Start-up requirements and current-drive issues for a pulsed DEMO, and potential implications for power output to the grid

The energy and power demands implied by start-up and attainment of operating conditions for a pulsed DEMO have been explored. The information gained has been used to establish the requirements both for transformer recharge and for an energy storage system designed to ensure the plant effectively maintains an uninterrupted 1 GW supply to the grid. It was determined that a minimum of approximately 150 MW of auxiliary heating would be required to access the desired operating conditions for the burn phase, and the current-drive potential of a heating system of this capacity was assessed to determine how the pulse length could be extended beyond purely inductive operation. The overall peak power and energy demand associated with the start-up phase of each pulse of output power was determined for a range of dwell times. These two quantities determine the costs of the subsystems required for the power provision during the transformer recharge phase and the energy storage needed for constant plant output. We are therefore able to produce a simple estimate of such costs as a function of dwell time. For falling dwell times, costs are found to rise sharply below around 500s, but they remain relatively flat as dwell times increase beyond around 1000 s, over the range considered. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.