Concentrated solar power (CSP) industry developments
Global CSP activities have seen a significant shift from developed countries, especially Spain and the United States, to emerging economies in recent year. These have been driven by the ongoing stagnation of the Spanish CSP market and the slowdown in the US CSP market. There have been ongoing CSP growths in some new markets including South Africa, the MENA region and particularly China. Many emerging economies including Morocco, Saudi Arabia, South Africa and the UAE have also been enforcing local content requirements in their new CSP programmes and plants. At the same time, the CSP industry, despite record efficiency improvements and declining system prices, has been unable to compete with conventional solar PV sector.
These developments have meant mixed fortunes for various CSP companies globally. The CSP industry’s largest developer and builder, Abengoa from Spain, has managed to avoid the threat of insolvency when it reached a USD1.2 billion (EUR1.14 billion) restructuring deal with its creditors. The company underwent significant changes, including the restructuring of ownership plus the disposal of their non-core solar PV and wind power assets. Abengoa’s rising debt was partially a result of Spanish energy reforms enacted in 2013. These reforms reduced the FITs for CSP facilities in Spain which then led to stagnation of the Spanish CSP market. However, ACWA has continued to grow as a developer, owner and operator. ACWA made strong inroads into the global CSP market, most notably through projects in South Africa and Morocco.
Other top companies engaged in CSP construction, operation and/or manufacturing areas included Rioglass Solar from Belgium; Supcon from China; Acciona, ACS Cobra, Sener and TSK all from Spain; Brightsource, GE and Solar Reserve all from the United States.
The innovative integration of CSP with TES power storage has improved ability for reliable continuous power supply by larger CSP renewable power plants integrated with TES systems. Various CSP TES-integrated facilities have demonstrated their ability to supply power continuously and reliably in the absence of sunlight and even throughout the night. A good example is that in South Africa the newly commissioned Khi Solar One CSP TES facility reached a technological milestone for the region when it completed a 24-hour cycle of uninterrupted solar power generation and supply.
Looking ahead, the bulk of the new CSP facilities globally will include TES or hybridised with other power plants, such as natural gas power plants. A good example is Israel’s Ashalim CSP facilities and the ISCC plants under construction in Saudi Arabia.
CSP innovation and cost reduction management
Globally, CSP plant generation costs have varied widely depending on the specific economic characteristics and DNI levels of a given location. In the US market, it has been found that CSP prices have declined in line with the trajectory proposed by the US DOE’s SunShot Initiative. The US initiative targeted a decline of 75% in the cost of CSP systems between 2012 and 2020. This has resulted in CSP generation cost coming down to USD0.06 per kWh. Cost declines have also been shown elsewhere globally, especially in emerging economies. Two good examples included a reduction of 30% over two bid cycles in Chile and a reduction of 43% over five bid cycles in South Africa (REN, 2018).
Although CSP costs have seen significant declines globally, CSP deployment has been hampered by a strong competition by a concurrent rapid and substantial decrease in the price of solar PV. These changes have helped to focus CSP developers to maximising values through the integrated application of CSP with TES systems. These CSP TES integrations have enabled CSP facilities to provide dispatchable power continuously globally which have helped to improve CSP competitiveness against other fossil and renewable power generation options.
R&D and innovation in CSP have continued to focus strongly on technological improvements and cost reductions in TES plus cost reductions in key CSP components including collectors. There are also developments in alternative applications of CSP and in better efficiency of the heat transfer process. CSP R&D efforts are being undertaken in various countries including Australia, Europe and the United States.
A good technological innovation example is that in Australia researchers have achieved 97% efficiency in converting sunlight into steam and generated “supercritical” steam at the highest temperatures that has been achieved by non-fossil-based thermal fuels. Pieces of research supported by the EU have yielded advances in thermochemical energy storage and hybridised CSP systems. In the United States, research currently undertaken included new advanced thermochemical storage systems (TES) for CSP, which will offer the possibility of increased energy storage density at lower costs. Another interesting research is the application of supercritical CO2 which should offer the potential to increase CSP efficiency and reduce further cost.
Whilst CSP power has remained more expensive than wind power and solar PV on a pure generating cost basis, the overall value of CSP with TES can be higher as a result of its ability to dispatch power during periods of peak demands. SolarPACES, an international network of CSP researchers and industry experts, has made a significant progress in quantifying the real value of CSP incorporating TES and standardising yield assessment methodologies required to evaluate new projects. CSP efficiency could also be improved further with the Brayton Cycle which uses air as the working fluid in a gas turbine. This is distinct from the Rankine Cycle, which has been used in existing CSP plants. These CSP Rankine cycle plants had made use of water as the working fluid, in conjunction with a steam turbine. The new Brayton cycle CSP plants should be able to achieve higher operating temperatures, which should then result in higher overall CSP efficiency.