What Are The Different Types of Renewable Energy?

Biomass Energy — Biomass energy is produced from non-fossilized materials derived from plants. Wood and wood waste are the largest sources of biomass energy, followed by energy from municipal solid waste (MSW) and alcohol fuels.

Wood — Wood biomass includes wood chips from forestry operations, residues from lumber, pulp/paper, and furniture mills, and fuel wood for space heating. The largest single source of wood energy is “black liquor,” a residue of pulp, paper, and paperboard production.

Municipal Solid Waste and Biogas — There are about 380 landfills that recover methane, which forms as waste decomposes in low-oxygen (anaerobic) conditions. The methane is burned to produce electricity and heat.

Biofuels — Biofuels include alcohol fuels, such as ethanol, and “biodiesel,” a fuel made from grain oils and animal fats. Most biofuel used in the United States is fuel ethanol produced from corn.

Hydropower — Hydropower is electricity produced from flowing water. As a result, hydropower output varies widely according to rainfall. Most hydropower is produced at large facilities built by the Federal Government, such as Grand Coulee Dam on the Columbia River in Washington State — the largest single electric power facility in the United States.

Geothermal Energy — Geothermal energy is energy from the hot interior of the Earth. Fissures in the Earth’s crust allow water heated by geothermal energy to rise naturally to the surface at hot springs and geysers. Wells drilled into the Earth allow heated steam or water to escape to the surface in a controlled manner to operate steam turbines and electricity generators.

Wind Energy — Water pumping windmills and small wind electric generators were once used throughout the United States. Rural electrification programs of the 1930s and 1940s largely replaced the need for these systems. Starting in the early 1980s, Federal and State Government policies and incentives led to a revival in wind power generation.

Solar Energy — Solar energy systems use radiation from the sun to produce heat and electricity. There are three basic categories of solar energy systems:

• Solar Thermal Systems for Heating Buildings and Water — Solar thermal systems use solar collectors to absorb solar radiation to heat water or air for space and water heating.
• Solar Thermal-Electric Power Plants — Solar thermal-electric power plants use concentrating solar collectors to focus the sun’s rays to heat fluid to a high temperature. This working fluid can then be used to generate steam to operate a turbine, which is then used to produce electricity in a generator. The three types of solar-thermal power systems used in the United States are parabolic trough, solar dish, and solar power towers.
• Photovoltaic Systems — Photovoltaic (PV) systems are based on solar electric cells, which convert solar radiation directly into electricity. Individual PV cells are configured into modules of varying electricity producing capacities. PV applications range from single solar cells for powering watches to large installations with hundreds of modules for electric power production.

Renewable Energy Incentives

Investment in and use of renewable energy is both encouraged and required by a range of State and Federal Government incentives and legislation. The following is a brief description of the major types currently in place:

Federal Renewable Energy Production Tax Credit (PTC) — The PTC is an inflation-adjusted tax credit for electricity produced from qualifying renewable energy sources or technologies.

Federal Income Tax Credits for Renewable Energy Systems — Tax credits of up to 30% of the cost of qualifying renewable energy systems are available through 2016.

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Renewable Portfolio Standards (RPS) and State Mandates or Goals — An RPS is a requirement that a percentage of electric power generation or sales come from renewable energy. Some States have specific mandates for power generation from renewable energy while others have voluntary goals. By the end of 2009 there were 42 States plus the District of Columbia with an RPS, State mandate, or goal.

Green Power Programs — U.S. consumers in many States can purchase electricity generated by renewable energy resources, termed “Green Power.” There are about 600 electric utilities in 47 States now offering green power to their customers. Most of these programs sell power produced by new wind and landfill gas-to-energy projects.

State Financial Incentives — Many States subsidize the installation of renewable energy equipment through a variety of measures. For example, in California, a State “buy-down” program (a grant for the purchase of small renewable energy systems) for photovoltaic (PV) equipment greatly increased the number and size of PV systems installed on houses and buildings.

Net Metering Programs — Net metering allows electric utility customers to install grid-connected renewable energy systems on their property and get credit for the amount of excess electricity the systems produce. Forty-two States and the District of Columbia now have State-wide net metering programs. The Energy Policy Act of 2005 required electric utilities nationwide to offer their customers net metering service upon request by 2008.

Prices for E-85 and Gasoline at a Gas Station in the Midwest

Ethanol and Other Renewable Motor Fuels — There are also a variety of Federal and State requirements and incentives for the production, sale, and use of ethanol, biodiesel, and other fuels made from renewable biomass. The Federal Energy Independence and Security Act of 2007 requires that 36 billion gallons of biofuels be used in the U.S. per year by 2022. Several states have their own renewable fuel standards or requirements. There are a variety of Federal programs that provide financial support and incentives for ethanol and other biofuels producers, and many states have their own programs that support or promote use of biofuels.