Sydney Water biomethane deal points to renewable energy future

In an Australian first, Sydney Water will start generating renewable biomethane for the gas grid following a new agreement with energy infrastructure company Jemena.

Sydney Water Head of Strategy and Corporate Social Responsibility Paul Higham said the move towards green gas aligns with the utility’s commitment to renewable energy and circular economy solutions.

“We've been looking at circular economy opportunities for a few years now. With wastewater treatment being a critical part of our business, it presents a fantastic opportunity for doing things differently with our bio-resources,” he said.

“We already use biogas to generate our own energy. We produce around 53 gigawatt hours per year of electricity, which is enough to power about 7000 homes. Our objective is to reduce emissions to the environment, as well as creating greater value from the products that we have.”

Higham said the pivot to green gas was inspired by recent biogas to grid operations being facilitated internationally, with Sydney Water working with Jemena to assess the feasibility of a similar project in Australia.

“As with any water utility, we have a long history of anaerobic digestion and the creation of bio-methane within our operation. We took a look at some of the international trends occurring and in Western Europe biogas to grid is starting to get a little bit of traction in the marketplace,” he said.

“Fundamentally, we asked ourselves if we could achieve a similar outcome. With Jemena being a regulated utility for the Sydney area, it was logical to have a conversation with them around whether they would be interested in working with us to bring green gas into the Sydney market.

“We've been working with them to explore the opportunity, including the proximity of the gas network which is crucial to making the solution viable.

“It's been a really great relationship that we’ve built over the last couple of years, with both organisations looking to innovate in their respective environments.”

Gas to energy

Higham said Sydney Water will be providing biogas produced at its Malabar Wastewater Treatment Plant, which will then be clarified with the help of a gas up-grader installed on site.

“Malabar is our largest wastewater treatment plant and already uses biogas to produce a large amount of renewable energy. And, with population growth, we're going to see increased ability to generate biogas,” he said.

“What we're providing as part of the partnership is the continued supply of our biogas to a gas up-grader, which Jemena are currently investing in.

“The upgrader will be located on our site, sitting parallel to our anaerobic digestion facilities and our combined heat and power generators to provide an optimal solution for the biogas that we create.”

Higham said the upgrader will convert the biogas created from Sydney Water’s anaerobic digesters into something that can be purified to about 98% methane before it is injected back into the gas grid, which is a part of Jemena's distribution network.

“The gas grid is in relatively close proximity to Malabar, which allows us to take the up-graded gas and inject it into the system,” Higham said.

“The product is essentially zero-emissions biogas. It's something that we can produce every day of the year. We will be providing gas for the equivalent of about 6300 homes.

“But, as with population growth in any big city, the opportunity will increase. And we're expecting the amount of gas to grow to the equivalent of around 13,000 homes by 2030. It leads to quite a large carbon reduction, too. By using renewable gas over fossil fuel, there is a reduction in about 5000 tonnes worth of CO₂ emission, which is roughly equivalent to 1900 cars off the road.”

Higham said the partnership with Jemena provides a real opportunity for Sydney Water to use its biomethane resources in the best way possible.

“While Malabar is our largest wastewater treatment plant, we have nine treatment plants that could be capable of doing a similar thing in the future, subject to the success of this project,” he said.