Storage in metal hydride powder enables faster refueling

Researchers at Purdue University made a step toward greater practicality of hydrogen-fueled autos. In research funded by General Motors, they developed a heat exchange system that quickly fills the tank with hydrogen and simultaneously dissipates the resulting heat. Via hydrogen storage in metal hydride, a tank can be filled in five minutes for a range of up to 500 kilometers, according to the researchers. Refueling time has been a challenge because refueling with hydrogen generates high temperatures and took relatively long.

The main problem with the faster metal hydride injection has been the high temperatures and the required cooling system. "Because hydrogen produces enormous heat, refueling without cooling requires at least 40 minutes. This solution is not practical," says head researcher Issam Mudawar. His concept is based on heat dissipation via a component mounted in the tank to circulate coolant and dissipate heat via fins when the hydrogen is absorbed. The metal hydride is bound in small compartments of a pressure chamber where the hydrogen is compressed and immediately absorbed by the hydride. "This process is reversible. The gaseous hydrogen can be released by the metal hydride when the pressure in the tank falls," explained Mudawar.

Daniel Kammerer, technology spokesperson for BMW, questions the development. "Metal hydride does enable the storage of hydrogen, but requires more energy due to the additional process steps such as the storage and retrieval." Also, higher pressure is required for injecting the gaseous hydrogen. "This raises the questions of the energy required for the process and the associated energy loading rate," notes Kammerer.

In 2006 BMW presented its Hydrogen 7, the first series-production hydrogen auto. So far there have been only 100 of the autos on the market worldwide. By next year BMW seeks to observe the acceptance of the vehicles on the part of consumers before discussing a successor model, states to Kammerer. "However, in the future there will be no way around the hydrogen auto. Because oil’s horizon is limited, alternatives will increase in importance." Presently the hydrogen to fuel the autos is largely still harvested from natural gas. "However, biomass is being used increasingly along with pressure electrolysis from green electricity," according to the BMW spokesperson.

Soruce: Pressetext.at