Global progress in sustainable technologies…
Converting Sewage into Green Energy
Global progress in sustainable technologies helped limit the increase in carbon dioxide emissions to under 1% in 2022. Still, emissions rose—and to meet global net-zero targets, greenhouse gas (GHG) emissions must fall by 45% by 2030.
Even with strong international commitments, the world is quickly approaching its remaining carbon budget—the threshold beyond which climate impacts become far more severe. Without swift, effective action to curb emissions, that budget could be exhausted within the next decade. Any successful mitigation strategy must therefore combine emission reductions with solutions that actively remove GHGs from the atmosphere.
According to the World Data Center, the energy sector accounts for roughly 73% of global GHG emissions, followed by agriculture and transportation. The water treatment sector directly contributes only about 1%, but water is essential across all industries—from high-purity water used in pharmaceutical production to cooling water in power plants. This makes improved water management a major opportunity to cut emissions.
Within the water sector, energy efficiency can be significantly enhanced by optimizing treatment processes, selecting the right treatment technologies, and ensuring that mechanical equipment operates efficiently. Moreover, anaerobic digestion can convert wastewater sludge into biogas that can be used to generate renewable heat or electricity, reducing dependence on external energy supplies and potentially enabling energy self-sufficiency.
Another challenge is nitrous oxide, a potent by-product of wastewater treatment. With a global warming potential 265 times higher than carbon dioxide, reducing nitrous oxide emissions through better treatment methods and operational practices is essential.
Technological advances across all sectors will continue to play a central role in emission reduction. Achieving meaningful progress requires a holistic approach that includes smarter water management and more effective use of existing treatment and distribution infrastructure.
If current trends persist, global emissions could reach 62 gigatons (GT) by 2030. The gap between projected emissions and the level needed to limit warming to 1.5°C would exceed 30 GT, according to the Intergovernmental Panel on Climate Change.
Converting Sewage into Green Energy
To combat climate change, cities and businesses are increasingly investing in technologies that modernize infrastructure, lower costs, and reduce emissions.
In southern France, the Montpellier metropolitan authority is upgrading the Maera wastewater treatment plant as part of the national Climate Air Energy strategy, designed to cut carbon emissions, expand renewable energy production, and safeguard water resources.
The modernization of Maera will expand treatment capacity from 470,000 to 695,000 population equivalent (PE) and incorporate a thermal sludge recovery system to generate renewable energy. By converting sludge into energy, the plant is expected to produce twice the amount of energy it consumes. Surplus energy will supply renewable gas to 9,000 local homes and provide heat to more than 7,500 households.
Remarkably, Maera’s capacity will increase by 10% in its first year without expanding the facility’s physical footprint. Upgrades include tertiary treatment for higher-quality discharge and low-energy-use technologies that enhance sustainability. By 2031, the plant is expected to cover 205% of its own energy demand, while reducing net CO₂ emissions by over 50%.
Sludge and organic waste can become valuable renewable resources when advanced technologies such as MemGas™ convert them into high-quality biogas.
MemGas™ uses membrane separation to purify raw biogas by separating methane from carbon dioxide, producing biomethane with more than 97% methane content. This renewable gas can then be injected into the local network for industrial or residential use. As part of the Maera upgrade, MemGas™ will deliver biomethane to the municipality with extremely low energy consumption and an efficiency of up to 99.5%.
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