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.

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 is one of a series of videos from the Switch Energy project. It describes three types of geothermal sources -- rare ones in which high temperatures are naturally concentrated near the surface, deep wells that require fracturing the rock and then circulating water to bring heat to the surface, and low temperature sources that use constant temperatures just below the surface to heat or cool a building. The latter two are more widely available but cost-prohibitive today.

This visualization includes a series of flow charts showing the relative size of primary energy resources and end uses in the United States for the years 2008-2012.

This suite of short video clips is part of a series produced by the Switch Energy project. There are several video segments that discuss different perspectives of biofuels as a renewable source of energy.