The present invention provides a system that recycles heat recovered from hot products of a carbonaceous feedstock gasification process back into the gasification process. The hot gaseous products are used to heat working fluids such as air and water to produce hot air, hot water or steam. The heated fluids are used to return heat back to the gasification process. The system also comprises a control system to optimize the efficiency of a gasification process by minimizing energy consumption of the process, while also maximizing energy production.