The US Department of Energy (DOE) launched the SunShot Initiative in 2011 with the goal of making solar electricity cost-competitive with power from conventional generation technologies by 2020. The initiative includes cost and performance targets for solar PV and CSP. Unlike PV, CSP technology captures and stores the sun’s energy in the form of heat, using materials that are low cost and materially stable for decades. This allows CSP with thermal energy storage (TES) to deliver renewable energy while providing important capacity, reliability and stability attributes to the grid, thereby enabling increased penetration of variable renewable electricity technologies. The technical report “Concentrating Solar Power Gen3 Demonstration Roadmap” released in January 2017 by NREL, will be used by the DOE to prioritise R&D activities leading to one or more technology pathways to be successfully demonstrated at a scale appropriate for the future commercialisation of the technology.
Today’s most advanced CSP systems are towers integrated with 2-tank, molten-salt TES, delivering thermal energy at 565°C for integration with conventional steam-Rankine power cycles. These power towers trace their lineage to the 10 MWe pilot demonstration of Solar Two in the 1990s. This design
has lowered the cost of CSP electricity by approximately 50% compared to parabolic trough systems; however, the decrease in cost of CSP technologies has not kept pace with the falling cost of PV systems.
Since the 2011 introduction of SunShot, the DOE’s CSP Subprogram has funded research in solar collector field, receiver, TES and power cycle sub-systems to improve the performance and lower the cost of CSP systems. In August 2016, the DOE hosted a workshop of CSP stakeholders that defined three potential pathways for next generation CSP (CSP Gen3) based on the form of the thermal carrier in the receiver: molten salt, particle or gaseous. Prior analysis by the DOE had selected the supercritical carbon dioxide (sCO2) Brayton cycle as the best-fit power cycle for increasing CSP system thermo-electric conversion efficiency. The research is designed to enable a CSP system that offers the potential to achieve the overall CSP SunShot goals. However, no one approach exists without at least one significant technical, economic or reliability risk (Figure 1). Read more…
Article published in: FuturENERGY March 2017