In previous articles, I have written about an alternative source of energy that is increasingly being used to produce energy in the form of electricity, that is waste. According to the Confederation of European Waste-to-Energy Plants (CEWEP), the old European continent currently is using 50 million ton of wastes at waste-to-energy plants each year, generating enough electricity for 27 million people. In addition, European Union (EU) legislation is strongly supporting the development of WTE plants as a strategy to reduce waste at landfills and for environmental protection (2).
Isle de Man (UK) WTE Plant (4)
Isle de Man is a small island located within the British Island System. Although, officially is a stand alone country, the UK has direct intervention on its main issues. The island is a 600 square mile that has received consistently tons and tons of waste produced in the UK. Mandatory EU legislation lead in 2000 to the approval by its own Congress of the installation and operation of one of the most efficient WTE plants known on earth.
The Isle de Man WTE plant has two incineration lines. The primary one has a 60 thousand tons/year capacity (municipal and commercial waste). The second line is designed specifically for the incineration of animal waste, clinical waste, and waste oils with a total capacity of 5000 tons/year. The plants operates 24 hour a day, 365 days a year with two yearly planned shutdowns for maintenance.
Main Processing Areas
A large reception hall allows waste trucks to maneuver and tip waste into a waste bunker with a holding capacity of 16 days. This is essential to the plant strategy because the receiving operation can continue for 16 days even if the plant is shut down for any technical or maintenance issue.
Control Room Area
All the operation of the plant is centralized in a control room. All site operations (loading, burning, air injection, etc) are automatically monitored from this control room area. The control is real time and continuous. Combustion efficiency as well emission parameters (C02, particle, water) are carefully monitored.
Boiler and Electricity generation
The thermal energy released by burning waste is used to cover water into super-heated steam. At high pressure, this steam powers a turbine-alternator to generate electricity. The plant is able to generate about 5.5 MWh, of which 1.5 is used by the plant while the rest is exported to the MANx Electricity Authority (for resale). Ash (technically called Bottom ash) left on the incinerator is carried out to a Bottom ash bunker for storage. A magnet is used to extract ferrous metals for recycling. Finally the rest of the ask is trucked to a landfill for final disposition.
Air Pollution Control Residue
Gases generated are cleaned using a variety of selective catalysts, spray absorbers, and active carbon injection. This removes dioxins, heavy metals, oxides, etc. After this cleaning the gas is further passed through fine-fabric bag filters to remove solid particles before releasing them.
Interestingly, the plant is evolving in offering new services. One of such new services involve what they call “confidential secure destruction service” which helps companies comply with the secure disposal of commercially sensitive materials such as paper records, computer disks, or goods. Also of importance is the use of the secondary line for burning animal carcasses and clinical waste.
(1) How do Waste to Energy Plants Work?
(3) 2007 SITA UK Isle De Man Annual Public Report