15 steps from waste to energy - start the journey here
It all starts at home, school or in the workplace. That’s where the waste that arrives at the Beddington ERF is created. The next time you have something that you no longer want or need, please stop and think! Before you throw it in the rubbish bin, could you reuse or recycle it? By reducing waste and putting the right stuff in the right bin, we can make sure that only non-recyclable rubbish ends up at the Beddington ERF.Back to TopGo to Next Step
Every week, recycling and rubbish is collected from homes and businesses across Croydon, Kingston, Merton and Sutton. Everything that has been sorted for recycling is sent to specialist processing facilities. Food waste is turned into energy at an anaerobic digestion plant. Anything that has not been sorted for recycling (in other words 'rubbish') is delivered to the Beddington ERF and transformed into energy.Back to TopGo to Next Step
Vehicles carrying the rubbish arrive at Beddington ERF. First they are weighed, they then continue to the tipping hall where they reverse up to the bunker to tip their loads. The huge waste bunker can store around a week’s worth of deliveries.
The waste is mixed and managed in the bunker by two large grab cranes. These cranes are operated by people in the Control Room, which has a large window overlooking the waste bunker. The waste is now ready to be used as a fuel to generate electricity and heat.Back to TopGo to Next Step
The two grab cranes lift the waste into large hoppers. Hydraulic rams push the waste into one of two combustion chambers. This is where the waste is burnt at very high temperatures under controlled conditions. The ERF’s operations system works in compliance with the Industrial Emissions Directive, this ensures temperatures of the gases in the combustion chamber remain at a minimum of 850°C for at least two seconds – this ensures complete combustion takes place.
Air which is sucked in from the tipping hall, is injected into the furnaces through holes under the furnace grates. This provides the oxygen needed for combustion (burning) to take place. It also creates a negative pressure in the tipping hall drawing air from the bunker into the process.Back to TopGo to Next Step
The fire in the furnace, which burns for >850°C for at least 2 seconds to ensure complete combustion, produces hot combustion gases, which are fed through to the boiler. Water flows through pipes around the boiler in the opposite direction to the hot gases. A heat exchange takes place, turning the water into steam. The steam is then superheated to 400°C and 60 bar pressure. Finally, it is released to drive the turbine.Back to TopGo to Next Step
The superheated steam produced in the boiler is released to drive a turbine. The turbine is a key piece of equipment in the ERF as it converts the heat energy (steam) into mechanical (kinetic) energy. How does it do this? It’s actually very simple. The turbine has fan blades mounted on a rotor. The high-pressure steam turns the blades, and thus the rotor.
This rotary motion (kinetic energy) is used to run a generator which generates electricity. It’s a very similar process to the one used by traditional coal power stations. The big difference is that waste is the fuel used at the start of the process, not coal.Back to TopGo to Next Step
The electricity produced by the generator is exported to the National Grid to supply homes, schools, shops, businesses and industry across the country. The Beddington ERF produces enough to power the facility itself plus around 60,000 homes.
Steam produced during the process can be used in a heat network to provide heating and hot water to local homes and businesses via highly insulated pipes. When heat is used in this way it means that the ERF can be called a Combined Heat and Power (CHP) facility.Back to TopGo to Next Step
After going through the turbine, the steam which has been produced by heating up the water, is condensed back to water by the air cooled condenser. The water can then be re-circulated through the process again and again.Back to TopGo to Next Step
As the waste is burnt in the furnace, gases are formed which need to be treated before they can be released into the atmosphere. Urea, hydrated lime and activated carbon are added to remove nitrous oxides, acid gases and adsorb heavy metals, dioxins, furans and volatile organic compounds in the energy recovery process. The gases are treated and tested continuously. Screens in the control room report back live data and allow operators to ensure the right amount of cleaning is undertaken at all times.Back to TopGo to Next Step
A fan draws the gases through bag filters which are coated with lime and activated carbon. This removes particles and creates a by-product called air pollution control residue (APCr).Back to TopGo to Next Step
Once the gases have been cleaned and filtered, they are ready to be released, along with steam, into the atmosphere via the flue stack (chimney).
The Beddington ERF operates according to an Environmental Permit that is issued by the Environment Agency. The permit sets strict limits on the emissions (gases) that are released into the atmosphere by the ERF. This means the Beddington ERF must comply with all the necessary regulations protecting both health and the environment.
Emissions are monitored every 10 seconds and converted into 10 minute, half-hourly and daily averages. Monitoring data from the Beddington ERF is published twice every month. For more information, see the Emissions Data section of this website. See our emissions monitoringBack to TopGo to Next Step
The Air Pollution Control Residue (APCr) captured by the bag filters (see step 10 - ‘Filter it’) is stored in a silo before being collected under controlled conditions by specialist vehicles.
APCr is taken to a licensed facility where it is further treated and can be used in the construction industry.Back to TopGo to Next Step
The ash which is left after the waste has been burnt (about 23% of the total) is called Incinerator Bottom Ash (IBA). It contains anything which did not burn at around 850°C – this includes metals, concrete and glass. The IBA drops off the furnace grate onto a conveyor belt below. It is stored in a bunker and then collected and taken to a licensed facility for processing.Back to TopGo to Next Step
At an off-site licensed facility, magnets are used to separate out the ferrous metals from the Incinerator Bottom Ash (IBA). These metals are sent for recycling. Non-ferrous metals are also separated out and recycled.Back to TopGo to Next Step
Once the metals have been separated out from the Incinerator Bottom Ash, anything that’s left is crushed, screened for quality and treated to create an aggregate for road building and other construction products.Back to TopGo to Next Step