Hydrogen makes an extraordinarily efficient and clean fuel. Three times as energy-efficient as petrol, Nasa used it to power its space shuttles. It can be used to generate electricity and only produces water as a byproduct.
And yet, scientists are struggling to scale up hydrogen production. Ironically, given hydrogen’s green potential, the cheapest and most viable sources are hydrocarbon-based compounds such as natural gas. But liberating hydrogen from fossil fuels creates carbon emissions that outweigh any environmental advantages.
Percival Zhang, professor of bioengineering at Virginia Tech Institute, says that the problem is not just technical but that, sometimes, “scientists have poor imaginations”. And so he wants to try something different: why not take advantage of an abundant natural resource, sugar? “Our idea is that simple,” he says. “We call the project Sweet Hydrogen.”
Biomass – trees, plants and other waste vegetable matter – is an abundant and rapidly renewable source of starch and sugars, that is nowadays used to produce biofuels. Exploiting biomass to produce sugar, and turning that sugar into hydrogen, could lead a change in global energy production.
In 2011, the US consumed 134bn gallons (507bn litres) of gasoline, but “with our technology, just 700m pounds [317,500 tonnes] of biomass would be enough to replace the whole yearly [gasoline] production,” says Zhang. The last official assessments estimate the availability of crop residues for biomass in the US to be about 157m tonnes per year.
Moreover, recent projections find that by 2030 the total biomass resources (coming from crop residues but also from forests, waste and energy crops) available for energy production will be close to 680m tonnes per year.
“So far there have been two different ways to produce hydrogen,” says Zhang. “Either you obtain it by heating fossil fuels, such as methane, or by separating water into oxygen and hydrogen through electrolysis.” The first solution produces emissions, while the latter is very expensive. “And you still need fossil fuels to perform electrolysis.”