Engineering news
Scientists from the universities of Pittsburgh and Oklahoma have published research into using wood to create new hydrocarbons, compounds of hydrogen and carbon generally found in crude oil. The research, published in The Royal Society of Chemistry’s Energy & Environmental Science journal, claims the “second generation biofuel” reduced emissions of greenhouse gases by 80 % compared to diesel.
The researchers studied oak wood as a fuel source because they claim popular biofuel alternatives, such as corn ethanol, might not offer greenhouse gas reductions compared to petroleum fuels. They said corn ethanol also uses a potential food source and could “consume” farmland, leading to a worldwide food shortage.
“Corn ethanol environmental impacts weren’t really studied until after its commercialisation,” said author and environmental engineer Vikas Khanna. “The great thing about this project is it addresses full life cycle sustainability questions of new fuel sources, before they come up later down the road.”
The team said grasses and industrial waste could also be turned into second generation biofuels. The scientists used pyrolysis, heating the wood to high temperatures in the absence of oxygen, to create the fuel. They said it could offer almost three times as much energy output per energy input compared to corn ethanol.
The wood biofuel could be used to power aircraft, said energy and environmental system expert Mark Barrett from University College London to Professional Engineering. He said electricity should be used to power as many vehicles as possible, including cars and other land vehicles, and hydrogen or ammonia for ships.
However, he said there are currently no feasible alternatives for aircraft as fuel needs to be energy-rich and compact enough to allow flight. “If you want something with the energy density of a hydrocarbon then it has to be a hydrocarbon, to get the range for aircraft and not to take up too much volume,” he said.
"Level of uncertainty"
Despite confirming the potential use of the oak biofuel, he said many questions remain around whether the production process is practical and if the fuel would offer the benefits researchers claimed. The greenhouse gas reductions may be achieved with the fuel in a lab setting, he said, but real-world tests could have very different results. The efficiency and energy needed for the fuel-creation process is also unclear, he added.
The source of the wood would also be an important factor in the fuel’s viability, he said. “You are taking away standing carbon in that wood and so the question is, how fast will that be replaced?” Creating fuel from a living source adds an extra level of uncertainty over the research’s potential future application, he added.
“Unfortunately one of the problems with living systems is they are very complex, not only at the tree level but at the ecological level within a wood or forest,” he said. “Basically it is incredibly hard to come up with firm figures. And you may come up with the figure for one forest but then for the one 10 miles away the data may be very different.”