Answer;
-Heat
-Electrical grid
-A hydrogen fuel cell is more efficient than a combustion reaction because very little of the released energy is released as heat. When used at home, a fuel cell eliminates the need for electrical grid because the cell is portable.
Step-by-step explanation;
-Fuel cells generate electricity by an electrochemical reaction in which oxygen and a hydrogen-rich fuel combine to form water. Unlike internal combustion engines, the fuel is not combusted, the energy instead being released electrocatalytically.
-Fuel cells have a number of benefits compared to combustion reactions; Fuel cells have a higher efficiency than diesel or gas engines, most fuel cells operate silently, compared to internal combustion engines, and they can eliminate pollution caused by burning fossil fuels; for hydrogen fueled fuel cells, the only by-product at point of use is water.