University of Surrey scientists' biofuel breakthrough

SCIENTISTS at University of Surrey say they have made a major breakthrough in the potential for vehicles powered by biofuel.

Until now the way hydrogen or methane gas has been stored has meant biofuel-dependent cars travel less than half the distance of gasoline powered vehicles.

But a team of chemical engineers at University of Surrey in Guildford has found a way which they say vastly improves fuel capacity.

The discovery has come after a two year collaborative study of metal organic frameworks - MOFs - by Guildford-based and US scientists.  

This has resulted in them producing two new MOF materials with the highest gas storage capacity ever recorded.

Dr Ahmet Ozgur Yazaydin, who led the theoretical part of the study, said the discovery could have dramatic implications for the energy industry.

"The breakthrough heralds a whole new dimension to the potential for using gas to power vehicles," he said.

"Currently prototypes of gas powered cars, such as those powered by compressed hydrogen or natural gas,  have a range which is less than half of what gasoline powered cars have. However, by using MOF materials larger amounts of gas can be stored  in fuel tanks. 

"These materials act like a sponge and holds more gas than it can be stored in an empty tank. 

"This discovery paves the way for gas powered cars to compete with those powered by gasoline so that they can travel roughly the same distance before refuelling. 

"With this technology one day people will even be able to fill their fuel tanks with natural gas supplied to their homes."

Dr Yazaydin and his team found that metal atoms within the MOFs are connected by organic linker molecules resulting in a network of molecular cages with vast internal surface areas ideal for storing gases. 

The higher the surface area, the larger the amount of hydrogen or methane that can be stored, and the further the vehicle can travel. 

He explained: "The key is exposing more surface per available space for gas molecules to stick. 

"Benzene molecules, which are commonly used in MOFs as organic linkers, are like hexagonal rings, and gas molecules can only stick onto the ring's outer surface, thus the inner sides of each benzene unit is essentially wasted space. 

"If you break the ring and straighten it then both sides become available for gas absorption. That is exactly what we did."

But Dr Yazaydin said it will take some years before the new material could see a practical, everyday use - although he thinks it will happen within the next decade.

He said: "The challenge is to produce this new material in bulk quantities. For now it has only been produced in the order of a few grams."

The study was published in the September issue of the Journal of the American Chemical Society.