Scientists discover record-breaking hydrogen storage materials - absorb 14% by weigth at room temperature

Scientists at the University of Virginia (UVa) have discovered a new class of hydrogen storage materials that could make the storage and transportation of energy much more efficient — and affordable — through higher-performing hydrogen fuel cells. The news is important for the bioenergy community, because, on a well-to-wheel basis, biohydrogen used in fuel cells is the most efficient and cleanest form of hydrogen utilization out of 28 generic fuel production and propulsion options for the gas (see earlier discussion of a large EU well-to-wheel study on hydrogen production, or see graph, click to enlarge).

Bellave S. Shivaram and Adam B. Phillips, the UVa physicists who invented the new materials, presented their findings today at the International Symposium on Materials Issues in a Hydrogen Economy.

In terms of hydrogen absorption, these materials could prove a world record. Most materials today absorb only 7 to 8 percent of hydrogen by weight, and only at cryogenic [extremely low] temperatures. Our materials absorb hydrogen up to 14 percent by weight at room temperature. By absorbing twice as much hydrogen, the new materials could help make the dream of a hydrogen economy come true. - Adam B. Phillips

In the quest for alternative fuels, UVa's new materials potentially could provide a highly affordable solution to energy storage and transportation problems with a wide variety of applications. They absorb a much higher percentage of hydrogen than predecessor materials while exhibiting faster kinetics at room temperature and much lower pressures, and are inexpensive and simple to produce.

The challenge of hydrogen storage is finding a way to store enough of it to make it worthwhile — enough to fuel a vehicle for its required driving range, within the constraints of weight, volume, efficiency, and cost. Current technologies — and their downsides — include:

• Compressed gases in pressurized tanks, like the ones that transport today's propane and natural gas — which could require large-volume tanks
• Metal hydrides — which are very heavy and thus reduce a vehicle's driving range.

Hydrogen is a poorly compressing, low-density gas, difficult to liquefy. A storage medium would need to be small, lightweight, and provide a high concentration of hydrogen to the weight of the storage material.

For the automotive industry, this medium also needs to be on board the vehicle, providing sufficient fuel to travel a range of 300 miles on a single tank— without sacrificing space, lifestyle or price. The primary goal is to get the largest amount of hydrogen into the smallest volume.

Yet another important feature is the ability to put hydrogen in the medium and take it out again without expending too much energy. Finally, it also has to be inexpensive, not too sensitive to impurities, and safe. This is a very tall order indeed.

The three most basic approaches to a storage solution are the following:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: biohydrogen :: hydrogen storage :: absorption :: materials science ::

• Physical storage: developing tanks for either compressed hydrogen gas or liquid hydrogen;
• Reversible chemical storage: storing the hydrogen in solid materials so it can be released and refilled without physically removing the storage medium from the vehicle
• Irreversible chemical storage: releasing hydrogen via an on-board chemical reaction with the storage material and replenishing the hydrogen off-board.

The new materials fit in the second category and are based on carbon/metal hybrid materials.

These materials are the next generation in hydrogen fuel storage materials, unlike any others we have seen before. They have passed every litmus test that we have performed, and we believe they have the potential to have a large impact. - Bellave S. Shivaram

The inventors believe the novel materials will translate to the marketplace and are working with the UVa Patent Foundation to patent their discovery.

The U.Va. Patent Foundation is very excited to be working with a material that one day may be used by millions in everyday life, said Chris Harris, senior licensing manager for the UVa Patent Foundation. According to him, Dr. Phillips and Dr. Shivaram have made an "incredible breakthrough" in the area of hydrogen absorption.

Phillips’s and Shivaram’s research was supported by the National Science Foundation and the U.S. Department of Energy.

We will report back as more details about the materials become available.

A quick note on biohydrogen: it may be the cleanest and most energy efficient way of producing hydrogen, the problem is that biomass can be used more efficiently still for the production of heat and electricity. For this reason, some bioenergy advocates are more in favor of a transition towards electric vehicles, because these would allow just as large a range of primary energy sources (including biomass, solar, wind, nuclear, etc...) and are surprisingly efficient and clean compared to hydrogen used in fuel cells. But then, such a transition requires major breakthroughs in battery technology. The jury is still out.

References:
UVa Today: University of Virginia Scientists Discover Record-Breaking Hydrogen Storage Materials for Use in Fuel Cells - November 9, 2007.

Biopact: Hydrogen out, compressed biogas in - October 01, 2006