Dispatchability is the ability of a power producing facility to provide electricity on demand. Dispatchable power plants, for example, can be turned on and off and adjust their power output on demand. Conventional power stations, like fossil fuel plants, are dispatchable but produce, among other things, CO2 emissions. STE plants, however, which produce electricity in a manner similar to conventional power stations, i.e., by driving a steam turbine, are also dispatchable.
Dispatchability is one of the characteristics that makes STE a favoured option among other renewable energy technologies. All solar thermal power plants can store heat energy for short periods of time and thus have a “buffering” capacity that allows them to smooth electricity production considerably and eliminates the short-time variations that non-dispatchable technologies exhibit during cloudy days.
What’s more, thanks to thermal storage systems and the possibility of hybridisation,4 solar thermal power plants can follow the demand curve with high capacity factors delivering electricity reliably and according to plan. Thermal storage systems also allow STE to provide power in the absence of direct solar radiation, such that periods of solar generation and demand need not coincide.
For this case, the solar thermal power plant supplies electricity when needed to help meet peak demand.
Firmness and dispatchability are the main benefits of STE. STE and other renewable energy technologies, such as PV and wind, can thus be combined in an energy system to balance supply. In this way, STE can replace fossil fuel power plants and contribute to a 100% renewable energy supply as one of the renewable technologies capable of following the demand curve and ensuring a 24/7 secure supply. STE plants can also contribute to the stability of the system, i.e., maintaining voltage and frequency within required ranges, and allowing further penetration and integration of intermittent sources without the need for fossil fuel back-up.
STE enhances electricity production from a local and free source substituting for fuels that are often imported from other countries.
Shams-1, the largest solar power plant in the Middle East, represents an important step forward in introducing renewable energy in Abu Dhabi, helping it meet its goal of achieving 7% of its primary energy consumption from renewable sources by 2020. The plant prevents approximately 175,000 tonnes of CO2 emissions each year. This is equivalent to planting 1.5 million trees or eliminating the use of 15,000 cars in a city like Abu Dhabi.