“Our new process would help end our dependence on fossil fuels,” said YH Percival Zhang, professor of biological systems engineering, “hydrogen is one of the most promising renewable fuels.”
The Virginia Tech team said it had managed to extract xylose, a very abundant plant sugar to produce a large amount of hydrogen, which previously remained just theoretically accessible. The method developed could even feature apply to all biomass sources.
This new method of producing hydrogen not only utilize renewable natural resources, but would release virtually no greenhouse gas emissions, and does not require expensive and heavy metals.
For seven years, the team of Prof. Zhang has focused his research on non-traditional ways to produce hydrogen at high efficiency and low cost, especially in the combination of enzymes. The method can release hydrogen with high purity in conditions of reaction at 50 ° C and at normal atmospheric pressure.
Biocatalysts are equipped with a group of enzymes artificially isolated from micro-organisms that thrive in extreme temperatures, some of which could increase the boiling point of water.
The researchers selected xylose as it comprises less than 30% of cell walls. But despite its abundance, the use of xylose to release hydrogen is limited. Natural or artificial microorganisms that most scientists use in their experiments are unable to produce pure hydrogen because these organisms grow and reproduce instead of dividing the water molecules.
Scientists at Virginia Tech have therefore separated a number of enzymes from indigenous microorganisms to create a non-existent specific combination as such in nature. Enzymes, when combined with xylose and polyphosphate, are able to release an unprecedented volume of hydrogen, where about three times larger than conventional methods production.
Interestingly, the energy stored in the water molecules is separated from xylose, which gives a high purity hydrogen atom capable of being directly used by the fuel cell proton exchange membrane.
Even more attractive, as this reaction takes place at low temperature, the energy production of hydrogen is greater than the stored chemical energy in xylose and polyphosphate. This results in an efficiency of over 100% – a net energy gain. This means that for the first time, the remaining low temperature heat may be used to produce energy. Other processes convert sugar into biofuels such as ethanol and butanol, but energy efficiency remains less than 100%, resulting in a loss of energy.
The hydrogen market is now about $ 100 billion. Because hydrogen is mainly extracted from natural gas, the manufacturing process is expensive and generates a large amount of carbon dioxide, a greenhouse gas. The industry also uses most often hydrogen to make ammonia fertilizer and refined in petrochemical products.