The advantage of corn over other crops is that it flourishes in the presence of nitrogen fertilizer. Sugarcane is not so hungry.
The cost of capturing fermentation CO₂ is low because fermentation CO₂ is almost pure with very little nitrogen in it. Thus almost all of the cost is the cost of compressing the CO₂, pumping it, and injecting it underground which is about $30 a tonne. Even a few percent of nitrogen will cause the CO₂ to misbehave while pumping, so capturing CO₂ from a combustion stream requires some kind of separation which historically has been an aniline stripper or something like the rectisol process, but maybe it will be aluminum formate or something else in the future. The aniline stripper costs about $50 a tonne.
The trouble with capturing fermentation CO₂ is that it is not scalable. There is a certain amount of it produced and it isn't enough to "save the Earth" but it is a low hanging fruit and it would help in the process in validating sequestration, as there are all kinds of questions about the permanence and safety of saline aquifer injection. (Don't get me started about the CarbFix water sequestration project...)
As for why you can't buy any good carbon credits it is the proliferation of junk carbon credits at low prices that keeps good ones off the market. Another problem is that many schemes are using the CO₂ to produce more oil
which on one hand is a real market for the CO₂ (in Texas you can drill and get CO₂ in some places and since the 1980s they will pump it sideways and use it for enhanced oil recovery) but doing so seems to be more problem than solution and it ties the project economically to the up-and-down cycles of the oil industry.
This is quite interesting, thanks for sharing. I had written off ethanol because of how gunked up it got with the American corn industry and the stupid fact that Iowa votes first in the US primary elections. Maybe there's something to this.
The advantage of corn over other crops is that it flourishes in the presence of nitrogen fertilizer. Sugarcane is not so hungry.
The cost of capturing fermentation CO₂ is low because fermentation CO₂ is almost pure with very little nitrogen in it. Thus almost all of the cost is the cost of compressing the CO₂, pumping it, and injecting it underground which is about $30 a tonne. Even a few percent of nitrogen will cause the CO₂ to misbehave while pumping, so capturing CO₂ from a combustion stream requires some kind of separation which historically has been an aniline stripper or something like the rectisol process, but maybe it will be aluminum formate or something else in the future. The aniline stripper costs about $50 a tonne.
The trouble with capturing fermentation CO₂ is that it is not scalable. There is a certain amount of it produced and it isn't enough to "save the Earth" but it is a low hanging fruit and it would help in the process in validating sequestration, as there are all kinds of questions about the permanence and safety of saline aquifer injection. (Don't get me started about the CarbFix water sequestration project...)
As for why you can't buy any good carbon credits it is the proliferation of junk carbon credits at low prices that keeps good ones off the market. Another problem is that many schemes are using the CO₂ to produce more oil
https://www.reuters.com/article/us-usa-energy-carbon-capture...
which on one hand is a real market for the CO₂ (in Texas you can drill and get CO₂ in some places and since the 1980s they will pump it sideways and use it for enhanced oil recovery) but doing so seems to be more problem than solution and it ties the project economically to the up-and-down cycles of the oil industry.