Independent peer review confirms EPA's approach to biofuels

On Friday, EPA released the findings of four independent peer-review panels that assessed the Agency's approach to measuring the lifecycle GHG emissions of different types of biofuels. All of the reviewers agreed that emissions from land-use change is an important impact from biofuels that we cannot afford to ignore. While the reviewers offered lots of helpful recommendations, they also broadly praised the quality of EPA's efforts. And while some reviewers ultimately concluded that EPA's models are not yet ready to be used in regulations, the majority endorsed EPA's basic approach.

The reviewers looked at the combination of models EPA used, the timeframe EPA used,  EPA's use of satellite imagery to determine land-use trends, and the emissions factors EPA used for international agriculture.

On the models the reviewers basically supported EPA's coupling of a pair of partial equilibrium models. While Dr. Michael Wang of Argonne National Lab agreed that the type of models should not be a problem he did raise concerns about transparency. On the other hand, John Sheehan at University of Minnesota and formerly at NREL stated: “EPA has, at this time, used the best available tools and approaches for assessing indirect land-use change effects of biofuels.”

On the timeframe, all of the reviewers agreed that EPA needs to shift from discounting time to discounting impacts. Dr. Kenneth Richards from University of Indiana raised some of the toughest questions about the ability of EPA's choice of a timeframe to be scientifically validated, but also stated: "I was pleased to see the extent to which EPA’s analysts had grasped both the conceptual and practical issues related to this type of work."

All of the reviewers assessing EPA's use of satellite imagery to predict land-use change patterns agreed that this was a scientifically valid approach and they all called for improvements over time such as more validation against local and regional ground truth.

EPA got the most general support for its assessment of international agriculture emissions. Dr. Kenneth Cassman from the University of Nebraska struck a common note when he said: “I believe the analysis uses the best available database for this analysis, and I do not know of any other data source.”

Unfortunately, the corn ethanol industry continued its campaign to suppress the science. Growth Energy, the newbie industry association set up by Poet, took a hear no evil approach and only focused on the portion of the comments that Growth agrees with. RFA and the National Corn Growers, unfortunately, must have decided that their attacks on the science had failed and so they should attack the messenger. They launched ad hominem attacks against the reviewers. (Here's RFA's and here's NCGA's.) Their logic seems to be that because there weren't any paid lobbyists for the industry on the review panel, it couldn't possibly be scientifically valid.

There's some irony here. RFA's rant largely boils down to the claim that because the peer review panel included noted corn ethanol skeptic, Tim Searchinger, "this is a perversion of what the peer review process is supposed to achieve." So how did Tim get on the panel? He was picked by an independent third party, the consulting firm ICF International. (See this explanation from EPA.) I'm sure EPA staff were groaning when they saw Tim's name on the list, but they were following the rules of good independent review, and ICF picked Tim because he knows more than almost anyone else about the models and issues involved. So basically RFA is trying to claim that there's bad science here because the peer review panel wasn't politically gerrymandered to their satisfaction.

About the Authors

Nathanael Greene

Director, Renewable Energy Policy, Energy & Transportation program

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