The Colorado-based company building a $56 million biofuels refinery in Alexandria said Monday it has raised $100 million in its fourth round of funding from investors.

North Bridge Venture Partners and Singapore-based Concord Energy were the lead investors in the latest round of investment. Cool Planet’s other investors, BP; Energy Technology Ventures, which consists of GE, ConocoPhillips and NRG Energy; Google Ventures; and the Constellation division of Exelon also increased their investment in the venture.

Cool Planet uses wood and other biomass to make gasoline. The Alexandria plant is the company’s first biofuel production facility.

Chief Executive Officer Howard Janzen said the company attracted a significant number of new international investors — more than half the new investors are from international firms — with “both a financial and strategic interest.”

Cool Planet’s technology is being looked at for a number of markets, including China, Southeast Asia and the Middle East, Janzen said.