The BBC is running a story [press release?] today that Carbon Capture and Storage would work more efficiently if we burnt our fuel in pure oxygen using a different theromodynamic cycle.
"Could [fossil fuel] power plants of the future produce zero emissions?" By Pia Gadkari BBC News, Washington
"Rodney Allam, chief technologist at 8 Rivers Capital, which owns Net Power, says: "The perception has been that to avoid emissions of [carbon dioxide] CO2, we have to get rid of fossil fuels.
"But unfortunately, fossil fuels represent over 70% of the fuel that's consumed in the world and the idea that you can get rid of that in any meaningful sense is a pipe dream." "
At the moment CCS is an even bigger pipe dream I'm afraid than dramatically slashing our fossil fuel use via the use of renewables (together with a system of cross border power grid interconnects).
In fact all our options for a future without CO2 emissions at the moment are pipe dreams of one sort or another.
The duty of the engineer is to find the pipe dreams that can be cost-effectively converted to reality, within a reasonable timescale.
I don't think CCS, in the forms so far proposed, will be one of them at the moment as they are fighting against the first and second laws of thermodynamics.
The fact we don't have enough secure places to hide away the CO2 underground is also a major problem.
The only long term hope for the CCS process (if CO2 can be captured efficiently) is to utilize solar energy in the north African deserts to convert concentrated CO2 back into energy somehow (or to allow for long term storage in the form of Calcium Carbonate say). More pipe dreams.
Anyway Allams CCS solution is to separate Oxygen from air somehow and then burn fossil fuel gas to generate electricity. The outputs water and CO2 can then be separated off.
No thermodynamic efficiencies for the "Allam Cycle" are presented.
He has moved the gas separation process to the input stage of his power station, which means he will have to take considerable amounts of energy from the grid in order to start this power station up. It also means that this system will need to be very reliable or will require large amounts of oxygen to be stored if they want to keep the plant producing energy in the event of a oxygen separation plant breakdowns.
Presumably he thinks cryogenic separation (or other method) of oxygen form ambient air is less difficult and less costly than cryogenic separation (or other method) of CO2 from the warm moist air output from a power station.
If he is producing his oxygen cryogenically he needs to warm it up prior to use in the combustor.
As far as I am aware non-cryogenic methods of oxygen separation are targeted at small scale production of oxygen only. If his company has found a non-cryogenic method of separating oxygen from air that is energy efficient and can be cheaply scaled up then this would be a remarkable achievement indeed.
It maybe more cost effective to split oxygen (and hydrogen) from water.
Another pipe dream.