The 15 Best Green Tech Startups

Venture capital firms have invested nearly $20 billion into hundreds of green technology startups over the past five years, according to Greentech Media, a San-Francisco based research and media company.

But with only a few of these startups expected to make it, how can the best be separated from the rest? CNBC asked Greentech Media Editor-in-Chief Michael Kanellos which 15 should be on our radar.

The selection criteria included technological edge, potential to disrupt the market, quality of the management team, market opportunity, amount of funding and hype power. Click ahead to to see which 15 companies made the cut.

By Brooke Sopelsa
Posted 18 April 2010

Note: For some companies, the number of employees and venture capital total are approximate figures.

VC Funding: $56.2 million
Employees: 41
Headquarters: Fremont, Calif.
Founded: 1996

Purfresh offers a range of solutions that purify, protect and preserve food and water. Growers use its products to keep food fresh on the way to store shelves, and bottlers use it to sterilize the plastic bottles before they put in the water. Coca-Cola (KO), Procter & Gamble (PG) and Safeway (SWY) are among the Purfresh's customers.

VC Funding: $11.4 million
Employees: 4
Headquarters: Houston, Texas
Founded: 2007

Laurus Energy develops underground coal gasification, UCG, projects throughout North America. The company digs a hole thousands of feet until it hits buried coal. It then heats the coal up underground and turns it into gas. By converting the coal into gas underground, much of the pollution stays underground.

VC Funding: $45 million
Employees: 64
Headquarters: South San Francisco, Calif.
Founded: 2005

LS9 produces renewable fuels and sustainable chemicals. The company is currently working with Procter & Gamble (PG) on green chemicals and Chevron (CVX) on fuel.

VC Funding: $8 million
Employees: 70
Headquarters: San Francisco, Calif.
Founded: 2004

Formerly known as Sustainable Spaces, Recurve performs residential energy retrofits in the San Francisco Bay area. It is also assembling a software package that will allow contractors around the world to cut down the time, cost and errors in conducting these kinds of retrofits. Co-founder Matt Golden is one of the driving forces behind the $6 billion Cash-for-Caulkers program recently introduced by President Obama.

VC Funding: $20 million
Employees: 50
Headquarters: Redwood City, Calif.
Founded: 2007

Hara creates software that tells companies how much power they consume. Its customers include Coca-Cola (KO), News Corp (NWS), Akamai (AKAM), Intuit (INTU), Brocade (BRCD) and Safeway (SWY).

VC Funding: $125 million
Employees: 150
Headquarters: Livermore, Calif.
Founded: 2002

Bridgelux is a manufacturer of light emitting diodes, LEDs. The company's $20 bulb, which saves $10 or more in power a year and lasts for a decade, comes out this spring. William Watkins, the former CEO of Seagate (STX), is now the head of Bridgelux.

VC Funding: $17 million
Employees: 35
Headquarters: San Francisco, Calif.
Founded: 2005

Adura provides wireless - lighting control and energy - management solutions to commercial buildings -- in a nutshell, it turns the lights off when no one is around and dims them when the sun is shining. In a recent test conducted by PG&E (PCG), Adura managed to cut the power delivered to lights by 72 percent.

VC Funding: $500 million (includes approx. $100m in public grants and funding)
Employees: 300
Headquarters: San Jose, Calif.
Founded: 2002

Nanosolar designs, engineers and manufactures thin-film, solar-power technology. The founders of Google (GOOG) - Sergey Brin and Larry Page - were among the first to provide seed financing for the company.

VC Funding: $96 million
Employees: 104
Headquarters: Jackson, Miss.
Founded: 1998

This smart-grid technology company enables utilities to communicate with any device on the grid. In lieu of private network build-outs, the company uses the existing cellular networks, which it claims simplifies and reduces the cost of smart meter deployments. The Tennessee Valley Authority selected SmartSynch to serve as the communications backbone in its renewable program.

VC Funding: $90 million
Employees: 100
Headquarters: Petaluma, Calif.
Founded: 2006

The company's signature technology - the Enphase Microinverter System - connects solar panels to homes. The product is meant to make solar power systems more productive, more reliable and smarter. Greentech's Kanellos predicts the microinverter business is a $2 billion market.

VC Funding: $400 million
Employees: 300
Headquarters: Sunnyvale, Calif.
Founded: 2001

Bloom Energy's on-site power generation system utilizes fuel - cell technology with roots in NASA's Mars program. "It's like having a power plant in your basement that's far more efficient than the grid. "The Bloom Energy Server is currently producing power for several Fortune 500 companies, including Bank of America (BAC), Coca-Cola (KO), eBay (EBAY), FedEx (FDX), Google (GOOG), Staples (SPLS), and Wal-Mart (WMT).

VC Funding: $100 million
Employees: 80
Headquarters: South San Francisco, Calif.
Founded: 2003

Started by two guys who met on the first day of college, Solazyme has become "the most successful algae firm by far." Its technology allows algae to produce oil and biomaterials in standard fermentation facilities quickly, efficiently and at large scale. The company has already landed deals with Unilever (UN), Chevron (CVX) and the Department of Defense.

VC Funding: $783 million (includes a $465 million Department of Energy loan)
Employees: 500
Headquarters: Palo Alto, Calif.
Founded: 2003

Tesla Motors designs, manufactures and sells high-performance, fully electric vehicles, as well as advanced electric-vehicle, powertrain components. The company has shipped out about 1,000 units of its speedy Roadster model and opened up retail outlets in the U.S. and Europe. Earlier this year, the company filed plans for an IPO.

VC Funding: $275 million (Source: Earth2Tech)
Employees: 500
Headquarters: Redwood City, Calif.
Founded: 2002

This smart-grid solutions company enables utilities to achieve operational efficiencies, reduce carbon emissions and help its customers monitor and manage their energy consumption. Silver Spring's customers include PG&E (PCG) and American Electric Power (AEP). An initial public offering may be in the wings.

VC Funding: $160 million
Employees: 52
Headquarters: Oakland, Calif.
Founded: 2006

BrightSource Energy develops utility-scale solar thermal power plants. The company currently has operations in Israel, Australia and the US, including partnerships with construction-giant Bechtel, Chevron (CVX) and the Department of Energy.