To limit risks when investing in alternative energy, Keith Fitz-Gerald notes, "We look for companies that have an actionable business model, a strong financial position, and an actual revenue stream."

The contributing editor to Monday Morning, a daily global news service, says, "One company that meets all these objectives is U.S. Geothermal (NASDAQ: UGTH). The firm has been in start-up mode for a few years now, but it's now set for the big time.

"Since I started following this tiny dynamo, the stock price has risen 278%. Even so, we're just starting to experience this company's true power -- pun absolutely intended.

"As its name implies, U.S. Geothermal is a renewable energy company focused on the production of electricity using geothermal energy. To break this down very quickly, geothermal power utilizes naturally heated underground water springs to turn turbines above ground by injecting water into the ground and pulling out steam.

"The company is sitting on two geothermal sites. There's the Raft River site (8.2 square miles), which is about 200 miles south of Boise, Idaho (formerly a geothermal test site for the Carter administration), and the Neal Hot Springs site in eastern Oregon (8.5 square miles).

What are the best energy investments for long-term investors? To answer this question, I surveyed 20 of the nation's leading financial newsletter advisors to find their current favorite ideas in the energy sector.

Interestingly, the advisors see the best opportunities in areas well beyond traditional oil firms; indeed, no one included in this report chose a major integrated oil company. Rather, the advisors have shown a preference for various oil services sectors, non-oil energy sources, and developing alternative technologies.

Some focus on areas such as deep-sea operations with Diamond Offshore Drilling Inc. (NYSE: DO), Transocean Inc. (NYSE: RIG) and Oceaneering International (NYSE: OII), while others look toward oil shippers such as Nordic American Tanker Shipping (NYSE: NAT) and refiners such as Valero Energy Corp. (NYSE: VLO).

Others chose companies that make specific products needed by the oil & gas industries such as NATCO Group Inc. (NYSE: NTG), which makes a wide range of oil & gas processing systems; Dresser-Rand Group Inc. (NYSE: DRC), a maker of control systems; Gardner Denver Inc. (NYSE: GDI), which makes compressor and fluid transfer systems; Tenaris (NYSE: TS), a maker of pipes and tublar products and Schlumberger Ltd. (NYSE: SLB), the largest and most diversified of the oil services companies.