Biogas from anaerobic digestion to benefit Australia

Australia has enormous potential to expand its biogas and bioenergy presence by producing biomethane through anaerobic digestion of industrial and municipal wastewater and sludge, industrial & food waste, and agricultural waste.

Australia has enormous potential to expand its biogas and bioenergy presence by producing biomethane through anaerobic digestion of industrial and municipal wastewater and sludge, industrial & food waste, and agricultural waste.

Capturing the methane from wastewater treatment plants and other facilities is providing a renewable gas, helping to decarbonise our economy. Hydroflux is stepping up to support this future growth.

Hydroflux has been involved in bioenergy for many years, primarily through its municipal wastewater treatment branch, Hydroflux Epco. It has designed and built digester covers for local government installations for over 20 years. At the same time, Hydroflux Industrial has built many anaerobic digestion projects for industrial customers who benefited by treating their wastewater anaerobically. Hydroflux Utilities has been involved in the bioenergy space by operating and maintaining sites.

One person with experience in this space is Manfred Beyrer, the general manager of bioenergy at Hydroflux. He has been involved in bioenergy for more than 15 years and is a respected member of the field. In his opinion, there is enormous potential for the Australian water industry to expand its bioenergy footprint.

What is happening in Australia?

Beyrer has been looking at the array of anaerobic digestion opportunities. One focus has been how the industry can better use what is otherwise considered waste as a feedstock for anaerobic systems, producing valuable biogas.

He pointed out that the organic waste in question can be almost anything. The critical points for the growth of the Australian bioenergy industry and its development within the water industry are using anaerobic wastewater treatment plants instead of complete reliance on aerobic systems where possible and diverting organic waste away from landfills. Both actions enable the capture and use of the gases that arise from the breakdown of materials, mainly methane (CH4).

“Capturing the fugitive gases released from waste ponds that are not aerated is important. Methane is 28 times more environmentally harmful than carbon dioxide (CO2). So the fastest way to reduce carbon emissions for many of these industries, whether abattoirs, wineries, meatworks, dairies, or whatever it is… could be to ensure they have the fewest possible fugitive methane emissions and use the valuable biogas as energy in their plant,” said Beyrer.

Smaller facilities could convert open lagoons into covered lagoons to capture the gas and flare it, creating carbon credits.

Why hasn’t this happened at scale in Australia?

One of the issues in Australia is that it has a spread-out population, with many smaller facilities that are too small to build commercially viable biogas plants. However, Beyrer pointed out that the market is shifting to incorporate shared anaerobic wastewater treatment for multiple facilities. These facilities could also receive suitable organic matter, presently sent to landfill.

“We are helping our clients by identifying options for pooling waste and feedstock across multiple sources. As a result, they can treat wastewater, sludge, and food waste from several places, which suits an anaerobic digestion system. Like a healthy diet, it can be found that a mixture of different ingredients enables operation at the highest levels,” he said.

What Hydroflux brings to the bioenergy space

The technology entering Australia is tried and tested, as it has been used in Europe for over a decade. The most significant difference that Hydroflux makes is working with clients from day one to understand their needs regarding wastewater and solid waste digestion.

“We talk to them about their wastewater and their discharge considerations. We talk about their organic waste, site size, energy constraints, and anything else that might impact their operations,” said Beyrer. “Some clients might want to use the generated biogas to offset their current fuel costs or create some of their electricity. Other clients might want to collect that gas to distribute it into the grid. So it all depends on the individual client and determining the best solution for them. That’s our biggest difference.”

Once they do the original plant design and establish that anaerobic digestion is viable, they can look at issues like pre-screening. Screening the wastewater or sludge is essential to prevent digesters from filling up with material that is not digested. Proper screening of materials increases the capacity of digesters while also removing impurities and improving the quality of the digestate as a fertiliser.

“We will also assist clients in developing the most energy-efficient system possible. We have access to a comprehensive range of technologies and processes that make this possible, including digesters with no moving parts inside,” Beyrer said.

Flexible membranes are the future of Australia

Europe has long been using flexible membranes to capture and store the biogas before using it to overcome the variations in biogas production and provide continuity in biogas supply.

The double membrane gas storage system is state‐of‐the‐art in biogas storage. A system that is robust, durable, and able to store variable amounts of gas at a constant pressure. The outer weather protection foil keeps the wind and rain away from the integrated inner gas storage foil.

Depending on the application, these systems can be constructed on top of tanks or mounted on the ground. Membrane gas storage systems provide a cost-effective and reliable alternative to the steel digester covers traditionally used in sewage treatment plants.

“Anaerobic lagoons typically use single membrane systems due to their size. Covering the lagoons with flexible membranes is essential to capture the gas,” said Beyrer. “Operating anaerobic systems under flexible membranes means that operators capture the otherwise fugitive gases and allow them to reduce their energy demands or flare the gas to avoid releasing harmful methane to the atmosphere.”

The utilisation of biogas & biomethane in Australia

Biogas can typically be used in several different ways. One of the most common and efficient uses of biogas is as a renewable fuel instead of fossil fuel in a boiler to create hot water or steam at the location where it is produced. It can create electricity where a biogas engine converts approximately 40 per cent of the energy into electricity and 40 per cent into hot water. The electricity can be supplied to the grid, and the hot water can be used for local demand.

New and upcoming opportunities exist to purify the biogas into Renewable Natural Gas by removing CO2 and other impurities. This purified gas can be injected into the existing natural gas grid, providing a renewable and carbon-neutral fuel for industries relying on gas as a fuel source whilst reducing their carbon emissions.

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