Better biofuel uses best of both worlds
Researchers have made a new type of biofuel with more energy than ethanol, and which can be produced more quickly and efficiently than other biofuels.
The study is published today (21 June) in Nature.
At present biofuel — most commonly in the form of ethanol — is produced biologically, using microorganisms to break down raw biomass into simple sugars, which are then fermented to produce ethanol.
Ethanol is a far from perfect fuel — its production can be slow and the amount of energy it produces is vastly less than conventional fuels such as petroleum.
James Dumesic, from the University of Wisconsin-Madison in the United States, and colleagues have created a new biofuel, dimethylfuran (DMF), using a combination of conventional biological and new chemical methods.
Their approach is quicker than the biological method and uses far less energy than existing chemical procedures.
They first use microorganism-derived enzymes to break down raw carbohydrate chains into fructose (a simple sugar). Then an acid and a metal are used to catalyse reactions that remove oxygen molecules from the mix — minimal oxygen being more desirable in transportation fuel.
Although DMF has not yet been tested as a fuel, Dumesic says it is superior to ethanol in several ways.
It boils at 20 degrees Celsius higher than ethanol, meaning it remains as a liquid in the fuel tank and becomes a vapour in the engine — necessary for a fuel.
DMF also has a 40 per cent higher energy density than ethanol, requiring a smaller fuel tank, and repels water, so the fuel won't absorb moisture from the air like ethanol.
Dumesic says DMF, like ethanol, could be used as a fuel additive to increase fuel efficiency and ensure cleaner emissions.
He adds that part of the production process is similar to methods now used by the petroleum industry, making it easier to scale up production.
But he warns that safety and environmental testing are needed before widespread use of DMF as a possible blending agent for transport fuels can be considered.
Reference: Nature 447, 982 (2007)