chapter  41
16 Pages

Hydrogen Storage in Nanoporous Carbon

Our society consumes an important part of the total energy for transporting goods and persons by means of machines based on fossil fuels: cars, trucks, ships, planes, etc. An alternative to

the present gasoline car is the hydrogen car. ™is car uses an electric motor based on a hydrogen fuel cell instead of electric batteries. ™ere are many advantages of hydrogen cars over electric battery and gasoline cars: hydrogen is very abundant and can be produced from water by electrolysis. ™e only emission from a hydrogen fuel cell is pure water. ™e main advantage is that the full recharge times of a hydrogen and an electric car with the same autonomy range, 200 km, are 10 min and about 8 h, respectively, using 110 V (3 h using 220 V). However, the eÀciency of the engine based on electric batteries is slightly larger (72%) than that of an engine based on hydrogen fuel cells (64%). ™e eÀciency of a gasoline engine is smaller (20%). Hydrogen has the highest energy content per mass (120 MJ/kg) compared with any other fuel. Gasoline has a smaller energy content per mass (44 MJ/kg). But it has a larger energy content per volume (35 MJ/L) than gaseous hydrogen at room temperature and 1 atm pressure (0.01 MJ/L) and liquid hydrogen. Electric batteries also have a smaller energy content per mass, but a larger energy content per volume than hydrogen. For instance, nickel hydride batteries have energy contents of 0.11-0.29 MJ/kg and 0.5-1.1 MJ/L.