Scientists at Ohio State University have created a cheaper, more flexible way to produce hydrogen from biofuel.
Led by Umit Ozkan, a professor of chemical and biomolecular engineering, the team has developed a new catalyst which can be used in the production of hydrogen from bioethanol. Ozkan, who presented the team's research last Wednesday at the American Chemical Society, claims the new catalyst may go some way to solving the critical barriers to the mass-market uptake of hydrogen powered cars.
While many have touted hydrogen as the green fuel of the future, the barriers Ozkan refers to relate to the production of the gas, which has traditionally been expensive and inflexible. The catalysts used have been costly and the conversion process has required large amounts of energy, which has resulted in high levels of indirect CO2 emissions when compared to conventional fuels.
Until now, rare metals such as rhodium and platinum have been used as catalysts in the production process; Ozkan said her goal was to create a cheap alternative that was based on readily available metals. She commented: "Precious metals have high catalytic activity and, in most cases, high stability, but they're also very expensive." "Rhodium is used most often, and it costs around $9,000 (£4,800) an ounce, our catalyst costs around $9 a kilogram."
A further problem which has restricted the widespread uptake of hydrogen has been the logistical difficulties involved in transporting the gas, which must currently be moved via high-pressure containers.
According to researchers the catalyst, which is made from calcium, cobalt and small grains of cerium oxide, can produce hydrogen with 90% efficiency at around 350 degC, which is relatively low for industrial standards. Ozkan argues that without the requirement for high temperatures and precious metals, hydrogen production onsite becomes a viable option, which in turn removes some of the problems associated with transportation.
"Instead of making hydrogen from biofuel at a centralised facility and transporting it to gas stations, we could use our catalyst inside reactors that are actually located at the gas stations. So we wouldn't have to transport or store the hydrogen, we could store the biofuel, and make hydrogen on the spot," she said.
Ozkan added that operating at lower temperatures would also bring energy savings. "And if the catalyst is highly active and can achieve high hydrogen yields, we don't need as much of it. That will bring down the size of the reactor, and its cost." The team also believes that further energy saving techniques could be employed such as using the waste CO2 and methane gases from production to supply some of the energy for the conversion process itself.
From an economic perspective, Ozkan believes that the price of hydrogen produced in this way could rival that of petroleum: "As gasoline prices continue to rise, hydrogen produced from renewable sources such as bio-liquids will be more and more competitive. Also, the possibility of using hydrogen in fuel cells will provide much higher efficiency than internal combustion engines can. So the actual cost, in dollars per mile, may already be lower."
Although the current research has focused on the conversion of bioethanol, the team believes that the catalyst could be adapted for use with other liquid biofuels.
If produced from sustainably sourced biofuel, hydrogen becomes a very effective way of reducing CO2 emissions. Friends of the Earth's biofuels campaigner, Kenneth Richter, warned however, that hydrogen is only as clean as the energy used to produce it. "Rather than being a clean alternative to fossil fuels, biofuels are actually increasing carbon dioxide emissions. Hydrogen-fuelled cars are still a long way off – the immediate priority for cutting emissions is smarter cars that burn less fuel."
While the biofuels debate rages, Japanese company Hrein Energy, has sidestepped the issue by creating hydrogen generators which are powered by fumes from a car's exhaust. The company wants drivers to retrofit their cars with their product as a means of increasing fuel efficiency and reducing emissions.
The system, which leaves behind some of the ethical baggage associated with the use of biofuels, utilises the otherwise wasted heat generated from a car's engine to convert chemicals into hydrogen. The gas is then mixed with air entering the engine which improves fuel efficiency and reduces emissions by a claimed 30 per cent.
If accurate, the system would allow the majority of cars to meet emissions limits proposed from 2012 within the European Union.
Guardian, ETA
