article: The days of filling your car with petrol may be numbered because researchers have boosted the efficiency of making hydrogen fuel from plant waste. US scientists have found a way to use discarded corn husks and stalks to make cheap hydrogen fuel that doesn't pollute the environment like fossil fuels. The breakthrough could one day see the fuel being produced locally and drivers stopping to refuel their vehicles at roadside bioreactors instead of pumping petrol into their motor. US scientists have found a way to use discarded corn husks and stalks to make cheap hydrogen fuel that doesn't pollute the environment like fossil fuels and it could accelerate the take up of biogas for cars . Eco-friendly hydrogen cars, which are already a reality, emit only water, but the gas is expensive and is not easy to store, meaning more research is needed for  hydrogen cars to become mainstream. Now, researchers at Virginia Polytechnic Institute and State University have shown that it’s possible to convert 100 per cent of the sugar in corn stalks and husks – a by-product of farming – into hydrogen gas, which can be used to power vehicles. It’s previously only been possible to convert between 30 and 60 per cent of plant sugar into hydrogen, by using industrial catalysts or fermenting techniques, The Independent reported. The ultimate aim is to produce large quantities of hydrogen from crop waste efficiently, because many present methods either cost too much or use food crops. The breakthrough could one day see the fuel being produced locally and drivers stopping to refuel their vehicles at roadside bioreactors instead of pumping petrol into their motor. For years, scientists have been working out how to develop fuel cell cars powered by pure hydrogen, but are unsure how to store the substance effectively. Now, researchers from India's Benaras Hindu University may be close to solving this problem using coconut kernels to store hydrogen in gas form. Storing liquid hydrogen is notoriously difficult as it must be held at extremely low temperatures, which is expensive and tricky in the confines of a car. To store it in its gaseous state, would mean that vehicles would have to be fitted with large, pressurised tanks, which is not practical. So instead, experts have focused on finding materials, such as carbon, which can absorb hydrogen and release it on demand. Professor Viney Dixit and his team, at the university’s Hydrogen Energy Centre created carbon from coconut kernels, which contain fatty and organic acids as well as potassium, magnesium and sodium. He says that the kernels, which are easily found, are cheap and can easily be converted into carbon. ‘Unlike graphene, Carbon nano tubes (CNTs) and other type of carbons, the production of carbon from solid endosperm is not time taking, he wrote in a research paper. ‘Therefore, its cost-effectiveness, good adsorption capacity and easy availability are its advantageous factors in regard to hydrogen storage.’ The researchers found that the carbon produced from the kernels could store a ‘considerable’ amount of hydrogen. Two scientists developed a process to make more efficient fuel by mixing biomass with a special solution comprising 10 enzymes that turn plant sugars into hydrogen and carbon dioxide. The enzymes were created in microbial fermenters using genetically engineered bacteria, which were then added to the plant waste and left for several weeks – although they would be left for far longer if the fuel was produced on a large scale. The breakthrough could produce a zero-emissions fuel that could speed up the movement toward hydrogen-powered vehicles, according to the study, which was published in the journal PNAS. ‘We have demonstrated the most important step toward a hydrogen economy -- producing distributed and affordable green hydrogen from local biomass resources,’ said study co-author Percival Zhang, a professor at Virginia Tech. Together with former doctoral student Joe Rollin, he founded a start-up called Cell-free Bioinnovations to work on the fuel. The process builds on previous research using xylose, ‘the most abundant simple plant pentose sugar, to produce hydrogen yields that previously were attainable only in theory,’ according to the study. Other hydrogen fuel production methods rely on highly processed sugars, but the Virginia Tech team used corn husks and stalks, which are known as dirty biomass, to cut costs and make the fuel easier to produce locally. Dr Rollin found that the process of breaking down corn husks and stalks into hydrogen and carbon dioxide can use both sugars glucose and xylose at the same time - not one after the other. The discovery means it is possible to speed up the rate at which hydrogen is released, while decreasing the area of the facility needed to produce it to the size of a gas station. Other hydrogen fuel production methods rely on highly processed sugars, but the Virginia Tech team used corn husks and stalks, (a stock image of the whole plantis shown) which are known as dirty biomass, to cut costs and make the fuel easier to produce locally . ‘We believe this exciting technology has the potential to enable the widespread use of hydrogen fuel cell vehicles around the world and displace fossil fuels,’ Dr Rollin said. Experts say it is hard to know how much the new approach might cost, but Lonnie Ingram, director of the Florida Centre for Renewable Chemicals and Fuels at the University of Florida - who was not involved with the study - said the work ‘represents a revolutionary approach that offers many new advantages. ‘These researchers have certainly broadened the scope of our thinking about metabolism and how it plays into the future of alternative energy production,’ he said. Researchers say they have the necessary cash to scale up their findings to a demonstration-level, which is the next step of the project. Professor Zhang said: ‘I think in three to five years we should be able to build a bioreactor that is something like a gas station which can produce 200 kilos of hydrogen fuel a day. ‘This would be enough to re-fuel about 40 or 50 cars.’
highlights: Virginia Polytechnic Institute and State University researchers found a way to use discarded corn husks and stalks to make cheap hydrogen fuel .
  Used efficient method to convert 100% of plant sugars into 'green' fuel .
  It's previously only been possible to convert 60% of sugars into hydrogen .
  Breakthrough could see motorists filling up at roadside bioreactors .
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