“Solar Energy” is NOT just about PV technology. There are also several other technologies using this free and abundant power of the sun to produce both heat and electricity. Solar Thermal Electricity (STE), also known as Concentrating/Concentrated Solar Power (CSP), is a technology that produces heat by using mirrors or lenses to concentrate sunlight into a heat receiver, which brings the solar energy to a heat transfer fluid. This heat can be used to generate electricity with a steam turbine or as process heat for industrial application.
Unlike PV that any household can install on its rooftop, STE power plants generate electricity mostly at utility-scale They are connected to the high voltage grid for transport and further delivery to end-users. By storing the thermal energy and/or using hybridization, STE is able to firmly deliver electricity on demand without additional cost – even after sunset. STE is grid-friendly not only due to thermal energy storage, but also due to the use of conventional turbine technology to generate electricity.
This is the most distinct feature of STE plants compared to other renewable energies that will allow for integration into the high voltage grids of even more RES sources without jeopardizing grid stability. This specific feature of dispatchability of the STE energy raises the overall value of the energy produced.
A remarkable cost reduction – around 50% – has been achieved by STE since 2007 with only 5 GW installed worldwide. Compared with the current situation of Wind (433 GW) and PV (321GW), one can easily figure out the real potential for cost reduction in the next years of STE plants.
Although STE plants are more capital-intensive than traditional fossil-fuel plants, their operating costs – once connected to the grid, are low, essentially because sunshine is free.
As of today, the cost of electricity produced by STE plants is lower than any newly announced nuclear power plants. Moreover, the LCOE of STE plants with storage capacity is much lower than PV plants with 6-hour battery storage. Ans it will continue to be so in the next decade. Apart from LCOE, policy makers and planners should consider the electrical system globally with a long-term vision, shifting from the current short-sighted COST approach to a full VALUE approach.
Prices for electricity produced by today’s STE plants fill the range from 12 to 16 c€/kWh depending on the irradiation level and most importantly on the financing conditions. They will continuously decrease over the coming years due to announced cutting-edge technology developments. The result will be that cost optimisation (also in manufacturing components), economies of scale after deployment of larger plants (i.e., 100-250 MW) are expected to further reduce the cost below 10 c€/kWh before 2020. Solar thermal electricity will be competitive against coal- and gas-fired power before 2020. STE is – and will continue to be – the necessary choice in sunny countries when considering addition of new capacity in long-term planning.
STE plants are today in most cases equipped with a heat storage system. During sunny hours, the collected solar energy is used not only to provide steam to the turbine but also to charge the thermal storage tank. Then, after sunset or during cloudy periods the energy can be drawn from the storage tank to deliver energy – on demand!
Normally the solar fields and the tanks are designed to cover 4 to 7 hours of operation but there is already a reference plant – Gemasolar in Spain – that can produce electricity continuously during the summer season, day and night, just like “base load” nuclear power plants.
From a system perspective, due to its built-in thermal storage capabilities, STE offers significant advantages over other renewable energy sources.
Furthermore, hybridization with biomass natural gas enhances the firmness of the delivery of solar thermal electricity to markets and grid operators.
With only 5 GW installed worldwide, STE technology is relatively new compared to other energy technologies. However, STE has a considerable huge potential in terms of electricity generation. A small part of the North African territory could meet the electricity demands of Europe, the Middle East and North Africa all together. The same also applies to the potential of STE plants in Southern Europe. For instance in Spain, 50 plants with a total 2300 MW are currently connected to the grid providing more than 4 TWh/year. STE represents already a share of more than 3% of the Spanish electricity generation mix during a significant part of a year.
Assuming an important capital cost reduction and the contribution of energy storage, the International Energy Agency (IEA) suggests that STE could become economically competitive for intermediate and peak loads within the current decade, due to reduced STE costs and increasing prices of fossil fuels and CO2. According to the 2014 edition of IEA’s Technology Roadmap for STE , the estimated production of STE could reach about 1000 TWh by 2030 and 4380 TWh by 2050, and could provide 4% of the electricity mix in Europe and 11% of global electricity mix. In other words, this will be a significant share in the energy mix.
In the future generation mix, dispatchable STE electricity from the Southern European countries combined with off-shore wind from the North See could complement seasonally each other and provide the bulk of the demand of Europe by 2050. Large hydropower along with other technologies such as on-shore wind or solar PV could also have a significant share. According to the study, adding STE to PV, solar power could provide up to 27% of global electricity by 2050 and become the leading source of electricity globally as early as 2040. All together they can achieve the goal of a practically carbon-free electrical system in the future.