5 ms·

Doesn’t sound exactly like the poster child for carbon capture (which I believe we need in some form). For one, ethanol — I would have to double check this but

by gdubs 5y ago

Doesn’t sound exactly like the poster child for carbon capture (which I believe we need in some form). For one, ethanol — I would have to double check this but last time I looked, ethanol represent a very tiny sliver of the energy pie. But again, as someone who calls themselves an environmentalist, I do think we need to be putting serious thought into capture, because I don’t think we’ll want to live with current levels of warming, let alone where the trajectory has us winding up even in best case drawdown scenarios.

PaulHoule 5y ago
The advantage of tying carbon capture to an Ethanol plant is that you get very pure carbon dioxide as a waste product of the fermentation process. If you want to capture carbon from combustion you need to separate the carbon from both water and nitrogen; you have to compress carbon dioxide to about 1500 psi to inject it underground and even a few percent of contamination will cause the gases to phase separate in the pump and in the pipeline and cause no end of trouble. The "gold standard" for purifying carbon dioxide from combustion is https://en.wikipedia.org/wiki/Amine_gas_treating https://en.wikipedia.org/wiki/Amine_gas_treating and that involves an expensive stock of amines. You might be able to lower the cost of purifying the gas by separating oxygen from nitrogen before burning the fuel, but you not only need to pay to do that, but you need to recycle the exhaust gases otherwise the temperatures will get too high and burn up your turbine. When you capture the carbon from a biofuel plant you are capturing it from the air and putting it underground opposed to a plant that burns fossil fuels which merely prevents carbon from entering the atmosphere. For all of those reasons, adding carbon capture to Ethanol plants is a good way to get practice at the storage part of CCS.

by gdubs 5y ago

PaulHoule 5y ago

The advantage of tying carbon capture to an Ethanol plant is that you get very pure carbon dioxide as a waste product of the fermentation process. If you want to capture carbon from combustion you need to separate the carbon from both water and nitrogen; you have to compress carbon dioxide to about 1500 psi to inject it underground and even a few percent of contamination will cause the gases to phase separate in the pump and in the pipeline and cause no end of trouble. The "gold standard" for purifying carbon dioxide from combustion is https://en.wikipedia.org/wiki/Amine_gas_treating https://en.wikipedia.org/wiki/Amine_gas_treating and that involves an expensive stock of amines. You might be able to lower the cost of purifying the gas by separating oxygen from nitrogen before burning the fuel, but you not only need to pay to do that, but you need to recycle the exhaust gases otherwise the temperatures will get too high and burn up your turbine. When you capture the carbon from a biofuel plant you are capturing it from the air and putting it underground opposed to a plant that burns fossil fuels which merely prevents carbon from entering the atmosphere. For all of those reasons, adding carbon capture to Ethanol plants is a good way to get practice at the storage part of CCS.