A study on the possibility of Flue Gas drawl from some of the 1000 to 1600 MW coastal coal fired power plants coming up in Tamilnadu for marine algae cultivation concluded that it would be cheaper to de aerate sea water with Anderson low cost de aeration system to secure CO2 from the sea itself than cooling power plant flue gases to below dew point, cleaning of particulates / SOx / NOx, corrosion control and pumping long distance for small absorption during sunshine.
A typical low ash coal fired 10 MW power plant could belch out up to 90,000 NM3 / Hr of flue gases at about 140 deg C containing permitted particulate loading of up to 150 mg / NM3 and other acid and gas pollutants. If algae can eat the 12 to 14 % CO2 content of flue gases without touching the 3% O2 content and cooling & cleaning of flue gases, a possibility may arise for the economic viability of carbon sequestration if low cost land for algae cultivation is available closer to the power plant and corrosion resisting gas pipes are selected. Near Chennai the present land cost quoted for a coastal power plant is Rs.60 lakh per acre.
Next question is can you use that CO2 from the power plant to grow algae? Yes, of course. But the problem with that is how many power plants have that much land available? And how many of those are in areas where you have water available? And how many of those are in areas where you have reasonably good climates. Once you put in those three boundary conditions, you come down to a fairly small number.
Even if we could capture all of the CO2 from a power plant, we could do it only during the daytime, we are not going to capture any at night and much less in the winter than summer months, at least in the northern hemisphere.
So the bottom line on all of this is that we cannot help power plants reduce their CO2 footprint to any significant extent. For coal-fired power plants, if we want to be serious about reducing their CO2 emissions, we have to get them to reduce CO2 emissions by 80 or 90 percent, not by the 10 or 20 percent we could do with algae under the best of circumstances. And the circumstances are not very good in most cases. So maybe a fraction of 1% of the CO2 emissions from coal-fired power plants will be amenable through algae capture and utilization.
With coal, we are talking about roughly 12 to 14% CO2 and for most natural gas systems have 4% to 5% of CO2 content. That makes a fairly big difference in terms of the energy required to just pipe and pump to transfer the CO2
by - Charles