Renewable Energy Opportunities for Wastewater Treatment Plants: A Case Study of Melbourne Water
Wastewater treatment plants (WWTPs) are critical in protecting public health and the environment by treating and managing sewage and other forms of wastewater. However, the operation of these facilities requires significant amounts of energy, typically derived from fossil fuels. Read how Melbourne Water’s WWTPs are leading the way towards net-zero emissions.
Several renewable energy options can be implemented at WWTPs, including solar, wind, hydro, and biogas. Depending on site-specific conditions, energy needs, and financial resources, these technologies can be deployed individually or in combination. The main renewable energy opportunities for WWTPs include:
- Solar photovoltaic (PV) systems: Solar PV systems generate electricity from sunlight and can be installed on rooftops, carports, or ground-mounted arrays. WWTPs are ideal candidates for solar PV systems, as they typically have large open spaces, high electricity demand, and long operating hours. Solar PV systems can also help to offset peak demand charges and reduce greenhouse gas emissions.
- Solar thermal: Solar thermal systems use solar energy to heat water, which can then be used for space heating, hot water, or industrial processes. WWTPs can utilize solar thermal for heating digester tanks, sludge drying beds, or other thermal loads.
- Wind: Wind turbines can generate electricity by harnessing the kinetic energy of the wind. However, WWTPs are generally unsuitable for wind energy due to their urban or suburban location and low wind speeds.
- Hydro: Hydropower can generate electricity by using the energy of flowing water. WWTPs near rivers, streams, or other water bodies can harness hydropower to supplement their electricity needs.
- Biogas: Biogas is a renewable fuel that can be generated by digesting organic waste, such as sewage sludge or food waste. WWTPs that operate anaerobic digesters can capture the biogas produced and use it for heat, power, or transportation.
Melbourne Water’s Biogas Renewable Energy Initiatives
The Victorian water sector is making significant strides towards achieving its renewable energy goals, and biogas plays a key role in this transition. Melbourne Water has set its sights on net-zero emissions by 2030, and biogas is critical to this strategy. At the Western and Eastern Treatment Plants, biogas — a by-product of sewage treatment — is captured and converted into renewable energy, reducing greenhouse gas emissions and reliance on non-renewable power sources.
Biogas is captured in anaerobic digesters and from covered anaerobic treatment lagoons at the Western Treatment Plant. This biogas, primarily made up of methane and carbon dioxide, is transferred to on-site power stations where it is combusted, generating around 70,000 megawatt hours (MWh) of electricity annually. This equates to meeting about 80% of the plant’s electricity needs, powering around 7,000 households. On occasions when the plant produces more energy than it consumes, the excess is exported to the electricity grid to support other Melbourne Water sites.
Melbourne Water has recently completed the construction of a second power station at the Western Treatment Plant, Power Station B, which is expected to produce over 100% of the site’s electricity needs on average once commissioned. This new facility will enable even greater capture and conversion of biogas into clean energy, with peak methane production occurring during summer.
Meanwhile, the Eastern Treatment Plant generates about 30% of its electricity from biogas, using seven power generators that can operate entirely on biogas, supplemented with natural gas as needed. Together, these efforts contribute significantly to Melbourne Water’s renewable energy initiatives, turning waste into a valuable resource and moving closer to a net-zero emissions future.
The Take-Out
WWTPs can utilize various renewable energy options to reduce operational costs, increase resilience, and promote sustainability.
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