Which Renewable Resource Produces The Most Electricity In The United States?

Renewable energy has become an increasingly important source of electricity generation in the United States over the past decade. Renewable energy comes from natural sources that are constantly replenished, such as sunlight, wind, water, plants, and geothermal heat. The main renewable energy sources used for electricity generation in the U.S. are hydropower, wind, solar, geothermal and biomass. According to the U.S. Energy Information Administration, renewable energy provided about 12% of total U.S. energy consumption and about 17% of electricity generation in 2019. Renewable energy is crucial for reducing greenhouse gas emissions from the electricity sector and mitigating climate change risks. The growth of renewable energy also enhances domestic energy security and strengthens the economy through investments and job creation.

Hydroelectric Power

Hydroelectric power is electricity generated from flowing water. It is one of the oldest and largest sources of renewable energy in the United States. Hydroelectricity is produced when falling or fast-flowing water spins a turbine connected to a generator (https://www.eia.gov/energyexplained/hydropower/where-hydropower-is-generated.php).

Most hydroelectricity in the U.S. is generated by dams and reservoirs on rivers. Dams help control water flow and create reservoirs, allowing hydroelectric plants to generate power consistently. Some hydroelectric plants are powered by tidal energy from the natural rise and fall of ocean waters (https://en.wikipedia.org/wiki/Hydroelectric_power_in_the_United_States).

In 2022, the total hydroelectric net summer capacity in the U.S. was about 79,980 megawatts. Hydroelectric power plants generated about 7.5% of total U.S. electricity generation in 2021. While the capacity for new large-scale hydroelectric dams is limited, existing dams can often be upgraded to generate more power.

Wind Power

Wind power has become a major source of renewable energy in the United States. In 2021, the U.S. had over 132,000 megawatts (MW) of installed wind power capacity, second only to China globally (U.S. Installed and Potential Wind Power Capacity and Generation). Wind turbines convert the kinetic energy in wind into mechanical power that runs generators to produce electricity. Utility-scale wind farms consist of hundreds of wind turbines spread out over large plots of land.

Most wind capacity in the U.S. consists of onshore wind farms, with turbines installed on land. However, offshore wind farms are growing, with turbines placed offshore where stronger and more consistent winds can dramatically boost energy output. Currently the U.S. has 42 MW of offshore wind capacity from the small Block Island Wind Farm off Rhode Island, but over 34,000 MW of proposed offshore capacity is in various stages of development (Wind power in the United States).

In 2021 wind power generated over 380 terawatt-hours of electricity, representing 9.2% of total U.S. utility-scale electricity generation. With around 146 gigawatts of total installed capacity, wind trails only natural gas and coal as the largest sources of U.S. electricity generation (Wind Power Facts and Statistics | ACP).

Solar Power

Solar power refers to the generation of electricity from sunlight. There are two main types of solar power technologies – solar photovoltaic (PV) and concentrated solar power (CSP). Solar PV converts sunlight directly into electricity using solar cells typically made of silicon semiconductors. CSP uses mirrors to concentrate sunlight to heat a fluid which is used to spin a turbine to generate electricity.

In the United States, most solar capacity comes from solar PV systems, with utility-scale solar farms accounting for the majority. But rooftop solar installations on homes, businesses, and other buildings are also a fast-growing segment. According to the Solar Energy Industries Association (SEIA), there was 118.2 gigawatts (GW) of total installed solar capacity in the U.S. as of Q3 2022, with 25.4 GW coming from small-scale solar PV. This is up from just 1.2 GW of total capacity in 2008, showing the rapid growth of the solar industry.

Solar power accounted for 4.3% of total U.S. electricity generation in 2021. In some states like California and Florida, the share is over 10%. The SEIA forecasts that solar will reach 20% of U.S. generation by 2025 as costs continue to fall and deployment expands. With abundant sunshine in many parts of the country, solar offers a clean, renewable way to produce electricity with zero emissions.

Geothermal Power

Geothermal energy is thermal energy generated and stored in the Earth. Water or steam carry geothermal energy to the surface, where it can provide a renewable source of heat and electricity generation.

Geothermal reservoirs of hot water or steam are accessed by drilling wells into geothermal resources. The energy harnessed can be used to generate electricity, provide direct heating, or can be used for a variety of applications like aquaculture. With 3,676 MW of installed geothermal capacity as of 2019, the United States remains the world leader with about 25% of the online capacity total. [1]

In 2021, 27 countries, including the United States, generated about 92 billion kWh of electricity from geothermal energy.[2] While the United States has substantial geothermal resources and installed capacity, growth has been gradual over the past decade.

[1] Wikipedia: Geothermal energy in the United States
[2] EIA: Use of geothermal energy

Biomass Power

Biomass power refers to electricity generated from renewable organic materials such as wood, agricultural waste, animal manure, and municipal solid waste. Biomass contains stored energy from the sun, which plants have converted into chemical energy through photosynthesis. Biomass can be burned directly as fuel or converted into other forms like biogas (methane) or biofuels such as ethanol and biodiesel.

Some key biomass energy sources include:
wind turbines and solar panels in a field.

  • Biogas – Methane gas produced from the decomposition of organic waste and used as fuel.
  • Biofuels – Liquid fuels like ethanol and biodiesel produced from crops, waste oils, and other biomass.
  • Wood and wood waste – A traditional biomass fuel burned to produce steam and electricity.
  • Municipal solid waste – Household garbage and landfill gas used as an energy source.

In 2022, biomass accounted for 5% of U.S. energy consumption, generating about 22.8 billion kWh of electricity. The EIA forecasts U.S. biomass power capacity to remain steady at about 6 gigawatts from 2024 to 2025 as older plants retire but new plants come online. Biomass power helps provide baseload renewable electricity and reduces landfill waste disposal.

Sources:

https://www.eia.gov/energyexplained/biomass/


https://biomassmagazine.com/articles/eia-biomass-power-capacity-to-hold-steady-in-2024-and-2025

Comparing Renewable Sources

According to the U.S. Energy Information Administration (EIA), in 2019 hydroelectric power accounted for 29% of U.S. utility-scale electricity generation from renewable sources, wind for 25%, solar for 13%, geothermal for 5%, and biomass for 18% [1]. Overall, renewable sources provided about 17% of total U.S. electricity generation in 2019.

Wind power has seen rapid growth in recent years, overtaking hydro as the top renewable electricity source in 2019. Solar power is also growing quickly, with generation more than doubling from 2018 to 2019. Projections show continued strong growth for wind and solar in the coming decades [2].

However, intermittent generation from wind and solar presents grid integration challenges. Other limitations include suitable geography for hydroelectric dams, windy locations for turbines, and large land areas for utility-scale solar. Overall cost-competitiveness with fossil fuels also remains a barrier for increased renewable penetration in some regions [1].

The Leader in Renewable Power

Hydroelectric power is currently the leading renewable energy source for electricity generation in the United States. According to the U.S. Energy Information Administration, hydroelectricity accounted for 28% of total renewable electricity generation and 6.5% of total electricity generation in 2020 https://www.eia.gov/energyexplained/renewable-sources/.

There are several reasons hydroelectric power has maintained dominance as the top renewable electricity source in the country. Hydroelectric dams and plants can generate massive amounts of electricity reliably and inexpensively once they are initially constructed. The technology is also well-established and has been widely used for decades. Many large hydro facilities were built between the 1930s and the 1970s in ideal locations near rivers and reservoirs. These existing hydro plants continue to generate electricity today with minimal fuel costs and emissions https://en.wikipedia.org/wiki/Renewable_energy_in_the_United_States. While growth of new large hydro projects has slowed, existing facilities and smaller hydropower continue leading renewable electricity generation.

Future Outlook

The future continues to look bright for renewable energy growth and adoption in the United States. Many projections predict rapid expansion of renewables in the coming years and decades.

According to the U.S. Energy Information Administration, renewables are expected to be the fastest growing source of electricity generation through 2050, with solar and wind accounting for over 80% of new capacity additions. Renewable generation is projected to increase from 21% of total generation in 2020 to 42% in 2050. [1]

Several key factors are driving this projected growth. First, costs continue to fall dramatically for renewables like solar and wind. Innovations and economies of scale are making these technologies more affordable and competitive with conventional sources. Second, many state and local governments have enacted renewable portfolio standards, carbon reduction goals, and other policies to incentivize renewables. Finally, corporations and utilities are procuring more clean energy to meet sustainability targets. [2]

Emerging renewable technologies to watch include offshore wind, wave/tidal, enhanced geothermal systems, and floating solar PV. These innovations have enormous potential but need further development and cost reductions. With continued policy support and private investment, they are poised for growth in the coming decades.

Policy and incentives will remain crucial to realizing America’s renewable energy future. Tax credits, rebates, renewable portfolio standards, and carbon policies all help accelerate the transition from fossil fuels. Bipartisan support for renewables has expanded under the Inflation Reduction Act, which provides long-term tax credits for wind, solar, geothermal, and more. Ongoing policy support at both the federal and state levels will ensure renewable energy continues its impressive growth.

Conclusion

In summary, hydropower is currently the largest source of renewable electricity generation in the United States, providing around 6.6% of total US electricity generation. However, continued growth is expected for other renewable sources like wind and solar power in the coming years.

Expanding renewable energy is critical for reducing greenhouse gas emissions, mitigating climate change, improving public health, and achieving energy independence. The costs of renewables like solar and wind continue to fall dramatically. With supportive policies and technological advances, renewable energy has the potential to supply a large share of US electricity generation in the future.

While hydropower leads currently, the outlook is bright for greater expansion of solar, wind, geothermal and other renewable sources. With their environmental and economic benefits, renewables will play a key role in building a sustainable energy future in the United States.

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