LUCA Technologies, a Golden, Colo. company developing technology to convert dirty coal into natural gas, has raised $20 million more in financing.

The company joins a host of others working on similar conversion technologies. LUCA’s technology is different in that it works underground, seeding changes to micro-organisms within hydrocarbon deposits like coal, which stimulates conversion into methane.
Silicon Valley venture firm Kleiner Perkins and Boston’s Oxford Bioscience Partners led the investment, according to VentureWire (subscription required). The company last year got $3 million in a first round of funding from BASF Venture Capital America.