"Most resources are depleting assets; they are no good once consumed. However, there are sources of renewal energy, and this area has been gaining attention because of environmental and global warming concerns, as well as fear about impending oil shortages," says Adrian Day.

The editor of The Global Stock Analyst explains, "Geothermal is truly environment-friendly (that is, it has a small footprint, has no residual waste, and is not a blight on the landscape), and unlike most green power, it is profitable."

"Alternative energies are not just a pie-in-the-sky dream," says Paul Tracy and Nathan Slaughter from the StreetAuthority Market Advisor. "Denmark generates as much as 30% of its power from wind, Iceland uses geothermal energy, and producers are bringing down the cost of solar power."

"Overall, companies involved in alternative power technologies, such as wind, solar, geothermal, and biomass, are getting plenty of attention from investors these days." Here, the advisors profile what they consider to the most attractive companies in the alternative energy space.

Suntech Power Holdings Co. (NYSE: STP), "which manufactures and sells photovoltaic (PV) solar cells, has two primary advantages: a low manufacturing cost base and highly efficient cells.

"For starters, Suntech is based in China, where labor costs (even for skilled research staff) are far lower than in the Western world. The Chinese government also subsidizes such research, further helping companies like Suntech.

"In addition, the firm's cells boast some of the highest conversion rates on the market, allowing the company to offer smaller panels that can produce as much electricity as far larger ones from competitors.

"Suntech has been ramping up its manufacturing capacity rapidly in recent years to keep pace with strong demand. Analysts are forecasting robust earnings growth of 45% annually over the next five years.