In this paper we show how to build an economically optimal feedback control strategy for the re-dispatch of electricity generation. We assume that the operator steers production in a set of controllable power plants by altering the active power set-point of each generator, within a set of predefined set-points. Theoperators strategy will be based on balancing the operating cost against the expected cost from unserved demand. Important aspects are ramp-rates at which production can approach the set-point, and switching costs arising from increased fuel consumption during ramping and wear and tear on production facilities.