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This mechanical battery, based on a spinning flywheel, can deliver short bursts of high power

Vishwa Robotics

The US Navy has a mechanical battery based on spinning flywheels, which store energy as they spun up and can discharge that energy in quick burst when stopped. It could be used to power laser weapons or railguns, or even store energy for homes.

Generators provide sustained power, but cannot be cranked up for short bursts of high power. For the latter, which is useful for directed energy weapons and railguns, the US Navy currently uses banks of lithium-ion batteries. These can …