In the world of biosolids management, the production of beneficial by-products such as fertilizers and biogas help heed the call for recyclable waste and renewable energy. One of the core components of this process are anaerobic digesters (AD) which are integral in the processing of biosolids. It is the essential part in the process where biomass is treated with chemicals and mixed continuously in a vacuum chamber for a few days resulting in the production of biogas which can be used as household gas or to fuel cars.
But the process of transforming the biosolids from wastewater by treatment plants is predicated on its dependence for power to keep the anaerobic digesters running. In the event of a natural calamity or disaster, it would be critical to keep the operation of the AD going under any circumstances. One solution being considered is to give wastewater treatment plants a microgrid which will provide emergency power that can keep it running for a few days without external power from the main grid.
Microgrids are not a new concept however. They have been deployed by a few treatment plants for years but adoption to this technology has been slow. In California for example, microgrids are currently being used by less than 3% of the plants around the state. The reason why microgrids haven’t experience widespread acceptance is because of the high costs, long return on investments, limited technology experience, and lack of viable microgrid demonstration.
The California Energy Commission has decided to boost interest in the technology by funding a $5 million investment in Rialto Bioenergy to demonstrate the value of microgrids for wastewater treatment plants that use anaerobic digesters. This grant is part of a larger pool of about $50 million that the commission is distributing via a competitive application process to advance commercialization of microgrids. It is their hope that the other 156 facilities peppered around the state would see the benefits of using microgrids and reduce any apprehension they may have towards this technology.
Rialto Bioenergy, a project of the Canadian company Anaergia, hopes to demonstrate a clear, repeatable, standardized microgrid configuration that reduces costs for both wastewater treatment plants and organics management facilities.
The demonstration facility will be located on a 5.7-acre site in the city of Rialto, part of the San Bernardino County. They plan on refurbishing an old biosolids plant that has been defunct for several years. It is expected that the will produce around 13.38 MW of energy from up to 1,080 tons per day combination of food waste, liquid waste and municipal biosolids. It will produce about 3 MW of renewable electricity and 8.2 MW of equivalent biogas which will be distributed by Southern California Gas for use in offsite power generation and vehicle fuel.
The microgrid they will develop will include a 2-MWh battery storage system and a 2 MW combined heat and power (CHP) unit. The biogas produced from the sewage sludge will fuel the CHP operation.
In the event of a power outage, the microgrid and the plant it powers will be able to “island” from the central grid and operate independently for a minimum of 3 days. It can even run for much longer if it can use the biogas it produces if there be ample supply of biosolids. Another advantage to using microgrids is that it can make the facility more energy efficient during normal operations because it can minimise electrical draw.
So microgrids not only minimizes energy at the plants but also help bring power back to the main grid. It can also mitigate some of the power draw that plants may need when the grid is under strain. The result is a reduction of greenhouse gas emissions by about 20 percent.
It is expected that Rialto Bioenergy will begin full operations and waste conversion by 2019.
If you are a municipality in Ontario and in need of a biosolids management solution, please feel free to contact us at 1 (877) 479-1388.