NSF has a few areas of interest under this program:
- Biomass Conversion, Biofuels, & Bioenergy
- Photovoltaic Solar Energy
- Wind & Wave Energy
- Energy Technology Assessment
- Fuel Cells
Keep in mind that these are pretty technical requests (so, they're not interested in funding solar panels to put on your business' roof), so please make sure you visit the NSF's funding opportunity announcement for all the specifics. The proposal window is from August 15 to September 15 of this year.