Energy from Waste (or EfW) is the generation of partly renewable electricity and/or usable heat from non-recyclable waste that would otherwise go to landfill in the UK, or to other countries as 'Refuse Derived Fuel'.
how does it work?
EfW facilities safely and effectively convert non-recyclable waste into clean, partly renewable baseload energy and useful by-products, while sustainably powering communities and protecting the environment.
Waste burns safely at very high temperatures.
High pressure steam -
Heat from the waste fire heats water in the boiler and creates high-pressure steam.
Electricity and heat production -
Superheated steam turns a turbine to generate electricity and some steam can be extracted for heating.
Metals and ash recover -
Ash and metal are recovered from the process to be recycled.
Air quality control -
Hot gases from the boiler are treated and filtered to meet strict air quality standards.
the energy from waste process
Click on a number to find out more about that stage of the process
1. Tipping hall
Waste is delivered to the facility in lorries. They enter the enclosed tipping hall and reverse up to the bunker edge. Air is sucked through the tipping hall and bunker and into the furnace so that odours do not escape.
2. Waste bunker
The waste is stored in the bunker waiting to be loaded into the furnace by crane. Around 10 days worth of waste can be stored here. Air is sucked through the tipping hall and bunker and used in the furnace so that odours do not escape.
The waste is burnt under very carefully controlled conditions to ensure safe and complete combustion, and maximise the amount of heat recovered as useful energy. The walls of the furnace are made up of pipes within which water is heated and turned into steam in the boiler drum.
4. Bottom ash
Those bits of the waste that don’t burn, eg metals and bricks, are part of the ash that falls off the furnace grate. This falls into water to cool it and is then put into a separate bunker before being taken away for recycling.
The very hot gases from the furnace are passed through the boiler. The steam from the boiler drum goes through tubes in the boiler to superheat it, ready to be sent to the turbine.
6. Air pollution control system
Having given up most of their energy to create useful heat in the form of steam, the flue gases have to be cleaned before they enter the chimney. The flue gases are injected with activated carbon and lime which react with pollutants such as acidic gases. The filters at the end of the system ensure that the residues, together with dust from the furnace, are captured so that the flue gas entering the chimney is well within the limits set by law. The system is controlled “real time”.
The chimney height will be calculated to ensure that the limited emissions allowed under law are dispersed safely.
8. Turbine hall
Superheated steam from the boiler is sent to the turbine where it is used to drive an alternator, generating useful electrical energy. Steam can also be taken from the turbine at pressures and temperatures suitable for use by local industry. This reduces their dependency on fossil fuels and improves the overall efficiency of the facility.
9. Air cooled condenser
The condenser takes the exhaust steam from the turbine. Very quiet fans send cool air up through the condenser tubes. Warm water goes back to the boiler, where it is used to make steam again.
10. Energy distribution
The energy in the waste has finally been turned into useful electricity and steam for use by local industry. Any excess electricity is sent to the grid locally, displacing fossil fuels. Steam will be sent to local industry through an above ground pipeline.
OVER 15 MILLION* TONNES OF NON RECYCLABLE
WASTE PER YEAR IS STILL GOING TO LANDFILL OR
BEING TRANSPORTED OVERSEAS
*source Tolvik Consulting, February 2019
why EfW over landfill?
In the UK now, there is over 15 million* tonnes of non-recyclable (or residual) waste per year that is still going to landfill or being shipped abroad for disposal. This is not sustainable, and we should be treating this waste as a resource.
Some of the non-recyclable waste from the east of England region is currently exported to continental Europe where it is used as fuel in Energy from Waste facilities. MVV look to bring their expertise to the area and create a new business for Wisbech to avoid transporting the waste overseas and to generate partly renewable energy for local businesses.
As an alternative to landfill, thermal treatment and efficient recovery of energy offers a number of advantages including environmental and financial benefits.
Landfill sites produce methane, which is 25 times worse than CO2 as a greenhouse gas and exporting waste requires it to be shredded, baled and transported far greater distances than treating it locally. Shredding, baling and transport all carry an additional carbon footprint, which can be avoided with a local solution.
*source Tolvik Consulting, February 2019