Storing Renewable Energy in Wastewater

Source: State of Green

Use surplus energy from renewable sources, such as wind turbines, to energize wastewater and transform the waste matter to biogas, which can be stored and used when the electricity price is high.
Scientists from Aarhus University are pursuing an innovative way of integrating wastewaster treatment into the electrical grid, ultimately transforming wastewater treatment plants into storage facilities for surplus renewable energy.
The conventional method for wastewater treatment is an aeration process that is a high on energy consumption and CO2 emissions, because large turbines must be powered to pump the water through the biological treatment process, and the bacteria needed to break down the waste matters emit CO2.
A sustainable alternative to wastewater treatment
The new idea transforms the treatment process into an energy production- and storage process through electromagnetic purification based on electricity from surplus renewable energy:
“Specifically, we will use an electromagnetic cell as an alternative to aeration. When an electrical current is applied to the wastewater, it starts a chemical process that breaks down the contaminants to gasses", explains Thomas Jensen, Ph.D. student and part of team behind the concept. 
Using wastewater plants as energy buffers
The idea of applying an electrical current to contaminants is not new and has already been tested with good results. The innovative feature lies in connecting the water treatment plants with the electricity grid:
"If we connect the water treatment plants to the electricity grid, we can utilize the energy resources more efficiently. We can ensure that the electromagnetic treatment only takes place during the night when people are sleeping and the surplus energy available from wind turbines typically is high. The biogases that develop during the electromagnetic reaction can be stored and utilized as an alternative to fossil fuels", explains Thomas Jensen.