are allowed to decompose to co 2 and their corresponding metal oxides the hot gas so produced during combustion consisting predominantly of co 2 and h 2 o if oxygen is used and n 2 co 2 and h 2 o if air is used as well as lesser amounts of oxides of nitrogen and sulfur is withdrawn from the reactor through gas withdrawal lines heat is recovered from the hot oc combustion gas to produce steam using steam generators of any suitable construction the steam can then be cycled for use in the nop cycle excess steam may be used to produce power by for example steam turbines or can be used directly where shaft power is required to power the process such as compression of air in the air separation process blowing of the oxidizing gas or flue gas to the es cycle or for driving electrical generators the electricity is also used on site to power the process and excess electricity is sold to the electric grid during the oc cycle co 2 is produced both from the combustion of the residual organic matter and the decomposition of carbonates after recovery of heat from the oc gas a portion of the cool co 2 laden gas is recirculated along with the air or oxygen to the bottom of the oc bed where it cools the lower bed and restores the alkali metal oxides to their carbonate form oxides of nitrogen and sulfur contained in the stream are deposited on the combusted shale where they react to form alkali metal salts oxides of n and s being more acidic than oxides of c or h will preferentially displace carbonates or hydrates on the combusted shale excess co 2 not required for conversion of alkali metal oxides to.