TRUCKEE, Calif. - The future is sure to hold a major transformation in the way we produce energy. Investors should always try to identify long term trends and act accordingly. The green energy sector has been a frustrating one for many investors. Traditional large cap energy stocks have performed well this year and we have seen the companies of the future, those that are focused on renewable energy, falter.The list of companies in the alternative energy sector that have filed for bankruptcy protection is large and includes names like Solyndra, A123 Systems, Abound Solar, Evergreen Solar and more. From an investor's perspective, investing in alternative energy stocks has been risky and frustrating.One thing for sure is that our global demand for energy is not going away and will increase. Another factor is that we are sure to see a gradual transition to clean, sustainable energy. One way to play energy is by investing in the big cap energy stocks of today. Why invest in the old school companies when the future is in the renewable energy companies? That's because the large cap companies that dominate today, that have very deep pockets are also likely to lead the transition to alternative sources by developing them and though mergers and acquisitions of profitable small companies.Geothermal energy is a clean, renewable source that is also fairly abundant. Most of the geothermal potential in the United States is in the west and California has the largest amount of geothermal generating capacity in the United States. Recently, I had the pleasure of interviewing Yehudit Bronicki, the CEO of Ormat Technologies for my radio show. According to her, the state of Nevada also has tremendous geothermal energy potential.Energy giant Chevron is the world's largest producer of geothermal, but they currently have no operations in the US. All of their geothermal activity is overseas at the present time. It remains to be seen if Chevron will expand into the US market, but it seems highly likely. Ormat is a local Reno based company that has been in business since 1965 and is a leader in geothermal energy. The stock is currently trading below book value and according to a recent article in Forbes appears to be "very oversold" at the present time.Geothermal is a clean, renewable energy source that should play a larger role in the future. I want to disclose that I own a small position in Ormat and am looking forward to our transition toward alternative energy sources.Kenneth Roberts is a Truckee based Registered Investment Advisor. Information on his money management service can be found at www.fusiontargetretirement.com or by calling 775-657-8065. Past performance does not guarantee future results. Consult your financial adviser before purchasing any security.