Finland is pioneering the use of heated sand as a large-scale energy storage system, decarbonising industrial heat with one of Earth’s most ordinary materials.
Industrial heat is responsible for around one fifth of the world’s carbon emissions. It is the part of the energy system that receives less attention than electricity generation but is arguably harder to decarbonise. Factories that need high-temperature heat for manufacturing processes, district heating systems that warm entire cities through underground pipe networks, these have been slow to transition away from fossil fuels because the alternatives have been expensive, complicated or simply not available at scale.
Finland has found one answer in sand. Large insulated silos, filled with ordinary sand, are heated to several hundred degrees using surplus electricity from wind and solar generation. The sand holds the heat because of its low thermal conductivity, losing it slowly over days or weeks. When heat is needed, it is drawn off and delivered to homes and factories through existing district heating networks.
The economics are compelling. Sand is one of the cheapest materials on Earth. It does not degrade through repeated heating and cooling cycles. It requires no rare minerals, no complex chemistry and no specialist handling. The silos that contain it are simple industrial structures, straightforwardly engineered and relatively inexpensive to build.
The timing of the system also solves a problem that has complicated the expansion of renewable electricity. Wind and solar generate power when conditions allow, not necessarily when demand is highest. A sand battery allows surplus renewable electricity generated on windy nights or bright afternoons to be stored as heat and released during the cold Finnish mornings when district heating demand peaks.
Several commercial installations are now operating in Finland, and interest from other countries with district heating networks is growing. The technology requires a dense network of insulated pipes to deliver the heat from storage to consumers, which is more common in Nordic countries than elsewhere in Europe but is present in cities across the continent.
A silo of warm sand on the edge of a Finnish town, quietly releasing heat through a January night. It does not look like a technological revolution. But it is solving a problem that seemed intractable just a decade ago, with a material that has been sitting under our feet all along.
Source: Euronews Green