Trash Batteries & 4 Other Weird Ways to Store Energy

TL;DR

Five unconventional energy storage methods — from pumped water to sewage-eating bacteria — offer grid-scale and small-scale alternatives to traditional electrochemical batteries.

Key Points

• 1.Pumped hydro (water batteries) dominate grid storage, accounting for over 90% of global grid energy storage. China's Fengning plant holds 45 million cubic meters of water for 40 GWh capacity; Australia's Snowy 2.0 (due 2029) will store 350 GWh — nine times more.
• 2.Geomechanical storage pumps water 300–600 meters underground to deform rock, storing energy in that pressure. Quidnet Energy demoed 35 MWh held for six months, though efficiency is only ~50%, offset by cheaper installation costs versus traditional hydro.
• 3.Thermal batteries heat materials like bricks, sand, or molten salt to 500–1700°C to store energy as heat. Morocco's Ouarzazate Solar Power Station uses molten salt to store 2,800 MWh; direct heat use hits ~95% efficiency, but converting heat back to electricity via turbines or thermophotovoltaics (TPVs) remains limited to ~44%.
• 4.Ice batteries freeze water or other materials overnight when electricity is cheap, using stored 'cold' for daytime cooling. New York's 11 Madison Avenue freezes 227,000 kg of ice daily — equivalent to 22.5 MWh — cutting peak-hour grid strain and electricity costs.
• 5.Microbial fuel cells use bacteria, algae, or fungi to strip electrons from biomass like soil or wastewater, generating electricity. Output is tiny — a 2024 state-of-the-art prototype achieved 10 mW/cm², about 100× less than a phone charger — but suits niche uses like farm sensors.