A steam generation system delivers heats water and carbon dioxide at high temperatures in the presence of one or more plasma arc torches and converts the materials into hydrogen and carbon monoxide. The converted gas is delivered to a heat recovery steam generator (“HRSG”) to produce steam, which may be used to power a steam turbine. Depending on the amount of steam and/or power desired, the system may use a control system to vary the flow, temperature and pressure of the gas delivered to the HRSG. The control system may do this by bringing additional torches on-line or off-line in the processing chamber, by adding unheated gas directly from a supply source, shunting the gas from the HRSG, and varying the flow of water delivered to the HRSG.