Recently, I spoke to Ron Alverson, past chairman of the American Coalition for Ethanol (ACE), about a “passion project” he’s been working on for a a number of years: soil carbon sequestration for corn, something that for him, goes back to his university years. He has been measuring soil carbon on his farm for over 30 years. That passion took on new meaning in this era of lifecycle analysis modeling for fuels under the RFS and LCFS programs. And what he is doing could have profound impacts for the industry and the fuels market not just in the U.S., but globally. Following are some excerpts from our discussion, which you can listen or download below or listen to it in ITunes. Also, ACE has published a whitepaper on the issue which is available here.
“I dug into those first land use change models and I realized that the numbers, the data that they were using to determine land use change from switches from forest land or grass land to crop land, some were pretty unreasonable. Searchinger had the carbon intensity doubling from corn ethanol, which made it a lot higher than fossil fuels but there were also some pretty reasonable guesses. It ended up to be 20-40 grams per megajoules. Even with those reasonable guesses corn ethanol didn’t show much reduction. So I looked at those assumptions they made in there and realized that, hey we’ve been growing soil carbon in our soils by using corn at a faster rate than they were calculating the changes from land use would be.
I realized we have just got to go to work and put out data to the lifecycle modelers to show that corn ethanol can really improve our carbon score if we account for what is taking place on thousands and thousands of corn farms across the United States. And unfortunately, even the current models that account for the total carbon intensity, the lifecycle of corn ethanol, still don’t account for the direct effects each biofuel crop has on soil carbon stocks. And that’s why I’ve decided we need to work on this in the industry and that’s what I have been working on.”
“I approached some of my friends that were soil scientists and one of them in particular, happened to be the head of what’s called the American Society of Agronomy. There are actually three groups, there is the American Society of Agronomy, the Crop Society of America and the Soil Science Society of America and they call themselves the tri-society. So I made those guys aware of what was happening. And I also pointed out that there was no accounting for the loss in soil carbon from removing that soil, from removing that crop residue.
They jumped on it right away. They acknowledged those guys that are doing that lifecycle modeling, they thought they were pretty good, they’re darn good engineers and they know fossil fuels and they know emissions really well but there was really little interaction with soil scientists when they developed those models to determine the carbon intensity. So, they decided to have this workshop in California, right near the CARB headquarters in Sacramento and invite in folks from CARB, folks from Argonne, soil scientists from all over the United States, crop scientists, farmers, ethanol industry folks, corn industry folks and others.
They hashed over the issue and the results of that, they specifically recommended that, hey we need to do a meta analysis to provide data for you guys that do this carbon modeling, to do that soil carbon accounting correctly in those models. The Department of Energy went to work with a bunch of soil scientists and they are apparently updating or looking at all the literature and they are going to update all their models to include that soil carbon accounting.
They will look at what corn does to soil carbon and what soybeans do to soil carbon or sugarcane ethanol does to soil carbon. It looks like in the end that corn grain ethanol will get a nice credit for soil carbon sequestration. Soybeans will probably be neutral or maybe a little negative on soil carbon as they just don’t produce enough crop residue to maintain soil carbon or build soil carbon. And sugarcane ethanol, as we know, you remove all the residue off that field then its all to the cane mill and that is combusted to more energy at the plant. Well, that is very hard on soil carbon. Sugarcane fields are likely losing soil carbon and that needs to be accounted for in sugarcane ethanol lifecycle analysis.”