Central receiver photovoltaics – A source of firm solar power

Abstract

The cost of variable renewable power in certain applications is now lower than ‘new build’ fossil power (1). However, the value of variable renewable power has plummeted even further when demand is low. While renewable energy generation (wind and PV) is only 9.5% of global power (2), this value reaches over 50% in certain locations at certain times, contributing to significant problems with grid stability and demand-supply mismatch. These factors can, at times, trigger curtailment of renewable generation capacity, making their variable power worthless. This is impeding the expansion of renewable energy generation, since asset utilization and the return on investment is decreasing. If we are to reach zero emissions by at least 2050, clean electricity must contribute over 60% to global electricity supply (3). To achieve this, the value of solar power must be restored such that profitable business can drive the necessary 5-fold expansion of PV alone in the next 10 years (3). This requires both flexible stabilizing storage and market recognition of the value that this brings. A key enabler to restore the value of variable renewable power will be low cost, long duration power storage which is flexible and clean. The authors have devised a method of exploiting the unique synergies between central receiver PV, heat engines and simple water storage to enable an integrated, dispatchable power storage system. This system permits solar power delivery ‘on demand’, and can also take excess, low-cost power from the grid to stabilize (and thereby maintain the value of) other renewable energy sources, such as wind or PV. This paper describes the high-level features of such a system which uses proven off the shelf equipment to provide GWh scale, long duration storage at a fraction of the cost of batteries. A 4MWe central receiver PV plant with integrated 17-hour storage of 3MWe-50MWhe is being constructed in Australia to demonstrate our concept for ‘dispatchable PV’ power.