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The food provisioning of European cities depends on the global food supply system. However, both economic crises, environmental pressure and climate change effects represent a risk for food chain stability. Urban agriculture (UA) increases the self-sufficiency and resiliency of cities and is able to deliver positive environmental and social benefits. However, its efficacy depends on several variables, including the type of UA and the geographical location of the city. This paper analyses ReFarmers’ pilot farm, a vertical high-yield hydroponic croft located in the urban area of Lyon, France, from a life cycle perspective. The results show that the hydroponic farm performs better than cultivations in heated greenhouses, and similarly to conventional open field farms. Moreover, the source of the electricity input is a determinant factor that, if carbon neutral (e.g. wind energy) allows vertical hydroponic production to outperform the two conventional types of agriculture.
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2212-8271 © 201 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Peer-review under responsibility of the scientific committee of the 25th CIRP Life Cycle Engineering (LCE) Conference
doi: 10.1016/j.procir.2017.11.048
Procedia CIRP 69 ( 2018 ) 540 545
ScienceDirect
25th CIRP Life Cycle Engineering (LCE) Conference, 30 April – 2 May 2018, Copenhagen, Denmark
Environmental impacts of urban hydroponics in Europe: a case study in
Lyon
Daina Romeoa, Eldbjørg Blikra Veaa, Marianne Thomsena*
aDepartment of Environmental Science, Aarhus University, Frederiksborgvej 399, Postboks 358, DK-4000 Roskilde, Denmark
* Corresponding author. Tel.: +45 8715 8602; fax: +45 8715 5021. E-mail address: mth@envs.au.dk
Abstract
The food provisioning of European cities depends on the global food supply system. However, both economic crises, environmental pressure
and climate change effects represent a risk for food chain stability. Urban agriculture (UA) increases the self-sufficiency and resiliency of cities
and is able to deliver positive environmental and social benefits. However, its efficacy depends on several variables, including the type of UA
and the geographical location of the city. This paper analyses ReFarmers’ pilot farm, a vertical high-yield hydroponic croft located in the urban
area of Lyon, France, from a life cycle perspective. The results show that the hydroponic farm performs better than cultivations in heated
greenhouses, and similarly to conventional open field farms. Moreover, the source of the electricity input is a determinant factor that, if carbon
neutral (e.g. wind energy) allows vertical hydroponic production to outperform the two conventional types of agriculture.
© 2017 The Authors. Published by Elsevier B.V.
Peer-review under responsibility of the scientific committee of the 25th CIRP Life Cycle Engineering (LCE) Conference.
Keywords: Life Cycle Assessment; Urban agriculture; Hydroponics
1. Introduction
The urban population in Europe has been growing at a
constant rate in the last 50 years, and is expected to reach 80%
of the total European population by 2050 [1]. This represents a
challenge for food provisioning, since cities are not able to
internally satisfy it [2]. Hence, the import of goods is
necessary to meet the food demand of urban citizens, which
has caused an increased dependency on the global food
production and supply system. Such a reliance on external
inputs represents a vulnerability when major political or
economic disruptions occur, and it can often be the leading
cause of such instabilities [3, 4]. The inequality in food
distribution represents an additional risk, worsen by the
increasing urban poverty [5, 6].
Adding on to the local challenges for food provisioning, the
global food supply chain is also vulnerable to big-scale
changes. In fact, climate change will put food security at risk
on several levels, for example by reducing yields and land
suitability, and by increasing frequency and severity of
extreme weather events [7]. Satisfying the demand of
fertilisers is another environmental challenge of food
production, given that mineral fertilisers are a non-renewable
resource that is being consumed at an increasing rate [8].
In addition to being vulnerable to disruptions, the food
system is also responsible of environmental degradation [9];
considering the environmental impacts generated by the final
consumptions of the European Union, the production and
distribution of foodstuff accounts for 30% of the impacts on
climate change, 33% of the impacts on ecotoxicity and 60% of
the impacts on eutrophication [10].
Urban agriculture (UA) has been proposed as a practice to
respond to the challenges presented above, and produce
positive environmental, economic and social effects, such as
shortening the food supply chain, reducing the emissions of
greenhouse gasses, microclimate improvement, improved
water management, improved diet-related health, and stress
reduction[3, 11–15]. Smit and Nasr [16] pointed out that urban
© 201 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Peer-review under responsibility of the scientifi c committee of the 25th CIRP Life Cycle Engineering (LCE) Conference
541
Daina Romeo et al. / Procedia CIRP 69 ( 2018 ) 540 – 545
agriculture could promote the development of a circular
economy by closing ecological loops using wastewater and
organic solid waste as inputs. However, urban agriculture is
not a homogeneous practice, and includes, among the others,
small commercial farms, community-supported agriculture,
community gardens, rooftop gardens or greenhouses,
hydroponic and aquaponics farms and indoor agriculture [17].
Mougeot [18] proposed to categorize UA based on types of
economic activity, products, location, area used, production
system, production scale, and product destination. Given this
variability, a case-by-case evaluation is needed to show if and
in what conditions UA can deliver positive impacts and can
replace conventional agriculture.
Urban agriculture has been studied from a life cycle
perspective, reporting different results that show that UA is
not a less impacting production system per se. For example,
Kulak et al. [14] calculated that up to 34 t CO2eq ha-1 a-1 could
be avoided by substituting conventional agricultural products
with vegetables from community gardens in the UK. On the
other hand, for Goldstein et al. [19] urban agriculture in
northern climates performs worse than its conventional
counterpart, mainly because of its high energy requirement
and/or low yields. Sanyé-Mengual et al. [20] evaluated a
rooftop greenhouse production in Barcelona: their results
show that the UA system had a lower impact on the
environment, but that crop efficiency was determinant for the
performance of the cultivation.
This case study analyses, from an environmental
perspective, a vertical hydroponic urban farm called “La Petite
Ferme du Grand Lyon” and based in Lyon (France), using
Life Cycle Assessment. The pilot farm is run by the private
company ReFarmers and produces leafy greens and herbs that
are sold directly to restaurants and citizens.
2. Methods
Life Cycle Assessment (LCA) is a methodology used for
the evaluation of the environmental impacts of a product or a
service. Its utility in the food sector has been recognized,
thanks also to the opportunity of improving the performance
of a product by acting on the most burdensome processes
[21].
2.1. Goal and scope definition
This work’s goal is to evaluate the environmental
performance of a high-yield vertical hydroponic farm, and to
compare it to conventional agriculture. The analysis shows
whether and to what extent this type of hydroponic is able to
produce vegetables with a lower environmental impact than
soil-based conventional agriculture. By showing if urban
agriculture can compete with conventional vegetable
production, this study highlights the strong and weak points of
urban hydroponic production in temperate continental
climates, and therefore supports the improvement and
development of sustainable urban food supply systems.
Urban agriculture is, in this case, a supplementary source
of vegetables; therefore, the capacity of urban hydroponic
agriculture to fulfil the entire food requirement of European
cities is outside of the scope of this study.
The modelling framework applied is attributional LCA.
According to the ILCD Handbook we identified our case
study as a Situation A “micro-level, product or process-related
decision support study”. In fact, by having a small market
share, the farm’s products can impact on the market solely to
a limited extent, generating only small-scale consequences
[22].
2.1.1 Functional unit
The selected functional unit is one kg of leafy greens
delivered to the retailer. To be able to perform the comparison
between hydroponic and conventional agriculture, we
assumed that: lettuce and leafy greens can be considered
substitutes, given their almost overlapping function; the
quality of the vegetables is the same for all cultivation types.
The same assumptions were made and described by Goldstein
et al. [19].
2.1.2 System boundaries
We performed a cradle-to-gate analysis considering the
cultivation phase and the transport of the products to the
retailers. Figure 1 shows the boundaries of the system. Capital
goods were included into the analysis as they are considered
fundamental assets in hydroponic cultivation. The end-of-life
of the capital goods was selected depending on the material:
steel, aluminium and iron parts are recycled, as well as PVC
and PE plastic components; the other plastic materials, which
cannot be recycled due to their composition, are sent to
incineration.
We had to exclude the process of pest control through
insect release; the insects are not bred in the farm, and no
literature data could be found about the breeding process of
parasitoids and the related inputs. The fixation of CO2by the
plants was omitted because the gas is expected to be released
in the near future as a biogenic emission of carbon dioxide.
Moreover, as we compare the same amount of produced
lettuce, the uptake of carbon dioxide is the same for both
types of cultivation. Since the fertilisers are not lost through
the soil, but remain available to the plants thanks to the
recirculation of the water, we assumed the fertilisers
emissions to be zero.
For conventional agriculture, we considered two
scenarios: the production and delivery of lettuce grown in
heated greenhouses (scenario S2) and the production and
delivery of open field cultivated lettuce (scenario S3); both
the scenarios were derived from the Ecoinvent database [23].
In all the three scenarios, the packaging of the vegetables
has not been included. This choice is justified by the fact that
the impact of packaging has been showed to be relatively low
[24].
2.1.3 Impact categories
The impact assessment was performed using the software
Simapro 8 and the ReCiPe methodology (version 1.13) at
Midpoint level. We focused on seven impact categories that,
accordingly to Goldstein et al. [19], are considered
representative of the main potential impacts of agriculture:
climate change (CC), freshwater and marine eutrophication
(respectively FE and ME), freshwater ecotoxicity (FT),
agricultural land occupation (ALO), water depletion (WD)
and fossil depletion (FD).
542 Daina Romeo et al. / Procedia CIRP 69 ( 2018 ) 540 – 545
2.1.4 Sensitivity analysis
Based on the results of the Life Cycle Impact Assessment
(LCIA), we performed a one-at-a-time (OAT) analysis of
scenario S1; the parameters that contributed most to the
impacts were varied of ±10%, and the change in the results
was calculated and discussed.
A scenario sensitivity analysis was also carried out for
scenarios S1 and S2: the type of one of the most impacting
inputs was changed to see the performance of the scenarios in
these new conditions.
3. Results and discussion
3.1. Life Cycle Inventory
The Life Cycle Inventory (LCI) of scenario S1 (Table 1)
consists of data provided by the farmers, covering four
months of production in 2016. The annual production was
extrapolated considering the seasonal variation of some
inputs, such as the water demand. Moreover, we took into
account that the production stopped for 1.5 months in winter
due to low temperatures. The losses of production in the farm
are indirectly accounted for, since the farmers reported the
yields as production ready to be sold, i.e. the losses has been
already subtracted.
The farm covers an area of around 325 m2, of which (at the
time of the analysis) only 18% were used for the plant
cultivation. The seedlings are not produced in the farm but
bought from a local organic company; since no direct data
were available, we refer to the seedling production process
from Stössel et al. [24]. We assumed no heating is required,
since the plant variety are selected according to the season.
A neighbour farm manages the transport to the retailers of
the vegetables from the hydroponic farm, together with their
production; a mass allocation was performed to distribute the
impacts of this process, and a car trip of 20 km per week was
estimated. No losses of products are assumed in this phase,
due to the length and frequency of the trip.
The Ecoinvent database was the source of the inventories
of scenarios 2 and 3. In particular, we referred to the market
activity dataset “market for lettuce, GLO, Allocation, at the
point of substitution, ecoinvent database version 3.3”, and to
the ordinary datasets “Stössel F., lettuce360 production, GLO
(Global), Allocation, at the point of substitution, ecoinvent
database version 3.3”, and “Stössel F., lettuce361 production,
GLO (Global), Allocation, at the point of substitution,
ecoinvent database version 3.3”.
Table 1. Life Cycle Inventory of scenario S1.
Out
p
ut U/M Value Lifetime
Leaf
y
g
reens
(
lettuce
)
k
g
1
In
p
uts U/M Value Years
Pol
y
ester
g
reenhouse k
g
4.34*10-5 15
Iron greenhouse kg 3.01*10-5 50
Aluminium greenhouse kg 3.29*10-4 50
Steel greenhouse kg 2.53*10-3 50
PVC greenhouse kg 1.23*10-4 50
Polyethylene greenhouse kg 6.39*10-4 15
Polycarbonate greenhouse kg 5.71*10-4 15
PVC structure kg 8.87*10-3 20
Recycled PET matrix media kg 7.04*10-3 5
Polyester rope kg 2.83*10-4 6
Steel hanging hook kg 4.96*10-5 50
PVC gutter kg 2.61*10-3 50
PVC pipe kg 1.27*10-4 50
PE tubing kg 2.16*10-4 25
Steel tubing kg 1.02*10-3 50
HDPE tank1 kg 2.31*10-4 25
Steel tank1 kg 2.76*10-4 25
HDPE tank2 kg 1.34*10-4 25
Irrigation pump n 3.73*10-5 10
Sump pump n 3.73*10-5 10
Organic seedlings n 1.96
Peat for seedlings cm339.1
N in fertiliser kg 2.57*10-2
P2O5in fertiliser kg 1.29*10-3
K2O in fertiliser kg 3.60*10-3
Nitric acid L 5*10-3
Potassium hydroxide pest kg 7.97*10-5
Coconut oil pest control kg 7.97*10-5
Water pest control kg 1.85*10-2
Electricity irrigation pump kWh 2.29
Electricity sump pump kWh 0.15
Water irrigation L 5.96
Urban land use m2a 2.24*10-2
Transport t*km 1.00*10-2
Figure 1. System boundaries.
543
Daina Romeo et al. / Procedia CIRP 69 ( 2018 ) 540 – 545
Table 2 reports the yields and the water and fertiliser inputs
required by the three scenarios. In scenario S1, five
cultivation cycles can be achieved per year, while scenarios
S2 and S3 support four cycles per year.
Table 2. Comparison of yield, water and fertiliser consumption of the three
types of cultivation.
3.2. Life Cycle Impact Assessment
As an overview, the urban vertical hydroponic production
(S1) shows the best performance in the categories of marine
eutrophication and agricultural land occupation. For climate
change, freshwater eutrophication, freshwater ecotoxicity and
fossil depletion, the impact is higher than on-field
conventional agriculture (S3). Anyway, in all cases except for
water depletion the performance of S1 is visibly better than
the production of lettuce in heated greenhouses (S2).
These results are explained by taking into consideration the
characteristics of the different systems. The vertical
hydroponic farm requires more capital goods than the other
types of cultivations, since it does not rely on soil substrate,
but needs vertical plastic structures and a recirculating
irrigation system, which requires electricity (see Figure 2).
For climate change, the consumption of electricity
contributes for two thirds to the impact in scenario S1, while
in scenario S3 the production and use of fertilisers are the
main responsible of greenhouse gas (GHG) emissions.
Whereas these two scenarios differ for only 0.10 kg CO2eq,
when lettuce is grown in heated greenhouses (scenario S2), it
is responsible of the emission of 7.08 kg CO2eq per every kg
of lettuce that reaches the supermarket.
By recirculating water and avoiding losses for infiltration,
scenario S1 has a water consumption seven times lower than
greenhouse conventional production, and around four times
lower than on-field cultivation, that benefits from rain events
(see Table 2). In Mediterranean climates, such as Greece, the
water demand per kg of lettuce production reaches 83 litres,
fourteen times higher than in vertical hydroponics [25].
However, the irrigation system requires a constant water flow
guaranteed by a pumping system, which consumes electricity.
The impact of electricity depends on how this electricity is
produced; given the location of the farm, we considered the
French energy mix, of which more than 70% is nuclear energy
[26]. The production of nuclear energy has a high requirement
of cooling-water, which explains why scenario S1 has a worse
impact on water depletion, even if it has a smaller direct water
consumption.
Table 3. Results of the Life Cycle Impact Assessment of 1 kg of lettuce
grown in the three scenarios: vertical hydroponic production (S1), heated
greenhouse production (S2) and on-field cultivation (S3). The results are
normalised with respect to the yields in Table 2.
The consumption of electricity for irrigation is among the
main contributing processes for all the impact categories, but
is less impacting than the consumption of heat of the
conventional greenhouse scenario. In facts, scenario S2 has
the worst performance (except for water depletion) in every
category.
The controlled temperature in S2 results in a doubled yield
with respect to on-field cultivation, but still half of the one of
vertical hydroponic (see Table 2). Having a high production
in a limited space is one of the main qualities of vertical
hydroponic systems. Moreover, since no soil is needed, the
cultivation can take place in many different spaces: on
rooftops, indoor, on abandoned industrial sites, on walls. An
additional positive characteristic of hydroponics is that the
quality and eventual contamination of the soil does not
represent a risk for the products – simply because the two
compartments are not in direct contact. This advantage is
shown in the agricultural land occupation of scenario S1: by
being soil independent and vertical, this type of hydroponics
requires from four to 20 times less agricultural land than
conventional agriculture.
However, this means that hydroponic production needs to
be supported by an external input of fertilisers to satisfy the
nutrient requirement of the plants. The use of NPK fertiliser in
the three scenarios is reported in Table 2. Scenario S1 needs
more nutrient input than greenhouse cultivation, but less than
on-field production, where part of the applied fertilisers is lost
due to leaching processes. The different NPK proportion
indicates that hydroponics allows an optimization of nutrient
supply to support the growth phases of the plants.
S1 S2 S3
Yield [kg/m2year] 44.7 20.0 10.4
Water consumption [L/kg] 5.96 42.3 23.2
Fertiliser use per kg of
product [kg/kg]:
N 0.0026 0.0016 0.0037
P as P2O50.0013 0.0005 0.0007
K as K2O 0.0036 0.0024 0.0052
Table 3 reports the results of the Life Cycle Impact
Assessment for the four scenarios.
Impact category S1 S2 S3
CC [kg CO2eq] 0.39 7.1 0.29
FE [kg Peq] 5.88*10-5 3.10*10-4 1.27*10-5
ME [kg Neq] 1.14*10-4 8.91*10-4 1.37*10-3
FT [kg 1,4-DBeq] 2.55*10-4 9.98*10-4 1.69*10-4
ALO [m2a] 0.024 0.522 0.095
WD [m3] 0.033 0.019 0.017
FD [kg oileq] 0.10 1.43 0.07
Figure 2. Process contribution of scenario S1 in the seven impact categories
544 Daina Romeo et al. / Procedia CIRP 69 ( 2018 ) 540 – 545
These results do not completely explain the impacts on
freshwater eutrophication: in scenarios S1 the production of
electricity and fertilisers are the main contributing processes,
and in scenario S2 the production of heat is the dominant
process. Scenario S3 has a negligible use of these inputs, but
needs more fertilisers, which determines the emission of
nutrients into the water streams. It is important to distinguish
where the emissions of nutrients take place, since
eutrophication is a local phenomenon. In this sense, in
scenario S1 and S2 the major risk of eutrophication is in the
areas where fuels, metals and fertilisers are extracted, i.e.
mining sites distant from the place of final use. On the
contrary, in scenario S3 the release of nutrients following the
application of fertilisers represents a noteworthy impact on
local water quality.
About marine eutrophication, the actors in play are the
same of freshwater eutrophication (electricity, fertiliser
production and use), but since scenario S3 has a high release
of nitrogen (which is the limiting factor of ME), its impact is
higher than scenario S1.
Regarding eutrophication, a merit of hydroponics is the
efficient use of nutrients, that, by being recycled with the
water, are not released through the soil but remain available
for the plants. The impact on freshwater ecotoxicity is due to
the heat consumption in scenario S2, whereas for the other
two scenarios several processes impact with the same order of
magnitude: electricity production, fertiliser production,
equipment production, pesticide production and transport.
The combination of equipment and energy requirements is
responsible of the impact of scenario S1 on fossil depletion.
Scenario S2, due to the necessity to heat the greenhouse, has a
performance more than ten times worse, while on-field
cultivation (S3), that is relatively low-input, has half the
impact of S1.
A benefit of urban agriculture is the shortening of the
supply chain and the reduction of losses during the transport
of the products. Thanks to the proximity of the farm to the
consumers, the vegetables are fresher and do not need to be
cooled during the delivery. For these reasons, we assumed
zero losses in the transport phase. For conventional
agriculture, on the other hand, the reported distribution losses
are approximately 12%.
3.2.1 Sensitivity analysis
To determine the influence of the main inputs identified in
the LCIA, we performed a one-at-a-time (OAT) analysis of
scenario S1 by varying the yield, the electricity consumption
and the water consumption by ±10%. The results in Table 4
show that the yield is the parameter that most affects the
results, especially when it changes negatively. Variations in
electricity consumption have different effects on the different
categories, but notably this parameter is more important than
water for the water depletion impact category.
We performed also a scenario sensitivity analysis where we
considered the case in which the hydroponic farm (S1) and
the heated-greenhouse farm (S2) use only wind energy to
satisfy their energy requirements. We chose this type of
energy because wind is the second renewable energy source in
France, after hydropower, and is easier to implement than the
latter [26].
Table 4. OAT sensitivity analysis.
As visualized in Table 5, the use of wind energy makes the
hydroponic production the least impacting method of
cultivation, except for the impacts on freshwater where it is
comparable to on-field agriculture. The use of wind energy in
the heated greenhouse improves the overall performance of
this scenario, however, this cultivation remains the one with
the highest impacts on the considered categories.
Table 5. Scenario sensitivity analysis: LCIA of scenario S1 using wind
energy as electricity input.
3.2.2 Data quality and limitations of the study
The quality of the data influences the results. The primary
data collected for scenario S1 refer to four months of
production. Even if the farmers considered the seasonal
variability for a better estimation of the annual consumptions,
e.g. the water consumption, we recognise that the annual
estimations could eventually not correspond to the actual
values.
Moreover, scenarios S2 and S3 are based on LCI datasets
representative of the Integrated Production in Switzerland.
Even though the authors of the datasets affirm that, most
probably, their data are representative for similar cultivations
in industrialised countries, these values cannot capture the
peculiarities of country-specific cultivation practices. In
conclusion, we acknowledge that the data do not have the
same level of precision, and this affects the quality of the
results.
To compare the performance of the systems, we chose the
environmental indicators considered the most representative
for LCA analyses of agricultural systems. We recognise that
the agricultural sector can deliver other positive and negative
effects, such as potential contribution to biodiversity, social
issues and economic development. Consequently, integrating
the analysis with other methodologies could give a broader
perspective on the impacts of agriculture on an environmental,
economic and social level.
Impact category Yield
+10%
Yield
-10%
Electricity
±10%
Water
±10%
CC [kg CO2eq] -9.1% +11.1% ±6.7% ±0.1%
FE [kg Peq] -9.1% +11.1% ±7.9% ±0.0%
ME [kg Neq] -9.1% +11.1% ±3.9% ±0.0%
FT [kg 1,4-DBeq] -9.1% +11.1% ±3.7% ±0.0%
ALO [m2a] -9.1% +11.1% ±3.1% ±0.1%
WD [m3] -9.1% +11.1% ±7.0% ±1.8%
FD [kg oileq] -9.1% +11.1% ±6.5% ±0.1%
Impact category S1 wind energy S2 wind energy
CC [kg CO2eq] 0.156 1.139
FE [kg Peq]1.61*10-5 6.60*10-5
ME [kg Neq]7.86*10-5 6.72*10-4
FT [kg 1,4-DBeq] 1.74*10-4 2.98*10-4
ALO [m2a] 0.0017 0.071
WD [m3]0.011 0.018
FD [kg oileq] 0.044 0.252
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Daina Romeo et al. / Procedia CIRP 69 ( 2018 ) 540 – 545
4. Conclusions
The results of the comparative analysis of lettuce
production in vertical hydroponic, heated greenhouse and on-
field cultivation show that the former is able to deliver higher
yields and have an environmental impact comparable to on-
field cultivation, and 2 to 12 times lower than heated
greenhouse production. A special case is represented by the
impact on water depletion, where the type of energy used
affects the results more than the direct water consumption. In
conclusion, the need of energy inputs is determinant for the
efficiency of plant production systems, as highlighted by the
bad performance of scenario S2, due to the need for heating.
When the needs of external inputs are satisfied using fossil-
based resources, the environmental performance decreases,
but if renewable sources are used, the high yields and
efficiency make vertical hydroponic the best production
system in the considered climatic area. Moreover, the ability
to grow local food without agricultural land occupation is for
sure an added value of vertical hydroponics, representing a
less environmentally harmful way to supplement the
vegetable demand of urban populations.
Acknowledgements
The research was performed as part of the DECISIVE
(Decentralised valorisation of biowaste) project
(www.decisive2020.eu/), funded by the European Union’s
Horizon 2020 research and innovation program under the
grant agreement N° 689229 and the Graduate School of
Science and Technology at Aarhus University. We thank our
project partner ReFarmers for sharing their data.
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... Considered at all relevant life cycle stages of the functional unit, results are used in this study to compare impacts of IVF and of UA supply chains [53]. Generating results for indicators such as GWP in CO 2 e per kg supports comparison with other LCA research into IVF technology [12,[58][59][60]. Ecotoxicity impact categories were applied as representative of toxicity impacts on urban environments [33], and serve to assess the technologies' impact on freshwater ecotoxicity, marine ecotoxicity, terrestrial ecotoxicity and human toxicity [57] (Table S2 and Figure S1). ...
... In CS, it is responsible for 10.01 kg (54%) and LS for 10.03 kg CO2e/kg (45%). This result was expected in an IVF system, as high energy demand in urban farm operations is a known challenge [46,[58][59][60]. In this study the primary consumption of electricity was from four inputs (climate system and equipment, LEDs and cleaning). ...
... In CS, it is responsible for 10.01 kg (54%) and LS for 10.03 kg CO 2 e/kg (45%). This result was expected in an IVF system, as high energy demand in urban farm operations is a known challenge [46,[58][59][60]. In this study the primary consumption of electricity was from four inputs (climate system and equipment, LEDs and cleaning). ...
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... A large share of the scientific and grey literature promotes vertical farming as a sustainable solution for food provisioning (Al-Chalabi, 2015;Benke and Tomkins, 2017;Despommier, 2011). However, assessments of the environmental implications of IVFs remain limited in scientific literature, with few cases applying systematic environmental assessments (Dorr et al., 2021;Martin et al., 2022;Romeo et al., 2018). A number of theoretical studies have assessed IVFs to compare their performance against competing systems such as open-field production and greenhouses, see e.g. ...
... In previous studies, packaging has been found to contribute only to a small share of the environmental impacts of IVFs. However, a large number of studies have also excluded packaging from their assessment (Graamans et al., 2018;Romeo et al., 2018;Weidner et al., 2022) motivating its minor share of the overall impacts. However, despite its relatively small share to the overall impacts, annually the total consumption of certain materials may contribute to a large environmental footprint (e.g. ...
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... Many authors promote these systems as a sustainable solution for urban areas (Despommier, 2009;Benke and Tomkins, 2017;Van Delden et al., 2021). However, evaluations of their benefits remain limited in the literature, with few studies assessing the sustainability of the systems (Romeo et al., 2018;Sanjuan-Delmás et al., 2018;Gentry, 2019;. Furthermore, despite some studies addressing the potential benefits of including these systems in urban environments (Eigenbrod and Gruda, 2015;Kozai and Niu, 2016;Eaves and Eaves, 2018), the literature remains limited. ...
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Resources such as fertile soil and clean water are already limited in many parts of the world. Additionally, the conventional use of arable land is becoming increasingly difficult, which is further exacerbated by climate change. Soilless cultivation systems do not only offer the opportunity to save water and cultivate without soil but also the chance to open up urban areas such as residential rooftops for food production in close proximity to consumers. In this review, applications of soilless farming systems are identified and compared to conventional agriculture. Furthermore, aspects of economic viability, sustainability and current developments are investigated. An insight into the most important soilless farming systems—hydroponics, aquaponics and vertical farming—is provided. The systems are then differentiated from each other and, as far as possible, evaluated in terms of their environmental impact and compared with conventional cultivation methods. Comparing published data analyzing the yield of hydroponic cultivation systems in comparison to soil-based cultivation methods enables a basic overview of the profitability of both methods and, thus, lays the foundation for future research and practical applications. The most important inert substrates for hydroponic applications are presented, and their degree of sustainability is compared in order to emphasize environmental impacts and affect substrate selections of future projects. Based on an assessment of the most important soilless cultivation systems, the challenges and developments of current techniques are highlighted and discussed.
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Urban agriculture appears to be a means to combat the environmental pressure of increasing urbanization and food demand. However, there is hitherto limited knowledge of the efficiency and scaling up of practices of urban farming. Here, we review the claims on urban agriculture’s comparative performance relative to conventional food production. Our main findings are as follows: (1) benefits, such as reduced embodied greenhouse gases, urban heat island reduction, and storm water mitigation, have strong support in current literature. (2) Other benefits such as food waste minimization and ecological footprint reduction require further exploration. (3) Urban agriculture benefits to both food supply chains and urban ecosystems vary considerably with system type. To facilitate the comparison of urban agriculture systems we propose a classification based on (1) conditioning of the growing space and (2) the level of integration with buildings. Lastly, we compare the predicted environmental performance of the four main types of urban agriculture that arise through the application of the taxonomy. The findings show how taxonomy can aid future research on the intersection of urban food production and the larger material and energy regimes of cities (the “urban metabolism”).
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The environmental sustainability of an organic and a conventional lettuce cultivation system, situated at Northern Greece, was investigated. Data from all stages (i.e. irrigation, machinery used, and fertilizing) of lettuce cultivation were collected and their sustainability was assessed by means of the life cycle assessment (LCA) methodology. Two different functional units, namely per hectare of cultivation and per ton of lettuce produced, were used and the environmental impacts, on mid and endpoint level, and CO2 emissions were estimated by means of the SimaPro 8 LCA software. It was found that the environmental footprint and the CO2 emissions were lower by 11% and 15%, respectively, for organic than for the conventional lettuce cultivation, when sustainability was assessed per area (ha) of cultivation. On the contrary, conventional lettuce cultivation showed a better environmental performance than organic by 51% and 53% in terms of CO2 emissions and total environmental impacts, respectively, when the amount of lettuce produced is used as the functional unit of calculations. This is attributed to the fact that the organic system, due to its lower crop yields, requires significantly larger cultivation area to achieve the same crop production with conventional. Moreover, it was found that in all cases the irrigation stage primarily contributed to most impact categories, due to its high energy demands for ground water pumping and the fossil-dependent Greek electricity grid. In addition, in all cases the conventional lettuce cultivation system yielded a significantly high impact onto freshwater eutrophication, due to the use of chemical fertilizers, thus posing serious stresses on local freshwater ecosystems. A sensitivity analysis was carried out and alternative, more sustainable, scenarios were proposed.
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The production and supply of food currently accounts for 20–30% of greenhouse gas (GHG) emissions in the UK and the government and nongovernmental organisations are seeking to reduce these environmental burdens. Local authorities all over UK establish community farms with the aim to produce more sustainable food for citizens. This study used environmental Life Cycle Assessment (LCA) to quantify the potential savings of food-related GHG emissions that may be achieved with the establishment of an urban community farm, based on a case study recently found in the London Borough of Sutton. The work identified elements of the farm design that require the greatest attention to maximise these savings. The greatest reductions can be achieved by selecting the right crops: (i) providing the highest yields in local conditions and (ii) usually produced in energy-intensive greenhouses or air-freighted to UK from outside Europe. Implications from further development of the farm on the local, unused land were examined, taking into account market requirements. This showed that land used on an urban fringe for food production could potentially reduce greenhouse gas emissions in Sutton by up to 34 t CO2e ha−1 a−1. Although the percentage of this reduction in total diet emissions is relatively low, the result exceeds carbon sequestration rates for the conventional urban green space projects, such as parks and forests.
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This paper describes how cities can be transformed from being only consumers of food and other agricultural products into important resource-conserving, health-improving, sustainable generators of these products. In particular, agriculture in towns, cities and metropolitan areas can convert urban wastes into resources, put vacant and under-utilized areas into productive use, and conserve natural resources outside cities while improving the environment for urban living. Agriculture within urban and peri-urban areas is defined as a common and beneficial land use. This paper also gives examples of urban agriculture programmes which help alleviate poverty while creating these benefits. -Authors