A University of Cambridge team of scientists has developed a way of using solar power to generate hydrogen that is both sustainable and relatively low cost. It simply uses natural light to generate hydrogen from biomass.

Dr. Moritz Kuehnel, from the Department of Chemistry at the University of Cambridge, joint lead author on a new research paper published in Nature Energy, said, “Lignocellulose is nature’s equivalent to armored concrete. It consists of strong, highly crystalline cellulose fibers, that are interwoven with lignin and hemicellulose which act as a glue. This rigid structure has evolved to give plants and trees mechanical stability and protect them from degradation, and makes chemical utilization of lignocellulose so challenging.”

A piece of paper placed in front of a solar light source. Image Credit: University of Cambridge. Click image for the largest view.

Biomass has been a source of heat and energy since the beginning of recorded history. The planet’s oil reserves are derived from ancient biomass which has been subjected to high pressures and temperatures over millions of years. Lignocellulose is the main component of plant biomass and up to now its conversion into hydrogen has only been achieved through a gasification process which uses high temperatures to decompose it fully.

The Cambridge chemists’ new technology relies on a simple photocatalytic conversion process. Catalytic nanoparticles are added to alkaline water in which the biomass is suspended. This is then placed in front of a light in the lab which mimics solar light. The solution is ideal for absorbing this light and converting the biomass into gaseous hydrogen which can then be collected from the headspace. The hydrogen is free of fuel-cell inhibitors, such as carbon monoxide, which allows it to be used for fuel.

The nanoparticle is able to absorb energy from solar light and use it to undertake complex chemical reactions. In this case, it rearranges the atoms in the water and biomass to form hydrogen fuel and other organic chemicals, such as formic acid and carbonate.

Joint lead author, Dr David Wakerley, also of the Department of Chemistry, said, “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. 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.”

The team used different types of biomass in their experiments. Pieces of wood, paper and leaves were placed in test tubes and exposed to solar light. The biomass didn’t require any processing beforehand.

The technology was developed in the Christian Doppler Laboratory for Sustainable SynGas Chemistry at the University of Cambridge. The head of the laboratory, Dr. Erwin Reisner, added, “Our sunlight-powered technology is exciting as it enables the production of clean hydrogen from unprocessed biomass under ambient conditions. We see it as a new and viable alternative to high temperature gasification and other renewable means of hydrogen production.”

Dr. Reisner summed up saying, “Future development can be envisioned at any scale, from small scale devices for off-grid applications to industrial-scale plants, and we are currently exploring a range of potential commercial options.”

One of the challenges facing modern society is what it does with its waste products. As natural resources decline in abundance, using waste for energy is becoming more pressing for both governments and business.

This technology sounds pretty good. No power source needed, just sunlight and inevitably some prep work on the feedstock. There is the matter of the alkaline water that would need handled more carefully than fresh water, but we aren’t informed as to how strong is the alkalinity. And naturally what are the circumstances of the waste material?

There is a huge supply of biomass, both unused and used. We need more data. What will a square meter of sunlit processing accomplish? How does one get the nanoparticles back? Congratulation are in order along with a bunch of encouragement.


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