BEYOND BATTERIES: Hydraulic Hybrids. “The LCO-140H bus, like other hydraulic hybrids, operates on the same principle as battery-electric hybrids: Recapture energy typically lost as heat during braking and use it to propel the vehicle. Instead of storing energy as electricity in a battery, it is stored as pressure in a tank. The system uses the engine to drive a hydraulic pump that charges an accumulator to high pressure. The accumulator delivers that pressure to a hydraulic motor that turns the wheels. During braking, the pump motors are reversed to recapture braking energy. The internal combustion engine shuts down whenever the accumulator charge is sufficient to drive the motor. It sounds complex, and the packaging can be tricky, but storing energy in pressurized fluid often is more efficient than storing it in a battery.”