Green Power: Energy Sources
Zero emission green power is generated from renewable energy sources
without creating air pollution.
Sun |
Solar radiation that reaches Earth's surface can generate
electricity in several ways. Photovoltaic systems use semiconductors
to convert light to electricity. Solar concentrators heat water to
create steam, which turns turbines to generate electricity.
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Wind |
The kinetic energy of wind can be harnessed to generate
electricity using wind turbines of many different sizes and
applications.
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Water |
Flowing water can be directed through hydropower turbines to
generate electricity. |
Earth |
In a typical geothermal facility, heat from within the Earth heats
water to create steam, which turns turbines to generate electricity. |
Tide
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Tidal power facilities operate by focusing the tides' daily cycles
of movement into an electricity generator. |
Waves |
In a wave power facility, a water column moves up and down to turn
a turbine to generate electricity.
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Ocean |
The thermal energy of the ocean can be harnessed to generate
electricity. Closed-cycle systems use the ocean's warm surface water
to vaporize a working fluid, which then expands and turns a turbine.
Open-cycle systems boil seawater to produce steam for use in a
turbine.
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Other green power is generated from renewable energy sources while
producing some air pollution.
Biomass |
In a typical biomass facility, waste wood is burned to heat water
to create steam, which turns turbines to generate electricity.
Biomass facilities emit air pollution, but use a renewable fuel
source. |
Landfill Gas
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Landfills produce potent greenhouse gases like methane, which can
be captured and used to generate electricity. In a typical landfill
gas facility, the combustion of these gases is used to create steam,
which turns turbines to generate electricity. Landfill gas
facilities emit air pollution, including nitrogen oxides, but use a
waste gas fuel source that would otherwise contribute to global
climate change. |
Municipal Waste
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In a typical municipal waste incinerator facility, waste from many
sources (including construction, residential and business trash) is
burned, creating steam to turn generating turbines. All
waste-to-energy incinerators carry air permits regulating the
amounts of air pollution they emit, and all reduce the volume of
material entering landfills. |
Alternatives to green power deplete nonrenewable energy sources.
Uranium |
Uranium is the primary fuel source for nuclear power. In a typical
nuclear power plant, fissionable atoms are split in a controlled
reaction to heat water to create steam, which turns turbines to
generate electricity. Undesirable impacts of nuclear power
generation include radioactive waste storage and protection,
decommissioning costs, risks of catastrophic accidents,
uranium-mining costs, and dependence on foreign sources of uranium. |
Coal |
In a typical coal-fired power plant, coal is burned to create
steam, which turns turbines to generate electricity. In a
cogeneration facility, the heat produced by burning coal may be used
for other purposes in addition to electricity generation.
Undesirable impacts of coal-fired power plants include air pollution
and coal-mining costs and associated environmental damage. |
Natural Gas |
Natural gas is a fossil fuel composed primarily of methane, a
potent greenhouse gas. In a typical gas-fired power plant, gas is
burned to heat water to create steam, which turns turbines to
generate electricity. When gas is used in a cogeneration facility,
the heat produced is used for other purposes in addition to
electricity generation. Undesirable impacts of gas-fired power
plants include air pollution and gas-drilling costs. |
Oil |
Oil (also called petroleum) is a fossil fuel composed of various
liquid hydrocarbons. In a typical oil-fired power plant, oil is
burned to create steam, which turns turbines to generate
electricity. Oil may also be used in a cogeneration facility, where
the heat produced by burning oil is used for other purposes in
addition to electricity generation. Undesirable impacts of oil-fired
power plants include air pollution, oil-drilling costs, and
dependence on foreign sources of oil. |
Tires |
In a typical tire-fired power plant, tires are chipped and burned
to create steam, which turns turbines to generate electricity. Tires
may also be burned in a cogeneration facility where the heat
produced is used for other purposes in addition to electricity
generation. Undesirable impacts of tire-fired power plants include
air pollution. |
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