Pursuing a powerful alternative to fossil fuels

Imagine a world free from ozone depletion, smog and dependence on Middle East oil. That’s the goal of one scientist at The University of Texas at Arlington.

“We must rid ourselves of fossil-fuel reliance and our dependence on politically unstable countries,” says Krishnan Rajeshwar, distinguished professor of chemistry and biochemistry and associate dean of science. “There is a finite supply of fossil fuels, and we will run out in the not-too-distant future.”

To help achieve his dream, Dr. Rajeshwar is exploring alternative fuel sources such as hydrogen—a clean-burning fuel whose only byproduct is water. One kilogram of hydrogen has energy equal to that of one gallon of gasoline. Hydrogen has the highest energy content per unit of weight of any known fuel.

Rajeshwar is studying how to separate hydrogen from water for use as an energy source. Other scientists have accomplished the feat using carbon-based fuels (methane) or nuclear energy, but both techniques leave byproducts like carbon dioxide and nuclear waste. Carbon dioxide accumulation in the atmosphere has been implicated in global warming and climate change.

Rajeshwar’s technique separates the water into hydrogen and oxygen using a completely renewable energy source—the sun.

Solar energy acts as the excitation agent to enable a semiconductor immersed in water to generate electronic carriers. These carriers, in turn, participate in the reactions that split the water into hydrogen and oxygen. The hydrogen can be stored and then converted to energy on demand to power automobiles, homes or even luxury boats.

The U.S. space program is well-acquainted with hydrogen as a fuel source. Its space shuttles have dual-compartment fuel tanks, one for liquid hydrogen and one for liquid oxygen. When the substances combine in a fuel cell, they ignite and burn, creating energy and water for use by astronauts during orbit. The fuel cells can make 25 pounds of water per hour.

More research is needed to make hydrogen as a renewable power source cost-effective. It is currently very expensive to produce, store, transport and distribute—nearly five times the cost of gasoline.

“The cost of hydrogen as a fuel source will not come down until demand for it increases,” Rajeshwar said.

The Hydrogen Fuel Initiative announced by President Bush in 2003 allocates $1.2 billion over five years to develop technologies to produce, store and distribute hydrogen for energy generation.

Smaller initiatives are also taking place, such as creation of the UT Arlington Center for Renewable Energy Science and Technology (CREST). The center will coordinate research, development and technology transfer in renewable energy sources. Its goals include finding new technologies for cost-effective and reliable hydrogen generation from renewable sources, as well as learning more about potential storage options and development of efficient, low-cost fuel cells.

— Becky Purvis