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Harnessing the power of leftover lignin

Research Lives: Muhammad Muddasar, PhD student, University of Limerick School of Engineering

Your project is looking at how we can use a component of wood called lignin in new ways – what is lignin?

Lignin is a very important part of trees and it is one of the most abundant organic or biological molecules on earth. It is one of the main components of wood, where it adds strength and rigidity to the cell walls, helping the tree to stand upright.

It’s a chemically complex and interesting molecule, but it is often removed during wood refining because when you remove lignin the wood becomes softer, and it takes away the colour of the material. The removed lignin is then generally burned as fuel or used as a binder for other materials.

What are you looking to do with that leftover lignin instead?


We believe we can use lignin to harvest and store energy from local sources of heat. So we are developing a thermoelectric energy harvester that uses the chemical properties of lignin in its structure.

How are you approaching that?

We do that by mixing lignin with a polymer in a liquid, and freezing it in a way that results in tiny vertically aligned channels. We add electrolytes into that matrix and put it between electrodes. Then if we make one side hot and one side cold, we get a voltage between the electrodes. We have already achieved that with steel electrodes, and now we are moving towards carbon electrodes, so that energy can be stored too.

Where might people ultimately use this kind of energy harvesting and storing system or battery?

One application might be in wearable electronic medical devices. So if you had a patch on your skin with this thermoelectric energy harvester built into it, then the difference between your body temperature and the temperature of the air could offer a way to generate and store energy and power the device.

Is this part of a bigger move to use wood products in new ways?

Yes my work on this is with my supervisor, Prof Maurice Collins, as part of the NXTGENWOOD project. The project is supported by the Department of Agriculture, Food and the Marine and involves people around Ireland in three SFI research centres – AMBER, APC Microbiome Ireland and BiOrbic. It broadly looks at new ways of using wood products. It fits in with the circular economy, where we want to make better use of what is now seen as low-value or waste products.

What do you like about doing a PhD?

I enjoy the creative aspects of it. You can experiment with different protocols to see what happens, you can see what ways to optimise it and measure how it performs.

And what have you found challenging?

I studied mechanical engineering in Pakistan, and when I moved here I needed to learn a lot about the chemistry of lignin and the processes we use. But thankfully I have good colleagues who supported me, and after the first six months or so it was much smoother and easier for me. I’m just starting my third year of the project now, and last year I was first author on a paper in advanced functional materials.

What kinds of hobbies do you enjoy in your spare time?

I love greenery, this is one of the reasons I wanted to move to Ireland, and I enjoy getting out and enjoying the clean air. I also love travelling and cooking, especially Pakistani food like biryani.

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Claire O'Connell

Claire O'Connell

Claire O'Connell is a contributor to The Irish Times who writes about health, science and innovation