Energy facility: The process

The operation of the plant consists of five main elements:

Kingswood Energy Facility - Process Diagram

The Process (Click to enlarge in a new tab/window)

Waste reception

Pre-treated waste with recyclable materials removed is delivered to the enclosed reception hall within the building. This area is operated under negative air pressure, preventing the escape of dust and odours.

Waste is transferred into a combustion chamber via a feed chute and airlock section.


Combustion is in two stages. Primary combustion is on a moving mechanical grate to help the mixing of burning and unburnt waste. This proven technology is successfully used across the world.

The combustion gasses from the primary stage are then heated further in a secondary chamber to a minimum of 850 degrees Centigrade for at least two seconds. This complies with the requirements of the Waste Incineration Directive and ensures the destruction of harmful particulates.

The burnt waste from the primary combustion is called ‘bottom ash’. This non-hazardous material amounts to approximately 25% of the input waste. It’s recycled as aggregates for the construction industry. Ferrous metals recovered from this ash are recycled.

Energy generation

Heat produced from the combustion process is fed into heat recovery boilers where it forms high-pressure steam to drive an electricity generation turbine, as with other power stations.

A small proportion of the electricity generated is used to power the facility. The majority (around 34 megawatts) is exported to the National Grid.

Since there are still large parts of the Kingswood industrial park which have not yet been developed, there is also the potential to supply heat and power to future development.

Emmission treatment

Emissions from the plant will be regulated by the Environment Agency. It will comply with the robust demands of the Waste Incineration Directive – legislation in place to protect the environment and public health.

Energy recovery technology has improved significantly over recent years and modern facilities not only meet these exacting standards but also consistently achieve much lower emission limits.

The greatest emissions would be carbon dioxide and water.

Information issued last year by the Health Protection Agency states that, ‘Incinerators that are well run and regulated do not pose a significant threat to public health’ and that potential damage to health is ‘likely to be so small that it would be undetectable’.

According to DEFRA, “Concern over health effects is most frequently cited in connection with incinerators. Research carried out to date shows no credible evidence of adverse health outcomes for those living near incinerators”. (Waste Strategy 2007)

Residue handling

Two types of residue will be collected in the flue gas treatment process. The first is fly ash and this will be taken off site for disposal.

The second is APC residue. This is collected separately to fly ash and will be suitable for use in the chemical treatment industry.

The combined quantities of these treatment residues would be in the region of 5% of the annual waste throughput (by weight).