Coal ash thermal battery

A thermal battery, comprising:

• a thermal-storage mass consisting essentially of coal ash and configured to store heat from a heat source;
• a conduit extending through the thermal-storage mass;
• and
• a working fluid contained in the conduit and configured to transfer heat to or from the thermal-storage mass,
• wherein the conduit is a first conduit included in a thermal-input system configured to input the heat from the heat source into the thermal-storage mass for storage in the thermal-storage mass, and the thermal battery further includes a thermal-output system configured to output the heat from the thermal-storage mass to a device, the thermal-output system includes a second conduit coupled to the device and extending through the thermal-storage mass separately from the first conduit and a second working fluid contained within the second conduit and configured to circulate through the second conduit from the thermal-storage mass, to the device, and back into the thermal-storage mass,
• wherein the thermal-output system further includes a working fluid reservoir configured to contain the second working fluid in a compressed state, a valve configured to meter release of the second working fluid from the working fluid reservoir and into the thermal-storage mass, and a regulator coupled to the second conduit between the thermal-storage mass and the device to control release of the second working fluid from the thermal-storage mass to the device after being heated in the thermal-storage mass,
• wherein the thermal-output system further includes a compressor between the device and the working fluid reservoir and the compressor is configured to change the second working fluid from a gas state to a liquid state after flowing through the device,
• wherein the thermal-output system further includes a second working fluid reservoir and the valve is a multi-port valve configured to selectively open and close the working fluid reservoir and the second working fluid reservoir to provide means for filling a first reservoir, included in the working fluid reservoir and the second working fluid reservoir, with compressed second working fluid from the compressor and releasing the second working fluid from a second reservoir, included in the working fluid reservoir and the second working fluid reservoir.

A method comprising:

• heating coal ash to provide heated coal ash,
• circulating a working fluid through the heated coal ash to provide heated working fluid,
• producing energy using the heated working fluid, and
• burning coal to produce the coal ash and residual heat, and transferring to the coal ash and the residual heat to a coal ash landfill to heat the coal ash in the coal ash landfill and provide the heated coal ash.