This video segment explores whether, in principle, renewable energy resources could meet today's global energy needs of about 15.7 terawatts.

This fuel cell animation demonstrates how a fuel cell uses hydrogen to produce electricity, with only water and heat as byproducts. The animation consists of four parts - an introduction, fuel cell components, chemical process, and fuel cell stack.

Sankey (or Spaghetti) diagrams parse out the energy flow by state, based on 2008 data from the Dept. of Energy. These diagrams can help bring a local perspective to energy consumption. The estimates include rejected or lost energy but don't necessarily include losses at the ultimate user end that are due to lack of insulation.

This animated slideshow introduces biodiesel as a fuel alternative. With concern about the use of petroleum-based fuels at an all-time high, biodiesel is experiencing a popularity surge. And algaeâotherwise known to some as pond scumâ are grabbing headlines as the next potential biodiesel superstar. But how and why do algae make oil? And why do they make so much of it? In this audio slide show, U.C. Berkeley's Kris Niyogi describes the process and its potential.

This video describes how geothermal heat resources in California have been tapped to supply 850 MW of electricity. Images and animations show how the area known as The Geysers has been developed to capture steam, produced from trapped rainwater and heated by the earth. Major challenges include finding suitable geothermal resources to develop, and ensuring that underground water is replenished.

This interactive diagram from the National Academy of Sciences shows how we rely on a variety of primary energy sources (solar, nuclear, hydro, wind, geothermal, natural gas, coal, biomass, oil) to supply energy to four end-use sectors (residential, commercial, industrial, and transportation). It also focuses on lost or degraded energy.

This short video shows how different biomass feedstocks are processed and refined into sustainable biofuels via biochemical and thermochemical processes.

This short video touches briefly on the future of global energy and which energy sources best meet four energy-choice criteria: affordable, available, reliable, and clean.

This video stitches together nine separate videos about energy sources (hydro, coal, geothermal, nuclear, wind, biofuels, solar, natural gas, and oil) from the Switch Energy site. Videos can be viewed as a group, or separately, each under their own title.

This video is one of a series produced by the Switch Energy project. It highlights the use of biofuels as a renewable source of energy.

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