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Future food-production systems: Vertical farming and controlled-environment agriculture

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The unremitting trends of increasing population, urbanization, diminishing water supply, and continuing climate change have contributed to declining stocks of arable land per person. As land resources for agriculture decrease, policy makers are faced with the challenge of sustainability and feeding the rapidly growing world population which is projected to reach approximately 9.7 billion in 2050. Solutions for improving future food production are exemplified by urban vertical farming which involves much greater use of technology and automation for land-use optimization. The vertical farm strategy aims to significantly increase productivity and reduce the environmental footprint within a framework of urban, indoor, climate-controlled high-rise buildings. It is claimed that such facilities offer many potential advantages as a clean and green source of food, along with biosecurity, freedom from pests, droughts, and reduced use of transportation and fossil fuels. In this article, the issues involved are evaluated together with potential advantages and disadvantages. Possible implications are identified for consideration by policy makers and to facilitate further economic analysis.
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Sustainability: Science, Practice and Policy
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Future food-production systems: vertical farming
and controlled-environment agriculture
Kurt Benke & Bruce Tomkins
To cite this article: Kurt Benke & Bruce Tomkins (2017) Future food-production systems: vertical
farming and controlled-environment agriculture, Sustainability: Science, Practice and Policy, 13:1,
13-26, DOI: 10.1080/15487733.2017.1394054
To link to this article: https://doi.org/10.1080/15487733.2017.1394054
© 2017 The Author(s). Published by Informa
UK Limited, trading as Taylor & Francis
Group.
Published online: 20 Nov 2017.
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RESEARCH ARTICLE
Future food-production systems: vertical farming and controlled-
environment agriculture
Kurt Benke
a,b
and Bruce Tomkins
b
a
School of Engineering, University of Melbourne, Parkville, Victoria, Australia;
b
Department of Economic Development, Jobs,
Transport, and Resources (DEDJTR), State Government of Victoria, AgriBio Centre, Bundoora, Victoria, Australia
ABSTRACT
The unremitting trends of increasing population, urbanization, diminishing water supply, and
continuing climate change have contributed to declining stocks of arable land per person.
As land resources for agriculture decrease, policy makers are faced with the challenge of sus-
tainability and feeding the rapidly growing world population which is projected to reach
approximately 9.7 billion in 2050. Solutions for improving future food production are exem-
plified by urban vertical farming which involves much greater use of technology and auto-
mation for land-use optimization. The vertical farm strategy aims to significantly increase
productivity and reduce the environmental footprint within a framework of urban, indoor, cli-
mate-controlled high-rise buildings. It is claimed that such facilities offer many potential
advantages as a clean and green source of food, along with biosecurity, freedom from pests,
droughts, and reduced use of transportation and fossil fuels. In this article, the issues
involved are evaluated together with potential advantages and disadvantages. Possible impli-
cations are identified for consideration by policy makers and to facilitate further economic
analysis.
ARTICLE HISTORY
Received 24 May 2017
Accepted 12 July 2017
KEYWORDS
Indoor agriculture; urban
farming; greenhouse;
sustainability; optimization
Introduction
An emerging global problem is the long-term
decreasing stock of agricultural land per capita.
Statistics on future growth of the world population
from the United Nations Food and Agriculture
Organization (FAO) reveal that arable land per per-
son is projected to decrease by 2050 to one-third of
the amount available in 1970 (FAO 2016). This
decline is forecasted to continue due to the effects of
climate change, the increasing geographic extent of
drylands, the reduction in fresh water supply, and
population growth (Fedoroff 2015). As shown in
Figure 1, this trend means that the planet is running
short of farmland to feed a growing number of peo-
ple (Fedoroff 2015; FAO 2016; USCB 2016). A more
complete list of prominent threats to the future sup-
ply of arable land would also include: climate
change, declining fisheries (prompting a greater food
burden on land-based products), increasing urban-
ization, rising costs of agribusiness (e.g. fertilizers,
fuel, pesticides), rapidly increasing population, soil
depletion, and degradation from over-farming and
poor production practices.
There is increasing realization that primary pro-
ducers such as Australia are too small to be the food
bowl for Asia as current agricultural production
would feed only about 60 million people (see
Linehan et al. 2012; Fact Check 2014). At the pre-
sent time, scaling up to provide for the regions
entire population of 3 billion people is physically
impossible. The comparative economic advantage of
Australia is in providing so-called clean, green, and
gourmet (CGG) foods for the rapidly growing mid-
dle and upper classes in Asia, particularly China,
while expanding the current volume of production
as fast as possible.
The practice of farming in Australia has evolved
in the face of environmental adversity by careful
planning, good management, and substantial
research and development. Primary industries in the
country, however, are encountering ongoing chal-
lenges due to uncertainties in climate, water supply,
invasive pests, soil degradation, and transportation
costs. The decline in arable land per person in
Australia also mirrors the global pattern (Figure 2).
Australian agriculture is competitive in the inter-
national economy, but may come under threat from
disruptive new technologies, such as intensive urban
farming.
Interest in vertical farming gained traction follow-
ing publication of the book by Despommier (2010)
who argued that the benefits of indoor greenhouse
CONTACT Kurt Benke kbenke@unimelb.edu.au School of Engineering, University of Melbourne, Parkville, 3010, Victoria, Australia
ß2017 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unre-
stricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
SUSTAINABILTY: SCIENCE, PRACTICE AND POLICY, 2017
VOL. 13, NO. 1, 1326
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farming could be multiplied greatly by building
high-rise buildings in urban environments. In the
CGG food category, pilot farms have been estab-
lished in various cities around the world including
London, New York, Singapore, and Tokyo. In par-
ticular, China, Japan, and Israel are devoting
resources to indoor factory farming due to issues
relating to climate, pollution, and urbanization.
The advantages and disadvantages of this approach
have been the subject of continuing analysis at the
industry level but more attention is needed with
respect to planning, policy, and economics.
Despommier (2010) proposed that one approach
to addressing the future trend of diminishing agricul-
tural resources, changing climate, and other factors
involves the concept of vertical farming. This
approach is characterized by an urban, indoor, high-
rise, climate-controlled factory with renewable energy
and recycling of waste. The factory farms would be
housed in the population centers of large cities or
regional towns. Vertical farming has the potential for
crop production all-year round in an air-conditioned
facility, eliminating transportation costs, with greater
control of food safety and biosecurity, and substan-
tially reduced inputs with respect to water supply,
pesticides, herbicides, and fertilizers.
In this article, we report on an evaluation pertain-
ing to the claims, potential, and limitations of verti-
cal farming and related food-production models.
The intention is to offer an introduction to vertical
farming and its derivatives, to assess the implications
for future food production, and to provide a
resource with information and recommendations to
inform policy makers and economists. Some issues
are underscored with a reference to the particular
situation in Melbourne, Australia.
Vertical farming
In this section, we introduce vertical farming in the
context of four issues: (1) drivers for farm innov-
ation, (2) the potential advantages offered by vertical
farming, (3) its origins in controlled-environment
agriculture, and (4) reference to some technology
issues, such as light-emitting diode (LED) illumin-
ation and genetics.
Drivers for farm innovation
A recent study released jointly by the University of
Melbourne and Deakin University reported that in
the absence of a change in policy planning, food
self-sufficiency for Melbourne from the surrounding
food bowl could fall dramatically as the urban popu-
lation doubles to 78 million by 2050 (Carey,
Larsen, and Sheridan 2016). The authors reported
that the food bowl currently provides 41%of the
total food supply for the city but this could drop to
18%due to climate change, population growth, and
diminishing supplies of arable land and water.
There are many drivers for urban food planning
and policy development. Morgan (2009) argues that
food production is multifunctional and has wide-
spread effects on public health, water, land, and eco-
nomic development. The so-called new food
equation refers to a combination of novel develop-
ments which are described as follows.
First, a surge in world-food prices in 20072008,
when the international price of wheat doubled and
the price of rice tripled, exacerbated food insecurity
for two billion people and caused food riots in some
parts the world. The global recession around 1991 is
reflected in a sudden disruptive transition in annual
data from the World Health Organization (WHO)
Figure 1. Decline of stocks of arable land in the world over
the period 19612013. Indicative trend line calculated using
data from the United Nations Food and Agriculture
Organization (FAO 2016). The discontinuity coincides with
the global recession in the early 1990s.
Figure 2. Decline of stocks of arable land in Australia over
the period 19612013. Indicative trend line calculated using
data from the United Nations Food and Agriculture
Organization (FAO 2016). The discontinuity and recovery
relate to the global recession in the early 1990s.
14 K. BENKE AND B. TOMKINS
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for arable land per person, which highlighted the
importance of economics with respect to the trend
in the availability of arable land (see Figures 1
and 2).
Second, climate change is intensifying heat stress,
droughts, and damage to ecosystems. This is espe-
cially important in developing countries where food
prices are already under pressure.
Third, land disputes and social tension increases
when local land is purchased by cash-rich investors
from Asia or the Middle East, often resulting in
resentment and spiraling property prices. Purchases
may be long term and not for immediate profit and
above market prices, and also to evade domestic reg-
ulations on crop types (e.g. growing water-hungry
crops in regions with droughts and water restric-
tions in the target market).
Finally, rapid urbanization is leading to resent-
ment and unpredictable food shortages in some
parts of Asia due to both depopulation of rural
regions by job-seekers and increasing urban sensitiv-
ity to variability in the food-supply chain due to
unstable labor availability.
These factors in combination are increasing com-
plexity and uncertainties in planning sustainable
food production (Morgan and Sonnino 2010). In
Australia, additional drivers for change include gov-
ernment priorities aimed at increasing employment.
New and emerging technologies, such as vertical
farming and its derivatives, may provide new jobs in
high technology, food processing, process mainten-
ance, infrastructure development, and research and
development. Note that urban farming also includes
clusters around regional towns as well as central
business district locations.
Another driver for change is that traditional food
suppliers in Australia and Canada have recognized
that they are too small to supply a large volume of
produce to the global market and there is a public
debate over the need to specialize in more profitable
CGG food production for affluent clients in China,
Japan, Singapore, and elsewhere. Finally, countries
that are export destinations for Australian produc-
tion, such as China and Japan, are also interested in
greenhouse farming and are emerging as direct com-
petitors to Australia in producing CGG foods using
intensive indoor methods.
Potential of vertical farming
The vertical farming model was proposed with the
aim of increasing the amount of agricultural land by
building upwards.In other words, the effective
arable area for crops can be increased by construct-
ing a high-rise building with many levels on the
same footprint of land (Despommier 2010; The
Economist 2010). One approach is to employ a
single tall glasshouse design with many racks of
crops stacked vertically. It is an extension of the
greenhouse hydroponic farming model and
addresses problems relating to the use of soils, such
as the requirement for herbicides, pesticides, and
fertilizers. Transportation costs can be eliminated
due to proximity to the consumer, all-year-round
production can be programmed on a demand basis,
and plant-growing conditions can be optimized to
maximize yield by fine-tuning temperature, humid-
ity, and lighting conditions. Indoor farming in a
controlled environment also requires much less
water than outdoor farming because there is recy-
cling of gray water and less evaporation. Because of
these features, its wider adoption is likely to occur
initially in desert and drought-stricken regions, such
as some areas in the Middle East and Africa, and in
small and highly urbanized countries such as Israel,
Japan, and the Netherlands. Vertical farming is also
attractive where there is a high demand for CGG
food in countries that suffer from heavy pollution
and soil depletion, such as parts of China.
Controlled environment agriculture
The vertical farming model is essentially an indoor
farm based on a high-rise multi-level factory design.
Typical features include innovative use of recycled
water augmented by rainwater or water from a
desalination plant, automatic air-temperature and
humidity control, solar panel lighting and heating,
and tunable 24-hour LED illumination. The LED
equipment can be controlled throughout a growing
season to emit a programmed spectrum of light that
is optimal for photosynthesis for different types of
crops. When coupled with regulation of temperature
and humidity, the effects of seasonality can be mini-
mized or eliminated.
An indoor vertical farm may not even need soil if
hydroponics is used. This cultivation technique
involves growing plants in a soil-free culture with
nutrient solutions. The plants are suspended in a
medium, such as rock wool or perlite, and provided
with nutrients, or the roots are directly bathed in
the nutrient liquid using the nutrient-film technique
(Jones 2016). Air conditioning provides a constant
flow of air which can be enriched with carbon diox-
ide (CO
2
) to further advance plant growth and
development. Both ambient and nutrient tempera-
tures can be held at specific levels that optimize the
rate of plant growth. Any nutrients and water not
absorbed by the roots can be recycled rather than
lost to the system. The approach is consistent with
CGG food production. It can be used to grow a
wide range of crops, pharmaceuticals, or herbs.
A variant of hydroponics is aeroponics which
involves spraying the roots of plants with atomized
SUSTAINABILTY: SCIENCE, PRACTICE AND POLICY 15
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nutrient solutions or mists (Christie and Nichols
2004). There is reduced need for fertilizers, herbi-
cides, and pesticides if there is effective isolation
from a harsh external climate. Such a factory would
essentially eliminate common constraints and risks
to productivity, including heat and drought, pests,
seasonality, and transportation costs from remote
locations. Volatility in markets can be addressed
because production can be planned according to
demand. There are also implications for future food
security and sustainability in the face of climate
change and diminishing land and water resources.
The principal design elements of a vertical farm
and its derivatives are shown in Figure 3. The use of
wind turbines and storage batteries for solar panels
add even further attraction to this approach. A
multi-level vertical farm may take on many configu-
rations including conversion from existing disused
warehouses or apartment blocks. An example of a
green building with similar characteristics to a verti-
cal farm is shown in Figure 4. Conversion of build-
ing stock from office or residential use to vertical
farming has potential for addressing the oversupply
of inner urban high-rise developments.
The agricultural potential of LEDs has been the
focus of research in greenhouse lighting (Yeh and
Chung 2009). The much lower energy requirements
of LED lighting in combination with photovoltaics
has resulted in rapid deployment in factory
applications. The photoreceptors in plants absorb
the light energy for the purpose of photosynthesis
and are affected by the wavelength and intensity of
light. The spectral content of illumination, such as
blue wavelength in LED lighting, has been found to
change the concentrations of nutritionally important
primary and secondary metabolites in specialty vege-
table crops (Kopsell, Sams, and Morrow 2015). In
particular, plant response to different wavelengths of
light from LED sources suggests very significant
improvements in productivity are possible.
In addition to wavelength, controlled lighting
with respect to intensity and time duration is
another area where potential optimization strategies
are possible and requires further investigation. In
particular, genetics research has a possible role to
play in matching plants to the available light spec-
trum for improved yield. Spectral sensitivity may
also extend beyond the visible wavelengths and into
the ultraviolet and infrared bandwidths with poten-
tial effects on growth rates.
Genetic engineering may also be able to enhance
growth of crops that are compatible with other con-
trolled indoor environmental conditions. For
instance, it might be possible to increase crop yield by
fine-tuning variables such as temperature, humidity,
and CO
2
levels. Determination of a doseresponse
model for light-sensitive cells would support system
optimization (Benke and Benke 2013).
Figure 3. Components of a vertical farm and their interactions.
16 K. BENKE AND B. TOMKINS
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Commercial derivatives
The following section outlines commercial examples
of multi-level indoor urban farming. Common fea-
tures are multi-rack climate-controlled enclosures
with very high productivity, food security, and sub-
stantially less use of land, water, and energy.
Another notable feature is rapid proliferation on an
international scale (see Figures 57).
Sky Greens (Singapore)
In Singapore, the so-called Sky Greens A-Go-Gro
technology is based on A-shaped towers, over six
meters high, consisting of up to 26 tiers of growing
levels. These tiers rotate at one millimeter per
second to provide uniform solar radiation as
depicted in Figure 5 (Krishnamurthy 2014). The
footprint of the system is only six square meters,
making it ideal for urban environments. In Kranji,
near Singapores central business district, 120 towers
have been erected and there are plans for an
additional 300 to support daily production of two
tons of vegetables. Current intentions call for build-
ing a further 2000 towers and for selling them over-
seas with a price tag of US$10,000 per tower. The
cost of vegetables produced by these towers in
Singapore is about 10%higher than imported prod-
uct and the system supplies 10%of the vegetable
market in Singapore. It provides the city-state with
greater food security and CGG produce.
Valcent Company (North America)
The company Valcent Products (Verticrop 2016) has a
technology that is a derivative of vertical farming that
is now in operation. The system involves multi-level
stacked plastic trays in a climate-controlled glasshouse
enclosure (rather than multiple floors). The racks are
rotatable (mechanized) and provide solar exposure.
The Vancouver-based company claims its vertical
hydroponic farming technology can produce over an
area of one standard residential lot (50 by 75 feet)
the equivalent output of a 16-acre farm (Laylin
2016). In contrast to a traditional farm, the vegeta-
bles require only 8%of the water and 5%of the
area. The produce is exported on a worldwide basis.
Highly efficient LED illumination is used to aug-
ment natural light from the glasshouse design. No
harmful herbicides or pesticides are used. Three staff
can oversee 4,000 square feet of plants and 2,000
square feet of space for germinating, harvesting, and
packing. They can process as many as 10,000 plants
every three days (Laylin 2012).
Mirai Company (Japan)
The Mirai company in Japan has developed and mar-
keted indoor multi-level farms with impressive pro-
duction statistics (Shimamura 2016). For example, one
Japanese farm comprises 25,000 square meters pro-
ducing 10,000 heads of lettuce per day (100 times
more per square foot than traditional methods) with
40%less energy, 80%less food waste, and 99%less
water usage than outdoor fields (Kohlstedt 2015;
Shimamura 2016). New factories are now being
planned for Hong Kong, Mongolia, Russia, and China.
Special purpose LED lighting allows plants to
grow up to two and half times faster and has
decreased the cycle of days and nights with opti-
mized temperature and humidity conditions. At pre-
sent, harvesting is still carried out on a manual basis
but robots are planned in future upgrades. Mirai
concentrates on fast-growing leafy vegetables that
can be sent to market quickly.
Advantages of vertical farming
Despommiers original vision was a world full of sky-
scrapers with multiple levels cultivating crops
Figure 4. The Grocon Pixel building is an example of a
green office building in Carlton near the Melbourne central
business district. The multi-level building in the foreground
has wind turbines on the roof and adjustable side panels for
controlling exposure to solar radiation. If converted into a
vertical farm, solar panels could be used on the roof and
sidewalls and interior lighting would use high-efficiency LED
sources. At nearby Lincoln Square there is a million liter
holding tank under construction for local reuse of storm-
water. The conceptual model illustrated is the twinning of a
residential tower with a vertical farm.
SUSTAINABILTY: SCIENCE, PRACTICE AND POLICY 17
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throughout the year. In addition to generating more
farmland on a single ground-level footprint, this
would, according to a review by The Economist
(2010), slash the transport costs and CO
2
emissions
associated with moving food over long distances. It
would also reduce the spoilage that inevitably occurs
along the way.In putting forth his pioneering con-
ception, Despommier outlined a number of reasons
why vertical farming could be highly attractive to pol-
icy makers: all-year-round crop production; higher
yields (by a factor of six or more depending on the
crop), avoidance of droughts, floods, and pests; water
recycling; ecosystem restoration; reduction of patho-
gens; provision of energy to the grid through methane
generation from compost; reduction in use of fossil
fuels (no tractors, farm machinery, or shipping), and
creation of new jobs. The closed environment could
conceivably be also suitable for translation to other
planetary environments in the context of space
exploration (Giroux et al. 2006).
The claimed benefits of vertical farming can be
categorized and summarized in terms of economic,
environment, social, and political dimensions
(see also Murase and Ushada 2006; Fitz-Rodriguez
et al. 2010; Despommier 2010; The Economist 2010;
Kozai 2013).
Economic advantages
The economic advantages of vertical farming are
numerous and include the prestige of marketing
premium CGG food with export-sales potential and
a lower cost base due to protection from floods,
droughts, and sun damage. There are essentially no
requirements for fertilizers, herbicides, or pesticides.
No soil is needed if hydroponics is used, only
nutrients and a water supply.
There is no requirement for long-distance trans-
portation due to localized production and no need for
farm machinery such as tractors, trucks, or harvesters.
There are no seasonality issues because continuous
crop production occurs all-year round and can be
programmed to match demand. An economic benefit
may arise from reallocation of large rural farms to
energy production from solar and wind sources.
Vertical farming could provide a competitive
edge for Australia by combining extensive research
and development with farming experience, big data,
and modern technology to improve productivity.
Environmental advantages
The environmental benefits are significant, including
providing healthy organic food not contaminated
Figure 5. Racks of vegetables in a glasshouse design with hydroponics (Source: Sky Greens 2017).
18 K. BENKE AND B. TOMKINS
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from chemicals. There is greatly reduced use of fos-
sil fuels by avoiding transportation from rural zones
to the urban customer base. Burning fossil fuels can
be minimized by employing solar panels, roof-top
wind turbines, and storage batteries. This will lead
to a reduction in ecosystem-carbon levels.
Fresh water is augmented by evaporation of black
and gray water to conserve water resources. There is
also the potential to rejuvenate the national ecosys-
tem so that rural land is reclaimed for vegetation.
Most importantly, vertical farming supports environ-
mental sustainability.
Social advantages
Vertical farming will provide new jobs in engineer-
ing, biochemistry, biotechnology, construction,
maintenance, and research and development oppor-
tunities for improving the technology. Enhanced
productivity can lead to lower food and energy costs
and improve discretionary incomes. The oversupply
of high-rise apartments and disused warehouses in
capital cities can be reduced by using empty build-
ings for multi-storey farms close to the consumer,
rejuvenating neglected neighborhoods. The model
may help to address isolation in remote rural com-
munities by re-skilling workers in technology for
vertical farms in local towns and cities.
Political advantages
A key political advantage of vertical farms is that cli-
mate-change commitments are more easily satisfied
and the technology supports adaptation and mitiga-
tion. The closed-system approach supports biosecur-
ity because of greater protection from invasive pest
species. A distributed network of vertical farms has
lower blackout risks and there is also reduced
dependence on a few large power stations that are
vulnerable to earthquakes or terrorist attacks.
Challenges to vertical farming
There have been critics of the original vision of ver-
tical farming as described by Despommier (2010).
For instance, Cox (2016) claimed that there are a
number of problems including the limited range of
crops suitable for this business model (originally
mostly vegetables such as lettuce, strawberries, and
tomatoes), together with the small proportion of the
population that could be serviced and the expensive
energy requirements. Furthermore, he contends that
only the plants on the top level would benefit from
solar radiation in a greenhouse environment and
energy supplied by photovoltaics is limited because
plants cannot be stacked in vertical arrays.
The arguments advanced by Cox have become
less relevant due to continuing advances in technol-
ogy. For example, solar panels are now more effi-
cient for energy generation and light exposure is
more cost-effective due to the advent of new cheap
and energy efficient LED lighting. Additional sun
exposure is possible using rotatable stacked arrays of
plants inside a single high-rise enclosure (Morrow
2008; Massa et al. 2008). The cost of storage bat-
teries is decreasing rapidly by analogy with Moores
Law in electronics. The new LED sources have
potential for greatly increased yield in greenhouse
settings due to matching spectral characteristics with
plant type and physiology (Massa et al. 2008;
Trouwborst et al. 2010).
The challenges to vertical farming may be sum-
marized as follows (Alter 2010; The Economist 2010;
Cox 2016). Start-up costs can be high if land is pur-
chased in central business districts. The number of
crops grown is not as great as for rural farming.
Production volumes are also not as large as broad-
acre farming and scaling-up may add cost and com-
plexity. More specific challenges are the need to
manage disruption to the rural sector, to raise
investment capital, and to train a skilled workforce.
Key performance indicators
Key performance indicators (KPIs) are metrics that
can be used to support the evaluation of vertical
Figure 6. A controlled-environment farm in Victoria showing
tomato crop.
SUSTAINABILTY: SCIENCE, PRACTICE AND POLICY 19
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farming. The KPIs may be quantifiable or qualitative
assessments based on modeling, analysis, literature
review, and expert opinion. The factors making up
the KPIs are itemized in Table 1. The tabulated val-
ues are discussed in greater detail in the following
subsections. Note that each KPI identified as satis-
fied may still be improved in future. An advantage
of the KPI table is that it highlights and ranks issues
of importance. This methodology also provides the
foundations for further analysis if there is a quanti-
tative dimension to the performance indicator.
Start-up costs
In many cities, such as Melbourne or Sydney,
startup costs relate mainly to very expensive real
estate in urban areas compared with rural land and
also depreciation costs on plant and machinery.
While disused warehouses may be available and land
reclamation might be possible, in the main this can-
not be regarded as a large-scale solution. A key
question for an investor is how many years to the
break-even point. A disadvantage of farming in
built-up inner city areas near the central business
district is the very high cost of property in some cit-
ies. For the purpose of conversion to commercial
use, the relevant reported apartment values for
Melbourne were in the vicinity of US$349,000
median for the lowest quartile in 2016 (REIV 2016).
A recent Victorian government report has set stand-
ards of 65 square meters minimum for human com-
fort and habitability (Design Standards 2016).
Assuming, conservatively, a figure of 100 square
meters for notional apartment size then the potential
cost for urban arable land would be around
US$3,491 per square meter.
For a hypothetical 10-level vertical farm, the land
cost would be reduced by an order of magnitude to
US$349 per square meter per arableunit. In con-
trast, rural values for Victoria were in the vicinity of
US$3,967 per hectare in 2015, or US$0.40 per square
meter (using data from Kuchel 2016). These calcula-
tions are approximate only and subject to modifica-
tions due to fit-out in the buildings but clearly
reveal the huge cost disparity in land values. The
history of property prices indicates a trend of greater
divergence between urban land and rural land in the
future suggesting that this will be a continuing chal-
lenge to the cost base of an urban farm. A startup-
urban farm may well be saddled with an initial cost
in the order of US$317 per square meter for arable
area, without construction and fit-out, which would
be reflected in the price of the product.
Beyond land values, a traditional single-level
greenhouse outside the inner urban area has been
Figure 7. Example of a large-scale indoor farm in Singapore (Source: Sky Greens 2017).
Table 1. Vertical farm key performance indicators (KPIs).
Key performance indicator Satisfied Partial Not satisfied
1. Start-up costs
2. Energy consumption
3. Number of crop types
4. Production volume
5. Scaling-up issues
6. Venture capital
7. Skilled workforce for maintenance
8. Disruption to the rural sector
9. Transport savings
10. Clean, green and gourmet food
20 K. BENKE AND B. TOMKINS
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estimated to cost around US$317 per square meter
in Victoria and as little as US$0.791.58 per square
meter in developing countries (Tomkins 2016).
According to calculations by Tomkins, one can grow
five times as much in an indoor setting relative to
the field, so therefore the cost reduces to US$70 per
square meter. Therefore, potential productivity
improvement on the same geometrical footprint of
land could be 50-fold. A derivative of vertical
farming is a single-level high-ceiling greenhouse
enclosure with multiple stacked racks, up to 10 lev-
els or more, which represents a further improvement
in infrastructure cost.
Australia has very expensive real estate in the
capital cities, which presents a planning difficulty at
the commercial scale (Parkinson 2016). In particular,
the high property prices may mean some investors
will see vertical farming as a proxy for the property
market. Nevertheless, several Japanese companies are
investing heavily in the infrastructure side to sup-
port this approach (Parkinson 2016).
In summary, infrastructure depreciation and
improved productivity will eventually lead to parity
with the annual running cost of outdoor farming,
but it is not clear when this will happen. If the yield
per hectare for indoor farming is much higher than
rural outdoor farming, perhaps as much as up to 50
times, this factor will eventually outweigh the initial
cost of land acquisition. The break-even point is the
number of years from startup, and this will largely
determine when the availability of CGG food is not
hampered by the cost structure. In the case of
Victoria, comparing the previously stated urban and
rural prices, and assuming 50-fold improved prod-
uctivity, the break-even point may well be an esti-
mated 67 years.
In contrast to Melbourne or Sydney, in some
areas in the United States, there is no shortage of
affordable properties in former industrial districts
located near major cities, such as New York and
Chicago, which are suitable for reuse for vertical
farming. This is not a matter of expensive land near
the central business district, but old industrial build-
ings standing vacant for decades and highly amen-
able to conversion to vertical farming without the
need for major investment. For instance, AeroFarms
in 2015 converted a former lumberyard in Newark,
NJ, into one of the largest vertical farms in the
world, with racks stacked twelve layers tall, in order
to grow kale, bok choi, watercress, lettuce, and other
baby-salad greens (Frazier 2017).
Energy consumption
Energy requirements are based on whether there is a
need for stand-alone off-the-grid farming or not,
which is not in itself a critical factor. Some
researchers have developed a rule of thumb that the
area of solar panels required would need to be a fac-
tor of twenty times greater than the arable area on a
multi-level indoor farm, which was impossible for
rooftop solar at that time (The Economist 2010).
Since then, project sponsors have submitted plans
for a new high-rise residential tower in Melbourne
that is sheathed in high-efficiency photovoltaics and
new generation LED lighting. The proposed Sol
Invictus building is described as an off-the-grid60-
level residential tower that will have rooftop-wind
turbines, doubled-glazed windows, and battery stor-
age from the solar panels (Johanson and Pallisco
2016). It was reported that the facade would have an
area of 3,000 square meters of photovoltaics plus
300 square meters of similar equipment on the roof.
This represents technology that is already two years
old and further improvement is likely by the time
construction begins two years from now. The exter-
nal energy requirements of an indoor farm have
diminished greatly and are likely to approach off-
the-grid operation at some time in the near the
future.
Number of crop types
Despommier (2010) and others claim that, in prin-
ciple, any crop can be grown in a vertical farming
greenhouse. Most current production involves let-
tuce species, plus tomatoes, and strawberries. Other
crops, including grain, grape, and tree fruit, are also
feasible options. Soy products would provide a pro-
tein substitute and could have an impact on the
meat industry. It is to be noted that soyprotein
replacement for chicken is already available in
supermarkets. Aquaculture and pharmaceutical pro-
duction may also be suitable for this type of farm-
ing, as is legal cannabis cultivation.
Frazier (2017) reported that a reason for leafy
greens being very popular as a crop is that they pro-
vide a premium profit margin, rather than any
inherent limitations in crop types. Supplying prox-
imate restaurants with fresh local produce has been
a successful marketing strategy by local urban farms.
Potatoes, sweet potatoes, and bulb onions have been
grown in a glasshouse by the second author using
hydroponics. Production of tree crops may require
more thought and effort but can be achieved by
growing mini-trees or on dwarfing rootstocks. This
form of cultivation may need more space between
the growth modules to allow taller crops but with
fewer vertical layers in the farm.
Production volume and scaling-up
Vertical farming does not as yet, in terms of produc-
tion volume, pose a risk to traditional agriculture.
SUSTAINABILTY: SCIENCE, PRACTICE AND POLICY 21
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This threat is likely to be some years away following
the extant trends cited earlier. It needs to be noted
that greater production volumes can be achieved by
vertical expansion in multi-rack systems, horizontal
expansion, or more construction sites around coun-
try towns.
The question that needs more research and ana-
lysis is the degree to which vertical farming could
undermine broad-acre production. Hamm (2015)
estimates that three facilities the size of the Empire
State Building could produce enough wheat to feed
New York City. The question is, would wheat and
other relatively low-value agricultural commodities
make economic sense given the high capital cost of
establishing and running a vertical farm. Low-value
field crops are not economically viable at present,
but this may change in the future with an ever
changing climate, scarce arable land, and diminish-
ing and intermittent resources such as water.
Once established, vertical farming expansion
would tend to be incremental in cost. Multi-floor
systems, however, may have the same limitations
which are evident with residential high-rise build-
ings, such as regulated height limits or fire security.
Production volume is not yet regarded as a limiting
factor in the special case of CGG food destined for
affluent clients. Implementation of the vertical farm-
ing model may be more pronounced toward the
year 2050 due to climate change and rapidly declin-
ing availability of arable land per capita. Volume
production and application to broad-acre crops
remain current limitations to vertical farming.
Venture capital
Venture capital could be attracted from local invest-
ors or from investors located overseas where there is
keen interest in CGG food, where land is at a pre-
mium, or where there is land contamination and air
pollution. Cost of food for affluent consumers is not
a major deterrent. Indoor farming is likely to be an
attractive target for funding or co-investment from
government, industry, and universities, due to the
nature and potential of the projects.
Skilled workforce for new jobs
Farming in high-rise buildings will generate new
careers for technologists, project managers, mainten-
ance workers, marketing, and retail staff. There will
need to be workers to manage planting, cultivation,
monitoring, harvesting, and research and develop-
ment (Despommier 2010). Consulting engineers will
be required to install and manage air-conditioning,
water recycling, and lighting controls. In industrial-
ized economies, there are few problems in providing
skilled labor or scientific resources due to the supply
of university-educated workers.
At the same time, novel industries may develop to
provide advanced electronic instrumentation and
services with consulting professionals advising on
derivatives of the vertical farming concept, such as
rooftop gardens on apartment buildings, office blocks,
restaurants, hospitals, and a technology-driven resur-
gence of the backyard greenhouse (Despommier
2010). The new jobs created may prove to be more
highly skilled and diverse and probably increase over-
all employment in the food-production sector. The
semi-automation of some aspects of the food cycle
will also provide opportunities for robotics and soft-
ware engineers for process improvement.
It is also possible to conceive of social benefits
that may accrue from the vertical farming model of
food production. It is well established that rates of
depression and suicide are higher in remote regions
and part of this problem relates to isolation and
lack of a vibrant social network, especially for
males (Roy, Tremblay, and Robertson 2014;
Fontanella et al. 2015). Vertical farming has ele-
ments of a collective enterprise with social interac-
tions among activities, providing meeting places for
socially isolated staff with opportunities for new
friendships.
Disruption to the rural sector
Potential disruption to the rural sector is an emerging
issue but contained in the short term by high startup
costs associated with vertical farming. The future out-
look entails the emergence of other less benign chal-
lenges to the sustainability of traditional farming
models. Costs for vertical farming are decreasing rap-
idly due to advances in automation and greenhouse
technology. Strategy and planning are needed to
address the transition to controlled-environment
agriculture, including education of government offi-
cials and farmers to familiarize them with the new
technologies and support for infrastructure
development.
Transportation savings
The location of food production in urban areas in
closer proximity to consumers is an attractive notion
and will likely result in dramatic reductions in trans-
portation costs. Vertical farming also cuts green-
house-gas emissions from trucks and therefore
supports adaptation and mitigation with respect to
climate change. It has been reported that 20%of
carbon emissions in the United States originate from
the farming sector (Despommier 2010). Marked
reduction in agricultural emissions is also plausible
for Australia.
22 K. BENKE AND B. TOMKINS
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Clean, green, and gourmet (CGG) food
The possibility of CGG food production is easily the
most attractive feature of the vertical farming model.
This aspect is less price sensitive to affluent consumers
in high-demand countries such as China. All-year-
round crop production without seasonality, in a cli-
mate-controlled environment (including both tem-
perature and humidity), will produce fresh produce
virtually on demand. There would be no weather-
related crop failures due to drought or flooding if
hydroponic and aeroponic technologies are employed.
Using recycled water and nutrients in a closed,
indoor, climate-controlled environment adds to food
security and can reduce or even completely elimin-
ate the need for pesticides and herbicides.
Contamination by pathogens or heavy metals will
no longer be an issue as occurs in rural farming.
There is scope for marketing the product in this
respect. Strict hygienic practices must still be
observed to minimize the risk of introduction of
pathogens and biological contamination into the
growing space. However, in a vertical farming situ-
ation, one can closely monitor the crop for signs of
pest or disease both manually and automatically
using sensing technologies. This mode of cultivation
is very well suited to adopting new and emerging
robotic technologies as well as remote-sensing pro-
cedures. This means that outbreaks are detected
early to enable diseased and infested plants to be
identified and disposed of appropriately. Any
residual contamination can be cleaned up when the
crop is harvested using strict hygienic practices.
One possible obstacle to vertical farming is that
some consumers may regard the products as
Frankenfoods,as discovered by managers of a giant
underground farm supplying Londons restaurants
(Curtis 2016) and another business that supplies
between 8%and 12%of the British output of toma-
toes, peppers, and cucumbers (Fletcher 2013). For this
reason, some enterprises may not publicize growing
conditions for fear of alienating consumers and desta-
bilizing sales potential. To minimize this issue, it can
be stressed that growing conditions are not different
from existing hydroponic facilities with respect to
germplasm, nutrition, and other cultural and produc-
tion practices. Furthermore, the plants are derived
from natural breeding programs with normal
nutrients supplied. There is an advantage that plants
are grown in a hygienic environment with reduced
need for pesticides and are in a closed system so there
is no environmental pollution from nitrogen leaching
or run-off.
Triple bottom line categories
Using the framework of the triple bottom line (TBL)
as described by Slaper and Hall (2011) allows us to
summarize the impacts associated with vertical
farming in Table 2. This assessment is based on a
combination of claimed advantages, cited literature,
and the KPI framework discussed previously and
presented in Table 1. Evaluation of these metrics
cannot be easily monetized but a statement of effects
supports qualitative evaluation and identifies issues
for later quantitative analysis. In the category of
Economics, impacts include improved productivity,
lower costs for farm chemicals, reduced losses from
floods and droughts, decreased transportation costs,
and all-year-round production. In the category of
Environmental, key impacts are export potential of
CGG foods, no soil required, reduced carbon levels,
and sustainability. In the category of Social, impacts
include employment, social interaction, and a more
holistic lifestyle where apartments and food can be
co-located in many cases.
Conclusion
The global megatrends of decreasing water supply,
increasing population, urbanization, and unabated
climate change have contributed to globally decreas-
ing stocks of arable land per person. Under these
circumstances, the sustainability of the traditional
farming model based on large rural farms is likely
to come under threat in coming decades. One
approach for engaging with this challenging problem
is vertical farming, which is based on controlled-
environment agriculture and greenhouse designs
suitable for urban settings.
This article describes vertical farming and its
derivatives and highlights the implications for future
food production. A number of the advantages and
Table 2. Triple bottom line potential impacts of vertical
farming.
Category Impacts
Economics Improved productivity
Reduced cost base for fertilizers, herbicides, and
pesticides
No losses due to floods, droughts or sun damage
Reduced transportation costs
No requirement for farm-rolling stock
Production can be programmed to match
demand because no seasonality issues
Environmental Export potential of clean, green, and food
No soil is required if hydroponics is used
Reduces fossil fuel use by employing renewable
energy sources
Reduction in carbon levels
Rejuvenation of the ecosystem
Environmental sustainability
Social Provides employment in regional areas
Addresses social isolation in remote rural com-
munities by providing jobs in towns
Increases demand for trade workers in construc-
tion, renovation, and ongoing maintenance
Provides new jobs in engineering, biochemistry,
biotechnology, construction and maintenance,
and research and development
Encourages a more holistic lifestyle where apart-
ments and food production are localized and
therefore reduces need for vehicles and transport
SUSTAINABILTY: SCIENCE, PRACTICE AND POLICY 23
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disadvantages associated with these cultivation meth-
ods are identified and investigated.
Vertical farming has been demonstrated at the
pilot scale and also at the production level and has
potential advantages over rural farming, including
the use of hydroponics, which challenges the need
for soil-based farming for a range of crops. Under
this mode of cultivation, productivity scales up with
the number of levels in a high-rise building or num-
ber of racks in a single high-rise enclosure. Many of
the supporting technologies have been explored in
past variations of greenhouse farming but are now
coalescing into commercially viable systems due to
rapid recent advances in electronics, engineering,
solar power, wind power, storage batteries, LED
lighting, water recycling, and computing power.
The challenge to traditional agriculture will occur
initially with the multi-rack mechanized system
within a single high-rise greenhouse. Multi-rack sys-
tems are already in operation globally and expand-
ing rapidly. For example, these technologies are
marketed by several major Japanese firms and sup-
ported by research at a number of universities
(Kozai 2013; Pantaleo 2014). There are also com-
mercial counterparts in the United States, Canada,
China, Israel, South Korea, and the Netherlands. In
time, funding for indoor-farming research will com-
pete with field hydrology and soil science, or even
against outdoor smart agriculturewhich uses the
Internet of Things, drones, and satellite imaging. In
the distant future, there is the prospect of fully auto-
mated urban farms based on vertical farming and
controlled-environment agriculture.
The potential benefits of vertical farming include a
sustainable food-production model with all-year-
round crop production, higher yields by an order of
magnitude, and freedom from droughts, floods, and
pests. The approach is compatible with water recy-
cling, ecosystem restoration, reduction of pathogens,
energy production by methane generation from com-
post, decreased use of fossil fuels (no tractors, plows,
or shipping), generation of new jobs for many years,
and low or no requirement for pesticides.
The construction industry could receive a boost
with rising demand for new vertical farming facto-
ries in urban areas and perhaps on the fringes of
regional towns. Future employment spurred by this
mode of cultivation and its derivatives has the
potential to provide new careers because engineers
will be needed to design and manage air condition-
ing, water recycling, and lighting, as well as the
overall optimization of complex systems. There will
be employment opportunities in maintenance, seed
planting, monitoring, and harvesting. In time, as
process automation proceeds, new job requirements
will include systems analysis and software
development.
A current problem is the high startup costs due
to land prices in inner urban areas in some global
cities (as described in the case of Melbourne). This
situation may be improved by recycling old build-
ings or using sites on city fringes and around
regional towns. In some rust beltstates in the
United States, there is no shortage of vintage struc-
tures and disused factories in outer suburban areas.
Another issue is energy consumption if full off-the-
grid production is required (which is being
addressed with evolving technology related to
renewable energy and battery storage). Infrastructure
depreciation will eventually lead to parity with the
annual running cost of outdoor farming, although it
is not clear when this crossover point will be
reached. Yields per hectare in a glasshouse are
claimed to be much higher than rural outdoor farm-
ing, by an order of magnitude at least, and this fac-
tor will help to compensate for the higher cost of
land.
The volume of output and biodiversity in vertical
farming is not yet a threat to the sheer scale of agri-
culture in regional broad-acre crops, such as wheat,
but this is changing. Production from indoor farms
continues to increase while the trend in regional
farming is toward ever lower levels of arable land
per person. The current dominating theme with
indoor agriculture is premium CGG food for export,
rather than production volume.
Important policy issues addressed by vertical
farming are food security and response to the effects
of climate change. Some urban centers, such as
Singapore, already produce 10%of leafy green vege-
tables by indoor farming because of a commitment
to enhance domestic food security. The closed-envir-
onment model can also be translated to remote
polar or desert regions, or even space exploration,
where food production on spacecraft or other plan-
ets may be necessary (Giroux et al. 2006).
In light of these circumstances, we proffer several
recommendations. First, there needs to be more
accurate quantification of the economics of vertical
farming and its derivatives using computer simula-
tion and detailed analysis of new commercial instal-
lations. Requirements for the business case include
analysis of cost base and profitability by investiga-
tion of full life-cycle analysis (LCA) with a trad-
itional farm as a benchmark. There is also a need to
estimate the number of years to reach parity with a
traditional farm with respect to return on invest-
ment (ROI), and a tradeoff study on key cost drivers
including land, plant depreciation, market demand,
and reduced transportation costs.
Second, the research needs to focus on investiga-
tion of vertical farming derivatives, such as single-
level greenhouse designs in novel urban configura-
tions, including underground, on rooftops in cities,
24 K. BENKE AND B. TOMKINS
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or in disused warehouses. The economic proposition
will likely vary with these options.
Third, we suggest greater in-depth exploration of
multiple-rack stacked designs that can be rotated
according to optimum solar exposure in a single
high-rise greenhouse enclosure. This derivative is
already in operation in some countries and repre-
sents an entry point to vertical farming technology.
Fourth, policy makers may consider development
of change-management strategies for future transi-
tion of affected parts of the field-horticulture indus-
try. This could entail education of farm workers
with new skills more suited to controlled-environ-
ment agriculture. Business and management skills
could also be addressed with education and profes-
sional assistance.
Fifth, it is necessary to begin to identify employ-
ment opportunities in technology, monitoring,
maintenance, customer service, and research and
development surrounding vertical farming. The job
mix may change in time with increasing levels of
process automation. For example, manual handling
and routine hardware maintenance may be replaced
by engineering skills in process control and moni-
toring, emergency repairs, and software
development.
Finally, there is a need for increased funding for
research in plant genetics for yield optimization,
extending the range of crop types, and fine-tuning
for optimal response to controlled variables such as
wavelength of LED lighting, temperature, humidity,
and CO
2
levels.
Acknowledgement
The authors thank Sevgi Kilic for her interest and
encouragement.
Disclosure statement
No potential conflict of interest was reported by the
authors.
ORCID
Kurt Benke http://orcid.org/0000-0002-7812-3671
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... Today the global food system must meet the world's growing needs. Meanwhile, we face many challenges in global food safety, such as increasing population, urbanization, diminishing water supply, continuing climate change, and decreasing stock of agricultural land per capita (Benke & Tomkins, 2017;Fedoroff, 2015). Considering these problems, future greenhouses are characterized by a more efficient cultivation system to produce specialized crops in the way of industrial production. ...
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... Penyesuaian lingkungan hidup tumbuhan dilakukan agar agrikultur dapat lebih berkelanjutan dan lebih mudah diterapkan di lahan terbatas. Berbagai parameter meliputi pencahayaan, suhu, kelembapan, dan pengairan dapat disesuaikan dan dikontrol (Benke & Tomkins, 2017). Dengan bantuan machine learning dan Internet of Things (IoT) menjadikan penerapan agrikultur menjadi lebih baik. ...
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Aeroponics involves spraying plant roots with a fine mist of a complete nutrient solution. At Massey University we have used aeroponics for both plant research and for crop production, and have developed systems for growing vegetable crops eg. tomatoes, cucumbers, potatoes and herbs, and flower crops Lisianthus and Zantedeschia. Aeroponic techniques have also been used as a research tool to examine gas levels in the root zone, crop nutrition and root growth.
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Light is one of the most important environmental stimuli impacting plant growth and development. Plants have evolved specialized pigment-protein complexes, commonly referred to as photoreceptors, to capture light energy to drive photosynthetic processes, as well as to respond to changes in light quality and quantity. Blue light can act as a powerful environmental signal regulating phototropisms, suppression of stem elongation, chloroplast movements, stomatal regulation, and cell membrane transport activity. An emerging application of light-emitting diode (LED) technology is for horticultural plant production in controlled environments. Work by our research group is measuring important plant responses to different wavelengths of light from LEDs. We have demonstrated positive impacts of blue wavelengths on primary and secondary metabolism in microgreen and baby leafy green brassica crops. Results show significant increases in shoot tissue pigments, glucosinolates, and essential mineral elements following exposure to higher percentages of blue wavelengths from LED lighting. The perception of energy-rich blue light by specialized plant photoreceptors appears to trigger a cascade of metabolic responses, which is supported by current research showing stimulation of primary and secondary metabolite biosynthesis following exposure to blue wavelengths. Management of the light environment may be a viable means to improve concentrations of nutritionally important primary and secondary metabolites in specialty vegetable crops. © 2015 American Society for Horticultural Science. All rights reserved.
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Light-emitting diodes (LEDs) have tremendous potential as supplemental or sole-source lighting systems for crop production both on and off earth. Their small size, durability, long operating lifetime, wavelength specificity, relatively cool emitting surfaces, and linear photon output with electrical input current make these solid-state light sources ideal for use in plant lighting designs. Because the output waveband of LEDs (single color, nonphosphor-coated) is much narrower than that of traditional sources of electric lighting used for plant growth, one challenge in designing an optimum plant lighting system is to determine wavelengths essential for specific crops. Work at NASA's Kennedy Space Center has focused on the proportion of blue light required for normal plant growth as well as the optimum wavelength of red and the red/far-red ratio. The addition of green wavelengths for improved plant growth as well as for visual monitoring of plant status has been addressed. Like with other light sources, spectral quality of LEDs can have dramatic effects on crop anatomy and morphology as well as nutrient uptake and pathogen development. Work at Purdue University has focused on geometry of light delivery to improve energy use efficiency of a crop lighting system. Additionally, foliar intumescence developing in the absence of ultraviolet light or other less understood stimuli could become a serious limitation for some crops lighted solely by narrow-band LEDs. Ways to prevent this condition are being investigated. Potential LED benefits to the controlled environment agriculture industry are numerous and more work needs to be done to position horticulture at the forefront of this promising technology.
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Solid-state lighting based on the use of light-emitting diodes (LEDs) is potentially one of the biggest advancements in horticultural lighting in decades. LEDs can play a variety of roles in horticultural lighting, including use in controlled environment research, lighting for tissue culture, and supplemental and photoperiod lighting for greenhouses. LED lighting systems have several unique advantages over existing horticultural lighting, including the ability to control spectral composition, the ability to produce very high light levels with low radiant heat output when cooled properly, and the ability to maintain useful light output for years without replacement. LEDs are the first light source to have the capability of true spectral composition control, allowing wavelengths to be matched to plant photoreceptors to provide more optimal production and to influence plant morphology and composition. Because they are solid-state devices, LEDs are easily integrated into digital control systems, facilitating special lighting programs such as "daily light integral" lighting and sunrise and sunset simulations. LEDs are safer to operate than current lamps because they do not have glass envelopes or high touch temperatures, and they do not contain mercury. The first sustained work with LEDs as a source of plant lighting occurred in the mid-1980s to support the development of new lighting systems to be used in plant growth systems designed for research on the space shuttle and space station. These systems progressed from simple red-only LED arrays using the limited components available at the time to high-density, multicolor LED chip-on-board devices. As light output increases while device costs decrease, LEDs continue to move toward becoming economically feasible for even large-scale horticultural lighting applications.
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Mass production of moss plant has been expected because of huge demand of roof top greening of factory buildings. A biotechnology for proliferation of sunagoke moss has been developed. It will be produced from plant factory. A bio-response feedback control strategy known as Speaking Plant Approach (SPA) was applied to the automated moss plant production system. Moisture content, water potential and leaf area index were measured and used for an Artificial Neural Network (ANN) model output. Three textural analysis features (Energy, Local homogeneity, Contrast) were obtained for input parameters of the model. The results of the experiment using ANN model show that it is possible to predict the moss water status parameters by using textural features. It was shown that through appropriate selection of the architecture of the network, all parameters of moss water status can be predicted. By using back-propagation supervised learning and inspection data method, ANN prediction model was tested successfully describing the relationship between textural features and water status parameters. It also produced high correlation between measured and predicted value (R2 ranged from 0.90 to 0.98) and minimum absolute error using inspection data. This indicates that SPA will become an attractive strategy for control system for moss production factory.
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Light-emitting diodes (LEDs) have tremendous potential as supplemental or sole-source lighting systems for crop production both on and off earth. Their small size, durability, long operating lifetime, wavelength specificity, relatively cool emitting surfaces, and linear photon output with electrical input current make these solid-state light sources ideal for use in plant lighting designs. Because the output waveband of LEDs (single color, nonphosphor-coated) is much narrower than that of traditional sources of electric lighting used for plant growth, one challenge in designing an optimum plant lighting system is to determine wavelengths essential for specific crops. Work at NASA's Kennedy Space Center has focused on the proportion of blue light required for normal plant growth as well as the optimum wavelength of red and the red/far-red ratio. The addition of green wavelengths for improved plant growth as well as for visual monitoring of plant status has been addressed. Like with other light sources, spectral quality of LEDs can have dramatic effects on crop anatomy and morphology as well as nutrient uptake and pathogen development. Work at Purdue University has focused on geometry of light delivery to improve energy use efficiency of a crop lighting system. Additionally, foliar intumescence developing in the absence of ultraviolet light or other less understood stimuli could become a serious limitation for some crops lighted solely by narrow-band LEDs. Ways to prevent this condition are being investigated. Potential LED benefits to the controlled environment agriculture industry are numerous and more work needs to be done to position horticulture at the forefront of this promising technology.