"Chemical Fuel Tank" Gives Hydrogen Storage New Hope

Wednesday, September 02 2009

Los Alamos National Laboratory and University of Alabama researchers have come up with a new method for recycling hydrogen-containing fuel materials, which could open the door to economically viable hydrogen-based vehicles. The researchers worked within DOE’s Chemical Hydrogen Storage Center of Excellence.

Ideally, a fuel should be lightweight to maintain overall fuel efficiency, and pack a high energy content into a small volume. Unfortunately, under normal conditions, pure hydrogen has a low energy density per unit volume - presenting technical challenges for its use in vehicles capable of travelling 300 miles or more on a single fuel tank (a benchmark target set by DOE).

In order to overcome some of the energy density issues associated with pure hydrogen, work within the Chemical Hydrogen Storage Center of Excellence has focused on using a class of materials known as chemical hydrides. Hydrogen can be released from these materials and potentially used to run a fuel cell. These compounds can be thought of as “chemical fuel tanks” because of their hydrogen storage capacity.

Ammonia borane is an attractive example of a chemical hydride because its hydrogen storage capacity approaches 20 percent by weight. The main drawback of ammonia borane has been the lack of energy-efficient methods to reintroduce hydrogen back into the spent fuel once it has been released. Until recently, after hydrogen release, ammonia borane couldn’t be adequately recycled.