Hydrogen fuel cell produces electricity by combining hydrogen and oxygen atoms and burns cleanly when converted to electricity and heat, with no greenhouse gas emissions from its combustion unlike conventional fossil fuels. Putting it simply, hydrogen energy is free from environmental issues such as fine dusts and CO2 emissions. Hydrogen also stores electrical energy generated by solar or wind power. Because hydrogen is generated by electrolyzing water with electricity. Hydrogen fuel cells have an efficiency of 50-60% when producing electricity alone and 80-90% when waste heat is recycled.