Pipelines can’t capture all the carbon emitted by ethanol plants
A company proposing an $8 billion carbon dioxide pipeline through eastern South Dakota says the project would be good for the environment.
The claim is based on the heat-trapping carbon dioxide emitted by the ethanol plant, which would be captured, transported through pipelines and stored underground in North Dakota.
“This carbon capture and storage scheme will be able to prevent the emission of 18 million tonnes of carbon dioxide into the atmosphere each year, or the equivalent of removing the annual CO2 emissions of four million cars from our roads,” the project website states.
While this is true, participating ethanol plants may still emit approximately 7 million tons Additional CO2 emissions every year. That’s because pipes can only capture some, but not all, of the carbon dioxide emitted by factories.
When ethanol plants convert corn into a gasoline additive, two types of carbon dioxide emissions are created: one from the fossil fuel used to power industrial equipment like boilers and grain dryers, and another from the corn during the fermentation process. carbon dioxide emissions.
Summit Carbon Solutions’ pipeline will capture carbon dioxide from corn fermentation. The carbon dioxide emitted by gas-powered machines will be released into the atmosphere.
“So the existing emissions associated with corn ethanol still haven’t been eliminated,” said Daniel Sanchez, an assistant professor in UC Berkeley’s Department of Environmental Science, Policy and Management.
Capturing carbon dioxide emissions from industrial equipment such as boilers and grain dryers is more expensive than capturing emissions from fermentation, Sanchez said. Industrial machinery uses large amounts of natural gas, which releases more carbon dioxide than carbon dioxide when burned as fuel. Additional processes are needed to separate carbon dioxide from water vapor and other gases, he said.
Iowa-based Summit has partnered with ethanol producers including poet and Valero Capture the carbon dioxide produced by fermentation at 57 ethanol plants in South Dakota and several other states and store it underground in North Dakota. The project, which has not yet received permits from South Dakota regulators, will utilize federal tax credit Designed to incentivize the prevention of greenhouse gas emissions.
Fermentation emissions unknown
EPA only Report The amount of carbon dioxide emitted by an ethanol plant when it is powered by natural gas. Emissions from the 57 ethanol plants Summit works with in 2022 will be approximately 7 million tons.
The EPA does not report CO2 emissions from corn fermentation. This is because fermentation emissions are thought to be periodic. Corn absorbs carbon dioxide from the air as it grows in cornfields. Then, when it’s fermented at an ethanol plant, it releases carbon dioxide back into the atmosphere. Eventually, farmers plant more corn, and the cycle continues.
Summit declined to disclose the amount of carbon dioxide emitted during corn fermentation at its 57 partner ethanol plants. Ben Nelson, director of carbon projects at Summit, said a typical 100-million-gallon plant can produce about 286,000 tons of fermented carbon dioxide.
Sanchez of the University of California, Berkeley, said that “modern and efficient” ethanol plants emit about 90,000 tons of fermentation carbon dioxide.
Different estimates mean the Summit pipeline and its 57 partner plants could capture between 5 million and 16 million tons of fermented carbon dioxide per year, both within the pipeline’s proposed 18 million tons capacity.
By comparison, there are approximately 1,300 power plants in the United States emitted By 2022, carbon dioxide emissions will be approximately 1.5 billion tons.
“This is both a huge pipeline project and a drop in the bucket,” Sanchez said.
Aim for a net negative
Sanchez added If ethanol plants replace It uses natural gas in a sustainable way while also capturing and storing the carbon dioxide emissions from fermentation, which can absorb more greenhouse gases from the atmosphere than are released during the plant-related ethanol production lifecycle.
Nelson pointed out 2022 report The Renewable Fuels Association says ethanol production could become net negative emissions by 2040. There are greater impacts to come, such as less destructive farming methods and growing cover crops.
Nelson said the average ethanol plant emits about 55 grams of carbon dioxide per megajoule (unit of energy) of ethanol produced, and Summit’s plan would reduce that to about 25 grams of carbon dioxide.
“Achieving net negative emissions will also require other efforts such as climate-smart agriculture, the use of renewable natural gas at ethanol plants, renewable electricity and improving plant efficiency,” Nelson said.
In South Dakota, some ethanol plants already receive so-called “renewable natural gas” from landfill emissions, a Brookings-area utility said Methane emissions are being sent Blending dairy manure into regional natural gas supplies.
This article was first published in south dakota searchlightis the Nebraska Examiner’s sister site in the national newsroom network.
