When it comes to energy resources, there is always the question of sustainability. It is important that resources provide enough energy to meet our needs—to heat our houses, power our cities, and run our cars. However, it is also important to consider how these resources can be used long term. Some resources will practically never run out. These are known as renewable resources. Renewable resources also produce clean energy, meaning less pollution and greenhouse gas emissions, which contribute to climate change.

The United States’ energy sources have evolved over time, from using wood prior to the nineteenth century to later adopting nonrenewable resources, such as fossil fuels, petroleum, and coal, which are still the dominant sources of energy today. But the Earth has a limited supply of these resources. Recently, renewable resource use has begun to increase. According to the U.S. Environmental Protection Agency, 11 percent of the U.S. energy consumption came from renewable resources in 2017.

There are some challenges associated with using renewable resources. For instance, renewable energy can be less reliable than nonrenewable energy, with seasonal or even daily changes in the amount produced. However, scientists are continually addressing these challenges, working to improve feasibility and reliability of renewable resources. 

Renewable resources include biomass energy (such as ethanol), hydropower, geothermal power, wind energy, and solar energy.

Biomass refers to organic material from plants or animals. This includes wood, sewage, and ethanol (which comes from corn or other plants). Biomass can be used as a source of energy because this organic material has absorbed energy from the Sun. This energy is, in turn, released as heat energy when burned.

Hydropower is one of the oldest renewable resources and has been used for thousands of years. Today, every U.S. state uses some amount of hydroelectricity. With hydropower, the mechanical energy from flowing water is used to generate electricity. Hydroelectric power plants use the flow of rivers and streams to turn a turbine to power a generator, releasing electricity.

Geothermal energy comes from the heat generated deep within the Earth’s core. Geothermal reservoirs can be found at tectonic plate boundaries near volcanic activity or deep underground. Geothermal energy can be harnessed by drilling wells to pump hot water or steam to a power plant. This energy is then used for heating and electricity. 

Wind energy generates electricity by turning wind turbines. The wind pushes the turbine’s blades, and a generator converts this mechanical energy into electricity. This electricity can supply power to homes and other buildings, and it can even be stored in the power grid.

Radiation from the Sun can be used as a power source as well. Photovoltaic cells can be used to convert this solar energy into electricity. Individually, these cells only generate enough energy to power a calculator, but when combined to create solar panels or even larger arrays, they provide much more electricity.

Searching for the right method of using renewable resources is a task that is growing ever more important as the Earth’s supply of nonrenewable resources continues to dwindle. Converting to renewable energy will not only better sustain the world’s rapidly growing population, but it will also provide a cleaner, healthier environment for the generations to come.


Renewable Resources

Geothermal power is a form of renewable energy created by powering electrical generators with the heat of the earth and naturally occurring subterranean hot water reservoirs.


living organisms, and the energy contained within them.

biomass energy

renewable energy derived from living or recently living organisms, mostly plants.

clean energy

electrical energy that does not pollute the atmosphere, water, or earth.

electrical energy

energy made available by a flow of electrical charge, through a conductor. Electrical energy is measured in Joules.


type of grain alcohol used as biofuel.


heat energy generated within the Earth.

geothermal power

the rate of producing, transferring, or using geothermal energy, usually in the form of electricity.

greenhouse gas

gas in the atmosphere, such as carbon dioxide, methane, water vapor, and ozone, that absorbs solar heat reflected by the surface of the Earth, warming the atmosphere.


energy generated by moving water converted to electricity. Also known as hydroelectricity.

hydroelectric power

usable energy generated by moving water converted to electricity.


energy resources that are exhaustible relative to the human life span, such as gas, coal, or petroleum.


able to convert solar radiation to electrical energy.

power grid

network of cables or other devices through which electricity is delivered to consumers. Also called an electrical grid.

power plant

industrial facility for the generation of electric energy.


energy, emitted as waves or particles, radiating outward from a source.

renewable energy

energy obtained from sources that are virtually inexhaustible and replenish naturally over small time scales relative to the human life span.

renewable resource

resource that can replenish itself at a similar rate to its use by people.


radiation from the sun.

solar panel

group of cells that converts sunlight into electricity.

solar power

rate of producing, transferring, or using solar energy.

tectonic plate

massive slab of solid rock made up of Earth's lithosphere (crust and upper mantle). Also called lithospheric plate.


kinetic energy produced by the movement of air, able to be converted to mechanical power.


instrument that generates power from the force of wind rotating large blades.

wind power

rate of producing, transferring, or using wind energy, usually measured in watts.

wind turbine

machine that produces power using the motion of wind to turn blades.