Renewable energy

Pages: 12 (2869 mots) Publié le: 6 décembre 2009
Abundant and economical energy is the life blood of modern civilizations, Oil has been
dominant in powering almost all machines that move and this makes oil uniquely versatile. Oil
powered airplanes carry 500 people across the widest oceans at nearly the speed of sound. Oil
powered machines produce and transport food. Oil powered machines are clearly ubiquitous and
our dependence onoil as fuel and source of energy cannot be over-emphasized. Clearly, we live
in the age of oil, but the age of oil is gradually drawing to a close. Studies have shown that if oil
production remains constant until it's gone, there is enough to last 42 years. It was estimated by
the Energy Information Administration (EIA) that in 2006 primary sources of energy consisted
of petroleum36.8%, coal 26.6%, natural gas 22.9%, amounting to an 86% share for fossil fuels
in primary energy production in the world while non-fossil sources such as hydroelectric 6.3%,
nuclear 6.0%, and (geothermal, solar, tide, wind ) accounted for a meager 0.9 percent.
Fossil fuels are non-renewable resources because they take millions of years to form, and
reserves are being depleted much fasterthan new ones are being formed. The production and use
of fossil fuels raise environmental concerns. The burning of fossil fuels produces around 21.3
billion tonnes (21.3 gigatonnes) of carbon dioxide per year, but it is estimated that natural
processes can only absorb about half of that amount, so there is a net increase of 10.65 billion
tonnes of atmospheric carbon dioxide per year.This enormous amount, unarguably, is the
primary source of greenhouse gases which culminates in global warming. Besides the depletion
of oil reserves, combating global warming and other problems associated with fossil fuels, has
necessitated a switch to renewable energy sources like Sunlight, Wind, Hydro and Geothermal
whose carbon emissions are relatively low compared to presentconventional energy sources.
The need for an alternative source of energy that is renewable, environmentally friendly and cost
effectiveis therefore inevitable.
The major advantage of hydroelectric systems is the elimination of the cost of fuel. Other
advantages include longer life than fuel-fired generation and low operating costs. Operation of
pumped-storage plantsimproves the daily load factor of the generation system. Overall,
hydroelectric power can be far less expensive than electricity generated from fossil fuels or
nuclear energy, and areas with abundant hydroelectric power attract industries.
The development of hydropower has become increasingly problematic in the United States. The
construction of large dams has virtually ceased becausemost suitable undeveloped sites are
under federal environmental protection. To some extent, the slack has been taken up by a revival
of small-scale development. But small-scale hydro development has not met early expectations.
As of 1988, small hydropower plants made up only one-tenth of total hydropower capacity.
Declining fossil-fuel prices and reductions in renewable energy taxcredits are only partly
responsible for the slowdown in hydropower development. Just as significant have been public
opposition to new development and environmental regulations.
Environmental regulations affect existing projects as well as new ones. For example, a series of
large facilities on the Columbia River in Washington will probably be forced to reduce their peak
output by 1,000MW to save an endangered species of salmon. Salmon numbers have declined
rapidly because the young are forced to make a long and arduous trip downstream through
several power plants, risking death from turbine blades at each stage. To ease this trip,
hydropower plants may be required to divert water around their turbines at those times of the
year when the fish attempt the trip. And...
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