The Science Behind Sustainability: Chemical Engineers Equipping Decision-Makers to Improve the Plastics Economy

To mark Earth Day’s focus on slashing plastic production, Amanda Jasi speaks to David Gardner and Andrea Paulillo to find out how they are helping to make the plastic system more sustainable

“DON’T demonise the plastic, it’s there for a purpose,” says David Gardner, a chemical engineer focused on sustainability. “Us and the way we use it is the issue.”

Its purpose is clear, with plastics a mainstay of everything from food and drink packaging to clothing fibres, construction materials to components for electronics, cars, and planes. The demon part comes thanks to emissions from fossil-based production and environmental damage caused by littering and microplastic release. Meanwhile, the linear economy means much of the useful plastic produced is lost to landfill, incineration, or the environment.

Up and up

“I’d like to think I’ve always done sustainability, but it hasn’t had such a ubiquitous name until quite recently,” says Gardner.

His earliest role was in a research centre for the then-public electricity sector. “A lot of the work there was actually to do with environmental concerns, so cleanup, reduction of contaminants in the waste streams, and things like that.

“I guess that was the early drive to recognising the issues that were around – not necessarily with plastics in those days – but with contaminants in the stream and how do you get those out, how to purify streams, how to process a stream to make it then reusable. That philosophy of clean up, reuse was there.”

He recognises that over time that discussion has moved further up the chain. “So not how do you clean it up, but how do you prevent it in the first place? And then even further up, how do you not even produce the contaminating material?”

Gardner is currently working on a project that encompasses this progression. Launched last September, the four-year, €7m (US$7.5m) European project Upstream is targeting litter, plastics, and microplastics.

It is initially focusing on addressing existing pollution by developing technologies to remove the target contaminants from wastewater treatment plants and waterways that it then aims to valorise. Later, the project will also work to prevent microplastic formation by developing bio-based and biodegradable plastics for a range of applications.

While Gardner is not able to discuss the specifics of his involvement in Upstream, he is more forthcoming about how he typically helps businesses achieve sustainability. He says: “[Companies] have looked at the environmental and the social impacts, when they do the analysis of ‘what is this product for?’ but then they don’t always carry that forward into the business model. What I’m trying to encourage people to do is embed those concepts into the business model at the same time.

“As chemical engineers we mustn’t be isolated from profitability, [or] long-term environmental and social impact. We need to be aware of that.” He says chemical engineers can feed into business plans, while at the same time providing the science for more sustainable and less environmentally damaging plastics.

Making trade-offs

Andrea Paulillo also first encountered the topic of sustainability as a young chemical engineer, while studying for his PhD at University College London (UCL). He has pursued the topic through to his professional life and is now a research fellow at UCL, with his work focusing on the use of life-cycle methodologies to assess the environmental, economic, and social performance of products and technologies.

“Why I pursued it?” he says. “Because I got very passionate about it. I understood the importance of the concept of sustainability and how we as chemical engineers can promote this concept and ensure that we develop technologies that align with this concept.”

Paulillo’s work in plastics includes a collaboration with another chemical engineer at UCL, Massimiliano Materazzi, who specialises in waste management technologies. Working alongside companies including Advanced Biofuels Solutions, they have been investigating technologies to convert waste into useful products. While these technologies do not solve the issue of a linear economy, they offer a way to valorise plastic waste that cannot be recycled, such as mixed plastics.

“One of the technologies is very well known, which is waste-to-energy,” says Paulillo. Used to generate electricity or heat, Paulillo adds that waste-to-energy has been around for a long time. He says: “The other [technology] is much more interesting and much newer, which is waste-to-hydrogen.”

Hydrogen can be used for energy production, or as a platform chemical – for example to produce ammonia.

Describing the research, Paulillo says: “We simulate the process to, for example, couple carbon capture with waste-to-hydrogen, and then we look at the environmental performance of doing that by a life-cycle assessment. For example, we quantify the carbon emissions. And then we look at different scenarios [to understand] how much we can reduce it, or what the environmental trade-offs are of this technology.

“There are [usually] trade-offs,” Paulillo adds. He notes that technologies very rarely have better economic, environmental, and social performance, at once, and it is also very unlikely for a technology to have better environmental indicators than another across the board.

“With my research, I want to provide the data and insights for the decision-makers and policymakers to make a choice. Because that choice will involve a trade-off, so they need to be aware of these trade-offs. And according to their priority – national priorities, regional priorities, the priority of a company – they decide ‘okay this is more important for us’ or ‘this is the indicator we focus [on]’ and therefore we choose this technology.”