New Technique Uses Solar Energy To Make Hydrogen From Biomass At Room Temperature



 Solar power may be useful for making hydrogen to power automobiles. Car companies around the world are working on electric cars that get their electricity from hydrogen fuel cells. The technology is appealing because fuel cells have only two byproducts — water vapor and heat. In fact, Honda plans to capture some of that water vapor and use it to humidify the interior of its upcoming Clarity fuel cell car that is scheduled to go on sale later this year.

The problem is, how to get all that lovely hydrogen in a way that doesn’t damage the environment? Hydrogen is one of the most reactive elements on the periodic table. It binds with anything and everything (water, for instance, is one hydrogen atom combined with two oxygen atoms). Pure hydrogen just does not exist in nature.

Chemically, the bonds hydrogen forms with other elements are extremely strong. It takes a lot of energy to break those bonds. In some cases, it can take more energy to create hydrogen than the purified hydrogen will contain.

In the US, most hydrogen is obtained from reforming natural gas, which sounds OK until you realize that most natural gas is derived from fracking — one of the dirtiest, least environmentally friendly human activities of all.

Hydrogen is contained in abundance in biomass waste — basically whatever is left over after plants stop growing. Corn stalks, switchgrass, lawn clippings, and food waste are all forms of biomass. Scientists know how to use biomass to make hydrogen but the process requires very high temperatures which means a lot of energy has to go in to get energy out.

Scientists at the University of Cambridge in England may have found an answer, however. They have developed a technique that uses solar power to produce clean hydrogen from biomass. The new technique involves the addition of catalytic nanoparticles to alkaline water containing biomass. The solution was put in front of a lab-based light that mimics sunlight.  The result was that some of the biomass was turned into hydrogen gas.

“There’s a lot of chemical energy stored in raw biomass, but it’s unrefined, so you can’t expect it to work in complicated machinery, such as a car engine,” David Wakerley, from the University of Cambridge’s Department of Chemistry, said in a statement.

“Our system is able to convert the long, messy structures that make up biomass into hydrogen gas, which is much more useful. We have specifically designed a combination of catalyst and solution that allows this transformation to occur using sunlight as a source of energy. With this in place we can simply add organic matter to the system and then, provided it’s a sunny day, produce hydrogen fuel.”

Different types of biomass, including wood and leaves, were used, and did not need to be processed prior to the experiments, the university said.

“Our sunlight-powered technology is exciting as it enables the production of clean hydrogen from unprocessed biomass under ambient conditions,” Erwin Reisner, head of the Christian Doppler Laboratory for Sustainable SynGas Chemistry, where the technology was developed, said.

“We see it as a new and viable alternative to high temperature gasification and other renewable means of hydrogen production,” Reisner added. He suggested that a range of potential commercial options were being explored.

The key word here is “ambient.” For us non-scientists, that means “room temperature,” which means no massive energy input needed to heat things up to get the hydrogen flowing. Up till now, hydrogen power has been a pleasant dream but hardly a practical one. Perhaps scientists have found a way to use solar power to change that equation.