Minnesota research team presents work on Bio-Oil and Biochar processing at CUTC

Written by Jonathan Eisenthal

A Minnesota –based research team has achieved positive test results in the initial phase of a promising new technology that uses microwave energy to process farm-based feedstocks into bioenergy and other advanced products.

Microwave Assisted Pyrolysis (MAP) would be an add-on technology that would take today’s ethanol plants closer to the conception of biorefineries, by allowing them to produce a number of chemical compounds, including bio-oil and biochar, in additional to transportation fuel and animal feed products they currently produce, according to Kurt Spokas.

Spokas, a research soil scientist with Agricultural Research Service (USDA), serves as the lead scientist of the project. U of M Prof. Roger Ruan and Prof. Bob Morrison are co-lead scientists on the project. The project has been underwritten with funding from Minnesota Corn Research & Promotion Council.

“A good real world example of the possibilities is the Dasani™ (PlantBottleTM) plastic bottles used by Coca Cola,” said Spokas. “They use plant-derived polymers versus the usual non-renewable fossil fuel sources, in order to make the PET plastic. The produced bio-oil from the MAP process could provide some of these building blocks for plastic polymers or other uses.  The possibilities could be endless. This MAP technology could improve the overall bottom line for ethanol plants. This is not something that would displace any of the plant’s current ethanol production–it would supplement it with higher value products.”

Spokas travels to the 2012 Corn Utilization and Technology Conference in Indianapolis on June 4 and 5 to present the initial findings.

One of the most promising aspects of the MAP technology is that it eliminates the need to dry down any distillers grains utilized in the production of the bio-oil and biochar. Trials have determined a mixture of 75 percent biomass (corn stover was used in the trials) with 25 percent distillers grains achieve the optimal yield of bio-oil.

“This potential utilization of a wet feedstock by MAP significantly reduces processing time and required energy inputs,” said Spokas.  “MAP has also been shown to positively influence the distribution of end-products to more liquid (bio-oil) products. “

Bio-char is a black carbon byproduct of the MAP process that could offer a high-value soil amendment product. Spokas noted that a major concern in the development of crop-residue based bioenergy production is the loss of nutrients. Bio-char could be a part of the means for replacing those nutrients, he said. It also serves as a stable form of carbon and offers the additional benefit of reducing atmospheric carbon emissions.

“The one unique aspect of DDGS is its nitrogen content,” said Spokas. “It’s a function of the protein present in the processed grains. MAP takes the parent material through chemical and thermal transformation, and renders the nitrogen and the carbon in a more stable form, compared to both residue and conventional fertilizer products—while the nutrients from untreated biomass residues lasts from 0 to five years, we estimate that biochar has a longer lifetime in the soil of 10 to 20 years or even longer.  This could provide the closed soil nutrient loop we are looking for so that processing crop residue for energy doesn’t lead to unsustainable nutrient loss from farm fields.”

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