In the race to bring hydrogen-fueled cars to market, virtually every manufacturer has settled on the compressed gaseous form with one notable exception. BMW has been the lone holdout for the use of liquid hydrogen. BMW's rationale is that liquid hydrogen is more dense than hydrogen gas, even when compressed to 10,000psi. Unfortunately getting hydrogen into liquid form, requires chilling it down to -282.57C -252.87C. Keeping it at that temperature requires a lot of insulation and hence a very bulky storage tank. Nonetheless, insulation is not perfect and the liquid hydrogen still warms up over time and boils. The vapor hydrogen then has to be vented to atmosphere. A BMW Hydrogen 7 left sitting for a week will end up with an empty hydrogen tank.

BMW has been working with a consortium of 34 automakers, aerospace, fuel companies, and universities for the past four and a half years to develop a new storage system for liquid hydrogen. The current cylindrical steel tanks are both heavy and challenging to package in a car and end up absorbing most of the trunk space. BMW's research and development arm Forschung und Technik, along with the consortium, has developed a new composite modular design that can be formed into different shapes allowing greater packaging flexibility. The new tank is claimed to be one third of the weight of the current tank design. It's not known if the new tank does anything to address the issue of fluid boiling. BMW will display the new tank at the StorHy conference in Poissy, France this week.

[Source: BMW]