We’ve talked a lot about the potential of turning algae into biodiesel, especially how it could be better for the environment than more conventional feedstocks, such as farm crops like soybeans and canola. But researchers at the University of Virginia are casting some doubt on that assumption.

This story on Greenbang.com says their new study finds that growing algae for fuel is more energy- and water-intensive than other biofuel crops, including switchgrass, canola and corn … plus, it could produce more greenhouse gasses:

“Given what we know about algae production pilot projects over the past 10 to 15 years, we’ve found that algae’s environmental footprint is larger than other terrestrial crops,” said Andres Clarens, the study’s lead author. “Before we make major investments in algae production, we should really know the environmental impact of this technology.”

But algae for biodiesel could still be a green venture if it is grown in ponds behind wastewater treatment facilities. That would also provide a source of feedstock that isn’t competing with food sources. The bottom line is: we need to look a little bit before leaping too far into algae-based biodiesel.