A method for transferring thermal energy to a separate endothermic process includes: (a) providing a carbon dioxide (CO2) stream and a carbonaceous fuel to a heater; (b) reacting the carbonaceous fuel in the heater to produce a heated stream; (c) transferring heat from the heated stream to the separate endothermic process; (d) separating the CO2 stream from the heated stream after (c); and (e) recycling the CO2 stream to the heater after (d).