A battery made of natural stone

The system CESAR, developed by Cees van Nimwegen and his Dutch company NICE developments, consists of a basalt-based battery that can store large quantities of electricity generated by solar panels and wind turbines.

In order to transfer to a green and circular economy, generating green energy using things like solar panels and wind turbines is one thing, but what if the sun doesn’t shine or the wind doesn’t blow? To make sure surplus energy doesn’t go to waste when there is a scarcity, the energy can be stored in batteries. The most common batteries, rechargeable lithium-ion batteries, however, have major environmental and social impact, as many components are toxic, becoming scarce, and are often sourced in places that violate human rights.

Basalt, on the other hand, is a quite common type of volcanic rock that easily absorbs heat. In the system, sustainably generated electricity is led through a system metal pipes, which heat up the stone, up to 500 degrees Celsius (930 degrees Fahrenheit).

The basalt is stored in a metal container, insulated by a layer of rock wool of 1 m (3 feet) thick. Thanks to this insulation, the heat can be stored for months, even years and be used to heat houses, for instance. All the materials can easily be recycled.

A proof-of-concept installation is currently in use in Sint-Oedenrode, the Netherlands. The system consist of a container with spiralling pipes and 40 m3 basalt, covered in a layer of rock wool. The energy of 50 PV solar panels are stored in summer and used to heat an event hall in winter. Another trial project is in Boekel, the Netherlands, where the energy of 700 PV solar panels will be stored to heat 36 houses all year round.

Video in Dutch

Photos: CESAR