There’s more to a barrel of oil than meets the eye. It’s not only an energy source but also the raw material for almost all our chemical products: fertilisers, pesticides, plastics, glues, paints, cosmetics, pharmaceuticals, cleaning products and more. Unless we come up with substitutes, we’re trapped into extracting oil.
Cameron Weber, who directs the Centre for Green Chemical Science at the University of Auckland, explains the problem. “About 10-15% of crude oil ends up as petrochemicals, and most of oil’s value comes from those. The remainder ends up as fuel. So, even if we replace all our energy with renewables, we still have to find somewhere to get chemicals from. That’s a much more complex problem than alternative energy.”
Enter green chemistry. “If we think about plastics, paints, cosmetics, cleaning products, all of the things that we encounter on a day-to-day basis, each of those is chemically different. For each one, we’re going to have to find an alternative. That’s either an alternative way to make the same compounds, starting from an entirely different source, or completely new materials that fulfil a similar role that are easier to make from these new sources.”
What is green chemistry? “It’s the design of chemical products and processes that minimise the use and generation of hazardous substances,” says Weber. “It means thinking through the entire process of making a chemical product, from types of reagents that you might use to prepare it to how safe the actual chemical product is itself.”
Green chemistry’s mission extends beyond finding new sources of chemical products. “Humanity hasn’t got the best track record with making chemical products that are 100% safe with no environmental and health consequences.” It involves thinking about environmental and health consequences in the design phase, “rather than trying to clean up the mess afterwards”.
The Auckland centre is working on projects making useful chemicals from waste streams, sometimes in collaboration with other agencies such as the forestry crown research institute Scion. The chemists and engineers can use grape marc (stems, skins and seeds) as a base for bioplastics and gel films for food packaging. Forestry waste is turned into lignocellulose-based chemicals. The chitin in crustacean shell waste may become pharmaceutical or cosmetics ingredients. Other bio-based products include cellulose-based surfactants, fire-retardant building papers, phosphorus- containing materials for making fine chemicals and a range of paper-based electronic devices.
The urgent need for green chemistry is endorsed by Ron McDowall, an Auckland-based engineer who spent many years working for the United Nations clearing some of the world’s most contaminated land. “Boy, do we need green chemistry,” he said. “The Anthropocene is truly here, and we’ve made a mess of this planet.” The problem with green chemistry, he says, is that it’s more expensive.
Weber is hopeful on that front. “The oil and gas industry had a large head start. The reason they can make things cheaply is partly because they make a wide range of different compounds and they’ve found markets for every single one of them. The hard part when you’re starting from scratch is you’re often targeting one product at a time. You really want a process to take a biomass feedstock, which has a range of components, and convert these into an equally large range of chemical products. That way, the cost of the process is divided among a range of products that have different applications, and it minimises the waste.”
All of chemistry’s traditional branches can contribute. “We need engineers, too, to make the processes apply at industrial scale,” Weber says.
