Hydrogen fuel cars closer after major fuel advancement
University of California at Los Angeles
March 6, 2006
Chemists at UCLA and the University of Michigan report an advance toward the goal of cars that run on hydrogen rather than gasoline. While the U.S. Department of Energy estimates that practical hydrogen fuel will require concentrations of at least 6.5 percent, the chemists have achieved concentrations of 7.5 percent -- nearly three times as much as has been reported previously -- but at a very low temperature (77 degrees Kelvin). The research, scheduled to be published in late March in the Journal of the American Chemical Society, could lead to a hydrogen fuel that powers not only cars, but laptop computers, cellular phones, digital cameras and other electronic devices as well.
The materials, which Yaghi invented in the early 1990s, are called metal-organic frameworks (MOFs), pronounced "moffs," which are like scaffolds made of linked rods -- a structure that maximizes the surface area. MOFs, which have been described as crystal sponges, have pores, openings on the nanoscale in which Yaghi and his colleagues can store gases that are usually difficult to store and transport. MOFs can be made highly porous to increase their storage capacity; one gram of a MOF has the surface area of a football field! Yaghi's laboratory has made more than 500 MOFs, with a variety of properties and structures.
"We have achieved 7.5 percent hydrogen; we want to achieve this percent at ambient temperatures," said Yaghi, a member of the California NanoSystems Institute. "We can store significantly more hydrogen with the MOF material than without the MOF."
MOFs can be made from low-cost ingredients, such as zinc oxide -- a common ingredient in sunscreen -- and terephthalate, which is found in plastic soda bottles.
"MOFs will have many applications. Molecules can go in and out of them unobstructed. We can make polymers inside the pores with well-defined and predictable properties. There is no limit to what structures we can get, and thus no limit to the applications."
In the push to develop hydrogen fuel cells to power cars, cell phones and other devices, one of the biggest challenges has been finding ways to store large amounts of hydrogen at the right temperatures and pressures. Yaghi and his colleagues have now demonstrated the ability to store large amounts of hydrogen at the right pressure; in addition, Yaghi has ideas about how to modify the rod-like components to store hydrogen at ambient temperatures (0¡V45aC).
"A decade ago, people thought methane would be impossible to store; that problem has been largely solved by our MOF materials. Hydrogen is a little more challenging than methane, but I am optimistic."
Cow manure + sunlight + metal ore = hydrogen fuel? A safe way for storing hydrogen
Researchers led by Michael Epstein at the Weizmann Institute of Science in Israel think they may have an energy efficient way of collecting solar energy to generate hydrogen, a key input for green energy technologies like fuel cells. Currently, most hydrogen is produced by processes that require the combustion of fossil fuels which produce polluting greenhouse gases.
5-10 million fuel cell vehicles possible by 2020
Given the right support, there could be 5-10 million fuel cell vehicles globally by 2020. The time horizon for the Hydrogen Economy is long - it is at least 20 years away for developed countries. But long term change requires short term change. China, India and Brazil have already developed active programmes of research on hydrogen fuel cells, which are tailored to their own needs and development goals. By developing their hydrogen roadmaps now, developing countries have the opportunity to monitor progress in the North and make informed, strategic decisions concerning this latest wave of technological change.
Danish researchers develop hydrogen tablet; stores hydrogen in inexpensive and safe material
Scientists at the Technical University of Denmark have invented a technology which may be an important step towards the hydrogen economy: a hydrogen tablet that effectively stores hydrogen in an inexpensive and safe material. With the new hydrogen tablet, it becomes much simpler to use the environmentally-friendly energy of hydrogen.
Organic solar cells will help spur viability of alternative energy
Imagine being able to "paint" your roof with enough alternative energy to heat and cool your home. What if soldiers in the field could carry an energy source in a roll of plastic wrap in their backpacks? Those ideas sound like science fiction -- particularly in the wake of the rising costs of fossil fuel. But both are on the way to becoming reality because of a breakthrough in solar research by a team of scientists from New Mexico State University and Wake Forest University.
How would hydrogen work in devices like cell phones, laptop computers and digital cameras?
"Instead of a battery, one would have a medium such as MOF that stores hydrogen and releases it into a fuel cell," he said.
Yaghi, whose research overlaps chemistry, materials science and engineering, has long been interested in making materials in a rational way.
"When I started out in chemistry, I always thought it should be possible to take two well defined molecules as building blocks and stitch them together into a predetermined chemical structure -- almost like you produce a blueprint of the structure ahead of time and then find the right building blocks necessary to build it. In this way, one can control the structure and the composition. This approach was difficult to implement at the beginning, but is not so difficult at this stage."
Hydrogen, when burned, produces only water, which is harmless to the environment, Yaghi noted. With MOFs, hydrogen is physically absorbed, and it is easy to take the hydrogen out and put it back in without much energy cost, he said.
"The challenge has been, how do you store enough hydrogen for an automobile to run for 300 to 400 miles without refueling?" Yaghi asked. "You have to concentrate the hydrogen into a small volume without using high pressure of very low temperature.
"Our idea was to create a material with pores that attract hydrogen, making it possible to stuff more hydrogen molecules into a small volume," he said.
In previous research, Yaghi and colleagues reported that MOFs also can store large amounts of methane (natural gas).
"We have materials that exceed the DOE requirements for methane, and we think we can apply the same sort of strategy for hydrogen storage," he said.
Additionally, Yaghi has shown that MOFs store prodigious amounts of carbon dioxide at ambient conditions, a development relevant to preventing carbon dioxide emissions from power plants and automobile tailpipes from reaching the atmosphere.
The research was funded by the National Science Foundation, the U.S. Department of Energy and BASF (a global chemical company based in Germany).
Co-authors of the present research report, which Yaghi conducted when he was on the faculty at the University of Michigan, are Adam Matzger, assistant professor of chemistry at Michigan, and Antek Wong-Foy, chemistry research associate at Michigan.
This is a modified University of California - Los Angeles press release.