But over the past years or so, humans increasingly turned to cheaper, dirtier energy sources such as coal and fracked gas. Now that we have increasingly innovative and less-expensive ways to capture and retain wind and solar energy, renewables are becoming a more important power source, accounting for more than one-eighth of U.
The expansion in renewables is also happening at scales large and small, from rooftop solar panels on homes that can sell power back to the grid to giant offshore wind farms.
Even some entire rural communities rely on renewable energy for heating and lighting. Nonrenewable sources of energy are only available in limited amounts and take a long time to replenish. Nonrenewable energy sources are also typically found in specific parts of the world, making them more plentiful in some nations than others.
By contrast, every country has access to sunshine and wind. Many nonrenewable energy sources can endanger the environment or human health. To top it off, all these activities contribute to global warming. Humans have been harnessing solar energy for thousands of years—to grow crops, stay warm, and dry foods. Solar, or photovoltaic PV , cells are made from silicon or other materials that transform sunlight directly into electricity.
Distributed solar systems generate electricity locally for homes and businesses, either through rooftop panels or community projects that power entire neighborhoods. Solar farms can generate power for thousands of homes, using mirrors to concentrate sunlight across acres of solar cells.
Solar supplies a little more than 1 percent of U. But nearly a third of all new generating capacity came from solar in , second only to natural gas. Today, turbines as tall as skyscrapers —with turbines nearly as wide in diameter—stand at attention around the world. Wind, which accounts for a little more than 6 percent of U. Top wind power states include California, Texas, Oklahoma, Kansas, and Iowa, though turbines can be placed anywhere with high wind speeds—such as hilltops and open plains—or even offshore in open water.
Hydropower is the largest renewable energy source for electricity in the United States, though wind energy is soon expected to take over the lead. Nationally and internationally, large hydroelectric plants—or mega-dams—are often considered to be nonrenewable energy. Mega-dams divert and reduce natural flows, restricting access for animal and human populations that rely on rivers. Small hydroelectric plants an installed capacity below about 40 megawatts , carefully managed, do not tend to cause as much environmental damage, as they divert only a fraction of flow.
Biomass is organic material that comes from plants and animals, and includes crops, waste wood, and trees.
When biomass is burned, the chemical energy is released as heat and can generate electricity with a steam turbine. Biomass is often mistakenly described as a clean, renewable fuel and a greener alternative to coal and other fossil fuels for producing electricity.
However, recent science shows that many forms of biomass—especially from forests—produce higher carbon emissions than fossil fuels.
There are also negative consequences for biodiversity. Still, some forms of biomass energy could serve as a low-carbon option under the right circumstances. For example, sawdust and chips from sawmills that would otherwise quickly decompose and release carbon can be a low-carbon energy source. Drilling deep wells brings very hot underground water to the surface as a hydrothermal resource, which is then pumped through a turbine to create electricity.
Geothermal plants typically have low emissions if they pump the steam and water they use back into the reservoir. There are ways to create geothermal plants where there are not underground reservoirs, but there are concerns that they may increase the risk of an earthquake in areas already considered geological hot spots. Some tidal energy approaches may harm wildlife, such as tidal barrages , which work much like dams and are located in an ocean bay or lagoon.
The solar market today There are nearly gigawatts GW of solar installed in the U. Get more solar data: browse our research archive Explore. Featured Resources.
Want to go solar? Check out the Portal. Need more answers on solar energy? Read our FAQ. Cold ocean water from deep below the surface can be used to cool buildings with desalinated water often produced as a by-product , and seaside communities can employ the methods to tap natural ocean energy described above to supplement municipal power and energy needs.
Ocean energy is an evolving source of alternative energy production, and with more than 70 percent of the surface of our planet covered by ocean, its future looks promising, depending on geographies and regulatory guidelines. These two types of renewable energy have to be produced using mechanical means, rather than by harnessing a natural process.
Bioenergy is a type of renewable energy derived from biomass to create heat and electricity or to produce liquid fuels such as ethanol and biodiesel used for transportation.
Biomass refers to any organic matter coming from recently living plants or animals. Even though bioenergy generates about the same amount of carbon dioxide as fossil fuels, the replacement plants are grown as biomass to remove an equal amount of CO2 from the atmosphere, keeping the environmental impact relatively neutral.
There are a variety of systems used to generate this type of electricity, ranging from directly burning biomass to capturing and using methane gas produced by the natural decomposition of organic material. How is bioenergy used? Businesses or organizations that transport goods or people can convert their fleets to vehicles that use biofuels such as ethanol or biodiesel. Manufacturing facilities can be equipped to burn biomass directly to produce steam captured by a turbine to generate electricity.
In some cases, this process can have a dual purpose by powering the facility as well as heating it. For example, paper mills can use wood waste to produce electricity and steam for heating.
Farm operations can convert waste from livestock into electricity using small, modular systems. Towns can tap the methane gas created by the anaerobic digestion of organic waste in landfills and use it as fuel for generating electricity. Learn more about bioenergy here. Hydrogen is the simplest comprised of one proton and one electron and the most abundant element in the universe, yet it does not occur naturally as a gas on earth.
Instead, it is found in organic compounds hydrocarbons such as gasoline, natural gas, methanol, and propane and water H2O.
Hydrogen can also be produced under certain conditions by some algae and bacteria using sunlight as an energy source. Hydrogen is high in energy yet produces little or no pollution when burned.
Liquid hydrogen has been used to launch space shuttles and other rockets into orbit since the s. Hydrogen fuel cells convert the potential chemical energy of hydrogen into electricity, with pure water and heat as the only byproducts.
However, the commercialization of these fuel cells as a practical source of green energy will likely be limited until costs come down and durability improves. Almost all the hydrogen used in the United States is used in industry to refine petroleum, treat metals, produce fertilizer and process foods. In addition, hydrogen fuel cells are used as an energy source where hydrogen and oxygen atoms are combined to generate electricity. There are also currently a few hundred hydrogen-powered vehicles operating in the United States, a number that could increase as the cost of fuel cell production drops and the number of refueling stations increases.
Other practical applications for this type of renewable energy include large fuel cells providing emergency electricity for buildings and remote locations, electric motor vehicles powered by hydrogen fuel cells and marine vessels powered by hydrogen fuel cells. Learn more about hydrogen power on the Energy Information Agency website.
Homeowners Track your energy and count your savings Homeowners Login. Ready to start saving? Set up a free online appointment today. Do you own a home? Yes No. What is your average monthly electricity bill? Company Optional. Green and Clean: Sustainable Energy Sources Five types of alternative energy are generated by harnessing a natural process, like sunlight or waves. Solar Energy Sunlight is a renewable resource, and its most direct use is achieved by capturing the sun's energy.
Capturing the Wind Wind can be considered a form of solar energy because of the uneven heating and cooling of the atmosphere cause winds as well as the rotation of the earth and other topographical factors. Geothermal: Power from the Earth Geothermal energy is derived from the heat of the earth.
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