The science behind net zero

May 16, 2024

Australia’s universities are spearheading the scientific innovations critical to achieving national targets in renewable energy, storage, and reduction of emissions.

Image: Professor Anita Ho-Baillie, John Hooke Chair of Nanoscience at The University of Sydney. Supplied by the University of Sydney

Australia plans to reach net zero emissions by 2050. With the transformation underway, the country’s universities are spearheading the scientific innovations critical to achieving national targets in renewable energy, storage, and reduction of emissions through agriculture and infrastructure.

Next-generation renewable energy technology

University science paved the way for Australia as a pioneer in photovoltaics. PERC solar cells, the brainchild of UNSW Scientia Professor Martin Green, continue to be the world’s most commercially viable silicon solar cell technology, reaching 25% efficiency.

Professor Anita Ho-Baillie, John Hooke Chair of Nanoscience at The University of Sydney, is boosting that efficiency by stacking together two different light-absorbing materials to expand the spectrum of sunlight solar cells can soak up. Perovskite forms the top layer to harvest high-energy rays, while the bottom silicon layer absorbs low-energy light.

“They’re working in tandem, making them more efficient in converting solar energy into electricity — up to 40%,” says Ho-Baillie. “We’re hoping to produce more power with less or the same amount of area, effectively reducing cost. And the more power we produce, the shorter the energy payback.”

Solar also powers the production of green hydrogen, another renewable energy source. Professor Tianyi Ma, a materials chemist at RMIT University, harnesses sunlight for his solar-to-hydrogen generator. This device is designed to float on water, with a photocatalyst-coated top layer that directly converts solar to hydrogen without the intermediate electricity generation and costly battery energy storage.

This simplifies the otherwise complex process of producing green hydrogen. “This results in lower costs and can potentially lead to large-scale utilisation of renewable energy,” Ma says. “And because it’s floating, it doesn’t occupy land space.”

Industry is hot on the trail of these next-generation technologies. Ho-Baillie is collaborating with Sydney-based solar tech startup SunDrive, while Ma
is working with industry partners and has recently been awarded a funding grant from the Australian Renewable Energy Agency.

Emerging avenues of research across the university ecosystem are integral to advancing renewable energy. Ho-Baillie’s group, for instance, includes undergrads as well as graduate students and post-doctoral researchers. “We’re educating and training the next generation to make renewable energy better,” she says.

Innovative chemistry for energy storage

While renewable energy is vital to realising net zero, storage is key to securing constant supply. For many, batteries are synonymous with energy storage.

University of Sydney professor of chemistry Thomas Maschmeyer and his research group formulated lithium-sulfur batteries. These can store more energy than lithium-ion ones and are a lower-cost and safer alternative.

The team also developed a novel electrolyte flexible enough to fit different anode types. As a result, lithium-sulfur batteries can match different configurations to power drones, electric vehicles and even electric planes.

In 2015, Maschmeyer founded energy storage startup Gelion, a spinout of his research at The University of Sydney. The company has since announced breakthroughs in lithium sulfur batteries that double the range of EVs and enable electric aviation. It is now globally positioned with partners in the UK and the US, poised to integrate its sulfur cathode platform technology into products spanning all current lithium battery applications. All these successes were made possible by Maschmeyer and his research group’s foundational scientific work at the university level.

“Batteries help us use our energy resources more efficiently, allowing us to change the model from centralised power with long transmission lines to local power with short transmission lines,” Maschmeyer says. “We need batteries to support the energy transition.”

University science is making hydrogen storage breakthroughs possible as well. Kondo-Francois Aguey-Zinsou, also a professor of chemistry at the University of Sydney, is working on hydride materials for hydrogen storage. These materials include metals and lightweight chemical elements capable of absorbing hydrogen like a sponge and storing it in compact form. They can store hydrogen in larger amounts and more safely than hydrogen’s current liquefied or compressed gas form.

Building scientific expertise in universities helps accelerate the progress of energy storage. “We need storage technologies if we are to deploy renewable energy at scale,” says Aguey-Zinsou. “Hydrogen will be part of that mix.”

Boosting soil carbon

Soil carbon sequestration can play a pivotal role in reducing Australia’s agricultural sector emissions.

“Evidence suggests carbon improves soil biodiversity and water retention and decreases erosion,” says Dr Elaine Mitchell, a Research Associate in soil carbon at QUT. “Drawing carbon out of the atmosphere where it’s causing harm and putting it into the soil means healthier, more productive soils.”

Universities are planting the scientific seeds to help bolster farmers’ soil carbon sequestration capabilities. Mitchell’s research, for instance, involves understanding how effective land management can generate long-term soil carbon gains. She’s investigating time-controlled grazing — grazing cattle at a higher density for a shorter duration — which has been shown to increase soil carbon stocks.

Additionally, she found that legumes, particularly species of Desmanthus, have deep tap roots, channelling carbon deep into the soil. They also contain compounds called tannins, “so when the cattle eat them, they reduce the production of methane in their guts,” Mitchell says.

Meanwhile, Annette Cowie, Senior Principal Research Scientist – Climate at the New South Wales Department of Primary Industries and Adjunct Professor at the University of New England Armidale campus, is exploring biochar, a carbon-rich form of charcoal, with researchers at UNE’s School of Environmental and Rural Science.

“As a soil amendment, biochar is much more stable and durable than carbon sequestered by building natural soil organic matter,” she says. 

Cowie adds that biochar is effective at building the soil’s nutrient- and water-holding capacity and reduces its nitrous oxide emissions.

Mitchell views soil carbon sequestration as a “short-term bridging solution allowing us to buy time while other technologies are developed and implemented. 

“It shouldn’t take away the focus from reducing emissions.”

Building energy-efficient infrastructure

Energy-efficient buildings are another component of the net zero transition. “Materials and design are critical as we move towards low-energy buildings,” says Dr Mark Dewsbury, senior lecturer at the University of Tasmania.

Dewsbury studies the hygrothermal performance of buildings, with a guiding motto of “build tight, ventilate right.”

Hygro refers to moisture, while thermal pertains to heat flow throughout the building envelope and how that envelope is designed relative to climate.

He notes that vented cavities behind cladding systems remove heat for improved cooling and allow water vapour to escape, reducing the risk of mould growth. When it comes to heating, placing insulation directly behind lining systems avoids losing heat. 

These findings inform recommendations for the Nationwide House Energy Rating Scheme, and published guides for architects and builders. Recycling of building materials will play another role. Concrete, for example, requires energy to mine, mix and transport but can be reused from demolished building sites instead.

“We need to be designing and constructing net zero buildings today so we meet our net zero goals by 2050,” says Dewsbury.
Rina Caballar

First published in Australian University Science, Issue 11

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