Natural gas is a fossil fuel, which means it is formed from the remains of ancient plants and animals. Renewable energy sources, on the other hand, are those that can be replenished naturally on a human timescale.

FERC is an independent agency that regulates the interstate transmission of electricity, natural gas, and oil. It also oversees the licensing of hydroelectric projects and the siting of natural gas pipelines.

PURPA was enacted in 1978 and requires electric utilities to purchase electricity from qualifying renewable energy sources at a price that is not less than the utility's avoided cost.

Combustion is a chemical reaction that involves the rapid burning of a fuel, such as coal, oil, or natural gas, in the presence of oxygen. This process releases heat energy, which can be used to generate electricity or power machinery.

Coal mining can have a number of negative environmental impacts, including air pollution from the release of sulfur dioxide and nitrogen oxides, water pollution from the discharge of mining wastewater, and land degradation from the removal of vegetation and the creation of spoil piles.

Photovoltaic cells, also known as solar cells, are devices that convert sunlight directly into electricity. This process is based on the photovoltaic effect, which is the generation of an electric current in a semiconductor material when it is exposed to light.

Nuclear power plants produce radioactive waste as a byproduct of the fission process. This waste must be carefully managed and disposed of to prevent it from harming human health or the environment.

Hydroelectric power plants use the energy of flowing water to generate electricity. This is done by damming a river or stream and using the force of the water to turn a turbine, which is connected to a generator.

Natural gas production can release a number of air pollutants, including methane, volatile organic compounds (VOCs), and nitrogen oxides. These pollutants can contribute to smog, acid rain, and climate change.

Geothermal power plants use the heat of the Earth's interior to generate electricity. This is done by drilling deep into the Earth and using the hot water or steam to turn a turbine, which is connected to a generator.

Wind turbines can kill birds by collision. This is a particular concern for large birds of prey, such as eagles and hawks, which are attracted to the moving blades of wind turbines.

Tidal power plants use the energy of the tides to generate electricity. This is done by building a dam or barrage across a tidal estuary and using the force of the incoming and outgoing tides to turn a turbine, which is connected to a generator.

Solar power does not produce any air pollution, water pollution, or land degradation. In fact, solar panels can actually help to reduce air pollution by offsetting the need for fossil fuel-fired power plants.

Bioenergy is the generation of electricity from organic matter, such as wood, crops, and manure. This is done by burning the biomass in a boiler to produce steam, which is then used to turn a turbine, which is connected to a generator.

Hydropower can have a number of negative environmental impacts, including air pollution from the release of methane and carbon dioxide, water pollution from the alteration of natural flow patterns, and land degradation from the construction of dams and reservoirs.