I have become a big fan of the EIA website for conducting energy law research.
The EIA was created in 1977 within the Department of Energy, and "by law, its data, analyses, and forecasts are independent of approval by any other officer or employee of the United States Government."
Its website has a staggering amount of information about energy sources from petroleum to nuclear power, including U.S. and international statistical data, reports, maps, analyses, and forecasts about the outlook for all types of energy.
There are Energy Profiles for each state, as well as for 215 countries around the world. A section explaining Basic Information (such as where oil comes from, or how to compare different types of heating fuels) is also provided on the main page.
This is just a brief sample of what the EIA has to offer - check it out!