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Melbourne Water finds an energy-saving solution

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04 Jun, 2024

This post was originally published on Sustainability Matters

Sewage and wastewater treatment is a highly energy-intensive process, presenting a challenge for water utilities seeking to meet net zero goals.

Melbourne Water’s Eastern Treatment Plant (ETP) treats almost half of all Melbourne’s sewage, an average of 330 million litres a day. Located in the Melbourne suburb of Bangholme, approximately 19 miles south-east of the city centre, the 1000 ha site was upgraded in 2012 to treat sewage to an advanced tertiary standard, producing Class A recycled water.

Shooting for net zero

Since opening in 1975, the ETP has always generated energy from sewage gas, and the site houses seven power generators that are capable of running solely on biogas — produced through the anaerobic digestion of sludge during the first and second phases of water treatment.

In 2020, Melbourne Water began a project with John Holland-KBR Joint Venture to upgrade the biogas handling system at the Eastern Treatment Plant to make it more efficient, resilient and futureproof. The project aimed to expand capacity, prevent corrosion and sedimentation, and extend the working life of equipment — with specific requirements to remove liquid droplets and moisture and to minimise the size and cost of any necessary cooling system.

Sewage transfer and treatment are responsible for about 85% of Melbourne Water’s total greenhouse gas (GHG) emissions, so contributing to the company’s net zero commitment was a main target for the project. “However, with existing assets nearing the end of their service life, ensuring that the new asset can service future production growth and plant upgrades was also essential,” said Nick Fung, Senior Project Manager at Melbourne Water.

Increasing reliability for the operations team onsite and improving safety across both operation and maintenance were further aims.

Selecting an energy-saving solution

The HRS BDS formed part of a wider upgrade to the biogas handling equipment at Melbourne Water’s Eastern Treatment Plant.

Biogas contains hydrogen sulfide (H2S) gas, which condensates out to form a highly corrosive liquid. Including a system to remove most of the moisture from the gas was therefore essential to minimise the amount of corrosion and degradation of the power station generators, while also limiting operational downtime and reducing the need to import electricity from the grid.

HRS Heat Exchangers was one of five companies invited to tender for the moisture removal equipment in the project. The HRS Biogas Dehumidification System (BDS) removes water from biogas, protecting combined heat and power (CHP) engines and generator sets from corrosion and cavitation. According to HRS, it condenses more than 90% of the water present in biogas by reducing the temperature to leave a clean gas. The addition of heat regeneration technology means the cold biogas produced can be used to pre-cool the incoming warmer biogas. This reduces the load on the final cooling heat exchanger and saves valuable energy.

The BDS supplied for the project has a maximum capacity of 4161 m3/h (4710 kg/h), while the inclusion of an energy recovery section subsequently reduces the eventual chiller load by 30%. This BDS consists of two heat exchangers, a regeneration unit and a final cooler, supplied on two skids. One skid — located in a hazardous area zone — contains the heat exchangers, a condensate knockout pot, a condensate drain line and all the relevant IECEx-rated instrumentation. The second skid contains a buffer tank, standby and duty glycol pumps, and all the relevant glycol line process control valves and instruments.

HRS also supplied an additional chiller and detailed process control descriptions, enabling the joint venture engineers to provide overall control and automation systems for the client.

Overcoming complex design parameters

The HRS BDS at Melbourne Water’s Eastern Treatment Plant incorporated some complex design elements.

The BDS needed to meet the requirements of two different operational stages, each of which contains four duty requirements. This meant a complex thermal design process was necessary to make sure that the supplied unit could meet all eight of the potential design scenarios.

Ella Taghavi, Project Manager and Technical Lead at HRS Heat Exchangers, explained: “Designing the BDS for the Melbourne Water project posed a significant challenge as it needed to cater to both current and future demands, with two very different conditions in each phase.

“The current first phase uses biogas supplied by the compressors and aftercoolers at an average pressure of 66 kPa. In the second (future) scenario, the gas is supplied following a number of additional treatments at an average pressure of 5 kPa and then supplied to the compressors. We therefore had to deal with two very different inlet conditions.

“The addition of heat regeneration added further complexity in terms of design. However, thanks to our cutting-edge technology, not only were capital costs reduced as a smaller chiller could be specified, but regeneration is also helping to lower ongoing operational costs.”

An efficient result

From being awarded the contract in July 2021, it took less than 12 months for HRS to install the bespoke BDS onsite, with commissioning completed in June 2022.

The John Holland-KBR team noted that of the five tendered solutions, the technology of the HRS BDS stood out, including the excellent technical support it provided to help develop the project further with Melbourne Water.

“Our experience in project management, construction and logistics enabled us to overcome early design challenges and respond to necessary changes during the design and construction process. As a result, we were able to deliver a high-quality product that has performed to specification since its installation,” Taghavi said.

The upgrade project has improved the quality of the biogas supply to the power station at ETP, providing more confidence in its ability to deliver more than 36,000 MWh (approximately 130 TJ) of thermal energy for process heating. This means a reduced reliance on natural gas, cutting down on emissions and making the operation more self-sufficient.

Top image caption: The HRS Biogas Dehumidification System (BDS) is specifically designed to improve the operating life and energy efficiency of biogas engines. Images courtesy of HRS Heat Exchangers.

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Turning down the heat: how innovative cooling techniques are tackling the rising costs of AI's energy demands

Turning down the heat: how innovative cooling techniques are tackling the rising costs of AI's energy demands

As enterprises accelerate their AI investments, the energy demand of AI’s power-hungry systems is worrying both the organisations footing the power bills as well as those tasked with supplying reliable electricity. From large language models to digital twins crunching massive datasets to run accurate simulations on complex city systems, AI workloads require a tremendous amount of processing power.

Of course, at the heart of this demand are data centres, which are evolving at breakneck speed to support AI’s growing potential. The International Energy Agency’s AI and Energy Special Report recently predicted that data centre electricity consumption will double by 2030, identifying AI as the most significant driver of this increase.1

The IT leaders examining these staggering predictions are rightly zeroing in on improving the efficiency of these powerful systems. However, the lack of expertise in navigating these intricate systems, combined with the rapidity of innovative developments, is causing heads to spin. Although savvy organisations are baking efficiency considerations into IT projects at the outset, and are looking across the entire AI life cycle for opportunities to minimise impact, many don’t know where to start or are leaving efficiency gains on the table. Most are underutilising the multiple IT efficiency levers that could be pulled to reduce the environmental footprint of their IT, such as using energy-efficient software languages and optimising data use to ensure maximum data efficiency of AI workloads. Among the infrastructure innovations, one of the most exciting advancements we are seeing in data centres is direct liquid cooling (DLC). Because the systems that are running AI workloads are producing more heat, traditional air cooling simply is not enough to keep up with the demands of the superchips in the latest systems.

DLC technology pumps liquid coolants through tubes in direct contact with the processors to dissipate heat and has been proven to keep high-powered AI systems running safely. Switching to DLC has had measurable and transformative impact across multiple environments, showing reductions in cooling power consumption by nearly 90% compared to air cooling in supercomputing systems2.

Thankfully, the benefits of DLC are now also extending beyond supercomputers to reach a broader range of higher-performance servers that support both supercomputing and AI workloads. Shifting DLC from a niche offering to a more mainstream option available across more compute systems is enabling more organisations to tap into the efficiency gains made possible by DLC, which in some cases has been shown to deliver up to 65% in annual power savings3. Combining this kind of cooling innovation with new and improved power-use monitoring tools, able report highly accurate and timely insights, is becoming critical for IT teams wanting to optimise their energy use. All this is a welcome evolution for organisations grappling with rising energy costs and that are carefully considering total cost of ownership (TCO) of their IT systems, and is an area of innovation to watch in the coming years.

In Australia, this kind of technical innovation is especially timely. In March 2024, the Australian Senate established the Select Committee on Adopting Artificial Intelligence to examine the opportunities and impacts of AI technologies4. Among its findings and expert submissions was a clear concern about the energy intensity of AI infrastructure. The committee concluded that the Australian Government legislate for increased regulatory clarity, greater energy efficiency standards, and increased investment in renewable energy solutions. For AI sustainability to succeed, it must be driven by policy to set actionable standards, which then fuel innovative solutions.

Infrastructure solutions like DLC will play a critical role in making this possible — not just in reducing emissions and addressing the energy consumption challenge, but also in supporting the long-term viability of AI development across sectors. We’re already seeing this approach succeed in the real world. For example, the Pawsey Supercomputing Centre in Western Australia has adopted DLC technology to support its demanding research workloads and, in doing so, has significantly reduced energy consumption while maintaining the high performance required for AI and scientific computing. It’s a powerful example of how AI data centres can scale sustainably — and telegraphs an actionable blueprint for others to follow.

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The message is clear: as AI becomes a bigger part of digital transformation projects, so too must the consideration for resource-efficient solutions grow. AI sustainability considerations must be factored into each stage of the AI life cycle, with solutions like DLC playing a part in in a multifaceted IT sustainability blueprint.

By working together with governments to set effective and actionable environmental frameworks and benchmarks, we can encourage the growth and evolution of the AI industry, spurring dynamic innovation in solutions and data centre design for the benefit of all.

1. AI is set to drive surging electricity demand from data centres while offering the potential to transform how the energy sector works – News – IEA
2. https://www.hpe.com/us/en/newsroom/blog-post/2024/08/liquid-cooling-a-cool-approach-for-ai.html
3. HPE introduces next-generation ProLiant servers engineered for advanced security, AI automation and greater performance
4. https://www.aph.gov.au/Parliamentary_Business/Committees/Senate/Adopting_Artificial_Intelligence_AI

Image credit: iStock.com/Dragon Claws

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