Here are some reliable resources from authoritative sources

Renewable Energy and Energy Efficiency
Energy Efficiency – The US Depatment of Energy’s homepage for energy efficiency.
Renewable Energy – The US Department of Energy’s homepage for renewable energy. Learn about solar, wind, biofuels, geothermal power and more.
Biofuels Basics – General information about biofuels from the EPA. Check out their resources and recent publications.
CSP – NREL’s page on their Concentrating Solar Power research.
Solar Water Heaters – Everything you need to know about solar water heaters.
AWEA – The American Wind Energy Association’s website.
US Hydropower Potential – DOE’s interactive map showing hydropower potential at non-powered dams.
Transportation – Check out the fuel consumption and greenhouse gas emissions associated with just about every vehicle on the market.
AutoEcoRating – An excellent resource for anyone on the market for a new car. AutoEcoRating’s advanced algorithm uses lifecycle assessment to calculate vehicles’ environmental footprints.
Fossil Energy
Carbon Capture and Sequestration – The US Department of Energy’s homepage for CCS.
US Natural Gas Data – From the Energy Information Administration.
Other Resources
US Energy Data – Want data? All the data you could ever want about US energy consumption, from the Energy Information Administration.
Government Incentives – DSIRE, the Department of Energy’s national database of federal and state incentives for renewables and energy efficiency.
NREL’s renewable energy conversion tool – Convert renewable energy values (kWh; MW) into other meaningful metrics, such as CO2 emissions offset or number of average households’ electricity needs met.