TEXEL Energy Storage, a Swedish energy storage startup founded in 2018, develops a simple, cheap thermochemical battery that can store electricity from renewable sources like solar cells and wind turbines. The battery is charged with renewable electricity by heating limestone (CaCO₃), which breaks down into CO₂ gas and calcium oxide (CaO). CO₂ can be stored with minimal energy loss. During discharge, CO₂ combines with CaO to regenerate CaCO₃. Heat released from the reaction is used to produce electricity. The design of the battery system improves its efficiency to 90%.
Challenges: Using lithium batteries to store renewable energy costs too much
More and more solar cells and wind turbines are being installed to produce clean electricity and cut down carbon emissions. The ability to store these intermittent renewable electrical energy would significantly increase the efficiency and reliability of solar and wind energy.
In order to preserve the high quality of electricity generated by renewable electric energy sources, it should be stored in rechargeable batteries, such as lithium-ion batteries. According to a BloombergNEF report, the average cost of lithium-ion batteries in 2021 was $132 per kWh. The cost of energy storage must range between $30 and $70 per kWh in order to provide baseload electricity at $0.10 per kWh with the optimal wind-solar mix. The high cost of lithium-ion batteries prevents their widespread applications as grid-scale energy storage solutions.
The storage of electricity as low-grade heat is a cost-effective solution. Nonetheless, this downgrade is not considered to be commercially viable. Instead, concentrated solar power has been used to focus the solar radiation either directly to a Stirling engine to produce electricity or to a heat storage to generate heat.
As solar cells and wind power plants become less expensive and more efficient, thermal storage of renewable electricity would become a solution that is simple and inexpensive.
TEXEL Energy Storage Technology
TEXEL Energy Storage (TEXEL) has developed a simple and cost-effective thermochemical battery for storing electrical energy from renewable sources. During charging, the thermochemical battery uses renewable electricity to heat calcium carbonate (CaCO₃, limestone), which decomposes at a high temperature into CO₂ gas and calcium oxide (CaO). CO₂ is stored in a tank. During discharge, CO₂ is released to react with CaO, and the resulting heat is used by a Stirling engine to produce electricity. Heat generated during the charging and discharging is supplied to buildings or used to preheat CO₂ gas, thereby improving the total efficiency of the system.
TEXEL energy storage
The diagram below depicts the TEXEL energy storage system.
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