The recent revelation that global carbon-dioxide emissions increased dramatically in 2010—and the attendant warnings from scientists about the looming dangers of global warming—underscored once again the need for the United States and the international community to reduce their dependence on fossil fuels and more comprehensively embrace alternative sources of energy. To what extent that will happen remains to be seen, of course, but publicly-traded companies dedicated to generating energy from solar, wind and tidal sources have emerged in recent years, ready to capitalize on what they hope will be an ever-increasing demand for their services.

Below is a listing of some of the alternative energy stocks to watch. For each company, we have included its ticker symbol and a brief description of the firm. In some instances, we also have included commentary from stock analysts as well as perspective from news articles and financial reports.

First Solar (NasdaqGS: FSLR) – The Tempe, Ariz.-based firm manufactures and sells photovoltaic solar modules, and also produces utility-scale photovoltaic power systems. First Solar’s shares jumped early today when it was announced that Warren Buffett's MidAmerican Energy Holdings unit agreed to purchase the company’s $2 billion Topaz Solar Farm being built in California. 

SunPower Corp. (NasdaqGS: SPWR) – The San Jose, Calif.-based company creates solar panels for homes and manufactures solar-power-system infrastructure for commercial properties, government buildings and utilities.

SunTech Power Holdings (NYSE: STP) – The China-based firm produces photovoltaic solar cells made of monocrystalline and multicrystalline silicon as well as solar modules. Its products are used in residential, commercial and utility applications.

Trina Solar Ltd. (NYSE: TSL) – The China-based company manufactures photovoltaic modules whose power output ranges from 165 watts to 240 watts.

Yingli Green Energy Holding Corp. (NYSE: YGE) – The China-based firm designs and produces photovoltaic cells and modules.

Solar-power companies have faced a tough market in 2011, as prices for their products have plummeted in the face of shrinking European demand, fallout in the United States from the bankruptcy of solar firm Solyndra and overproduction of solar products in China, according to financial website However, the firms listed above are “good bets to survive the current slump,” according to this Reuters article. The sector is likely to be characterized by mergers as it seeks a supply-demand balance, “a trend that could draw major Asian conglomerates deeper into the renewable energy sector,” the Reuters article adds.

LDK Solar (NYSE: LDK) – The China-based company produces monocrystalline and multicrystalline solar wafers used in the construction of solar cells. After LDK recently lowered its forecast for its third-quarter and total 2011 revenue figures, Wells Fargo analyst Sam Dubinsky said he is “not convinced [LDK] shares are a viable investment” and dropped coverage of the company, according to Reuters.

RenTech Inc. (AMEX: RTK) – Among its various services, the Los Angeles-based company develops and licenses technologies that generate transportation fuels from several sources, including municipal waste and biomass as well as coal.

Broadwind Energy (NasdaqGS: BWEN) – The Naperville, Ill.-based firm manufactures gears and towers for wind turbines, and also installs the turbines. In the third quarter of this year, the sales of its wind towers totaled $29.7 million, up from $17.3 million during the same period in 2010.

Ocean Power Technologies (NasdaqGM: OPTT) – The Pennington, N.J.-based company builds buoys that produce electricity by capturing the energy contained in ocean waves. In the first quarter of its 2012 fiscal year, the company took in $1.9 million in revenue, compared with $1.4 million during the first three months of fiscal year 2011.

Cosan Ltd. (NYSE: CZZ) – Among its various activities, the Brazilian firm produces ethanol fuel from sugar cane. The company also generates electricity from sugar cane bagasse. In an article on, financial writer Aaron Levitt says, “Sugarcane ethanol from Brazil could be seen as the only commercially available, economical and low-carbon biofuel available on the marketplace today. Brazil has over 30 years’ worth of history as a large-scale commercial sugar cane biofuel producer. For investors, that means betting on leader Cosan.”

Are there other alternative energy companies to watch? Who did we leave out? Let us know in the comments below.

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