DARPA is the well-known Defense Advanced Research Projects Agency of the U.S. Department of Defense. It conducts top-secret defense research projects, like X, Y and Z. The "advanced research projects" model seems to be working because the government recently launched another Advanced Research Projects Agency, ARPA-E. The E is for energy. It's probably not as stealthy as DARPA, but it's potentially much more important.
ARPA-E operates under the Department of Energy and is responsible for funding research projects that aim to improve our use of energy resources or develop new energy resources. Some of the funded projects are or will be very experimental, not falling in line with previous or even current energy research. All of this funding and research will help us to reduce or eliminate our dependence on fossil fuels.... hopefully.
ARPA-E states that it funds research projects in six major categories of energy technology advancement, plus one category of "other projects." They give their major categories catchy names, which I guess the goal is to help people to remember them better:
BEEST (better batteries)
IMPACCT (reduced carbon dioxide emissions)
GRIDS (grid-scale energy storage)
ADEPT (soft magnetics, high-voltage switches, high-density charge storage)
Electrofuels (microorganism-based biofuel production)
BEETIT (energy-efficient building cooling technology)
It seems that the research programs that are funded by ARPA-E are lines of research that are proposed or maybe already underway at universities, research institutions and private companies. I think in a way, it's good to have these major funding categories to help focus research efforts to accelerate innovation and progress. It might also encourage collaboration among the different groups that are working in the same area of research. I think, though, that the "other projects" category will become ever larger, possibly overtaking all of the other categories in number. ARPA-E will probably need to expand its core research categories as projects in the "other projects" category are funded.
My personal favorite is the Electrofuels category because it acknowledges that people with my basic science training in yeast (the best model organism, but sometimes difficult to translate into real-world applications) have an important role to play in improving our energy outlook.