It may look like rubbish, but food waste does have its uses. It could even be converted into valuable graphite and hydrogen. An EU-funded project is setting out to do just that. The process being developed combines established Anaerobic Digestion (AD) with an innovative Microwave Plasma technology to transform waste into treasure.
THIS IS what a project called PlasCarb is aiming to do, PlasCarb is a EUR 3, 8 million initiative funded by EU’s 7th Framework Programme (FP7), aims to use innovative technology to produce – EU identified critical and valuable products- graphitic carbon and renewable hydrogen from food waste. The PlasCarb consortium is composed of seven partners from five European countries, whose complimentary expertise will enable the required results to be successfully delivered.
PlasCarb will use mixed food waste as a feedstock to manufacture products for two significant growing markets: high value graphitic carbon and renewable hydrogen (RH2).
“The objective of PlasCarb is twofold,” says project coordinator Neville Slack from the Centre for Process Innovation in the UK. “One objective is to see how we could utilise food waste instead of sending it to landfill or just putting it through an anaerobic digester to generate electricity. The second is looking at potentially critical outputs”, synthetic graphite and green hydrogen.
Natural graphite, a high grade of coal, is 1 of 20 raw materials that the EU has identified as critical to its economy and for which it is largely dependent on imports. A reliable source of synthetic graphite, such as from the PlasCarb process, could help secure Europe’s supply and green hydrogen would help to minimise the environmental footprint of many promising applications.
The PlasCarb partners are planning to develop a plant that will integrate the whole process, from the production of biogas to the isolation and purification of graphitic carbon and green hydrogen.
The biogas is generated from food waste, which is broken down in an anaerobic digester. The aim is then to split this gas into its two main components – methane and carbon dioxide – using a filtration and cleaning process developed by the project, Slack explains. The now biomethane (CH4), once isolated, is injected into the plasma reactor, where it is heated using low-energy microwave technology until the molecules come apart, forming graphitic carbon (C) and hydrogen (H2).
One of the challenges says Slack, lies in ensuring that the process delivers carbon in the desired form. Another arises from the complexity of separating the two substances. Further steps are required to divide the two and eliminate impurities.
Getting this facility up and running will be the culmination of nearly three years of joint research into the necessary technologies and processes. By the time the project ends in November 2016, the partners hope to have operated this plant for at least one month, processing over 150 tonnes of food waste into more than 25 000 cubic metres of biogas.