Storing electricity underground and without batteries? It is possible
A ground water pit / Image: Getty.
Water is a substance used to store heat energy. An American company wants to pump it deep into the Earth’s crust to collect electricity. How exactly does it work?
There are many ways to save energy. In America, giant batteries often get the attention, but other lesser-known technologies are also used there. The latter includes underground heat storage, as the earth’s crust retains heat. It’s a property already exploited by a number of players in energy storage, including US company EarthBridge, which has designed a system called the Geobattery.
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How does this geothermal storage work?
Jio battery It is intended to store excess energy from renewable sources. So it is connected to a solar or wind power plant to maintain balance between production and demand.
The technology first considers a well with a depth of more than 300 meters. The excess energy is used to bring water to the surface and heat it with an electric heat pump. The hot water is then sent to an underground tank where the heat is stored. To destock, the system draws in the hot resource and sends it to a turbine that drives an alternator to generate electricity. The water is then sent to its starting point, the well.
The facility does not require geothermal hot springs, making it more geographically flexible. However, the company relies on sedimentary basins, which are the most suitable location for this type of storage plant.
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Long term storage system
According to the US Department of Energy (DoE), long-term storage corresponds to storage capacity greater than 10 hours. Earthbrickday doesn’t give any information about the efficiency of its system, but on the other hand, it confirms that the storage will be of the long-term type (or LDES for long-term energy storage). In fact, a geobattery can store thermal energy for 10 to 1000 hours (approximately 33 days), thanks to which the installation cost can be reduced to less than $10 per kilowatt hour (kWh).
LDES is currently considered one of the key levers of the energy transition. In the United States, these technologies will be important when solar and wind power represent more than 50% of the energy mix. Due to their production variability, these resources are highly efficient with long-term storage devices of more than 10 hours. However, LDES should complement and not replace short-term storage systems.
To meet this demand, EarthBridge is planning a nationwide rollout, including the state of Texas, very soon. He was already awarded a geothermal lease by the Texas General Land Office in early May.
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