This introductory video describes the basic principles of residential geothermal heat pumps.

This video discusses how methane digesters turn waste from dairy cows, food garbage, and other organic matter into usable gases and other fuels.

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

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.

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 interactive visualization created by FRED (Free Energy Data), displays energy supply (by source) and demand (by use) for each state in the US from 1960 to 2010; forecasts through 2035 are available as well.

FRED is an open platform to help state and local governments, energy planners and policy-makers, private industry, and others to effectively visualize, analyze, and compare energy-use data to make better energy decisions and form sustainable strategies.

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.

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