e. A combination of strategies is needed to reduce greenhouse gas emissions. The most immediate strategy is conservation of oil, gas, and coal, which we rely on as fuels for most of our transportation, heating, cooling, agriculture, and electricity. Short-term strategies involve switching from carbon-intensive to renewable energy sources, which also requires building new infrastructure for alternative energy sources. Long-term strategies involve innovative research and a fundamental change in the way humans use energy.

This short video surveys the different current and potential sources of energy - both non-renewable and renewable. It provides some discussion of the pros and cons of the different sources and explains how they are used to produce energy that people can use.

This simplified animation of a geothermal power plant from the U.S. Department of Energy illustrates commonalities with traditional power-generating stations. While there are many types of geothermal power plants, this animation shows a generic plant.

This video reviews key points as well as pros and cons of nuclear power.

This video is from the Energy 101 video series. It explains the process for converting micro-algae into fuel and makes the case that algae-based biofuels hold enormous potential for helping reduce our dependence on imported oil.

In this interactive, students can investigate a typical hydrogen fuel cell prototype car from its fuel cell stacks to its ultracapacitor, a kind of supplementary power source.

The limited-production vehicle seen in this feature is a Honda 2005 FCX, which is typical of the kinds of hydrogen fuel cell cars that some major automakers are researching and developing.

In this activity, students conduct a life cycle assessment of energy used and produced in ethanol production, and a life cycle assessment of carbon dioxide used and produced in ethanol production.

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 video is one of a series from the Switch Energy project. It reviews the environmental impacts of various energy resources including fossil fuels, nuclear, and renewables. CO2 emissions as a specific environmental impact are discussed.

In this activity, students learn about the pros and cons of co-firing woody biomass fuels with coal to produce electricity.