What are Greenhouse Gases?

The Greenhouse Effect [Image: NOAA Paleoclimatology]
The Greenhouse Effect
[Image: NOAA Paleoclimatology]

Gases in the Earth's atmosphere that trap heat are referred to as "greenhouse gases". Some of these greenhouse gases occur naturally in the atmosphere but are augmented by inputs from human activities. Others are unnatural compounds that are only created and emitted into the atmosphere from human activities. The principal greenhouse gases released into the atmosphere from human activities are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases. The U.S. Environmental Protection Agency inventories greenhouse gas emissions and sinks and provides information about greenhouse gases and climate change.

Renewable Energy Sources

Renewable energy sources come from natural resources that are constantly replenished and will never run out, in contrast to nonrenewable energy sources such as fossil fuels. Many of these renewable energy sources are also "clean", meaning they emit few or no greenhouse gases. However, all of these energy resources have associated advantages and disadvantages, including cost effectiveness and environmental impacts. Find out more about the common sources of renewable energy in this section, including biofuels, geothermal energy, hydropower, solar energy, and wind energy.

BiofuelBiofuels
Biofuel energy is sourced from plant, animal, or microbial matter, and can be developed into different types of fuels.
GeothermalGeothermal Energy
Geothermal sources of heat, hot water, or steam come directly from the earth and are converted into electricity or used for heating
HydropowerHydropower
Hydropower, or hydroelectricity, is derived from the kinetic energy of moving water.
Solar EnergySolar Energy
Solar energy harnesses the ubiquitous thermal energy and solar radiation of the sun through photovoltaic or solar thermal technology.
WindWind Energy
Blades spinning on a turbine or windmill capture kinetic energy from the wind and convert it into electricity or mechanical energy.


Department of the Interior New Energy Frontier

Wind turbines [Photo: U.S. Department of the Interior]
Wind turbines
[Photo: U.S. Department of the Interior]

The U.S. Department of the Interior (DOI) New Energy Frontier is focused on responsible and environmentally sound energy development in the United States. The Department of the Interior manages one-fifth of the nation's landmass, and many of the agencies within the DOI recognize the need for renewable energy production, including the Bureau of Land Management (BLM), the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE), and the Bureau of Reclamation (BOR).

Source: U.S. Department of the Interior

National Renewable Energy Laboratory

National Renewable Energy Laboratory logo

The National Renewable Energy Laboratory (NREL) is a federally operated scientific laboratory under the U.S. Department of Energy Office of Energy Efficiency & Renewable Energy, dedicated to renewable energy research, development, and implementation. NREL began in 1977 and focuses on renewable electricity, renewable fuels, integrated energy system engineering and testing, and strategic energy analysis.

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