Was that a collective groan from investors and entrepreneurs when the National Venture Capital Association and Thomson Reuters said there were no venture-backed IPOs in the second quarter? The news was another reminder of a weak economy.

But only two days into the third quarter, water-desalination company Energy Recovery broke the IPO drought, raising $68.7 million (see Green Light post). The shares, offered at $8.50 per share, reached $11 per share during the company's Nasdaq debut, and have remained above the offer price, closing at $9.83 per share Thursday. 

Raising money can be tough for greentech. Still, that hasn't blunted companies' ambitions. Miasolé, a thin-film solar-cell maker in Santa Clara, Calif., is close to raising between $200 million and $220 million, reported VentureWire. That amount would make the investment the largest venture funding for any solar company to date.

More than 100 thin-film companies are vying for a slice of the market, according to a recent Lux Research report, which forecast that thin-film solar will occupy 28 percent of the solar market by 2012 and generate $19.7 billion in sales.

Here is a look at other companies that also caught investors' attention last week:

Private:

Fuels and Transportation:

  • The Masdar Clean Tech Fund and the Virgin Green Fund on Monday announced they had bought DuraTherm, which is developing petroleum-recycling technology, for an undisclosed amount. DuraTherm, based in Texas City, Texas, treats waste from petroleum and olefin-related businesses.
  • Intelligent Energy on Wednesday said it had raised $13.6 million to commercialize its hydrogen fuel-cell technology. The company, based in the United Kingdom, plans to license its technology and has worked with others to develop concept vehicles. Its projects have included Suzuki's motorcycle Crosscage, PSA Peugeot Citroen's hybrid delivery car and fuel-cell aircraft with Boeing Research and Technology Europe.
  • TranSiC raised 24 million Swedish krona ($4 million) in venture capital from Industrifonden, Volvo Technology Transfer and Midroc New Technology. The company develops bipolar junction transistors for building hybrid electric cars and other products.
  • Silvigen, a fuel-processing consultant for the power industry, raised £1.75 million ($3.47 million) from the Foresight Group, according to Growth Business. The Yorkshire, U.K.-based company, which plans to produce biofuels for the power industry, already has contracts with a "major U.K. power generator," according to the Website, and expects to use the money to build a biofuel plant.

Other:

  • Manchester Bobber, which is commercializing a wave-power technology first developed at the United Kingdom's University of Manchester, reported is seeking £11 million ($21.84 million). The money would go toward a pilot project to build an array of closely spaced bobbing floats that can harness the power of the waves.
  • Ensartech, a Dutch firm developing waste-smelting technology, raised an undisclosed amount from Icos Capital and the Capricorn Cleantech Fund. On its Website, the company claims its technology can convert 100 percent of all types of waste into energy, but offers no other information.
  • Integrity Block, based in Los Altos, Calif., got $2.7 million in cash and debt financing to expand its business of making concrete block-replacement materials. Investors included Navitas Capital and Western Technology Investment.
  • RF Biocidics, which is developing a radio frequency-based disinfectant, received an undisclosed amount of funding from Boston-based Allied Minds. The investment established the company, which spun out of the University of California at Davis. The company's technology uses radio-frequency heating, instead of chemicals or radiation, to kill pathogens and insects in food while preserving its quality.

Public:

  • Argan  (AMEX: AGX) on Wednesday said it had raised $25 million by selling 2.2 million shares to institutional investors. The company, based in Rockville, Md., last month announced it had teamed up with Invenergy Wind to build wind farms in the midwestern U.S. states and Canada. Argan is a holding company for Gemma Power Systems, Southern Maryland Cable and Vitarich Laboratories.
  • Energy Recovery (NSDQ: ERII), which is developing water-desalination technology, on Wednesday raised $68.7 million through an initial public offering (see Green Light post). The company, based in San Leandro, Calif., sold 14 million shares at $8.50 per share.
  • Solar-cell manufacturer China Sunergy (NSDQ: CSUN) on Tuesday said it had sold $54.5 million in convertible senior notes to institutional investors.