Present sources of energy & New sources of energy
Biomass (organic matter) can be used to provide heat, make fuels, and generate electricity. This is called bioenergy. Wood, the largest source of bioenergy, has been used to provide heat for thousands of years. But there are many other types of biomass—such as wood, plants, residue from agriculture or forestry, and the organic component of municipal and industrial wastes—that can now be used as an energy source. Today, many bioenergy resources are replenished through the cultivation of energy crops, such as fast-growing trees and grasses, called bioenergy feedstocks.
Unlike other renewable energy sources, biomass can be converted directly into liquid fuels for our transportation needs. The two most common biofuels are ethanol and biodiesel. Ethanol, an alcohol, is made by fermenting any biomass high in carbohydrates, like corn, through a process similar to brewing beer. It is mostly used as a fuel additive to cut down a vehicle's carbon monoxide and other smog-causing emissions. Biodiesel, an ester, is made using vegetable oils, animal fats, algae, or even recycled cooking greases. It can be used as a diesel additive to reduce vehicle emissions or in its pure form to fuel a vehicle.
Heat can be used to chemically convert biomass into a fuel oil, which can be burned like petroleum to generate electricity. Biomass can also be burned directly to produce steam for electricity production or manufacturing processes. In a power plant, a turbine usually captures the steam, and a generator then converts it into electricity. In the lumber and paper industries, wood scraps are sometimes directly fed into boilers to produce steam for their manufacturing processes or to heat their buildings. Some coal-fired power plants use biomass as a supplementary energy source in high-efficiency boilers to significantly reduce emissions.
Even gas can be produced from biomass for generating electricity. Gasification systems use high temperatures to convert biomass into a gas (a mixture of hydrogen, carbon monoxide, and methane). The gas fuels a turbine, which is very much like a jet engine, only it turns an electric generator instead of propelling a jet. The decay of biomass in landfills also produces a gas—methane—that can be burned in a boiler to produce steam for electricity generation or for industrial processes.
New technology could lead to using biobased chemicals and materials to make products such as anti-freeze, plastics, and personal care items that are now made from petroleum. In some cases these products may be completely biodegradable. While technology to bring biobased chemicals and materials to market is still under development, the potential benefit of these products is great.
Coal
America has more coal than any other fossil fuel resource. The United States also has more coal reserves than any other single country in the world. In fact, 1/4 of of all the known coal in the world is in the United States. The United States has more coal that can be mined than the rest of the world has oil that can be pumped from the ground.
Large coal deposits can be found in 38 of the 50 states
Coal is used primarily in the United States to generate electricity. In fact, it is burned in power plants to produce more than half of the electricity we use. If your family uses an electric stove, you use about half a ton of coal a year. If your water heater is electric, you are using about two tons of coal a year. If you have an electric refrigerator, that's another half-ton a year. Even though you may never see coal, you use several tons of it every year!
The material that formed fossil fuels varied greatly over time as each layer was buried.
Geothermal
Geo (Earth) thermal (heat) energy is an enormous, underused heat and power resource that is clean (emits little or no greenhouse gases), reliable (average system availability of 95%), and homegrown (making us less dependent on foreign oil).
Geothermal resources range from shallow ground to hot water and rock several miles below Earth's surface, and even farther down to the extremely high temperatures of molten rock called magma.
Hydrogen
Hydrogen is the simplest element; an atom consists of only one proton and one electron. It is also the most plentiful element in the universe. Despite its simplicity and abundance, hydrogen doesn't occur naturally as a gas on the Earth—it is always combined with other elements. Water, for example, is a combination of hydrogen and oxygen (H²O). Hydrogen is also found in many organic compounds, notably the "hydrocarbons" that make up many of our fuels, such as gasoline, natural gas, methanol, and propane.
Natural Gas
It is colorless, shapeless, and in its pure form, odorless.
For many years, it was discarded as worthless. Even today, some countries (although not the United States) still get rid of it by burning it in giant flares, so large they can be seen from the Space Shuttle. Yet, it is one of the most valuable fuels we have.
Natural gas is made up mainly of a chemical called methane, a simple, compound that has a carbon atom surrounded by four hydrogen atoms. Methane is highly flammable and burns almost completely. There is no ash and very little air pollution.
Natural gas provides one-fifth of all the energy used in the United States. It is especially important in homes, where it supplies nearly half of all the energy used for cooking, heating, and for fueling other types of home appliances.
Solar
Sunlight—solar energy—can be used to generate electricity, provide hot water, and to heat, cool, and light buildings.
Photovoltaic (solar cell) systems convert sunlight directly into electricity. A solar or PV cell consists of semiconducting material that absorbs the sunlight. The solar energy knocks electrons loose from their atoms, allowing the electrons to flow through the material to produce electricity. PV cells are typically combined into modules that hold about 40 cells. About 10 of these modules are mounted in PV arrays. PV arrays can be used to generate electricity for a single building or, in large numbers, for a power plant. A power plant can also use a concentrating solar power system, which uses the sun's heat to generate electricity. The sunlight is collected and focused with mirrors to create a high-intensity heat source. This heat source produces steam or mechanical power to run a generator that creates electricity.
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