Virtuous circles
From waste to resource, with the help of chemistry
This month the European Commission will present a strategy for a circular economy in the EU. The strategy embraces reusing, recycling, repairing and refurbishing, products and materials to reduce the amount of waste in Europe. If agreed it will change the way many products are developed and produced.
The circular economy concept mimics biological ecosystems, where all components are continually recycled and waste products from one process act as a resource for another process. That’s in sharp contrast with our usual manufacturing approach, which tends to be linear – a product is manufactured, used and discarded after use.
The idea of changing waste from something we discard into a rich resource is now becoming mainstream, but we still have a long way to go to realise the potential of what we throw away.
Realising the potential of waste will help us to tackle the challenge of minimising our energy demands and tackle the effects of the unsustainable use of resources on our climate. Anthropogenic climate change is especially topical at the moment given the talks designed to create a legally binding international agreement at COP21 in Paris . Six years ago, the climate change summit in Copenhagen (COP15) agreed to keep the global rise in temperature to 2°C this century. Some commentators have highlighted that if that commitment is to be met, we are going to have to leave a lot of fossil fuels in the ground. To protect our planet we need to develop sustainable alternative energy supplies and materials, as well as using less energy and materials overall. It’s clear that we need a mix of energy technologies as alternatives to using fossil-based resources.
Adding value
The good news is that lots of progress is being made in this area. Within the mix of alternative fuels, biomass is increasingly under the spotlight – including biomass from waste streams. Waste is also being exploited as a new source of materials – so if waste is used to its full value, it could help address our needs both for energy and materials.
Many existing platform chemicals – which are the starting points for chemical-based industries from pharmaceuticals to plastics – come from the processing of crude oil in refineries. If waste processing is going to be a major alternative, extracting chemical value from waste streams will have to happen alongside fuel generation. The biorefineries being developed are designed not just to generate biofuel but to make other useful chemicals from the biomass feedstock along the way. This adds value to the process, making the overall operation more economical.
Regulators, too, are attempting to help the move towards more renewable alternatives. The EU has given each member state a target of at least 10% of transport fuel coming from renewable sources by 2020 (precise amounts vary country by country ranging from 10% with Malta and 49% in Sweden). Biofuels including biofuels from waste will provide the bulk of this renewable fuel for transport, since they can be incorporated relatively easily into existing fuel supply infrastructure.
A huge potential resource
But what do we actually mean by waste and where does it come from? The waste collected by local authorities from our homes is a real mixture. The precise make-up may vary around the world, but of the 21.6 million tonnes of waste collected from households in England in 2013, 3.6 million tons was garden, food and other compostable waste, 5.7 million tons was dry recycled waste including glass, paper, plastic, metals and electrical waste and a remaining 12 million tons was everything else: including 6.9 million tonnes which was sent to landfill and 2.8 million tonnes which was incinerated. When we take waste from industrial processes into consideration the figures really stack up. Within the EU in 2015 food waste alone amounted to 89 million tonnes, with approximately 15% contributed by the UK. It’s no surprise, then, that many researchers in academia and industry are focusing their efforts on how to process waste to produce useful fuel and other chemical outputs.
At Aston University’s European Bioenergy Research Institute Professor Karen Wilson is using chemical catalysis to develop fuels and other useful chemicals from agricultural waste. For example, producing hydrolysed sugars from rice straw, which can then be used to produce the platform chemical, 5-(hydroxymethyl) furfural (5HMF). A process like this is a favourable alternative to burning the straw, which often happens. It generates a valuable chemical feedstock, and reduces potential harm to human health and the environment from releasing greenhouse gases and particulates into the atmosphere through burning.
At York University’s Green Chemistry Centre of Excellence Dr Andy Hunt and colleagues have developed ways of extracting useful chemicals from food waste. Limonene, from orange peel, can be used as an alternative to toluene, which is obtained from oil. Toluene is an important precursor to other chemicals as well as being a common industrial solvent, but in addition to coming from a fossil-fuel origin is also toxic to humans.
Creating a circular economy
Government agencies and funding bodies have been working to help connect research with industry to drive innovation, with some initiatives have directly involved ways of extracting value from waste. For example, two years ago the BBSRC in the UK launched their 13 Networks in Industrial Biotechnology and Bioenergy (NIBBs). With a budget of £18 million, the aim was to foster collaborations in fields such as food waste processing, anaerobic digestion, and the challenges of developing useful products from waste wood. Chemists are actively involved in these networks and we have collaborated with at various levels, including around some of our recent symposia and conferences. Members of the FoodWasteNet network were active participants in our Renewable chemicals from Waste symposium, and Directing Biosynthesis IV was supported by NPRONET.
We need to foster the interdisciplinary mix necessary for researchers to tackle the challenges of waste valorisation, and our members are bringing their chemical science expertise to bear in many areas. For example our ISACS17 meeting in Brazil, Challenges in Renewable Energy covered a range of research areas including food and agricultural waste utilisation. Our Microplastics in the Marine Environment workshop focused on this particular category of waste, with speakers including researchers, representatives of NGOs, and industry representatives.
Wider economic and societal factors will also play their part, of course, and our moving into the circular economy will have as much to do with changing the way we think about manufacturing processes and the design of consumer products as anything else. Factors such as oil price, feedstock availability and financial and regulatory incentives will play an important role, because these influence the economic favourability (or otherwise) of biomass from waste utilisation compared to other more conventional processes based on oil. However, without the enthusiasm and creativity of the research community, progress will not be possible. As far as the circular economy goes, chemistry really can help us to complete the circle.