The benefits of anaerobic digestion: Eneraque Renewables

anaerobic digestion

Anaerobic digestion is a climate solution that plays a crucial role in Australia’s waste management and renewable energy production, says Heather Millar, Chief Marketing Officer of Eneraque Renewables.

Farmers are increasingly adopting anaerobic digestion to manage agricultural waste such as manure and crop residue. Landfill sites, wastewater treatment plants and organic waste facilities are all candidates for anaerobic digestion technologies, producing biogas and nutrient-rich by-products. 

“Waste-to-energy projects using anaerobic digestion are gaining traction in Australia,” Heather says. 

“By converting organic waste into energy, these projects contribute to a sustainable energy mix while addressing waste management challenges.”

With more than 40 years’ experience in delivering waste to energy projects and dozens of working plants, Eneraque Renewables is offering engineering, procurement, and construction of biogas plants from the feedstock management and anaerobic digestion infrastructure, through to onsite power generation and beyond to biogas upgrading systems and grid injection.

Heather says this unique capability provides clients with one partner for their entire plant build, along with the option for ongoing maintenance and operation by the service team.

Eneraque Renewables’ innovation team continuously researches state-of-the-art technology available globally. Heather says the firm’s expertise and point of difference lies in ensuring the finished design and equipment adheres to Australian and New Zealand standards and will work within specific local infrastructure frameworks – something that cannot be achieved by importing technology from overseas. 

“We see too many project developers burnt by directly importing technology or pre-built equipment from overseas – they find it is not up to standard, near impossible to retrofit or maintain and often just simply doesn’t work because it hasn’t been designed for APAC,” she says.

“We’re generally using about 10 per cent of the base technology, and the remainder needs to be custom engineered and manufactured by our Brisbane-based team.

“We have the right partnerships in place to be able to deliver this technology seamlessly.”

Heather Millar, Eneraque Renewables Chief Marketing Officer. Image: Eneraque Renewables

Anaerobic digestion technologies in Australia vary, from mesophilic systems operating at moderate temperatures to thermophilic systems operating at higher temperatures. Each technology has its advantages and is employed based on specific needs, such as energy requirements and the type of feedstock.

Continuous Stirred Tank Reactors (CSTR) are a common technology where organic materials are continuously added to a tank, and the mixture is stirred to maintain a uniform environment for microbial digestion.

CSTR offers a stable and controlled environment for microbial activity, making them a reliable choice for anaerobic digestion projects in Australia.

Anaerobic Sequencing Batch Reactors (ASBR) involves filling a reactor with organic material, allowing it to undergo anaerobic digestion, and then emptying it in a sequential manner. The reactors provide flexibility in handling varying organic loads, making them adaptable to diverse waste streams in Australia.

Plug Flow Digesters facilitate a more linear flow of organic material through the digestion process, promoting better control over retention times and optimising biogas production.

Like most renewable energy initiatives, policy and regulatory support is essential to its success. Heather says feedstock variability and economic viability remain challenges in the anaerobic digestion sector in Australia. 

But she says the regulatory landscape is evolving, with a focus on promoting sustainable practices. Government incentives and policies also aim to encourage the adoption of anaerobic digestion systems, aligning with broader environmental goals.

Ongoing research and development continue to drive innovations. Emerging technologies, such as advanced digester designs and optimised feedstock management, are expected to enhance efficiency and scalability.

Heather says those considering the commercial viability of a biogas plant are also now assessing the full range of income streams that can be generated as part of the process. 

The digestate that remains after anaerobic digestion and bio-carbon dioxide (CO2) are both recognised as commercial products, with the potential to provide plant owners with a return on their investment. 

“Adherence to waste management regulations is essential to ensure the safe and environmentally responsible use of digestate in Australia”

Australian farmers leverage digestate as a nutrient-rich soil amendment, enhancing soil health and promoting better crop yields. Its nutrient content, including nitrogen, phosphorus, and potassium, makes it suitable for use as a fertiliser, reducing reliance on chemical fertilisers and promoting sustainable agriculture practices.

Digestate can be applied to degraded or contaminated land to aid in rehabilitation and revegetation. 

It can be further processed into compost and could be used to fertilise crops specifically grown for energy production, such as biomass crops for bioenergy, fostering a closed-loop approach in the agricultural and energy sectors.

However, plant owners must be aware of regulations and guidelines that could impact the handling and application of digestate, especially on crops intended for human consumption.

“Adherence to waste management regulations is essential to ensure the safe and environmentally responsible use of digestate in Australia,” Heather says.

The advantage of using bio-CO2 from anaerobic digestion is its renewable and sustainable nature, contributing to reduced environmental impact compared to CO2 derived from fossil fuel sources.

Heather says during biogas upgrading the impurities in the biogas, including CO2, are separated to produce a purified methane stream. The separated CO2 can be considered as bio-CO2, as it originates from biological processes. This bio-CO2 can then be used for various applications, such as in agriculture, food and beverage, medical, and industrial processes. 

Likewise, liquefied bio-CO2 can be used in a variety of applications across industries, including for carbonating beverages, such as sodas and sparkling water.

“Anaerobic digestion contributes to the Australian economy by creating jobs, attracting investment, and establishing new opportunities in the renewable energy sector. Its economic impact extends beyond waste management,” Heather says.

“Eneraque Renewables believes in the power of renewable gas to help Australia reach net zero ambitions and to create a more sustainable future, while turning waste into a profitable resource.” 

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