About biogas
Since gas supply is in the news, just a quick pointer that the on-shore creation of biogas is an important link in the hydrochar value chain.
Consider the lowly chicory root. While chicory is a popular delicacy cherished for its bitter taste, its root has seen better times when it was still the to go-to produce used for creating ersatz coffee. Nowadays it’s mostly agricultural waste.
Not the kind ingredient to normally play a major role in geopolitics. But tides have turned quickly, not only since we started discussing the logic of global supply chains in general, but especially now that we’re questioning the logic of importing gas in particular.
Turns out the chicory root might provide a small puzzle piece to the solution. Researchers from the universities in Stuttgart-Hohenheim and Karlsruhe subjected the lowly root to a three step-process of sugar extraction, hydrothermal carbonization, and anaerobic digestion, increasing the carbon yield up to 96% vs 40% for only the anaerobic digestion step.
Normally we would mostly be interested in the hydrothermal carbonization step, but the public discussion about finding alternative sources of gas gives us the opportunity to point out that yes, there is a source, often enough it’s in our native soil, and we currently underuse it. It just needs to be extracted, and adding a HTC process step to the mix just might make it economically feasible.
The researchers in Hohenheim and Karlsruhe are not the only ones to combine biogas creation and hydrothermal carbonization. Other researchers have successfully combined the two processes using algae, barley, wheat straw, tofu, orange pomace, cellulose, swine and cow dung, or the lowly sewage sludge.
Using wet biomass for biogas production already happens to a limited extent. Adding a HTC step can significantly increase carbon efficiency and in turn economic feasibility, and it also produces hydrochar, the many beneficial uses of which are the focus of this newsletter.
This somewhat sophisticated reaction path could be extended by another stage: the thermal decomposition of biogas (methane) into hydrogen and carbon, another research topic at Karlsruhe. This decomposition of biogas yields green hydrogen and carbon, which could be used as activated carbon and/or for sequestration.
In this multi-stage process, we would ultimately only obtain the hydrogen and waste heat. The involved carbon would be completely sequestrable — in short, we can convert biological waste into energy (hydrogen and heat) and carbon that we can put away.
 | A guest post by
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 | A guest post by
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