This online calculator converts from one energy unit to another - from gallons to British thermal units (Btu), kilowatt/hours to megajoules, short tons to metric tons.

The activity follows a progression that examines the CO2 content of various gases, explores the changes in the atmospheric levels of CO2 from 1958 to 2000 from the Mauna Loa Keeling curve, and the relationship between CO2 and temperature over the past 160,000 years. This provides a foundation for examining individuals' input of CO2 to the atmosphere and how to reduce it.

This animated video outlines Earth's energy. The video presents a progression from identifying the different energy systems to the differences between external and internal energy sources and how that energy is cycled and used.

This video segment highlights how the U.S. military is the single largest user of energy in the nation, but it is also trying to reduce its carbon bootprint. Scenes taped at Fort Irwin and Camp Pendleton show the Army and Marines experimenting with wind and solar in order to reduce the number of fuel convoys that are vulnerable to attack.

In this activity, students work through the process of evaluating the feasibility of photovoltaic solar power in 4 different US cities.

In this hands-on engineering activity, students build a tabletop wind turbine. Students get acquainted with the basics of wind energy and power production by fabricating and testing various blade designs for table-top windmills, constructed from one-inch PVC pipe and balsa wood (or recycled materials). The activity includes lots of good media and Web resources supporting the science content.

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

In this video clip from Earth: The Operators' Manual, host Richard Alley discusses China's efforts to develop clean energy technologies and to reduce CO2 in the atmosphere, by building coal plants using CO2 sequestration technology. (scroll down page for video)

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 video segment from NOVA's Saved By the Sun hour-long video, students learn about photovoltaics and see how two families are using solar technologies in their homes. The video introduces the ideas of state incentives and net metering benefits.