Energy and the New Reality, Volume 1: Energy Efficiency and the Demand for Energy Services Chapter 7: Agricultural and Food System Energy Use L. D. Danny Harvey [e-mail]

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Energy and the New Reality, Volume 1Energy
Efficiency and the Demand for Energy Services
Chapter 7 Agricultural and Food System Energy
Use L. D. Danny Harveyharvey_at_geog.utoronto.ca
Publisher Earthscan, UKHomepage
www.earthscan.co.uk/?tabid101807

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Energy Use in the Food System

• Energy used in producing food
• Energy used in transporting and processing food
• Energy used to make packages for food
• Energy used by food retailers
• Energy used by consumers in getting, storing and
  cooking food

3
Energy Used In Producing Food

• Energy to make fertilizers and pesticides
• Fuels for tractors and other equipment
• Fuels for heating and ventilation of farm
  buildings, livestock and poultry facilities
• Electricity for irrigation (if used), lighting,
  buildings
• Embodied energy in equipment and buildings

4
Figure 7.1 Energy used during the production of
food in the US
Source Schnepf (2004, Energy Use in Agriculture
Background and Issues, CRS Report for Congress
RL32677, www.nationalaglawcenter.org/assets/crs/RL
32677.pdf)
5
Figure 7.2 Energy use in the US food system
Total non-solar energy input 10.8 EJ/yr Food
energy produced 1.48 EJ/yr
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Nitrogen

• Occurs in the atmosphere as N2 (78 of air)
• Needs to be converted to NH4 (ammonium) in order
  to be useable (assimilable) by plants a process
  called nitrogen fixation
• Only certain bacteria, which live in the roots of
  only certain plants, can carry out nitrogen
  fixation
• Some ammonium is oxidized to nitrate (NO3-) in a
  process call nitrification and taken up by plants
  in that form

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Figure 7.3 Nitrogen Cycle
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Non-energy issues related to N fertilizer

• Leaching into groundwater and runoff into streams
  and eventually the oceans
• Growing incidence of coastal oceanic dead zones
  due to eutrophication
• Emissions of N2O (a powerful GHG) associated with
  nitrification and denitrification reactions
• NO emissions, contributing to loss of
  stratospheric O3
• NO and NO2 emissions (NOx), contributing to
  buildup of tropospheric O3 and to acid rain

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Distribution of eutrophication-assisted coastal
dead zones
Source Diaz et al (2008, Science 321, pp926-929)
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Distinction

• Nitrogen fertilizer is manufactured, requiring
  energy inputs and a source of H2, which is
  combined with atmospheric N2 to produce NH4 as a
  first step (both the energy and H2 come from
  natural gas at most N-fertilizer plants, although
  the Chinese use coal)
• Phosphorus fertilizer is mined from P-containing
  rocks (phosphates)

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Figure 7.4 Global P flow
Source Cordell et al (2009a, Global
Environmental Change 19, 292305,
http//www.sciencedirect.com/science/journal/0959
3780)
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Figure 7.5 Distribution of P reserves
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Non-energy issues with respect to P fertilizer

• Environmental impacts of mining, due to
  contamination of most phosphate deposits with
  toxic heavy metals (As, Hg, Pb, Cd)
• Inability to use most of the economically-availabl
  e phosphate (reserves) as fertilizer due to heavy
  metal contamination
• Likely peaking of phosphate supply within 20-30
  years even without toxicity constraints

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Figure 7.6 Historical and projected annual P
supply from mining, the latter obtained using the
logistic function combined with estimates of the
ultimate cumulative use
Source Cordell et al (2009a, Global
Environmental Change 19, 292305,
http//www.sciencedirect.com/science/journal/0959
3780)
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Figure 7.7a World N Fertilizer Consumption
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Figure 7.7b World P Fertilizer Consumption
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Figure 7.7c World K Fertilizer Consumption
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Figure 7.8a Worldwide N Fertilizer Consumption in
2001
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Figure 7.8b Worldwide P Fertilizer Consumption in
2001
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Figure 7.8c Worldwide K Fertilizer Consumption in
2001
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Figure 7.9 Worldwide Fertilizer Energy Use in 2001
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Strategies to reduce the amount of energy used in
making fertilizers

• Increase the efficiency in manufacturing
  fertilizers
• Reduce the demand for chemical fertilizers

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Strategies to reduce the demand for chemical
fertilizers

• Use any applied chemical fertilizers more
  effectively, so that less is needed
• Substitute organic (natural) fertilizers for
  inorganic (manufactured) fertilizers

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Figure 7.10 Fertilizer embodied energy
25
Ways to reduce waste and runoff of inorganic
fertilizers

• Apply only what is needed based on updated
  measurements of soil conditions
• Apply fertilizers 2-3 times per year rather than
  1 large application per year (sometimes in the
  fall!)
• Apply fertilizer in rows during seeding rather
  than over the entire field (10-30 savings)
• Maintain fertilizer application equipment (20
  savings)

Overall estimated savings potential in The
Netherlands 35-40
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From Table 7.4, percentage of added N fertilizer
that is absorbed by plants, as measured on farms

• For corn in the north central US 37
• For rice in Asia when no guidance is given to
  farmers 31
• For rice in Asia when fertilizer application is
  adjusted to match needs 40
• Wheat in India, poor year 18
• Wheat in India, good year 49

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Figure 7.11 US corn yield and fertilizer use
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Organic fertilizers

• Manure
• Crop residues
• Food processing wastes
• Human wastes

29
Issues related to use of organic fertilizers

• Proximity to fields (especially with large
  centralized feedlot operations)
• Bulk
• Contaminants (an issue with municipal sewage
  plant sludge)
• Controlled release of nutrients

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Pesticide use and energy intensity
Table 7.5 Worldwide and US pesticide use during
1998-1999, and energy intensities.
Sources Pretty (2005, in Issues in Environmental
Science and Technology, No 21, Sustainability in
Agriculture, Royal Society of Chemistry, London
) for use and Helser (2006, in Encylcopedia of
Pest Management, Taylor Francis, London ) for
intensities.
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A number of jurisdictions in the world have set
aggressive targets for reducing pesticide use, or
are experimenting with systems involving much
lower use of pesticides.

• 50 reduction targets for the Canadian provinces
  of Ontario and Quebec
• Integrated Pest Management (IPM) projects have
  been carried out around the world
• A survey of 62 IPM projects from 26 countries
  found that crop yield increased when pesticide
  use was decreased in 60 of the cases
• This could be related to an overall improvement
  in management practice associated with the
  training that farmers received as part of IPM, or
  due to money saved on pesticides being invested
  in other ways to increase yields

32
Low-input farming systems

• No-till agriculture
• Organic agriculture
• Urban agriculture

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No-till agriculture

• Avoids tilling (overturning) the soil
• Saves fuel, conserves soil moisture and reduces
  wind erosion
• Usually is accompanied by increased use of
  herbicides (tilling removes weeds this is no
  longer done) and sometimes by increased use of
  fertilizers
• Net result very little change in energy use

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Table 7.7 Comparison of energy inputs for
conventional and organic farming in Finland.
Required land areas are given as hectares per
functional units (FUs) of either 1000 kg bread or
1000 litres milk.
Source Grönroos et al (2006, Agriculture,
Ecosystems and Environment 117, 109118)
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Table 7.8 Comparison of energy inputs (GJ/ha/yr)
for conventional and organic systems of farming
for two case studies in Denmark.
Source Jørgensen et al (2005, Biomass and
Bioenergy 28, 237248, http//www.sciencedirect.c
om/science/journal/09619534)
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Table 7.9 Comparison of measured energy inputs
and yields for current conventional and organic
farming in Denmark, and as expected for future
organic farming.
Source Daljaard et al (2002, in Economics of
Sustainable Energy in Agriculture, Kluwer
Academic Publishers, Dordrecht, The Netherlands)
37
Table 7.10 Comparison of energy inputs (MJ/kg)
and yield (t/ha) for corn in southwestern
Ontario, Canada, using chemical fertilizers or
swine manure.
Source McLaughlin et al (2000, Canadian
Agricultural Engineering 42, 917)
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Table 7.11 Comparison of energy inputs (GJ/ha)
during the last 5-year rotation in a 32-year
field experiment involving winter barley, winter
wheat, and sugar beets in Germany on relatively
fertile soil using either chemical fertilizers or
manure.
Source Hülsbergen et al (2001, Agriculture
Ecosystems and Environment 86, 303321)
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Summary on low-input farming systems

• There is typically a 35-50 reduction in the
  energy required to produce a given amount of food
  using organic methods compared to conventional
  methods
• Yields (food production per unit of land area)
  typically fall by 10-20 (sometimes by
  35,sometimes not at all)
• However, current crop varieties have been
  optimized through breeding for conventional
  systems of production. Re-optimization for
  organic systems may result in no reduction in
  yield
• If this is insufficient, modest reductions in
  meat consumption could readily compensate for
  decreases in agricultural yields due to a shift
  to organic agriculture

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Energy Use by Fisheries

• Fish are one of the most energy-intensive food
  products
• Energy intensities have increased in recent years
  due to the use of larger ships (one huge shipped
  trawling until it is full carries more tonne-km
  of cargo than many smaller ships with the same
  total capacity) and the greater distances
  travelled now from the home port for most fleets
• Extermination of the worlds commercial fisheries
  will occur by 2050 if current trends continue
  (algae will take over the oceans)
• As the remaining stock is further depleted, the
  energy expended for tonne of fish harvested will
  increase further

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Table 7.12 Ratio of fossil fuel energy input to
protein energy output for various US fisheries.
Source Rawitscher and Mayer (1977, Science 198,
261264)
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Table 7.13 Ratio of fossil fuel energy input to
protein energy output for various aquaculture
fisheries.
Source Pimental and Pimental (2008, Food,
Energy, and Society, 3rd Edition, CRC Press,
Boca Raton)
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Role of diet
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Figure 7.12 Phytomass energy flows in the world
food system.
Source Wirsenius (2003, Journal of Industrial
Ecology 7, 4780)
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Table 7.15 Ratio of phytomass energy input to the
metabolizable energy of animal products consumed
by humans (MJ/MJ).
Source Computed from data in Wirsenius (2000,
Human use of land and organic materials, Ph D
Thesis, Chalmers University of Technology,
Göteborg, Sweden)
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Table 7.16 Food energy consumption (including
losses by wholesalers and beyond) and phytomass
energy requirements for different diets assuming
inverse efficiencies of 1.5 for plant food, 7.7
for dairy products and 44.6 for land meat
products.
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Figure 7.13 Diet and waste in the food system
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Figure 7.14a Trends in global meat consumption
49
Figure 7.14b Trends in total global and average
per capita meat consumption
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Figure 7.15 Per capita meat consumption in
various countries
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Estimates of the total energy inputs for the
production of different food products
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Table 7.21 Estimated lifecycle secondary energy
inputs for food consumed in Sweden and the UK up
to the point of delivery to retail outlets. The
lifecycle energy inputs given here do not include
phytomass inputs.
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Figure 7.16 Energy embodied in a can of corn
Source Pimental and Pimental (1996, Food Energy,
and Society, 2nd Edition, University Press of
Colorado, 186201)
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Figure 7.17a GHG emissions per MJ of food energy
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Figure 7.17b GHG emissions per gm of food protein
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Figure 7.18 GHG emission per litre of beverage
57
Figure 7.19a Personal energy use, USA in 2002
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Figure 7.19b Personal energy use, Australia in
1993
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Figure 7.19c Personal energy use, UK in 1996
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Figure 7.19d Personal energy use, Sweden in 1996
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Figure 7.20. Comparison of per capita energy use
in supplying food in different countries
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The preceding estimates of energy input account
for all the energy used to produce the crops that
are fed to animals, but do not count the energy
of the crop phytomass itself.However, the crop
phytomass has energy value and so could be used
as a solid biofuel, or the land used to produce
the food for animals could instead be used to
produce bioenergy crops that are more suitable as
an energy sourceIn the following table, the
energy inputs used to produce different animal
products are combined with the energy value of
the food that is fed to the animals
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Table 7.22 Phytomass feed requirements per MJ of
animal product when fed grain or allowed to graze
on pasture, and fossil fuel energy and total
energy inputs per MJ of animal product. Two
forage entries are given for beef, the first for
high-quality pasture and the second for
low-quality pasture.
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Table 7.23 Comparison of annual energy use by a
family of four.
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Summary of Energy and Environmental Impacts of
Meat-based vs Vegetarian Diets

• Greater requirements for fertilizers, pesticides
  and water (to produce the phytomass that is fed
  to animals) (corn, most of which is fed to
  cattle, has one of the highest N requirements)
• Impacts of fertilizer runoff on coastal oceans
  (anoxic dead zones)
• Waste disposal problems and difficulty/impossibili
  ty of recycling nutrients in intensive animal
  production systems)
• Much greater land requirements a driving force
  (for example) of Amazon deforestation (much of
  which is to produce cattle for export to North
  America, or to produce soybeans that are fed to
  cattle in North America)
• Current levels of fish consumption are
  unsustainable, threatening eventual collapse of
  marine ecosystems and already threatening other
  species that depend on some of the same fish
  species

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Other considerations

• Health
• - High levels of consumption of red meat are
  associated with greater incidence of colorectal
  cancer
• - Hormones in grain-fed beef are hazardous
  (pregnant women should not eat such meat)
• - However, personal health will be worse if
  the wrong kinds of foods (especially starchy and
  sugary foods) are substituted for meat
• Ethics
• - Degrading treatment of animals prior to
  slaughter in the energy- and land-efficient,
  intensive meat production systems
• - Killing other sentient beings merely for ones
  personal pleasure (i.e., the taste of meat)

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Localized vs Globalized Agriculture

• Distance transported
• Efficiency of transport and of the distribution
  system
• Differences in land productivity in different
  regions
• Differences in the energy efficiency of the
  production system in different regions
• Differences in energy used for packaging
• Energy used for storage or in greenhouses for
  locally-produced food
• Food losses during storage and transport
• Comparison with energy use by consumers driving
  to and from a grocery store
• Meeting nutritional requirements of vegetarian
  and vegan diets

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Table 7.24 Comparison of the energy inputs
(embodied energy) in providing locally-produced
apples in Europe and apples imported from New
Zealand by ship. Losses during transport and
storage are neglected here.
Source Canals et al (2007, Environmental Science
and Pollution Research 14, 338344)
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Other considerations in the choice of local vs
imported food when the imported food comes from
developing countries

• Production and export of food from countries with
  warm climates and lots of sunshine (such as in
  Africa) could be a significant source of
  employment and income for these countries
• This in turn could spur large increases in
  agricultural yields, thereby reducing overall
  land requirements for agriculture (and will
  indirectly lead to lower rates of population
  growth and eventual population stabilization
  in the future)
• However, today some poor countries export food to
  the developed world while some of their own
  people go hungry

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Supplemental figure trends in agricultural
yield in different world regions
Source Hazell and Wood (2008, Phil. Trans Roy.
Soc. B, 383, 495-515)