What is Green Power?
Green power is a marketing term for electricity that is partially or entirely generated from environmentally preferable renewable energy sources, such as solar, wind, geothermal, biomass, biogas, and low-impact hydro. Green power is sold to support the development of new renewable energy sources. Products made with green power always contain a higher percentage of electricity from renewable energy sources than conventional electrical service.
A New Choice
Today there are substantial differences among energy sources that are used to create electricity. Conventional methods of electricity generation in the United States use fossil or nuclear fuels - forms of power generation that can be harmful to human health and the environment. However, market changes are making cleaner ways of producing power increasingly available, and consumers now have the ability to choose how their power is generated.
Green power offers electricity users a choice to support newer technologies that capture renewable energy sources to create electricity. These renewable sources are continuously replenished by nature and significantly reduce the environmental impacts of electricity generation.
Conventional electricity generation causes air emissions. Fossil fuel-fired power plants are responsible for 67 percent of the nation's sulfur dioxide emissions, 23 percent of nitrogen oxide emissions, and 40 percent of man-made carbon dioxide emissions. Also, power plants are the main source of mercury emissions in the United States. Electricity generation using renewable energy offers an alternative with zero or significantly lower emissions.
Reducing Electricity's Environmental Impact
By choosing green power, homes, businesses, and governments support the development of cleaner forms of power generation and reduce their own environmental impact. And as more green power is developed, the overall environmental impacts associated with electricity generation will be reduced.
Wind, Solar and More
Currently, less than 2% of the nation's energy supply is generated from non-hydro renewable resources. The majority of our nation's electricity is generated from fossil fuels. To learn more about the environmental impacts of different sources of electricity generation, visit EPA's Clean Energy Web site.
Renewable Energy Sources
Wind energy is produced using wind turbines that capture the energy created by the blowing wind. Spinning wind turbine blades connect to an electric generator, which in turn produces electricity. Since the early 1980s, wind turbines have been steadily increasing their electrical output while also decreasing their costs. The average large-scale wind turbine now generates 1.5 MW of electricity, enough to power over 450 homes for one year, more than 15 times the capacity of wind turbines installed two decades ago. Wind power costs were often higher than 30 cents per kilowatt-hour in the early 1980s, but today they are often less than 5 cents per kilowatt-hour. As a result of these advances, wind energy is one of the fastest growing and most widely used renewable energy sources. Installed wind energy capacity currently exceeds 6,300 MW, and more than 1,500 MW of wind power serves the voluntary green power markets. Since 2000, nationwide installed wind turbine capacity in the United States has more than doubled.
Solar power is produced using solar cells, also known as photovoltaics. Photovoltaic cells can turn light ("photo") energy into electricity ("voltaics"). Like batteries, solar cells generate direct current (DC) which is then converted to alternating current (AC) using inverters. Solar cells can be used to generate electricity on-site at facilities, and they are often mounted on rooftops.
Geothermal energy is heat from underneath the Earth's surface that can be harnessed as steam, and the steam can be used to spin an electrical generator to produce electricity. Most of the nation's geothermal electrical resources are located in the western part of the United States.
Low-impact (small) hydropower is created when the flow of water spins a turbine in a setting that has reduced environmental impacts. Eligible facilities meet criteria such as minimum impact on river flows, water quality, fish passage, and watershed protection. In the absence of information on these environmental criteria, a minimum generating capacity (30MW) determines eligibility.3 Eligible hydropower facilities often operate in a "run of the river" mode, in which little or no water is stored behind a dam.
Biomass is organic material that releases energy as heat when burned. Examples of biomass fuels include wood, wood waste, straw, manure, and agricultural crops. Most biomass power plants burn biomass fuels directly to produce steam. This steam is usually captured by a turbine, and a generator then converts it into electricity.
Biogas (or methane) is produced when organic material (biomass) decays. This gas can be captured at landfills and wastewater treatment plants and then burned to generate electricity. Biogas can be used in a fuel cell to generate electricity. Fuel cells are not renewable energy unless they use a renewable fuel.
Benefits of Going Green
The primary benefit of buying green power is environmental protection. For many organizations, the electricity they purchase is a significant source of air pollution and greenhouse gas emissions. Voluntary green power consumers are making a real difference environmentally by supporting the development of new power plants that generate electricity with significantly less air pollution and no net increase in greenhouse gas emissions.
Green power leaders have achieved numerous benefits from purchasing green power, including:
- Avoiding air pollution and greenhouse gas emissions
- Meeting organizational environmental objectives
- Providing a hedge against future electricity price instability
- Demonstrating civic leadership
- Generating positive publicity and enhancing public image
- Generating customer, investor, or stakeholder loyalty, and employee pride
- Stimulating local economies
- Stimulating long-term cost reductions for renewable energy
- Increasing domestic security through a more diverse fuel mix
- Reducing the vulnerability of our nation's energy infrastructure
Information provided by the Environmental Protection Agency.