The National Academies: What You Need To Know About Energy

The National Academies

What You Need To Know About Energy

Our Energy Sources

Two questions immediately strike us: Will we have enough affordable energy in the near future? What will we do for the long term?

The answers depend on our inventory of sources. Our energy supply comes mainly from fossil fuels, with nuclear power and renewable sources rounding out the mix. These sources originate mostly in our local star, the Sun. Electricity falls into its own category because it’s an energy carrier and not a primary source. Here we explore the pros and cons of each resource and look at some of the emerging technologies that could transform our energy situation in the future.

Relative contributions of energy sources to total U.S. energy consumption in 2008.

The Sun

Most of the energy we capture for use on Earth originates in the nuclear reactions powering our Sun.

Coal, oil, natural gas, biomass, and even the wind and hydropower we harness to generate electricity, originally derive their energy content from the Sun. Learn how our local star is the ultimate energy source.

More about the sun


40% of U.S. energy from all sources is used to generate electricity.

Experts predict a 26% increase in the demand for electricity in the United States by 2030. What sources do we currently depend on to generate our electric power supply and how might that change in the future?

More about electricity

Fossil Fuels

In 2008, fossil fuels provided almost 85% of the energy used in the United States.

Fossil fuels supply the affordable energy we need for many of the functions essential to our society. Learn about the costs and benefits of each of these sources, including the risks of maintaining the status quo.

More about fossil fuels


20% of our electricity was generated by nuclear fuel in 2008.

Nuclear power provides about 9% of the total U.S. energy supply. What are the implications of expanding this resource?

More about nuclear

Renewable Sources

7% of our total energy use comes from renewable energy sources, such as wind, solar, and hydropower.

Renewable energy sources lessen our dependence on foreign energy and do not emit greenhouse gases. Experts predict that over the next two decades, renewable energy will provide a growing portion of U.S. overall energy. Find out more.

More about renewable sources

Emerging Technologies

An increasing share of future energy needs will be met by technologies now in the research or development phase.

Public and private research into technologies that could improve—or even completely change—our energy situation has been active for years. Learn about a few of our options and the problems they address.

More about emerging technologies

Explore Other Topics

Energy Videos

Video thumbnail


America's Energy Future

View YouTube Channel

Energy Hands-on

What do you know about energy?

Nuclear power provided what percentage of the total U.S. energy supply in 2008?

  • Sorry, that’s incorrect.

    Nuclear power accounted for 9% of the U.S. energy supply in 2008.

  • Correct!

    Nuclear power accounted for 9% of the U.S. energy supply in 2008.

  • Sorry, that’s incorrect.

    Nuclear power accounted for 9% of the U.S. energy supply in 2008.

Energy Defined

Pulverized Coal

Coal that has been crushed into a fine dust prior to combustion, allowing the coal to burn more rapidly and efficiently.

View our full glossary