Storage
Storage in liquid form is very expensive. It requires significant investment and substantial facilities for the liquefaction process, conservation and making it operational in liquid form at 20 Kelvin (-253°C !).
This form of storage is used for very particular applications.
Historically hydrogen has been strored in gas form under pressure. Practically storage, gaseous hydrogen must be pressurized to several hundred atmospheres and stored in a pressure vessel or tank (made of steel or composite material).
Main issues:
-
Poor volume density
Fuel Energy density (kWh/l) Hydrogen 2 (to 700 bar) Natural gas 3 (to 200 bar) Diesel 8 (liquid) - Safety (real or perceived)
- Energy expenditure required for compression (uses 10 to 25% of gas energy content)