- Founded: 2009 by Laurence Kemball-Cook, who envisioned using foot traffic as a renewable energy source.
- Technology: The tiles use electromagnetic induction—copper coils and magnets—to generate 2–4 joules of energy per step.
- Applications:
- Powering LED lights, advertising panels, or phone chargers.
- Gathering data on pedestrian flow and engagement.
- Used in smart cities, brand activations, and public installations.
The sand battery is simplicity itself. “We just heat air and [circulate it] through sand,” says Liisa Naskali, COO of Polar Night Energy. But materials other than sand can be used. The new battery actually uses crushed soapstone chips from a local fireplace manufacturer. Sand, or other material crushed into sand-size particles, has the ability to store heat for weeks. Unlike some other batteries, the system doesn’t rely on chemicals, doesn’t degrade, and won’t catch on fire. In operation, the sand battery has demonstrated a round trip efficiency of 90 percent.