October 08, 2009
Problems With Coal CO2 Capture For Sequestration
Carbon capture and sequestration is still just one big research project.
"Until there is a market, the technology won't take off," says Howard Herzog, principal research engineer with the MIT Energy Initiative. "It's amazing that there are as many projects going on that there are today; they are all research and development projects that are funded with subsidies."
My own take on carbon capture and sequestration (CCS): It is effort in the wrong direction. What we need is more effort to make nuclear, wind, and solar cheaper. If (or when) they become cheaper than coal electric they will displace coal via market mechanisms. Coal with CCS stands a very good chance of costing as much as nuclear power. Capturing the CO2 costs energy which requires more coal to be burned to power the CO2 capture process. Plus, the CO2 capture requires more capital equipment to do the capture. Since coal with CCS costs more than coal without CCS lots of lobbyists oppose the former.
Did you know that excessive CO2 pressure underground can cause seismic activity? The article examines other aspects of CCS.
One of the geological challenges faced by Duke Energy and others investigating in CCS is ensuring that the pressure inside reservoirs deep beneath the surface of the earth doesn't climb too high as carbon dioxide is injected. "There are only certain safe levels that you can raise the pressure to before you get into issues of seismicity," Herzog says.
Want to stop and reverse the rise in atmospheric carbon dioxide? Cheaper clean energy sources are key. China now burns more coal than the United States, Japan, and Europe combined. India's coal consumption is rising too. The only way developing countries will shift to cleaner energy sources is if those sources cost less. Developed country demand for solar, wind, and nuclear serves its most useful purpose by scaling up demand to levels that cause costs to fall. Those cost declines are essential for a cleaner energy future.
Wind -> Ammonia -> Algal Protein
Looks like it will pay for the reengineering of the coal plants to oxycoal to capture pure CO2 and pipe it to the desert southwest areas with low hail probability. Need a land area the size of Ohio.
Only problem is, this produces such an abundance of protein, at the price equivalent of alfalfa, that there would be little point in doing agriculture anywhere. The US's fossil fuel CO2 alone would create so much broad-spectrum amino acid protein that if it were directly consumed by humans, everyone in the world could have a diet richer than the US in protein. Oh, sure, you can run it through a couple of trophic layers to get some high grade predator fish farmed out in the ocean desert or something, but then the "environmentalists" who seem to prefer turning the rainforests into soybeans and can't tell the difference between ocean desert mariculture and near-coast mariculture would have a fit, and we can't have _that_ can we?
seem to prefer turning the rainforests into soybeans
My understanding is that "environmentalists" don't like biofuels - I think your criticism is better aimed at more traditional sources of demand for fuel, or demand for ag products.
can't tell the difference between ocean desert mariculture and near-coast mariculture
Could you elaborate on that?
The major problem with CCS is our bad selection of (dirty, cheap) technologies in the past. This can be corrected. One of the features of oxygen-blown IGCC is that it rather neatly separates many of the components of the syngas, and makes it relatively simple to go further. The Wabash River plant (which I went past just yesterday, but plant security wouldn't let me photograph) already:
- Hydrolizes carbonyl sulfide to H2S and CO2.
- Captures H2S in an acid-gas scrubbing system which also picks up CO2 (they could be co-sequestered).
There are existing processes for separating CO from syngas (the COSORB process is one). If it was burned in an oxy-fuel combustion system using a supercritical CO2 turbine, the thermal efficiency could be very high (offsetting parasitic losses) and the product stream would be nearly pure CO2. The non-CO fuel stream is H2 with a bit of CH4, which is very nearly carbon-free.
Most of the technologies to do this are available off the shelf. We need to start building pilot plants pronto.