbejimba, et
al., 2021). Regarding the intense energy consumption of the process, (O’Brien et al., 2022) estimates
a nominal cost of the energy needed for the process of $1.15/kg of artificial carbohydrate. This can
vary widely depending on the energy cost, between $0.71-2.86/kg for electricity costs between
$50−200/MWh.
Fig. 6 shows a simple scheme of proposed synthesis routes from CO2to digestible carbohydrates;
expanded synthesis schemes can be found in (García Martínez, Alvarado, et al., 2021)’s Figure A1
and (O’Brien et al., 2022)’s Figure 3. The routes discussed here use formaldehyde as an intermediate
for nonbiological synthesis of sugar, but longer routes through CO2-based methanol or propylene
are also possible — see (O’Brien et al., 2022) and the section on glycerol from hydrocarbons.
Fig. 6. Selected electrosynthetic routes for digestible sugar production from CO2and water,
adapted from (García Martínez, Alvarado, et al., 2021).
7.2.1 Sugars from CO2and H2
The well-known formose reaction has for a long time enabled the conversion of CO2-derived
formaldehyde into a complex, mildly toxic sugar mixture containing racemic combinations of
C4-C7 sugars. Recently, a long-sought innovation has enabled the selective synthesis of digestible
sugars from the formose reaction thanks to the development of a highly selective chiral catalyst by
Air Company, obtaining “primarily d-glucose and d-ribose along with d-fructose as a minor
component” (García Martínez, Alvarado, et al., 2021).
The Air Company process takes CO2(from the atmosphere) and H2gas (through electrolysis of
water) as inputs into a tubular, fixed-bed flow reactor which, with the help of a catalyst,
hydrogenates the CO2into alcohols and water, which are then distilled to produce methanol. Next,
the methanol is dehydrogenated into a formaldehyde, which then undergoes a polymerization
reaction to produce simple sugars. This process won first place in the 2021 NASA CO2conversion
challenge by demonstrating the synthesis of a mixture of carbohydrates composed of right handed
enantiomers (García Martínez, Alvarado, et al., 2021), the digestible non-toxic variety, using a
selective chiral catalyst. Of note is their pilot methanol production facility (first part of the sugar
process), which can process CO2at a maximum of 350 tonne/year (C. Chen et al., 2022).
26

Another participant in the NASA challenge, team SSwEET used CO2-derived glycolaldehyde to
autocatalyze sugar formation by reacting with the formaldehyde, both obtained through
electrosynthesis (Cestellos-Blanco et al., 2022), but the sugars produced are racemic and thus not
recommended for consumption (García Martínez, Alvarado, et al., 2021).
Similar to lignocellulosic sugar, sugars derived in this way can also be used as a platform chemical
for the production of various other nutrients of interest as described in the following sections. The
main drawback is these technologies are at an early stage, and further work to optimize the
process for large scale production is needed.
7.2.2 Glycerol from CO2and water
Glycerol can be synthesized from CO2and water via formaldehyde and DHA efficiently through
electrochemical means (García Martínez, Alvarado, et al., 2021). There is still no proof of concept or
food safety studies for this technology. However, by 2022, systems to convert CO2to formic acid
are estimated to have reached pilot scale (Masel et al., 2021). Equation 7 shows an overall chemical
reaction from CO2and water to glycerol via DHA (see Fig. 6), disregarding side reactions. Further
research is needed to prove the concept, reduce the energy usage, prove the food safety, and the
scalability to characterize the potential of the method as a resilient food in the event of ASRS.
(7)
3𝐶𝑂2+ 4𝐻2𝑂 → 𝐶3𝐻8𝑂
3
+ 3. 5𝑂2
8 Discussion
The technologies described in this work are distributed across a wide range of technology
readiness levels and market readiness levels. As we have seen, some are now being developed to
produce new economically competitive sustainable products (e.g. various single cell proteins,
synthetic fats from CO2), while others lost their market niche to agricultural analogues (e.g.
synthetic fat and methanol single cell protein) or are not ready to compete with them in current
market conditions (e.g. sugars from cellulosic biomass or synthesized from CO2). Some are at very
early stages of development (e.g. carbohydrates from CO2), while some others have been produced
at industrial scale (e.g. synthetic fat and methane single cell protein) or form the basis of mature
markets (e.g. methionine synthesis and vitamin C and lysine biosyntheses).
Displacing unsustainable agricultural and ocean products is one way for these technologies to have
a major positive impact through industrial implementation. To give some examples: alleviating 1)
the pressure that high CO2-intensity proteins such as beef and other meats, as well as some oil
crops, put on the environment by using fermentation technologies (e.g. SCP for proteins and
synthetic fats for oils and butter), 2) the pressure that fishing puts on ocean biodiversity (e.g.
displacing fishmeal using low-cost SCPs, and displacing omega-rich fish products using microbial
fats), 3) the pressure that palm oil puts on forests through chemical synthesis of fats, and 4) the
enormous suffering that animal agriculture inflicts in nonhuman animals using these technologies
to displace animal agriculture products. However, more research is needed on the environmental
impacts to deploy these sustainably, e.g. life cycle assessments.
27

The large-scale deployment of gas-based SCPs, synthetic fats, and lignocellulosic sugar (as well as
derived nutrients) should be given special attention thanks to their potential to produce significant
quantities of valuable nutrients using widespread raw materials with relatively low resource
intensity (especially lower fertilizer, water, and land use per unit of food produced than
industrialized agriculture), and potentially with lower CO2 emissions depending on
implementation. In terms of increasing resilience to agricultural catastrophes, piloting the
repurposing of existing infrastructure for the production of these foods would be particularly
valuable.
Further work will focus on the market and technology readiness level of these technologies, but
some developments that many of the technologies would benefit from include: conducting food
safety and nutritional studies which verify that the novel foods created from these technologies are
safe and nutritious for humans and/or animals, working on regulatory approval of the foods to
ensure catastrophe readiness, investing more into research and process optimization, primarily for
the resilient food technologies that are in the earliest stages of development, and increasing
government support by dedicating public resources towards resilient food technologies to speed
up their development.
8.1 Future work on resilient food synthesis
This section focuses instead on the future work in the field of production of food without
agriculture to increase the resilience of food systems. Estimating the potential for emergency
response of all the different food production methods described in this work is an important first
step for prioritization. García Martínez et al. calculated the production cost and ramp-up speed at
which various technologies could be deployed as a response to an abrupt sunlight reduction
catastrophe such as a nuclear winter (García Martínez, Egbejimba, et al., 2021; García Martínez,
Brown, et al., 2021; García Martínez, Alvarado, et al., 2022; García Martínez, Pearce, et al., 2022;
Throup et al., 2022). The results are given in Fig. 7, and the methodology for ramp-up speed
estimation based on historical construction speed data and 24/7 construction speed methods is
described in the cited articles and in particular detail in the supplementary material of (García
Martínez, Egbejimba, et al., 2021). Using 24/7 construction (46% capital cost increase from regular),
it would take an estimated capital of $4.2 trillion to deploy enough lignocellulosic sugar plants to
produce the equivalent of the entire calorie requirements of the global population (Throup et al.,
2022). Synthetic fat from petroleum is estimated to require $0.2-0.9 trillion to produce the
equivalent of the global fat requirements, assuming 15% of dietary intake from fat (García
Martínez, Alvarado, et al., 2021). Methane SCP would require $6.1 trillion for fulfilling caloric
requirements and $1.2-1.9 trillion for fulfilling global protein requirements (García Martínez,
Pearce, et al., 2022), while H2/CO2SCP would require $7.1-15.8 trillion for calories and $1.4-4.8
trillion for protein (García Martínez, Egbejimba, et al., 2021). These expenditures are considered
financially feasible in a global catastrophic scenario, given that national governments spent at least
$17.2 trillion in stimulus packages during the COVID-19 pandemic, a catastrophe of considerably
smaller magnitude than an ASRS. The models estimate that the limitation in mass deployment of
these food sources is instead on available construction capacity and labor availability. Performing
similar analyses for all the other non-agricultural food sources would benefit humanity’s
emergency response capabilities to agricultural catastrophes.
28

29

Fig. 7. a) Ramp-up speed of various non-agricultural food production sources for deployment using
24/7 construction after a global agricultural catastrophe. Values are given in terms of the amount
of caloric requirements of the global population (at 2,100 kcal/person/day) fulfilled over time by the
factory deployment, on a 2020 basis, for the average of expected capital cost of the factories, and
assuming a low food waste value of 12%. Note that the values are given for each food source
assuming all industrial resources are used for each process, and not distributed among the
different options. b) Retail cost to consumers for fulfilling the equivalent of one’s daily calorie
requirements, estimated as twice the breakeven production cost. Data from (García Martínez,
Egbejimba, et al., 2021; García Martínez, Brown, et al., 2021; García Martínez, Alvarado, et al., 2022;
García Martínez, Pearce, et al., 2022; Throup et al., 2022).
These ramp-up forecasts can be improved in many ways. Using chemical equipment supplier data
at the component level (reactors, vessels, heat exchangers, etc.) to analyze the possible bottlenecks
that could arise during mass-scale deployment in a more precise way than the abovementioned
simple models based on the current manufacturing expenditures of related industries. Labor
availability and retraining analyses would help understand the degree to which qualified labor
availability may be a limitation to fast response in a catastrophe. Construction time forecasts can
be improved by using higher quality historical data as a reference class, and ideally real data from
24/7 construction pilots carried out for each of these methods. Pilot testing of 24/7 construction
methods for food without agriculture factories would also allow for better capital cost estimates
and food cost and price estimates. The latter would also benefit from the inclusion of these food
production methods in economic equilibrium analyses of catastrophic scenarios, such as the recent
analysis of (Hochman et al., 2022) for a nuclear war scenario.
In addition, there are many steps that could be taken now to increase societal resilience to abrupt
agricultural catastrophes using non-agricultural food sources. The abovementioned capital
intensive pilot tests could be enabled by funding from governmental science grantmaking
institutions or capital investors to enhance societal resilience, in particular 24/7 construction and
repurposing pilots for lignocellulosic sugars (e.g. converting a paper mill to a biorefinery) and
single cell proteins (e.g. from methane) seem to be the most promising for emergency resilience at
the moment. Demonstrating the capacity of these methods to be deployed quickly in the event of a
global catastrophe and/or preemptively building some of the infrastructure now would likely help
enable a sufficiently fast catastrophe response in general. For example, after the onset of an ASRS,
policymakers and lawmakers should encourage private industry to construct and repurpose
factories that produce non-agricultural resilient foods that can be used as food for humans,
feedstock for biofuel, and/or feed for animals. Industry may need funding assistance or other
incentives from policymakers to successfully construct the number of factories needed in a
catastrophe.
Collecting information from interviews with industry experts working on these technologies
would serve to better estimate labor requirements and ramp-up speed feasibility, and ideally there
should exist resources such as guides written by them on building and operating the plants.
Generic plant front-end engineering design packages, ideally open-source and perhaps developed
by academia, would serve as a blueprint to enable companies around the world to respond to a
catastrophe faster and more effectively. Governmental risk management institutions could
30

generate coordinated response plans for the materials and labor deployment to a collection of
pre-approved sites to enable a sufficiently rapid emergency response. Emergency response plans
could include communication materials to be used in a catastrophe for improving the awareness of
and knowledge on these technologies to the public and researchers (García Martínez, Pearce, et al.,
2022). Repurposing studies (and ideally pilots) for characterizing the potential of existing
industries for non-agricultural food production, such as was done by (Throup et al., 2022), could
help enable a more effective, rapid, and economical emergency response.
8.2 Ethical considerations
Most of these technologies are currently under development, with their potential still being
explored, but some are already calling for their mass deployment at the gigatonne scale (Dinger &
Platt, 2020; O’Brien et al., 2022). As development continues, it will become increasingly important
to understand the tradeoffs between food security and environmental benefits versus potential
downsides of mass application. Further research is needed at the intersection of food without
agriculture and ethics, including environmental, economic, and health impacts, before these
systems are developed to the point where they could fulfill a significant share of humanity’s food
intake. For example, the research field on the health impacts of ultra-processed foods (while still
rife with research challenges and lacking sufficient high-quality evidence) is studying the
possibility that more intensively processed foods increase the risk of obesity and other adverse
health outcomes, even after controlling for relevant factors (e.g. the increased energy intake these
foods tend to produce) (Gibney & Forde, 2022). Considering how the synthetic foods described here
are by definition heavily “processed”, researchers developing them should pay attention to future
findings in the field of nutrition. As these technologies develop the potential to displace
agricultural production, it becomes more relevant to look into the effects on agricultural
livelihoods and overall employment, including uncertainties such as if this would economically
impact agricultural workers, and to what degree. Other ethical concerns warranting future
research include the importance of perceived “naturalness” in food to consumers, and the justice
component of historical transitions from traditional to industrial processes, see (Davis et al., 2023).
In addition, while requiring less resources such as fertilizer, water, and land than agriculture,
non-agricultural food technologies may require larger quantities of mined materials and metals
than industrial factories of agricultural fertilizer and machinery.
From an even longer-term perspective, (Holt, 2021) explored the question of whether it would be
desirable for humans to “cut the umbilical cord” linking humanity to the Earth’s biosphere
(referring to ecological services such as traditional food production), if the capacity to do so is
developed. She argued that doing so is “morally undesirable unless done in the service of reducing
negative impacts on the biosphere”, because of the rare potential of Earth’s biosphere to help
humanity recover from a global civilizational collapse or possibly even recreate intelligent life in
case of human extinction, and also because of its conceivable intrinsic value. She further argues
that synthetic food production is a particularly noble form of techno-adaptation, to the degree that
it can help preserve the biosphere, a form of “conscious decoupling”.
31

9 Concluding remarks
The enormous potential of the myriad methods to produce food without agriculture is
demonstrated by the many selected methods described in this work. More than the entire global
demand of sugar can be provided through conversion of lignocellulosic biomass without
increasing wood removals, and this could also be done through repurposing existing industries
such as paper mills. It could also be used as a platform for most nutrients of relevance to human
diets through fermentation technologies, such as all 3 macronutrients, all amino acids (including
all nine essential amino acids), the essential fatty acids, and multiple vitamins and micronutrients
of interest. CO2is more energetically expensive as a starting material, but is virtually endless and
can be converted into all 3 macronutrients, with models suggesting that it could be used to fulfill
the entire global human protein demand through single cell proteins in just 6 years. Single cell
protein from natural gas or biogas can be produced at lower costs and capital expenditures at even
faster rates. Models suggest that converting hydrocarbons to fat substitutes (synthetic oil or
butter) can be done rapidly and at an affordable cost to alleviate supply losses during an
agricultural catastrophe, in some cases with lower CO2emissions than some common agricultural
products such as butter and Brazilian or Indonesian palm oil.
These closed-environment, polycentric food production systems minimize or remove key risks
such as trade restrictions, environmental degradation (pollution, soil erosion), extreme weather
events, changing climates, pathogens, and pests. Developing these and other food without
agriculture technologies can make great positive contributions to the sustainability and resilience
of food systems, land use change, food supply in extreme environments such as space missions and
humanitarian missions, and food supply in extreme conditions such as agricultural catastrophes
and potentially existential catastrophes.
More research and resilience work is urgently needed to realize the potential of many technologies
for production of food without agriculture, such as process development and optimization or food
safety and nutritional studies. In particular, for increasing resilience to global agricultural
catastrophes, pilot testing of these technologies at relevant scales, pilots for repurposing existing
industries for food production, and pilots of rapid construction (24/7) methods applied to them
would be of considerable help, as well as generating open source front end engineering design
packages and rapid deployment plans and operational guides.
CRediT author statement
Juan B. García Martínez: Conceptualization, Writing - Original Draft, Writing - Review & Editing,
Visualization, Project administration, Supervision, Funding acquisition.
Jeffray Behr: Writing - Original Draft, Writing - Review & Editing
David C. Denkenberger: Writing - Review & Editing, Funding acquisition
32

Funding
This research was supported by the Alliance to Feed the Earth in Disasters (ALLFED).
Declarations of interest: none
Acknowledgements
Thanks to Shannon Nangle, Ian McKay, Kathleen Alexander, Ross Tieman, and Adin Richards for
their insights. Thanks to Cx Bio for providing additional companies working on food production
from single cell oils.
33

References
Alvarado, K. A., García Martínez, J. B., Brown, M. M., Christodoulou, X., Bryson, S., & Denkenberger,
D. C. (2023). Food production in space from CO2 using microbial electrosynthesis.
Bioelectrochemistry,149, 108320. https://doi.org/10.1016/j.bioelechem.2022.108320
Alvarado, K. A., García Martínez, J. B., Matassa, S., Egbejimba, J., & Denkenberger, D. (2021). Food in
space from hydrogen-oxidizing bacteria. Acta Astronautica,180, 260–265.
https://doi.org/10.1016/j.actaastro.2020.12.009
Anneken, D. J., Both, S., Christoph, R., Fieg, G., Steinberner, U., & Westfechtel, A. (2006). Fatty Acids.
In Ullmann’s Encyclopedia of Industrial Chemistry. American Cancer Society.
https://doi.org/10.1002/14356007.a10_245.pub2
Averesch, N. J. H., Berliner, A. J., Nangle, S. N., Zezulka, S., Vengerova, G. L., Ho, D., Casale, C. A.,
Lehner, B. A. E., Snyder, J. E., Clark, K. B., Dartnell, L. R., Criddle, C. S., & Arkin, A. P. (2023).
Microbial biomanufacturing for space-exploration—What to take and when to make.
Nature Communications,14(1), Article 1. https://doi.org/10.1038/s41467-023-37910-1
Bagnato, G., Iulianelli, A., Sanna, A., & Basile, A. (2017). Glycerol Production and Transformation: A
Critical Review with Particular Emphasis on Glycerol Reforming Reaction for Producing
Hydrogen in Conventional and Membrane Reactors. Membranes,7(2).
https://doi.org/10.3390/membranes7020017
Barone, G. D., Cernava, T., Ullmann, J., Liu, J., Lio, E., Germann, A. T., Nakielski, A., Russo, D. A.,
Chavkin, T., Knufmann, K., Tripodi, F., Coccetti, P., Secundo, F., Fu, P., Pfleger, B., Axmann, I.
M., & Lindblad, P. (2023). Recent developments in the production and utilization of
photosynthetic microorganisms for food applications. Heliyon,9(4), e14708.
https://doi.org/10.1016/j.heliyon.2023.e14708
Bonrath, W., Gao, B., Houston, P., McClymont, T., Müller, M.-A., Schäfer, C., Schweiggert, C., Schütz,
J., & Medlock, J. A. (2023). 75 Years of Vitamin A Production: A Historical and Scientific
Overview of the Development of New Methodologies in Chemistry, Formulation, and
Biotechnology. Organic Process Research & Development,27(9), 1557–1584.
https://doi.org/10.1021/acs.oprd.3c00161
Cai, J., Lovatelli, A., Garrido Gamarro, E., Geehan, J., Lucente, D., Mair, G., Weimin, M.,
Bondad-Reantaso, M., & Roubach, R. (2021). Seaweeds and microalgae: An overview for
unlocking their potential in global aquaculture development. FAO - Fisheries and
Aquaculture Circular NFIA/C1229. https://doi.org/10.4060/cb5670en
Cai, T., Sun, H., Qiao, J., Zhu, L., Zhang, F., Zhang, J., Tang, Z., Wei, X., Yang, J., Yuan, Q., Wang, W.,
Yang, X., Chu, H., Wang, Q., You, C., Ma, H., Sun, Y., Li, Y., Li, C., … Ma, Y. (2021). Cell-free
chemoenzymatic starch synthesis from carbon dioxide. Science,373(6562), 1523–1527.
https://doi.org/10.1126/science.abh4049
Capson-Tojo, G., Batstone, D. J., Grassino, M., Vlaeminck, S. E., Puyol, D., Verstraete, W.,
Kleerebezem, R., Oehmen, A., Ghimire, A., Pikaar, I., Lema, J. M., & Hülsen, T. (2020). Purple
phototrophic bacteria for resource recovery: Challenges and opportunities. Biotechnology
Advances,43, 107567. https://doi.org/10.1016/j.biotechadv.2020.107567
Cestellos-Blanco, S., Louisia, S., Ross, M. B., Li, Y., Soland, N. E., Detomasi, T. C., Cestellos Spradlin, J.
N., Nomura, D. K., & Yang, P. (2022). Toward abiotic sugar synthesis from CO2 electrolysis.
Joule,6(10), 2304–2323. https://doi.org/10.1016/j.joule.2022.08.007
Chamorro-Cevallos, G. (2015). ASPECTOS NUTRICIONALES Y TOXICOLÓGICOS DE SPIRULINA
(ARTHROSPIRA). NUTRICION HOSPITALARIA,1, 34–40.
34

https://doi.org/10.3305/nh.2015.32.1.9001
Chen, C., Garedew, M., & Sheehan, S. W. (2022). Single-Step Production of Alcohols and Paraffins
from CO2 and H2 at Metric Ton Scale. ACS Energy Letters,7(3), 988–992.
https://doi.org/10.1021/acsenergylett.2c00214
Chen, L. (2024). Emerging Protein-Rich Ingredients For Aquaculture (pp. 95–105). Hatch Blue.
https://hatchinnovationservices.com/protein-rich-aquafeed-ingredients
Choi, K. R., & Lee, S. Y. (2023). Systems metabolic engineering of microorganisms for food and
cosmetics production. Nature Reviews Bioengineering,1(11), Article 11.
https://doi.org/10.1038/s44222-023-00076-y
Christodoulou, X., Okoroafor, T., Parry, S., & Velasquez-Orta, S. B. (2017). The use of carbon dioxide
in microbial electrosynthesis: Advancements, sustainability and economic feasibility.
Journal of CO2 Utilization,18, 390–399. https://doi.org/10.1016/j.jcou.2017.01.027
CIA. (1984). USSR: Single Cell Protein Industry (IA 84-10027). Central Intelligence Agency.
https://www.cia.gov/readingroom/docs/CIA-RDP91T01115R000100080003-4.pdf
Cornils, B., Lappe, P., & by Staff, U. (2014). Dicarboxylic Acids, Aliphatic. In Ullmann’s Encyclopedia of
Industrial Chemistry (pp. 1–18). John Wiley & Sons, Ltd.
https://doi.org/10.1002/14356007.a08_523.pub3
Davis, S. J., Alexander, K., Moreno-Cruz, J., Hong, C., Shaner, M., Caldeira, K., & McKay, I. (2023).
Food without agriculture. Nature Sustainability, 1–6.
https://doi.org/10.1038/s41893-023-01241-2
Demain, A. L., & Sánchez, S. (2019). Microbial Synthesis of Primary Metabolites: Current Trends and
Future Prospects. In Fermentation Microbiology and Biotechnology, Fourth Edition (4th ed.).
CRC Press.
Denkenberger, D. C., Cole, D. D., Abdelkhaliq, M., Griswold, M., Hundley, A. B., & Pearce, J. M. (2017).
Feeding everyone if the sun is obscured and industry is disabled. International Journal of
Disaster Risk Reduction,21, 284–290. https://doi.org/10.1016/j.ijdrr.2016.12.018
Denkenberger, D. C., & Pearce, J. M. (2014). Feeding Everyone No Matter What: Managing Food
Security After Global Catastrophe. Academic Press.
Difusa, A., Talukdar, J., Kalita, M. C., Mohanty, K., & Goud, V. V. (2015). Effect of light intensity and
pH condition on the growth, biomass and lipid content of microalgae Scenedesmus species.
Biofuels,6(1–2), 37–44. https://doi.org/10.1080/17597269.2015.1045274
Dinger, F., & Platt, U. (2020). Towards an Artificial Carbohydrates Supply on Earth. Frontiers in
Sustainable Food Systems,4. https://doi.org/10.3389/fsufs.2020.00090
Dolganyuk, V., Belova, D., Babich, O., Prosekov, A., Ivanova, S., Katserov, D., Patyukov, N., & Sukhikh,
S. (2020). Microalgae: A Promising Source of Valuable Bioproducts. Biomolecules,10(8), 1153.
https://doi.org/10.3390/biom10081153
Dondapati, S. K., Stech, M., Zemella, A., & Kubick, S. (2020). Cell-Free Protein Synthesis: A
Promising Option for Future Drug Development. BioDrugs,34(3), 327–348.
https://doi.org/10.1007/s40259-020-00417-y
Drauz, K., Grayson, I., Kleemann, A., Krimmer, H.-P., Leuchtenberger, W., & Weckbecker, C. (2007).
Amino Acids. In Ullmann’s Encyclopedia of Industrial Chemistry. John Wiley & Sons, Ltd.
https://doi.org/10.1002/14356007.a02_057.pub2
Dunn, C., Nangle, S. N., & Ziesack, M. (2023). Carbon efficient two-phase high-productivity fermentation
system (World Intellectual Property Organization Patent WO2023015241A1).
https://patents.google.com/patent/WO2023015241A1/en?inventor=shannon+nangle&oq=sh
annon+nangle
EFSA NDA, Turck, D., Bohn, T., Castenmiller, J., De Henauw, S., Hirsch-Ernst, K. I., Maciuk, A.,
35

Mangelsdorf, I., McArdle, H. J., Naska, A., Pelaez, C., Pentieva, K., Siani, A., Thies, F., Tsabouri,
S., Vinceti, M., Cubadda, F., Frenzel, T., Heinonen, M., … Knutsen, H. K. (2022). Safety of an
extension of use of Yarrowia lipolytica yeast biomass as a novel food pursuant to Regulation
(EU) 2015/2283. EFSA Journal,20(7), e07450. https://doi.org/10.2903/j.efsa.2022.7450
Eggersdorfer, M., Laudert, D., Létinois, U., McClymont, T., Medlock, J., Netscher, T., & Bonrath, W.
(2012). One Hundred Years of Vitamins—A Success Story of the Natural Sciences.
Angewandte Chemie International Edition,51(52), 12960–12990.
https://doi.org/10.1002/anie.201205886
FAO & WHO. (2023). Joint FAO/WHO food standards programme codex committee on food additives
fifty-third session discussion paper on the development of a standard for yeast. Codex
Alimentarius.
https://www.fao.org/fao-who-codexalimentarius/sh-proxy/en/?lnk=1&url=https%253A%252
F%252Fworkspace.fao.org%252Fsites%252Fcodex%252FMeetings%252FCX-711-53%252FCR
Ds%252Ffa53_crd06e.pdf
Farinas, C. S. (2018). Chapter 9—Solid-State Fermentation for the On-Site Production of
Cellulolytic Enzymes and Their Use in the Saccharification of Lignocellulosic Biomass. In A.
Pandey, C. Larroche, & C. R. Soccol (Eds.), Current Developments in Biotechnology and
Bioengineering (pp. 169–183). Elsevier. https://doi.org/10.1016/B978-0-444-63990-5.00009-8
Fineberg, H. (1979). Synthetic fatty acids. Journal of the American Oil Chemists’ Society,56(11),
805A-809A. https://doi.org/10.1007/BF02667451
García Martínez, J. B., Alvarado, K. A., Christodoulou, X., & Denkenberger, D. C. (2021). Chemical
synthesis of food from CO2 for space missions and food resilience. Journal of CO2
Utilization,53(101726). https://doi.org/10.1016/j.jcou.2021.101726
García Martínez, J. B., Alvarado, K. A., & Denkenberger, D. C. (2022). Synthetic fat from petroleum
as a resilient food for global catastrophes: Preliminary techno-economic assessment and
technology roadmap. Chemical Engineering Research and Design,177, 255–272.
https://doi.org/10.1016/j.cherd.2021.10.017
García Martínez, J. B., Brown, M. M., Christodoulou, X., Alvarado, K. A., & Denkenberger, D. C.
(2021). Potential of microbial electrosynthesis for contributing to food production using
CO2 during global agriculture-inhibiting disasters. Cleaner Engineering and Technology,4.
https://doi.org/10.1016/j.clet.2021.100139
García Martínez, J. B., Egbejimba, J., Throup, J., Matassa, S., Pearce, J. M., & Denkenberger, D. C.
(2021). Potential of microbial protein from hydrogen for preventing mass starvation in
catastrophic scenarios. Sustainable Production and Consumption,25, 234–247.
https://doi.org/10.1016/j.spc.2020.08.011
García Martínez, J. B., Pearce, J. M., Throup, J., Cates, J., Lackner, M., & Denkenberger, D. C. (2022).
Methane Single Cell Protein: Potential to Secure a Global Protein Supply Against
Catastrophic Food Shocks. Frontiers in Bioengineering and Biotechnology,10, 906704.
https://doi.org/10.3389/ioe.2022.906704
Gibney, M. J., & Forde, C. G. (2022). Nutrition research challenges for processed food and health.
Nature Food,3(2), 104–109. https://doi.org/10.1038/s43016-021-00457-9
Greene, C., Scott-Buechler, C., Hausner, A., Johnson, Z., Lei, X., & Huntley, M. (2022). Transforming
the Future of Marine Aquaculture: A Circular Economy Approach. Oceanography, 26–34.
https://doi.org/10.5670/oceanog.2022.213
Greenfield, H., & Southgate, D. A. T. (2003). Review of methods of analysis. In Food Composition
Data: Production, Management, and Use (2nd ed., p. 146). Food and Agriculture Organization
of the United Nations.
36

Greenshields, R., Rimmington, A., & Rothman, H. (1990). Practitioners’ forum perestroika and soviet
biotechnology. Technology Analysis & Strategic Management,2(1), 63–76.
https://doi.org/10.1080/09537329008523995
Groenewald, M., Boekhout, T., Neuvéglise, C., Gaillardin, C., W. M. van Dijck, P., & Wyss, M. (2013).
Yarrowia lipolytica: Safety assessment of an oleaginous yeast with a great industrial
potential. Critical Reviews in Microbiology,40(3), 187–206.
https://doi.org/10.3109/1040841X.2013.770386
Han, P., You, C., Li, Y., Shi, T., Wu, H., & Zhang, Y.-H. P. J. (2023). High-titer production of
myo-inositol by a co-immobilized four-enzyme cocktail in biomimetic mineralized
microcapsules. Chemical Engineering Journal,461, 141946.
https://doi.org/10.1016/j.cej.2023.141946
Hann, E. C., Overa, S., Harland-Dunaway, M., Narvaez, A. F., Le, D. N., Orozco-Cárdenas, M. L., Jiao,
F., & Jinkerson, R. E. (2022). A hybrid inorganic–biological artificial photosynthesis system
for energy-efficient food production. Nature Food,3(6), Article 6.
https://doi.org/10.1038/s43016-022-00530-x
Harris, L. I., Richardson, K., Bona, K. A., Davidson, S. J., Finkelstein, S. A., Garneau, M., McLaughlin,
J., Nwaishi, F., Olefeldt, D., Packalen, M., Roulet, N. T., Southee, F. M., Strack, M., Webster, K.
L., Wilkinson, S. L., & Ray, J. C. (2022). The essential carbon service provided by northern
peatlands. Frontiers in Ecology and the Environment,20(4), 222–230.
https://doi.org/10.1002/fee.2437
Hochman, G., Zhang, H., Xia, L., Robock, A., Saketh, A., Mensbrugghe, D. Y. van der, & Jägermeyr, J.
(2022). Economic incentives modify agricultural impacts of nuclear war. Environmental
Research Letters,17(5), 054003. https://doi.org/10.1088/1748-9326/ac61c7
Holt, L. A. (2021). Why shouldn’t we cut the human-biosphere umbilical cord? Futures,133, 102821.
https://doi.org/10.1016/j.futures.2021.102821
Ishizaki, A., & Tanaka, K. (1990). Batch culture of Alcaligenes eutrophus ATCC 17697T using
recycled gas closed circuit culture system. Journal of Fermentation and Bioengineering,69(3),
170–174. https://doi.org/10.1016/0922-338X(90)90041-T
Klein, B., & Davis, R. (2023). Algal Biomass Production via Open Pond Algae Farm Cultivation: 2022
State of Technology and Future Research. National Renewable Energy Laboratory (NREL),
Golden, CO (United States). https://www.osti.gov/biblio/1984451
Kouidri, C. M., & Taylor, W. F. (1970). The study of the synthesis of glycerol (NASA-CR-114276). National
Aeronautics and Space Administration (NASA). https://ntrs.nasa.gov/citations/19710008201
Lackner, M., Drew, D., Bychkova, V., Mustakhimov, I., Lackner, M., Drew, D., Bychkova, V., &
Mustakhimov, I. (2022). Value-Added Products from Natural Gas Using Fermentation
Processes: Fermentation of Natural Gas as Valorization Route, Part 1. In Natural Gas—New
Perspectives and Future Developments. IntechOpen.
https://doi.org/10.5772/intechopen.103813
Lebarbe, T. (2013). Synthesis of novel “green” polyesters from plant oils: Application to the
rubber-toughening of poly(L-lactide) [PhD thesis, Université Sciences et Technologies -
Bordeaux I]. https://theses.hal.science/tel-00965638
Linder, T. (2023). Beyond Agriculture─How Microorganisms Can Revolutionize Global Food
Production. ACS Food Science & Technology,3(7), 1144–1152.
https://doi.org/10.1021/acsfoodscitech.3c00099
Liu, H., Song, Y., Fan, X., Wang, C., Lu, X., & Tian, Y. (2021). Yarrowia lipolytica as an Oleaginous
Platform for the Production of Value-Added Fatty Acid-Based Bioproducts. Frontiers in
Microbiology,11. https://www.frontiersin.org/articles/10.3389/fmicb.2020.608662
37

Liu, J., Xu, J.-Z., Rao, Z.-M., & Zhang, W.-G. (2022). Industrial production of L-lysine in
Corynebacterium glutamicum: Progress and prospects. Microbiological Research,262,
127101. https://doi.org/10.1016/j.micres.2022.127101
Macauley-Patrick, S., Fazenda, M. L., McNeil, B., & Harvey, L. M. (2005). Heterologous protein
production using the Pichia pastoris expression system. Yeast,22(4), 249–270.
https://doi.org/10.1002/yea.1208
Masel, R. I., Liu, Z., Yang, H., Kaczur, J. J., Carrillo, D., Ren, S., Salvatore, D., & Berlinguette, C. P.
(2021). An industrial perspective on catalysts for low-temperature CO 2 electrolysis. Nature
Nanotechnology,16(2), Article 2. https://doi.org/10.1038/s41565-020-00823-x
Matassa, S., Papirio, S., Pikaar, I., Hülsen, T., Leijenhorst, E., Esposito, G., Pirozzi, F., & Verstraete, W.
(2020). Upcycling of biowaste carbon and nutrients in line with consumer confidence: The
“full gas” route to single cell protein. Green Chemistry,22(15), 4912–4929.
https://doi.org/10.1039/D0GC01382J
Max, B., Salgado, J. M., Rodríguez, N., Cortés, S., Converti, A., & Domínguez, J. M. (2010).
Biotechnological production of citric acid. Brazilian Journal of Microbiology,41(4), 862–875.
https://doi.org/10.1590/S1517-83822010000400005
McPherson, A. T. (1966). Chemical and Biochemical Production of Food for Man and Animal. Journal
of Animal Science,25(2), 575–581. https://doi.org/10.2527/jas1966.252575x
Moomaw, W., Berzin, I., & Tzachor, A. (2017). Cutting Out the Middle Fish: Marine Microalgae as the
Next Sustainable Omega-3 Fatty Acids and Protein Source. Industrial Biotechnology,13(5),
234–243. https://doi.org/10.1089/ind.2017.29102.wmo
Nangle, S. N., & Ziesack, M. (2022). Engineered bacteria and methods of producing triacylglycerides
(World Intellectual Property Organization Patent WO2022173810A1).
https://patents.google.com/patent/WO2022173810A1/en?inventor=Marika+Ziesack&oq=Mar
ika+Ziesack
Narala, R. R., Garg, S., Sharma, K. K., Thomas-Hall, S. R., Deme, M., Li, Y., & Schenk, P. M. (2016).
Comparison of Microalgae Cultivation in Photobioreactor, Open Raceway Pond, and a
Two-Stage Hybrid System. Frontiers in Energy Research,4.
https://www.frontiersin.org/articles/10.3389/fenrg.2016.00029
Neubauer, C., & Landecker, H. (2021). A planetary health perspective on synthetic methionine. The
Lancet Planetary Health,5(8), e560–e569. https://doi.org/10.1016/S2542-5196(21)00138-8
O’Brien, C. P., Watson, M. J., & Dowling, A. W. (2022). Challenges and Opportunities in Converting
CO2 to Carbohydrates. ACS Energy Letters,7(10), 3509–3523.
https://doi.org/10.1021/acsenergylett.2c01550
Okoro, V., Azimov, U., Munoz, J., Hernandez, H. H., & Phan, A. N. (2019). Microalgae cultivation and
harvesting: Growth performance and use of flocculants - A review. Renewable and