Most of us would be familiar with how hot pavement can get on a summer’s day – and how long it can store heat. It seems concrete may be key to cheap large scale energy storage in the near future.
Norwegian company NEST AS has developed a special concrete called Heatcrete to be used for solid-state thermal energy storage (TES). Heatcrete demonstrates superior thermal performance over normal concretes and was developed in partnership with HeidelbergCement.
The full battery system consist of steel heat exchangers cast into Heatcrete cells, with a heat transfer fluid flowing through the exchangers. The heat transfer fluid can be oil, water, steam or gases. Temperature is controlled through various manifolds and a smart valve control algorithm.
NEST can be used in conjunction with a concentrating solar power (CSP) plant or utilise surplus electricity from other renewable energy sources such as solar panels or wind turbines after it has been converted to heat.
NEST says Heatcrete has been heated up to 550°C without any evidence of degradation. Heatcrete is expected to be able to withstand millions of cycles, with normal usage considered low cycle fatigue.
The company says its system will cost significantly less than molten salt energy storage; both in terms of initial outlay and operating expenditure. It’s also able to operate at lower temperatures and the materials used are easy to source, unlike molten salts that are only available from a few sources.
NEST is a fully modular and scalable system, from 100’s of kWht to 1000’s of MWht.
The incremental cost to install a relatively small TES solution to capture surplus energy from a CSP plant that otherwise would be dumped is relatively small as existing infrastructure can be utilised and no additional investment in equipment such as steam turbine capacity is required.
NEST is currently testing a 1-megawatt concentrated solar power (CSP) system at the Masdar Institute’s Beam Down facility.
The company expects to have completed testing its technology in October; with it commercially available in the fourth quarter of this year.
Inventor of the NEST system is Professor Pål G. Bergan; who has a Master of Science from NTNU (NTH) in Civil and Environmental Engineering and a doctoral degree in Computational Mechanics from University of California, Berkeley.
News item provided courtesy of Energy Matters Australia
