For centuries humans have relied on various sources of power with solar energy providing the most reliable source. Indeed solar energy is vital to the survival of all organisms in natural ecosystems on Earth. Although about 50% of all solar energy captured by worldwide photosynthesis is used by humans, it is still inadequate to meet all human needs. This includes food production, forest products, and other biomass needs. In addition to solar, energy sources have ranged from human, animal, wind, tides, and water energy, to wood, coal, gas, oil, and nuclear sources for fuel and power.
Since about 1700, abundant fossil fuel energy supplies have supported agricultural production that has been needed to feed an increasing number of humans, as well as improve the general quality of human life. In agriculture, fossil energy is used in the production and powering of farm machinery that reduces the need for human power, and also in the production of fertilizers and pesticides that help increase crop yields. Ample and affordable fossil energy has made it possible to purify and transport water, as well as to support industry and an extensive transport system. All these energy-based improvements have enhanced human health and quality of life.
Worldwide, about 421 quads (1 quad = 1 x 1015 BTU) of fossil energy, mainly oil, gas, and coal, are utilized each year for all activities. Of this, 103 quads are utilized in the US. Developed nations annually consume about 70% of the fossil energy worldwide, while the developing nations, which have about 75% of the world population, use only 30%. The US, with only about 4% of the world's population, consumes about 25% of the world's fossil energy output.
Per capita use of fossil energy in the US is about 10 0001 of oil equivalents per year, more than 12 times the per capita use in China. Industry, transportation, home heating, and food production account for most of the fossil energy consumed in the US.
In essence ample energy supplies, especially fossil energy, have been supporting rapid population growth including agricultural production. In fact, the rate of energy use from all sources has been growing even faster than world population growth. Thus, from 1970 to 1995, energy use increased at a rate of 2.5% per year (doubling every 30 years) compared with the worldwide population growth of 1.7% per year (doubling in about 40 years).
During the next 20 years, energy use is projected to increase at a rate of 4.5% per year (doubling every 16 years) compared with a population growth rate of 1.2% per year (doubling every 58 years).
Some nations, like China and others that have high rates ofpopulation growth, are increasing fossil fuel use to augment their agricultural production of food and fiber. For example, in China since 1955, there has been a 100fold increase in fossil energy use in agriculture for fertilizers, pesticides, and irrigation.
However, in general, world fertilizer use per capita has declined by more than 17% since 1989; this is especially true in the developing countries, because of fossil fuel shortages and high prices. This has had a negative effect on food production and the availability of food.
All fossil fuels must be considered finite energy resources. The world supply of oil is projected to last approximately 40-50 years at current production rates. Worldwide, the natural gas supply is considered adequate for 40-50 years and coal for 50-100 years.
Furthermore, reports that current oil and gas exploration drilling data have not borne out the earlier optimistic estimates of the amount of these resources yet to be found in the US. Both the production rate and proven fossil fuel reserves have continued to decline. US domestic oil and natural gas production have been declining for more than 30 years and are projected to continue to decline. Approximately 90% of US oil resources already have been mined. Natural gas supplies already are in short supply in the US and it is projected that the US will deplete its natural gas resources in about 20 years.
At present the US is importing more than 63% of its oil. This dependency puts the US economy at risk due to fluctuating oil prices and difficult political situations, such as the 1973 oil crisis and the 1991 Gulf War.
Renewable Energy Sources
Along with population growth, energy use of all sources will escalate. The US is now using more than 103 quads of energy.
Attention is turning to possible sources of energy that will be renewable for use in agriculture, industry, and transportation. The most reliable renewable sources are solar based, like wind, biomass, photovoltaics, hydropower, and solar thermal. The efficiency of each depends on their geographic location. All require inputs of fossil fuel and large amounts of land. In general, these renewable sources will occupy about 17% of total US land in order to collect solar energy. No cropland will be used, but some of the land use will compete with forest and pasture land use.
Even if all these technologies are perfected and constructed and operating, they will provide less than 50% of current US energy use. The pro-ethanol lobby has suggested that ethanol production from corn and cellulose can replace the need for oil in the US. Currently the US is producing 4.5 billion gallons of ethanol without charging for the oil and natural gas inputs. This is using 18% of all US corn and represents only 1% of US petroleum use. If 100% of US corn were used, it would provide only 6% of current US petroleum use.
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Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.