Washington, June 5 : Researchers at the Lawrence Livermore National Laboratory have developed an experimental hybrid vehicle whose storage tank can hold liquid hydrogen (LH2) for six days, without venting any of the fuel.
The invention of the cryogenic pressure vessel has dramatically increased the amount of time it takes to start releasing hydrogen during periods of long-term parking, compared with the present-day liquid hydrogen tanks that can hold hydrogen for merely two to four days.
The researchers have revealed that their LH2 tanks hold super-cold liquid hydrogen at around -420 Fahrenheit.
They point out that the existing automotive LH2 tanks start venting evaporated hydrogen vapour due to the pressure that builds as heat from the environment warms the fuel inside after being parked three to four days, even when one uses the best thermal insulation available.
According to them, recent testing of their prototype has shown that their storage tank has a thermal endurance of six days, and the potential for as much as 15 days.
The researchers also say that while the present-day automotive LH2 tanks operate at low pressure of two to 10 atmospheres, their cryogenic capable pressure vessel is much stronger, and can operate at hydrogen pressures of up to 350 atmospheres.
They also say that the high-pressure capability of the new storage tank means that a vehicle's thermal endurance improves as the tank is emptied, and is able to hold hydrogen fuel indefinitely when it is about one-third full.