Cleaning the flue gas to stringent limits
The APC System
The Air Pollution Control (APC for short) system is the process that removes potentially harmful substances from the flue gas. For the plant at North Yard, MVV utilises a process called SNCR (selective non-catalytic reduction) together with the injection of dry sodium bicarbonate (also used as baking powder) and activated carbon, together with a fabric filter.
The residue of the APC, including the fly ash, is transported off-site in special sealed containers to the north of England under contract with a specialist contractor. APC residues are classified as hazardous because they are alkaline (like cement).
The emissions are reduced to below very stringent regulatory standards before being released to the atmosphere. MVV continuously monitors the majority of emissions from the facility. Other trace emissions must be monitored by sampling; this is carried out at regular intervals as required by the Environment Agency and with its agreement. The emissions data are logged and stored and reported to the Environment Agency. They are also available on a weekly basis on MVV’s website. [Link to emissions data archive]
The Environment Agency acts as an independent monitor of the plant’s outputs. If limits were breached, it has the power to shut down the plant and impose fines accordingly.