"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, "Avoiding Bioenergy Competition for Food Crops and Land" (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:

Most calculations claiming that bioenergy reduces greenhouse gas emissions do not include the carbon dioxide released when biomass (e.g., from maize) is burned. They exclude it based on the theory that this release of carbon dioxide is matched and implicitly “offset” by the carbon dioxide absorbed by the plants growing the biomass feedstock. Yet if those plants were going to grow anyway (e.g., for food), simply diverting them to bioenergy does not remove any more carbon from the atmosphere and therefore does not offset emissions from burning that biomass. In effect, these analyses "double count" plant growth and thus "double count" carbon.

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."

What's more, the report notes, "solar cells do not require land with plenty of water and good soils."

Despite all this, governments and some researchers continue to promote goals related not only to biofuels for transportation, but also to other forms of bioenergy, including the use of wood and grasses—from new plantings or even existing forests—for electricity and heat generation.

This is a mistake, warns the report: "Although photosynthesis is an effective means of producing food, wood products, and carbon stored in vegetation, it is an inefficient means of converting the energy in the sun’s rays into a form of non-food energy useable by people."

In light of their findings, the authors recommend phasing out bioenergy that uses crops or that otherwise makes dedicated use of land. Doing so, they say, will require five policy changes:

• Governments should fix flaws in the accounting of the carbon dioxide consequences of bioenergy in climate treaties and in many national- and state-level laws.
• Governments should phase out the varied subsidies and regulatory requirements for transportation biofuels made from crops or from sources that make dedicated use of land.
• Governments should make ineligible from low-carbon fuel standards biofuels made from crops or from the dedicated use of land.
• Governments should exclude bioenergy feedstocks that rely on the dedicated use of land from laws designed to encourage or require renewable energy.
• Governments should maintain current limits on the share of ethanol in gasoline blends.

The New York Times notes: "Many of the pro-biofuel policies adopted by Western governments date to a period when other types of renewable energy were viewed as prohibitively expensive. But costs for wind and solar power have plummeted over the past decade, and the new report points out that for a given amount of land, solar panels are at least 50 times more efficient than biofuels at capturing the energy of sunlight in a useful form."

Andrew Steer, president of the World Resources Institute, told the Times, "I would say that many of the claims for biofuels have been dramatically exaggerated. There are other, more effective routes to get to a low-carbon world."