“The quest for bioenergy at a meaningful scale is both unrealistic and unsustainable,” says a new report from the World Resources Institute that calls into question Western governments’ support for energy policies that encourage large-scale conversion of plants into fuel.

The study, “” (pdf), published Thursday, is a wide-ranging look at the costs and benefits associated with producing plant-based energy, or biofuels.  It finds that dedicating crops, such as corn or sugarcane, or land to generating bioenergy—as the U.S. and some European countries are already doing and aiming to do even more—is an inefficient use of the world’s natural resources.

Further, the report states: “[B]ioenergy that entails the dedicated use of land to grow the energy feedstock will undercut efforts to combat climate change and to achieve a sustainable food future.”

Not only do today’s principal biofuels, which mostly use corn or sugarcane, simply divert crops from the food supply into the energy supply, their champions rely on “overly optimistic estimates of emissions reductions,” according to the analysis.

Co-authors Tim Searchinger and Ralph Heimlich explain:

In contrast, the study claims that “[o]n most of the world’s land, PV systems today can generate more than 100 times the useable energy per hectare than bioenergy is likely to produce in the future even using optimistic assumptions.”