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A new generation of fuel cells will make use of lignin, a paper production byproduct, to produce energy.
While last week we had a look at a new lignin-based duct tape, this time we will be exploring another potential application of this biopolymer disposed of during the paper production process. In addition to rechargeable and non-rechargeable conventional batteries, there’s another breed of battery that has become the focus of scientific research over the last few years — fuel cells. The main elements used so far have been hydrogen and methanol, but both have disadvantages. Usually, the former is obtained from natural gas and non-renewable energy sources, releasing carbon dioxide in the process. The latter, while abundant in nature, also releases greenhouse gases when used as fuel. However, following the idea of a circular economy-based outlook, scientists have found a way to use a waste product to power batteries.
In order to produce paper from wood, cellulose must be separated from lignin. Every day, tons of this substance ends up in landfills, despite having several interesting applications. One of them has been researched by the Laboratory of Organic Electronics at Linköping University in Sweden — a lignin-based fuel cell that produces electricity in a similar way to current ethanol or methanol batteries. Nevertheless, this polymer needs to be processed before it can be used as fuel. This means that the complex lignin molecules must be broken down to obtain benzenediols, which are energy-rich chemical compounds. One of them, catechol, which makes up 7% of lignin, is the substance that the Swedish researchers have chosen as their core fuel.
Having said so, catechol is incompatible with metallic electrodes, such as in the platinum-based ones used in fuel cells. The researchers were thus compelled to use polymer electrodes instead. Specifically, a polymer that goes under the name of PEDOT: PSS, the applications of which had hardly been researched in this field previously.
The outcome has been an innovative fuel cell built from cheaper materials than those available on the market while avoiding carbon dioxide emissions. Although the system has yet to be improved, it is undoubtedly an innovative technology with great potential.
Current applications of fuel cells
While fuel cells are not as widespread as lithium or cadmium batteries, they can provide energy in many situations. Transport, especially urban buses, is one of the most common applications. However, they can also be used as portable electricity generators, producing from 5 to 500 kW. Finally, they are also expected to play an important role in the production of electricity in homes, which has already been piloted in Japan. In general terms, the main advantages of fuel cells are their considerable range, instant recharge, and lightness.