Sapphire Energy, Inc.

The Top 10 Clean-Tech Companies

Companies that make everything from solar panels to renewable-crude oil continue to be big draws for funding from the venture-capital community.

But a company that rewards consumers for recycling led The Wall Street Journal's second-annual ranking of venture-backed clean-tech companies.

Two solar-power firms, Suniva Inc. of Norcross, Ga., and eSolar Inc. of Burbank, Calif., came in second and third, respectively.

The Top 10 Clean-Tech ranking, announced Wednesday at the Journal's ECO:nomics Executive Conference in Santa Barbara, Calif., seeks to identify green companies with the greatest potential to succeed in an increasingly competitive sector.

A team from venture-industry tracker VentureSource calculated the rankings based on a strict set of criteria applied to 516 U.S.-based venture-backed businesses in clean technology. On March 10, the Journal plans to publish its 2011 Next Big Thing ranking of the top 50 US venture-backed companies across all industries, drawn from more than 5,700 firms. (VentureSource is owned by News Corp., which also owns Dow Jones & Co., publisher of the Wall Street Journal.)

Candidates were analyzed on the amount of capital raised in the past three years; the track records of each company's founders, managers and investors; and the percentage change in its valuation in the 12 months ended Nov. 30.

The list also reflects the difficulties in identifying companies with the best odds for success. Last year, Solyndra Inc. of Fremont, Calif., ranked No. 1, in part because it had secured a $535 million government loan on top of $286 million in venture capital. But amid heavy competition, Solyndra had a difficult 2010 and in June scrapped plans for an initial public offering.

Recyclebank, a unit of Recycle Rewards Inc., Suniva and eSolar also appeared on last year's list. RecycleBank jumped three spots from last year's No. 4 rank, while Suniva and eSolar remained steady at No. 2 and No. 3.

The remaining companies on the 2011 list are: No. 4 MiaSolé of Santa Clara, Calif., a maker of thin-film solar cells; No. 5 Opower Inc. of Arlington, Va., a developer of software for utility companies that helps consumers boost energy efficiency; No. 6 GreatPoint Energy Inc. of Cambridge, Mass., which makes technology that converts coal, petroleum coke and biomass into natural gas; No. 7 SeaMicro Inc. of Santa Clara, a provider of low-power servers for data centers; No. 8 Boston-Power Inc. of Westborough, Mass., a maker of lithium-ion batteries; No. 9 Luxim Corp. of Sunnyvale, Calif., a provider of energy-efficient lighting technology; and No. 10 Sapphire Energy Inc. of San Diego, a producer of "green crude" from algae, sunlight and carbon dioxide.

On Twitter, the hashtag for this project is #nextbigthing.

--Riva Richmond contributed to this article.

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