Construction work is about to start on a 5 MWe waste-to-power plant in Northwich, UK, that will employ an enzyme-based process developed by Dong Energy.
The new process is designated REnescience, and it has been under test at a demonstration plant in Copenhagen since 2009. The new plant, due to go into operation in 2017, will accept 120 000 tonne of unsorted household waste annually, producing combustible gas which will be burned in gas engines to generate power. As an advanced waste treatment plant the project will qualify for support under the Renewables Obligation. It was granted planning permission by Cheshire West and Chester council at the beginning of February.
Brent Cheshire, Dong Energy's UK chairman, commented: "The REnescience plant in Northwich will be able to receive unsorted household waste, which - through enzyme treatment - will be converted into biogas as well as recyclable plastics and metals."
In the REnescience process, unsorted MSW is wetted and heated up to temperatures appropriate for enzymatic hydrolysis. Through this enzymatic action, biodegradable materials are liquefied, which permits easy separation of the non-degradable solids. Processing is robust, with no requirement for shredding, which makes the process much simpler and results in a high biomass capture.
Liquefaction is key in the REnescience process. Enzymes are added into the waste stream in a specially designed reactor. Biodegradable content of unsorted waste is liquefied and separated, in a ballistic separation process , from the non-degradable solid content to create a pumpable bioliquid with high biomethane potential.