Sustainable development 2
• Sustainable agriculture
• Sustainable agriculture integrates three
main goals: environmental stewardship,
farm profitability, and prosperous farming
communities. These goals have been
defined by a variety of disciplines and may
be looked at from the vantage point of the
farmer or the consumer.
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Description
Sustainable agriculture refers to the ability of a farm to produce food indefinitely,
without causing irreversible damage to ecosystem health. Two key issues are
biophysical (the long-term effects of various practices on soil properties and
processes essential for crop productivity) and socio-economic (the long-term ability of
farmers to obtain inputs and manage resources such as labor).
The physical aspects of sustainability are partly understood (Altieri 1995). Practices
that can cause long-term damage to soil include excessive tillage (leading to erosion)
and irrigation without adequate drainage (leading to accumulation of salt in the soil).
Long-term experiments provide some of the best data on how various practices affect
soil properties essential to sustainability.
While air and sunlight are generally available in most geographic locations, crops also
depend on soil nutrients and the availability of water. When farmers grow and harvest
crops, they remove some of these nutrients from the soil. Without replenishment, the
land would suffer from nutrient depletion and be unusable for further farming.
Sustainable agriculture depends on replenishing the soil while minimizing the use of
non-renewable resources, such as natural gas (used in converting atmospheric
nitrogen into synthetic fertilizer), or mineral ores (e.g., phosphate).
• Possible sources of nitrogen that would, in principle, be
available indefinitely, include:
• recycling crop waste and livestock or human manure
• growing legume crops and forages such as, peanuts, or
alfalfa that form symbioses with nitrogen-fixing bacteria
called rhizobia
• industrial production of nitrogen by the Haber Process
uses hydrogen, which is currently derived from natural
gas, but could instead be made by electrolysis of water
using electricity (perhaps from solar cells or windmills) or
• genetically engineering (non-legume) crops to form
nitrogen-fixing symbioses or fix nitrogen without
microbial symbionts.
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The last option was proposed in the 1970s, but would be well beyond the
capability of current (2006) technology, even if various concerns about
biotechnology were addressed. Sustainable options for replacing other
nutrient inputs (phosphorus, potassium, etc.) are more limited.
In some areas, sufficient rainfall is available for crop growth, but many other
areas require irrigation. For irrigation systems to be sustainable they must
be managed properly (to avoid salt accumulation) and not use more water
from their source than is naturally replenished, otherwise the water source
becomes, in effect, a non-renewable resource. Improvements in water well
drilling technology and the development of submersible pumps have made it
possible for large crops to be regularly grown where reliance on rainfall
alone previously made this level of success unpredictable. However, this
progress has come at a price, in that in many areas where this has
occurred, such as the Ogallala Aquifer, the water is being used at a greater
rate than its rate of recharge.
Socioeconomic aspects of sustainability are also partly understood.
Regarding nonindustrialized farming, the best known analysis is Netting's
(1993) study on smallholder systems through history.
• Economics
• Given the finite supply of natural resources, agriculture
that is inefficient may eventually exhaust the available
resources or the ability to afford and acquire them. It
may also generate negative externality, such as pollution
as well as financial and production costs. Agriculture that
relies mainly on inputs that are extracted from the earth's
crust or produced by society, contributes to the depletion
and degradation of the environment. Despite this
continuing practice, unsustainable agriculture continues
because it is financially more cost-effective than
sustainable agriculture in the short term.
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In an economic context, the need for the farm to generate revenue depends
on the extent to which it is market oriented and on government subsidy. The
way that crops are sold must be accounted for in the sustainability equation.
Fresh food sold from a farm stand requires little additional energy, aside
from that necessary for cultivation, harvest, and transportation (including
consumers). Food sold at a remote location, whether at a farmers' market or
the supermarket, incurs a different set of energy cost for materials, labour,
and transport.
To be sold at a remote location requires a complex economic system in
which the farm producers form the first link in a chain of processors and
handlers to the consumers. This practice allows greater revenue because of
efficient transport of a large number of items, but because it produces
externalities and relies on the use of non-renewable resources, shipping,
processing, and handling, it is not considered sustainable[citation needed].
Moreover, such a system is considered vulnerable to fluctuations, such as
strikes, oil prices, and global economic conditions including labour, interest
rates, futures markets, and farm product prices[citation needed].
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In Third World agriculture, much of what is known about the social components of
sustainability comes from anthropologist Robert Netting's work. In Smallholders,
Householders: Farm Families and the Ecology of Intensive, Sustainable Agriculture,
he defines an important cross-cultural pattern of high-labor, high-production
cultivation exemplified East Asian paddy rice cultivators, African cultivators such as
the Kofyar, alpine peasants, and Mesoamrican farmers of raised fields. One key to
socio-economic sustainability in such systems is that these farmers systems provide
for much of their own subsistence and also participate in the market.
From a system's view, the gain and loss factors for sustainability can be listed. The
most important factors for an individual site are sun, air, soil and water as rainfall.
These are naturally present in the system as part of the larger planetary processes
and incur no costs. Of the four, soil quality and quantity are most amenable to human
intervention through time and labour. (The economic input depends solely on the
price of labour and cost of machinery used).
Natural growth and outputs are also subject to human intervention. What grows and
how and where it is grown are a matter of choice. Two of the many possible practices
of sustainable agriculture are crop rotation and soil amendment, both designed to
ensure that crops being cultivated can obtain the necessary nutrients for healthy
growth.
• Methods
• Monoculture, a method of growing only one crop at a time in a given
field, is a very widespread practice, but there are questions about its
sustainability, especially if the same crop is grown every]. Growing a
mixture of crops (polyculture) sometimes reduces disease or pest
problems (Nature 406:718, Environ. Entomol. 12:625) but
polyculture has rarely, if ever, been compared to the more
widespread practice of growing different crops in successive years
crop rotation with the same overall crop]. For example, how does
growing a corn-bean mixture every year compare with growing corn
and bean in alternate years? Cropping systems that include a
variety of crops (polyculture and/or rotation) may also use replenish
nitrogen (if legumes are included) and may also use resources such
as sunlight, water, or nutrients more efficiently (Field Crops Res.
34:239)
• Some pesticides, though sometimes useful in the short term, can
harm the soil food web, a complex ecology of micro-organisms in
soil that helps sustain the plant from the roots down[]. Experiments
comparing plants grown in soil compared to plants grown through
hydroponics have shown a thirty-three percent higher growth rate
when there are beneficial soil microorganisms available[citation
needed].
• Certain pesticides synthesized by chemical companies can impart a
sometimes fatal toxicity to humans[citation needed], livestock and
insect pollinators, such as bees and butterflies, which may be
necessary for plant success[citation needed]. Without insect
pollinators, farm labor must be expended to manually pollinate each
plant. Crops such as cacao beans and vanilla are examples of crops
requiring highly labor-intensive practices in the absence of natural
pollinators.
• Throughout history, farmers seeking to grow
crops usually confine themselves to growing
only the fastest and most productive plants.
Such practices can result in growing crops
without the genetic diversity found in
wildlife[citation needed]. Without such diversity
in the genes, crops may become more
susceptible to disease and crop failure[citation
needed]. The Irish potato famine is a well-known
example of the dangers of monocultural and
mono-varietal crop cultivation[citation needed].
• Many scientists, farmers, and businesses have debated how to
make agriculture farming sustainable[citation needed]. One of the
many practices includes growing a diverse number of perennial
crops in a single field, each of which would grow in separate season
so as not to compete with each other for natural resources[citation
needed]. This system would replicate the biodiversity already found
in a natural environment, resulting in increased resistance to
diseases and decreased effects of erosion and loss of nutrients in
soil[citation needed]. Nitrogen fixation from legumes, for example,
used in conjunction with plants that rely on nitrate from soil for
growth, will allow the land to be reused annually[citation needed].
Legumes will grow for a season and replenish the soil with
ammonium and nitrate, and the next season other plants can be
seeded and grown in the field in preparation for harvest[citation
needed]. This method is considered to require a minimal amount of
outside resources[citation needed].
• In practice, there is no single approach to sustainable
agriculture, as the precise goals and methods must be
adapted to each individual case. There may be some
techniques of farming that are inherently in conflict with
the concept of sustainability, but there is widespread
misunderstanding on impacts of some practices. For
example, the slash-and-burn techniques that are the
characteristic feature of shifting cultivators are often cited
as inherently destructive, yet slash-and-burn cultivation
has been practiced in the Amazon for at least 6000 years
(Sponsel 1986); serious deforestation did not begin until
the 1970s, largely as the result of Brazilian government
programs and policies (Hecht and Cockburn 1989).
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Urban planning
There has been considerable debate about which form of human residential habitat may be a
better social form for sustainable agriculture. Generally, it is thought that village communities can
improve sustainability in that such communities tend to provide a cooperative environment that
supports farming[citation needed].
Many environmentalists pushing for increased population density to preserve agricultural land
point out that urban sprawl is less sustainable and more damaging to the environment than living
in the cities where cars are not needed because food and other necessities are within walking
distance[citation needed]. However, others have theorized that sustainable ecocities, or
ecovillages which combine habitation and farming with close proximity between producers and
consumers, may provide greater sustainability[citation needed].
The use of available city space (e.g., rooftop gardens and community gardens) for cooperative
food production is another way to achieve greater sustainability[citation needed].
One of the latest ideas in achieving sustainable agricultural involves shifting the production of food
plants from major factory farming operations to large, urban, technical facilities called vertical
farms. The advantages of vertical farming include year-round production, isolation from pests and
diseases, controllable resource recycling, and on-site production that eliminates the need for
transportation costs[citation needed]. While a vertical farm has yet to become a reality, the idea is
gaining momentum among those who believe that current sustainable farming methods will be
insufficient to provide for a growing global population[citation needed].
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References
Altieri, Miguel A. (1995) Agroecology: The science of sustainable agriculture.
Westview Press, Boulder, CO.
Jahn, GC, B. Khiev, C. Pol, N. Chhorn, S. Pheng, and V. Preap. 2001. Developing
sustainable pest management for rice in Cambodia. pp. 243-258, In S. Suthipradit, C.
Kuntha, S. Lorlowhakarn, and J. Rakngan [eds.] “Sustainable Agriculture:
Possibility and Direction” Proceedings of the 2nd Asia-Pacific Conference on
Sustainable Agriculture 18-20 October 1999, Phitsanulok, Thailand. Bangkok
(Thailand): National Science and Technology Development Agency. 386 p.
Lindsay Falvey (2004) Sustainability - Elusive or Illusion: Wise Environmental
Management. Institute for International Development, Adelaide pp259.
Hecht, Susanna and Alexander Cockburn (1989) The Fate of the Forest: developers,
destroyers and defenders of the Amazon. New York: Verso.
Netting, Robert McC. (1993) Smallholders, Householders: Farm Families and the
Ecology of Intensive, Sustainable Agriculture. Stanford Univ. Press, Palo Alto.
Sponsel, Leslie E. (1986) Amazon ecology and adaptation. Annual Review of
Anthropology 15: 67-97.
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Sustainable industries
From Wikipedia, the free encyclopedia
Jump to: navigation, search
The earliest mention of the phrase sustainable industries appeared in 1990 in a story about a
Japanese group reforesting a tropical forest to help create sustainable industries for the local
populace. (Dietrich, Bill. "Our Troubled Earth – Japan." The Seattle Times. November 13, 1990.
Page F-2.) Soon after, a study entitled “Jobs in a Sustainable Economy” by Michael Renner of the
Worldwatch Institute was published, using the term sustainable industries. (1991)
This 1991 report concluded, "Contrary to the jobs-versus-owls rhetoric that blames environmental
restrictions for layoffs, the movement toward an environmentally sustainable global economy will
create far more jobs than it eliminates. The chief reason: non-polluting, environmentally
sustainable industries tend to be intrinsically more labour intensive and less resource intensive
than traditional processes." While the conclusion may be subject to some debate, it nevertheless
formed an important Among the features of sustainable industry offered in the paper were energy
efficiency, resource conservation to meet the needs of future generations, safe and skillenhancing working conditions, low waste production processes, and the use of safe and
environmentally compatible materials. Some of the benefits, however would be offset by higher
prices (due to labor costs) and a theoretically larger population needed to perform the same
amount of work, increasing the agricultural and other loads on
• Sustainable energy sources are energy sources which are not
expected to be depleted in a timeframe relevant to the human race,
and which therefore contribute to the sustainability of all species.
This concept is termed sustainability. An additional criterion for strict
sustainability, useful for short- and medium-term decisions is social
and political sustainability of an energy technology.
• Sustainable energy sources are most often regarded as including all
renewable sources, such as solar power, wind power, wave power,
geothermal power, tidal power, and others.
• Fission power and fusion power meet the definition of sustainability,
but there is controversy over whether or not they should be regarded
as sustainable for social and political reasons
• Renewable energy sources
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• Wind power is one of the most environmentally friendly sources of
renewable energy
– Main article: renewable energy
• Renewable energy sources are those whose stock is rapidly
replenished by natural processes, and which aren't expected to be
depleted within the lifetime of the human species. In most cases,
these energy sources have technical challenges to overcome before
they are economically competitive with conventional methods of
electricity generation. Approaches to overcoming these challenges
are a field of active research, and are described on the relevant
generation method pages.
• The well-known renewable energy options can be classified by the
natural process that provides their energy:
• Direct solar energy:
• Solar cells use semiconductors to directly convert sunlight into
electricity. Primary challenges with their use are low efficiency,
energy-intensive manufacture, and power variability due to weather
and nightfall.
• Solar thermal plants use concentrated sunlight as a heat source to
power a heat engine which generates electricity. Primary challenges
with their use are manufacture and maintenance of large mirror
arrays and power variability due to weather and nightfall.
• Solar updraft tower plants use sunlight to heat a contained mass of
air, setting up convection currents that cause air to exit through a
chimney from which power is tapped. Primary challenges with their
use are low efficiency, construction and maintenance of the large
structures required, and power variability due to weather (a Solar
updraft tower has enough heat capacity to function through night).
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Indirect solar energy:
Ocean thermal energy conversion uses the temperature difference between the
warmer surface of the ocean and the cooler lower depths to drive a heat engine. The
primary challenges with ocean thermal energy conversion's use are low efficiency
and the construction and maintenance of large structures in a sea environment.
Wind power uses wind turbines to draw energy from large-scale motion of air. The
primary challenges with wind power's use are the large areas required to produce
useful amounts of electricity, and power variability due to weather.
Hydroelectricity uses dams to draw energy from the flow of water from high-altitude
areas to areas with lower altitudes. Primary challenges with hydroelectricity's use are
the environmental damage caused by the construction of dams, and the scarcity of
remaining sites for power generation.
Wave power uses floats to extract mechanical energy from the motion of waves.
Primary challenges with wave power's use are the large areas required to produce
useful amounts of electricity, and disruption of coastal environments.
Biofuel uses products of plants, animals, or bacteria to provide fuels that can be used
in a manner similar to fossil fuels. The primary challenge with biofuel's use is the
availability of suitable feedstock in sufficient quantity for large-scale adoption. The
environmental and economic benefits of non-cellulosic ethanol have been heavily
critiqued by many, including Brad Ewing of Environmental Economics & Sustainable
Development[1] and Lester R. Brown of Earth Policy Institute[2]
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Radioactive decay within the Earth:
Geothermal power uses the temperature difference between the earth's surface and
its interior to drive a heat engine, generally at a location such as a hot spring where
the heat has been transported most of the way to the surface by natural processes.
The primary challenge with geothermal power's use is low power generation
efficiency for most sites.
Rotation of the Earth:
Tidal power uses dams to draw energy from the changes in water height due to tides
produced by the gravitational influences of the moon and sun as Earth rotates. The
primary challenges with tidal power's use are the large area required to produce
useful amounts of electricity, and disruption of coastal environments.
Processes powered by solar energy will be renewed for as long as the sun remains
on the main sequence (approximately 5 billion years). Processes powered by
radioactive decay within the Earth will be renewed for time comparable to the half-life
of uranium 238 (4.5 billion years) and thorium 232 (14 billion years). Processes
powered by the Earth's rotation will last until the Earth becomes tidally locked to the
Sun (though tidal acceleration would eject the moon from Earth orbit earlier). Both of
these would take longer than the expected lifetime of the sun to occur.
• Sustainable sources not considered
renewable
• Sustainable energy sources that aren't
renewable are those whose stock is not
replenished, but for which the presently
available stocks are expected to last for as long
as human civilization cares to use them.
• These energy sources are derived from nuclear
energy, as other forms of stored energy found on
Earth do not have sufficient energy density to
supply humanity indefinitely.
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Fission power uses the nuclear fission of heavy elements to release energy that
drives a heat engine. Primary challenges with the use of fission power are the
production of small quantities of highly-radioactive waste in the form of spent fuel,
larger quantities of less-radioactive waste in the form of activated structural material,
and (for use as a long-term power source) the need to perform intensive processing
of highly-radioactive fuel bundles, both to reclaim unused fuel in spent fuel rods, and
to reclaim plutonium 239 and uranium 233 that have been bred from uranium 238
and thorium 232, respectively.
Fusion power uses the nuclear fusion of isotopes of hydrogen to release energy that
drives a heat engine. Primary challenges with the use of fusion power are that the
technology required to build a useful fusion power plant are still under development,
and that substantial quantities of radioactive waste in the form of activated structural
material is produced.
Fission power's long-term sustainability depends on the amount of uranium and
thorium that is available to be mined. Estimates for fuel reserves vary widely, but if
breeder reactors and fuel reprocessing are assumed, tend to be tens of thousands of
years or longer (uranium is approximately as common in Earth's crust as tin or zinc (2
ppm), and thorium as common as lead (6 ppm)).
• Fusion power's long-term sustainability depends on the
amount of lithium that is available to be mined (for
deuterium-tritium fusion), or the amount of deuterium
available in seawater (for deuterium-deuterium fusion).
Lithium is a reasonably common component of Earth's
crust, being about 10 times as common as thorium (65
ppm). Deuterium (a hydrogen isotope) occurs wherever
hydrogen is found (principally in water), at about 150
ppm. As it can be extracted easily from seawater,
economically viable reserves of deuterium are for
practical purposes unlimited.
• Technical sustainability of nuclear power
• Discussions are re-emerging on proper
classification of nuclear energy under such
umbrella terms as "renewable" and "sustainable"
These attributes bring moral gains or eligibility
for development aid under various jurisdictions.
• The primary argument in favor of "renewable"
status is the relatively inexhaustible supply of
fuel available (uranium and thorium for fission or
hydrogen for fusion). See also: Renewable
energy, Nuclear power section.
• Proponents, such as environmentalists James Lovelock,
Patrick Moore (Greenpeace co-founder), Stewart Brand
(creator of The Whole Earth Catalog), and Norris
McDonald (president of the AAEA), also claim that
nuclear power is at least as environmentally friendly as
traditional sources of renewable energy, making it the
best future solution to global warming and the world's
growing need for energy. They note that nuclear power
plants produce little carbon dioxide emissions and claim
that the radioactive waste produced is minimal and wellcontained, especially compared to fossil fuels. [3]
• In 2001, professors Jan Willem Storm van Leeuwen and
Philip Smith released a study which argued that, though
nuclear plants don't produce any CO2 directly, the
energy required for the rest of the nuclear fuel cycle
(uranium mining, enrichment, transportation) and power
plant life cycle (construction, maintenance,
decommissioning) leads to significant carbon dioxide
emissions, especially as usage of lower-grade uranium
becomes necessary.[4] In 2000, however, Frans H. Koch
of the International Energy Agency reported that,
although it is correct that the nuclear life cycle produces
greenhouse gases, these emissions are actually less
than the life cycle emissions of other renewables, like
solar and wind, and drastically less than fossil fuels.[5]
• Political sustainability of nuclear power
• This section is a stub. You can help by expanding it.Some critics of
nuclear energy argue that deployment of nuclear reactors in many
countries would accelerate the proliferation of nuclear weapons
technology that has many links with civilian use of nuclear materials.
Some nuclear reactors (especially heavy water moderated reactors)
create the materials necessary for these weapons.
• The issue of fuel reprocessing and/or long-term repository of nuclear
waste materials also remains contentious. Very few coutries have
developed waste depositories for high-level radioactive waste (see:
Yucca Mountain Repository USA; Gorleben Germany; Forsmark,
Sweden).
• Due to opposition to nuclear power many countries (Austria, Italy,
Sweden, Germany) have effectively banned further development of
nuclear energy showing a clear lack of political sustainability under
present conditions.
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Living machines
From Wikipedia, the free encyclopedia
Jump to: navigation, search
The living machine at Oberlin College with a settlement tank in the foreground and
filtering tanks in the background
Living Machines are a form of biological wastewater treatment designed to mimic
the cleansing functions of wetlands. They are intensive bioremediation systems that
can also produce beneficial by-products such as methane gas, edible and ornamental
plants, and fish. Aquatic and wetland plants, bacteria, algae, protozoa, plankton,
snails, clams, fish and other organisms are used in the system to provide specific
cleansing or trophic functions. In temperate climates, the system of tanks, pipes and
filters is housed in a greenhouse to raise the temperature, and thus the rate of
biological activity. The initial development of living machines is generally credited to
John Todd, and evolved out of the bioshelter concept developed at the now-defunct
New Alchemy Institute. Living Machine is a trademarked term held by Living Designs
Group, LLC of Taos, New Mexico. Living machines fall within the emerging discipline
of ecological engineering, and many similar systems are built in Europe without being
dubbed “Living Machines.”