Abstract: An electrochemical engine for a vehicle comprises a storage tank containing hydrogen-retention material which reversibly takes-up and stores hydrogen at a hydrogen-storage temperature and releases it upon heating to a release temperature. A fuel cell stack using the released hydrogen produces electricity and heat by-product. A primary coolant flow circuit extends from a radiator, through the fuel cell stack and the storage tank, and back to the radiator, and has a coolant-distribution valve intermediate the fuel cell stack and the storage tank. A bypass coolant flow line extends from the coolant-distribution valve to the radiator. During operation, the heat by-product of the fuel cell stack is transferred via the primary coolant flow circuit to the storage tank for heating the hydrogen-retention material to release hydrogen for fueling the fuel cell stack.