To store short-term data in an entirely renewable grid thermal energy storage at concentrated solar power plants can be competitive with batteries, according to the results of a study based on an ideal grid model. Seasonal storage needs could best be met with power-to-gas-to-power technology.
Concentrating solar power and thermal storage of energy (CSP+TES) may be priced competitively with battery storage in order to create the lowest-cost 100% renewables grid across the continental US Researchers have discovered.
For seasonal storage, power-to-gas-to-power had lower costs than CSP+TES.
Researchers developed a basic grid model that assumed lossless, free transmission throughout America’s continental US. They concluded that their findings could be used to inform future research with more precise models. They also they believed that a realistic model representing transmission will not significantly alter the functions of the storage and generation technology they examined. This study is published by the journal Advances in Applied Energy.
With CSP mirrors, sunlight is directed onto receivers that contain the fluid for heat transfer, and the heat is then used to drive the steam turbine. The addition of thermal energy storage allows electricity to be produced later.
CSP is more expensive than solar PV. And when the study was run without TES, they chose not to use CSP. However, TES is less expensive than battery storage in addition, when TES adds CSP the technology is able to compete with batteries, according to the study. The savings in system costs of the addition of CSP and TES to an existing battery-powered system was modest, at 0.07 cents per kWh.
In order to increase the use of the combined technology costs reductions in CSP will be more crucial in comparison to cost savings for TES. But continuing reductions in the cost of batteries as predicted by NREL and others, could hinder the use of CSP+TES.
With power-to-gas-to-power (PGP) technology, renewable power is used to generate hydrogen from water, using electrolyzers. The hydrogen is then utilized to create electricity with fuel cells in the process that was modeled by researchers.
Storage requirements for seasonal storage in the 100% renewables grid were met by PGP storage capacity of 89,000GWh as per the model. Storage that is short-term, often that involves daily cycles was met with smaller capacity, 620GWh of storage of thermal energy providing 0.6 percent of the total power supply as well as 350GWh capacity for battery storage.
Demand response was depicted in the model through permitting the system to provide less than the traditional usage of the profile “by paying a high cost.” Intentions to increase the flexibility of demand “could minimize the value” of CSP+TES, as the authors stated.
Methane gas units with different percentages of generation were permitted in an analysis of sensitivity the model chose batteries when methane gas production was cut to 5%. The model selecting PGP that had methane gas at or below 2% and chose CSP+TES with methane gas less than 0.1 percent.
The open-access article provides all the cost elements of storage and generation technologies that are being studied and is entitled “The role of concentrated solar power with thermal energy storage in least-cost highly reliable electricity systems fully powered by variable renewable energy.”