Linköping University (LiU) researchers have developed a new fuel cell using Lignin, a cheap and readily available biopolymer.
Lignin consists of a large number of hydrocarbon chains woven together, which can be broken down in an industrial process to its energy-rich constituent parts, benzenediols.
One of these parts, catechol makes up 7% of lignin. Researchers at the Organic Energy Materials group at LiU, led by Professor Xavier Crispin, have discovered that this type of molecule is an excellent fuel for use in fuel cells.
The fuel most often used in tradition fuel cells is hydrogen gas, which reacts with oxygen from the air. The chemical energy is converted in the fuel cell to electricity, water and heat.
Nevertheless, 96% of the hydrogen produced worldwide is from non-sustainable sources, and is accompanied by carbon dioxide emission.
Other fuels used in fuel cells are ethanol and methanol, but these produce also carbon dioxide as a by-product. The electrodes necessary to attract the fleeing electrons are usually made from platinum, which is both expensive and scarce.
Benzenediols, on the other hand, are aromatic molecules, and metal electrodes cannot be used in fuel cells based on benzenediols since the reactions are slightly more complex.
The researchers instead use electrodes made from the popular conducting polymer PEDOT:PSS.
PEDOT:PSS has the interesting property of conducting electricity, while at the same time having a surplus of protons. This means that it functions as both electrode and proton conductor.
“PEDOT:PSS is a perfect catalyst for the reaction with a benzenediol such as catechol,” says Crispin. He contends that the chemical energy of the fuel is converted to electricity without carbon dioxide being formed.
“When a fuel such as ethanol is used in a fuel cell, people usually claim that it has zero impact on the climate, since the carbon dioxide is a component of a circulation. This means that ethanol is considered to be a green fuel.”
“We can now manufacture electricity without any emission of carbon dioxide at all, which makes our fuel supergreen. The technology also both cheap and scalable,” says Crispin.
The researchers have calculated that the amount of electricity produced by the new fuel cell is approximately the same as the current ethanol-based and methanol-based fuel cells.
Image and content: Domtar/Linköping University