By 2030, 70% of our electricity will be generated by wind and solar energy, according to the Climate Agreement. But what if the sun doesn’t shine, or the wind doesn’t blow? Inventor Cees van Nimwegen is working on a solution: a durable battery of basalt, a common type of stone.

The efficient and safe storage of sustainably generated electrical energy is necessary for a successful energy transition. If more electricity is generated during the day than is necessary, it should be able to be stored to prevent network overload (and, for example, to power the washing machine at night).

At the moment we mainly use rechargeable lithium-ion batteries for energy storage. However, the environmental and social impact of the production of these batteries is considerable. Previously we wrote about the problems surrounding the extraction of the necessary raw materials, human rights violations and recycling. According to Van Nimwegen, his ‘basalt battery’ is a sustainable alternative. “The world is moving away from gas and co2 emissions have to be reduced. So switching to sustainably generated energy is a necessity,” he said.

But how do we heat our homes and buildings? According to the inventor, large-scale use of heat pumps is not the solution: this would require a gigantic grid increase of the central electricity network. “For the time being, the solution seems to be the decentralized generation of energy with wind and sun, and then store it close to where it is needed as heat.”

Van Nimwegen put his words into action, and developed the CESAR system with his company NICE developments. In this installation, sustainably generated energy is converted into heat which is then stored in basalt. This is a common type of stone that is well capable of absorbing heat. The basalt is warmed up by directing the current through a tube system through the stones. The basalt can go up to 500 °C! The stones are located in a metal shell, surrounded by an insulation layer of stone wool more than 1 meter thick. The insulation allows the heat to be retained for months and even years.

In a sustainable system, Van Nimwegen stresses: “All the necessary materials are completely durable and reusable.” At a later date, the heat can be returned to a heat grid, for example to heat homes. That is exactly what is going to happen in Ecodorp Boekel, a sustainable district in Brabant (Netherlands) where 36 climate-positive homes are currently being built.

Next year NICE developments will start building the basalt battery that will supply all these homes with heating and hot water. The European Union and the province of North Brabant are enthusiastic and contribute with subsidies. In addition, a basalt battery is installed in Sint-Oedenrode for the heating of 22 houses. The storage capacity of that system will exceed 100,000 kWh.

To give you an idea of how much that is: it allows you to supply 36 households with electricity. And that’s just the beginning. Van Nimwegen: “We see enormous potential for the CESAR system, think of an annual energy storage of more than thousands of gWh.” We are talking about hundreds of thousands of households.

Cees isn’t the only one who sees the potential of basalt as a battery. In Germany, Siemens is working with the University of Hamburg on a similar system. For the basalt battery: the larger the system, the higher the efficiency. If coal burning becomes more expensive in the future, the basalt battery could also become an interesting alternative for the industry. Hydrogen is now seen as a major contender for energy storage in addition to lithium-ion batteries. According to the inventor, however, hydrogen storage still requires a lot of innovation. His system is distinguished by its simplicity. Van Nimwegen: “Until a better method of bulk storage is found, I expect that one cannot get around our system.”

Joseph Mandell

Mandell is currently working towards a medical degree from the University of Central Florida. His main passions include kayaking, playing soccer and tasting good food. He covers mostly science, health and environmental stories for the Scientific Origin.