Imagine you’re a factory owner who wants to make your operations more sustainable. Where do you start? If your machines currently run on fossil fuels, they might be expensive to replace or convert. The new equipment might not run smoothly. You might incur unexpected costs. You might need to change your processes. You might even find your carbon footprint doesn’t shrink as much as you expect. 

Change is fraught with risk. Risk can be expensive. Yet the rewards of sustainability can be great both for a business’s bottom line and for the planet. That’s why Waipapa Taumata Rau, University of Auckland Professor Brent Young is working to help industry de-risk change, particularly in favour of sustainability.

To make change more predictable, Young, a member of the Chemical and Materials Engineering department, is working with a number of companies to model process systems by creating digital twins of those systems.

Young’s digital twins aren’t avatars or chatbots. They’re detailed models of factories and processes, hyper-realistic not in the sense of skin tones or mannerisms but in their inputs, functions and outputs. His computer-based models follow the laws of physics, chemistry and biology. They account for predictable events such as equipment ageing or getting gummed up as well as unpredictable ones such as power outages and earthquakes. 

Once a digital twin is validated as running realistically, it can model what happens when circumstances change. For example, what happens when heat pumps are installed in a factory? When a company switches to renewables? More complex models are possible too. For example, a digital twin can model how a factory will interact with community infrastructure if it becomes a net producer of renewable energy rather than a consumer. 

Digital twins usually start with existing industrial processes. But what if a sustainable new process doesn’t yet exist on an industrial scale? Young is working with colleagues from the Faculty of Engineering to model these too.

With Senior Lecturer Wei Yu, Young is figuring out how best to recover phosphorus from wastewater.

“Phosphorus is in limited supply and there are predictions that if we continue at the current rate, mineable phosphorus might cease to be available within a century, maybe less,” says Young. “However, there’s phosphorus in wastewater, both from fertiliser runoff and from sewage sludge –our urine is one source of it. Technologies do exist to recover that phosphorus for reuse, so we’ve been doing lab work and modelling to understand those processes and optimise them.”

With Associate Professor Saeid Baroutian, Young is working to optimise technologies such as hydrothermal processing and supercritical extraction, which can break down toxic materials and extract valuable compounds from what would otherwise be waste. 

Also with Baroutian, Young is researching ways to capture greenhouse gases used in operating rooms. Though carbon dioxide is the best-known greenhouse gas, anaesthetic gases such as desflurane and sevoflurane are, molecule for molecule, far more potent in their ability to warm the planet. Currently, the anaesthetic gas patients exhale is simply vented out of hospitals. Baroutian and Young are looking at ways to absorb these gases before they hit the atmosphere.

“All these processes need to be cost-effective to be viable,” says Young. “Modelling can show how to make them economically feasible.