A renewable resource is a natural resource which can replenish with the passage of time,
either through biological reproduction or other naturally recurring processes. Renewable
resources are a part of Earth's natural environment and the largest components of its ecosphere.
A positive life cycle assessment is a key indicator of a resource's sustainability.
In 1962, Paul Alfred Weiss defined Renewable Resources as: "The total range of living organisms
providing man with food, fibers, drugs, etc...". Renewable resources may be the source of power
for renewable energy. However, if the rate at which the resource is consumed exceeds
its renewal rate, renewal and sustainability will not be ensured. The term renewable resource
also describes systems like sustainable agriculture and water resources. Sustainable harvesting
of renewable resources can reduce air pollution, soil contamination, habitat destruction and
land degradation. Gasoline, coal, natural gas, diesel and other
commodities derived from fossil fuels, as well as minerals like copper and others, are
non-renewable resources without a sustainable yield.
Renewable resources endangered by the industrial world
Overfishing
"Ocean over fishing is simply the taking of wildlife from the sea at rates too high for
fished species to replace themselves." Tuna meat is driving overfishing as to endanger
some species like the bluefin tuna. The European Community and other organisations are trying
to regulate fishery as to protect species and to prevent their extinctions. The United
Nations Convention on the Law of the Sea treaty deals with aspects of overfishing in articles
61, 62, and 65. Examples of overfishing exist in areas such
as the North Sea of Europe, the Grand Banks of North America and the East China Sea of
Asia. The decline of penguin population is caused
in part by overfishing, caused by human competition over the same renewable resources
Sustainable agriculture
The phrase sustainable agriculture was coined by Australian agricultural scientist Gordon
McClymont. It has been defined as "an integrated system of plant and animal production practices
having a site-specific application that will last over the long term". Expansion of agricultural
land has an impact on biodiversity and contributes to deforestation. The Food and Agriculture
Organisation of the United Nations estimates that in coming decades, cropland will continue
to be lost to industrial and urban development, along with reclamation of wetlands, and conversion
of forest to cultivation, resulting in the loss of biodiversity and increased soil erosion.
Although air and sunlight are available everywhere on Earth, crops also depend on soil nutrients
and the availability of water. Monoculture is a method of growing only one crop at a
time in a given field, which can damage land and cause it to become either unusable or
suffer from reduced yields. Monoculture can also cause the build-up of pathogens and pests
that target one specific species. The Great Irish Famine is a well-known example of the
dangers of monoculture. Crop rotation and long-term crop rotations
confer the replenishment of nitrogen through the use of green manure in sequence with cereals
and other crops, and can improve soil structure and fertility by alternating deep-rooted and
shallow-rooted plants. Other methods to combat lost soil nutrients are returning to natural
cycles that annually flood cultivated lands such as the Flooding of the Nile, the long-term
use of biochar, and use of crop and livestock landraces that are adapted to less than ideal
conditions such as pests, drought, or lack of nutrients.
Agricultural practices are the single greatest contributor to the global increase in soil
erosion rates. It is estimated that "more than a thousand million tonnes of southern
Africa's soil are eroded every year. Experts predict that crop yields will be halved within
thirty to fifty years if erosion continues at present rates." The Dust Bowl phenomenon
in the 1930s was caused by severe drought combined with farming methods that did not
include crop rotation, fallow fields, cover crops, soil terracing and wind-breaking trees
to prevent wind erosion. The tillage of agricultural lands is one of
the primary contributing factors to erosion, due to mechanized agricultural equipment that
allows for deep plowing, which severely increases the amount of soil that is available for transport
by water erosion. The phenomenon called Peak Soil describes how large-scale factory farming
techniques are jeopardizing humanity's ability to grow food in the present and in the future.
Without efforts to improve soil management practices, the availability of arable soil
will become increasingly problematic. Methods to combat erosion include no-till
farming, using a keyline design, growing wind breaks to hold the soil, and widespread use
of compost. Chemical fertilizer and pesticides can also have an effect of soil erosion, which
can contribute to soil salinity and prevent other species from growing. Phosphate is a
primary component in the chemical fertilizer applied most commonly in modern agricultural
production. However, scientists estimate that rock phosphate reserves will be depleted in
50–100 years and that Peak Phosphate will occur in about 2030.
Industrial processing and logistics also have an effect on agriculture's sustainability.
The way and locations crops are sold requires energy for transportation, as well as the
energy cost for materials, labour, and transport. Food sold at a local location, such a farmers'
market, have reduced energy overheads.
Deforestation
As well as being a renewable resource for fuel and building material, trees protect
the environment by absorbing carbon dioxide and by creating oxygen. The destruction of
rain forests is one of the critical causes of climate change. Deforestation causes carbon
dioxide to linger in the atmosphere. As carbon dioxide accrues, it produces a layer in the
atmosphere that traps radiation from the sun. The radiation converts to heat which causes
global warming, which is better known as the greenhouse effect.
Deforestation also affects the water cycle. It reduces the content of water in the soil
and groundwater as well as atmospheric moisture. Deforestation reduces soil cohesion, so that
erosion, flooding and landslides ensue. Rain forest shelter many species and organisms
providing local populations with food and other commodities. In this way biofuels may
well be unsustainable if their production contributes to deforestation.
Endangered species
Some renewable resources, species and organisms are facing a very high risk of extinction
caused by growing human population and over-consumption. It has been estimated that over 40% of all
living species on Earth are at risk of going extinct. Many nations have laws to protect
hunted species and to restrict the practice of hunting. Other conservation methods includes
restricting land development or creating preserves. The IUCN Red List of Threatened Species is
the best-known worldwide conservation status listing and ranking system. Internationally,
199 countries have signed an accord agreeing to create Biodiversity Action Plans to protect
endangered and other threatened species. Water resources
Water can be considered a renewable material when carefully controlled usage, treatment,
and release are followed. If not, it would become a non-renewable resource at that location.
For example, groundwater is usually removed from an aquifer at a rate much greater than
its very slow natural recharge, and so groundwater is considered non-renewable. Removal of water
from the pore spaces may cause permanent compaction that cannot be renewed. 97.5% of the water
on the Earth is salt water, and 3% is fresh water; slightly over two thirds of this is
frozen in glaciers and polar ice caps. The remaining unfrozen freshwater is found mainly
as groundwater, with only a small fraction present above ground or in the air.
Water pollution is one of the main concerns regarding water resources. It is estimated
that 22% of worldwide water is used in industry. Major industrial users include hydroelectric
dams, thermoelectric power plants, which use water for cooling, ore and oil refineries,
which use water in chemical processes, and manufacturing plants, which use water as a
solvent. Renewable energy
Renewable energy is energy from natural resources such as sunlight, wind, rain, tides, waves
and geothermal heat. Common applications of renewable energies are electricity generation
and motor fuels. The reported problem with these renewable
resources is that it is difficult and expensive to harness enough power from them to match
the effectiveness of non-renewable resources. Solar Energy
Solar energy is the most abundant and easily available renewable resource, and has been
harnessed by humans since ancient times. The solar energy not used by man is used by plants
and other organisms in photosynthesis. In one year, the Sun delivers more than 10,000
times the energy that humans currently use, and almost twice the amount of energy that
will ever be obtained from all of the planet's non-renewable resources.
Solar power is the conversion of sunlight into electricity, either directly using photovoltaics(1.7
V), or indirectly using concentrated solar power. Concentrated solar power systems use
lenses or mirrors and tracking systems to focus a large area of sunlight into a small
beam. Photovoltaics convert light into electric current using the photoelectric effect.
There are many domestic applications of solar power including solar cookers, solar stills,
solar water heating, solar heating and air conditioning.
Wind Power
Wind power is the conversion of wind energy into a useful form of energy. Most modern
electrical wind power is generated by converting the rotation of turbine blades into electrical
currents by means of an electrical generator. Windmills provide mechanical power, and were
originally developed for milling grain for food production.The basic technique adopted
in the blades of windmill to facilitate proper rotation is the pressure difference among
the blades. Other industrial uses of windmill machinery are windpumps, used for water pumping
or drainage. Wind power is also used to propel ships using
sails.
Hydropower
Hydropower is energy derived from the movement of water in rivers and oceans, originally
used for irrigation and the operation of various mechanical devices. Since the early 20th century,
the term is used almost exclusively in conjunction with the modern development of hydro-electric
power. Conventional hydroelectric power involves creating a dam, and using the resulting water
force to turn a water turbine and generator. Other electricity generating methods are run-of-the-river
hydroelectricity, which captures the kinetic energy in rivers or streams, without the use
of dams, and pumped-storage hydroelectricity, which stores water pumped during periods of
low demand to be released for generation when demand is high.
Geothermal Energy
Geothermal energy comes from the Earth's crust and originates from the original formation
of the planet and from radioactive decay of minerals. The available energy from the Earth's
crust and mantle is approximately equal to that of incoming solar energy.
Geothermal heating is the direct use of geothermal energy for heating applications. Since paleolithic
times, naturally occurring Hot springs have been used for bathing.
Geothermal electricity is electricity generated from geothermal energy using technologies
like superheaters, flash steam power plants and binary cycle power plants. The first geothermal
power station was built at Larderello, Italy. Other countries that have geothermal power
stations are Japan, Iceland, the Philippines and the United States. In Iceland, geothermal
energy is used for electricity and heat.
Biofuel
A biofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels
include fuels derived from biomass conversion, as well as solid biomass, liquid fuels and
various biogases. Bioethanol is an alcohol made by fermentation,
mostly from carbohydrates produced in sugar or starch crops such as corn, sugarcane or
switchgrass. Biodiesel is made from vegetable oils and
animal fats. Biodiesel is produced from oils or fats using transesterification and is the
most common biofuel in Europe. Biogas is methane produced by the process
of anaerobic digestion of organic material by anaerobes., etc. is also a renewable source
of energy. Renewable materials
Biomass
Biomass is biological material from living, or recently living organisms, most often referring
to plants or plant-derived materials. As a renewable energy source, biomass can either
be used directly, or indirectly—once or converted into another type of energy product
such as biofuel. The use of biomass helps to sustain climate change, increase energy
efficiency, and decrease greenhouse gas emission. Biomass is all biologically produced matter
based in carbon, hydrogen and oxygen. The estimated biomass production in the world
is 146 billion tons a year, consisting of mostly wild plant growth. Biomass energy is
derived from six distinct energy sources: garbage, wood, plants, waste, landfill gases,
and alcohol fuels. Historically, humans have harnessed biomass derived energy since the
advent of burning wood to make fire, and wood remains the largest biomass energy source
today. The biomass used for electricity generation
varies by region. Forest by-products, such as wood residues, are common in the United
States. Agricultural waste is common in Mauritius and Southeast Asia. Animal husbandry residues,
such as poultry litter, are common in the UK. The biomass power generating industry
in the United States, which consists of approximately 11,000 MW of summer operating capacity actively
supplying power to the grid, produces about 1.4 percent of the U.S. electricity supply.
Bioplastics
Bioplastics are a form of plastics derived from renewable biomass sources, such as vegetable
fats and oils, corn starch, pea starch or microbiota. The most common form of bioplastic
is thermoplastic starch. Other forms include Cellulose bioplastics, biopolyester, Polylactic
acid, and bio-derived polyethylene. The production and use of bioplastics is generally
regarded as a more sustainable activity when compared with plastic production from petroleum,
however manufacturing of bioplastic materials is often still reliant upon petroleum as an
energy and materials source. Because of the fragmentation in the market and ambiguous
definitions it is difficult to describe the total market size for bioplastics, but estimates
put global production capacity at 327,000 tonnes. In contrast, global consumption of
all flexible packaging is estimated at around 12.3 million tonnes.
Bioasphalt
Bioasphalt is an asphalt alternative made from non-petroleum based renewable resources.
Manufacturing sources of bioasphalt include sugar, molasses and rice, corn and potato
starches, and vegetable oil based waste. Asphalt made with vegetable oil based binders was
patented by Colas SA in France in 2004. See also
References
Further reading Panwar, N. L., Kaushik, S. C., & Kothari,
S.. Role of renewable energy sources in environmental protection: A review. Renewable & Sustainable
Energy Reviews, 15(3), 1513-1524. Retrieved April 7, 2012, from ScienceDirect.
Masters, G. M.. Renewable and Efficient Electric Power Systems. Hoboken, NJ:John Wiley & Sons.
Sawin, Janet. "Charting a New Energy Future." State of the World 2003. By Lester R. Brown.
Boston: W. W. Norton & Company, Incorporated, 2003.
Krzeminska, Joanna, Are Support Schemes for Renewable Energies Compatible with Competition
Objectives? An Assessment of National and Community Rules, Yearbook of European Environmental
Law, Volume VII, Nov. 2007, p. 125