An EU Project Aims to Turn Food Waste into Graphene

Carbon and hydrogen could be a lot more desirable than methane.

Jan 19 2015, 12:30pm

​Image: ​szczel/Flickr

​Food waste is just that—a waste, not just of food, but also the time, money, and the natural resources that went into making it in the first place. It also pumps polluting g​ases out into the atmosphere. Food waste is bad.

Obviously the best solution is not to waste food in the first place, but one EU project is looking into how remaining waste could be turned into something useful. The Plas​Carb project aims to transform methane created by the anaerobic digestion of food waste (a process that breaks it down into methane and carbon dioxide) into something more desirable: graphene and renewable hydrogen.

Turn waste into a carbon wonder material and a renewable energy resource? It sounds like a compelling concept.

2014 estimate sugge​sts that over 100 million tonnes of food are wasted in the EU every year, a figure expected to rise to 126 million tonnes by 2020. Meanwhile, we keep hearing more uses for super-strong, super-conductive carbon form graphene, and hydrogen is already in great demand.

The UK's Centre for Process Innovation (CPI), which is leading the project and outlined the work in a recent news post, adds that the vast majority of hydrogen is currently produced from fossil fuels, so a renewable source would have other advantages.

Project Manager Neville Slack of CPI answered some questions about the process over email. The first step is to convert food waste into biogas—a mixture of methane, carbon dioxide, and impurities—through the process of anaerobic digestion, which is already used in some places to deal with fo​od waste.

The PlasCarb initiative will monitor this for one year, to observe the quantity and composition of the biogas they're getting and assess the economical viability of removing impurities. "Life cycle analysis will ensure that the approach is sustainable," added Slack.

Then comes the "low energy microwave plasma process;" the second step that converts the methane gleaned from anaerobic digestion into graphitic carbon and hydrogen. The plasm​a process essentially breaks molecular bonds, in this case splitting methane into the carbon and hydrogen it's made up of.

"The key element of innovation is the generation of large homo­geneous non-equilibrium plasma zones for cracking methane into valuable carbon products at atmospheric pressure with potential for industrial scale operation," wrote Slack.

What they hope to end up with is hydrogen and "graphitic carbon" (of which one form is graphene—experts will work to characterise what ultimately comes out). Part of the project involves making sure the right sort of carbon comes out, rather than less valuable glassy or amorphous forms.

If all goes to plan, it's a matter of assessing the feasibility of dealing with waste this way, and whether there's enough of a market for it. The CPI says that it has the infrastructure to trial the microwave plasma process in a pilot.

The project is currently a year into its three-year timeline, and it's very much in pilot stage. The participants admit that it won't help reduce food waste, but could reduce its impact by creating resources that might otherwise be imported or supplied by unsustainable means.

Nevertheless, the best action remains to minimise food waste to begin with, and the EU continues to work toward that goal, aiming to cut waste 30 percent ​by 2025. Innovative solutions to a problem sound cool, but preventing it in the first place is better.