High-temperature Pumping of Silicon for Thermal Energy Grid Storage

Journal Article · 10 June 2021 · Energy

DOI: https://doi.org/10.1016/j.energy.2021.121105 · OSTI ID:1879108

Amy, Caleb  ^[1]; Pishahang, Mehdi ^[2]; Kelsall, Colin C.  ^[2]; LaPotin, Alina  ^[2]; Henry, Asegun ^[2]

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1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Massachusetts Institute of Technology
2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

As the cost of renewable energy falls below fossil fuels, the key barrier to widespread sustainable electricity has become availability on demand. Energy storage can enable dispatchable renewables, but only with drastic cost reductions compared to current batteries. One electricity storage concept that could enable these cost reductions stores electricity as sensible heat in an extremely hot liquid (>2000 °C) and uses multi-junction photovoltaics (MPV) as a heat engine to convert it back to electricity on demand, hours or days later. This paper follows previously reported technoeconomics and liquid containment, examining equipment that would be needed to exchange heat between resistive heaters, a molten silicon storage tank above 2000 °C, and a heat engine. Herein, we report on a pump that was designed and tested to circulate the liquid silicon between these three regions and the effect of spatial thermal cycling was simulated in models and experiments. While the pump successfully circulated silicon between 1800-2080 °C for ten hours, circulation with a temperature gradient caused it and other non-isothermal experiments to dissolve significantly due to the temperature dependent solubility of not only carbon, but also silicon carbide which otherwise protected the graphite infrastructure. Furthermore, methods to reduce dissolution and an alternative embodiment are presented.

• Research Organization: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E); USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• Grant/Contract Number: AR0001858; EE0008375; EE0008381
• OSTI ID: 1879108
• Journal Information: Energy, Journal Name: Energy Vol. 233; ISSN 0360-5442
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English