Energy business

The energy industry is full of start-up opportunities, so it's no surprise that it was the fastest-growing category among privately-held companies on the 2008 Inc. 500 | 5000 list -- with a median four-year growth rate of 287.5 percent among 79 companies on the list. These companies run the gamut from dealing in solar energy to alternative fuels. Due to growing consumer demand to save on energy costs, companies that install efficient lighting systems or cut down on heating costs by installing solar panels are well positioned for future growth. In addition, economic stimulus funds for energy projects nationwide amount to $43 billion, creating opportunities for entrepreneurs with a scientific background to break into areas such as biofuel and wind power.