Phase 1 of the Environmental Permitting Programme (2005-2008) created a single regulatory system to integrate Waste Management Licensing and Pollution Prevention and Control and create a simplified system. EPP 1 was introduced in 2007 as the Environmental Permitting (England and Wales) Regulations 2007, replacing individual 41 statutory instruments.

• vegetable waste from agriculture and forestry
• vegetable waste from the food processing industry (providing the heat generated is recovered)
• fibrous vegetable waste from pulp making (provided this happens on the site of waste generation and the heat generated is recovered)
• wood waste (with the exception of wood waste which has been treated with wood preservatives or coatings containing halogenated organic compounds or heavy metals)
• cork waste
• radioactive waste
• animal carcasses covered by the Animal By-Products Regulations

However the Environment Agency recently announced their position that they do not consider virgin timber as waste, and it is not subject to waste regulatory controls. This, however, only covers virgin timber, which is defined in their regulatory position statement. Timber that has been treated in any way, or used, is classed as non-virgin timber, and is not totally de-regulated in this way, though may still be exempt from WID if not treated with halogenated organic compounds or heavy metals.

In addition, experimental plants that are used for research, demonstration and testing, and also treat less than 50 tonnes of waste per year, are also excluded from the WID.

Even plants that are excluded from the WID by virtue of the fact that they only treat excluded wastes may still require a Pollution Prevention and Control (PPC) Permit, a Waste Management Licence or an Exemption.

Under very limited circumstances waste derived fuel (WDF) may cease to be waste before it is used as fuel if it has been subject to some form of processing, however this is subject to ruling by courts and is not expected to apply in many cases.

Thermal conversion of treated wood waste, as well as other industrial wastes and co-products, is most likely to be covered by the WID. In addition, material defined as 'hazardous waste' is subject to specific constraints under the WID. Timber from construction and demolition sites is also assumed to be covered by WID unless it can be shown to be otherwise.

The WID imposes requirements on the types of waste permitted at a given plant, delivery and reception of the waste, the thermal conversion equipment used and the operating conditions required, abatement plant, emissions monitoring requirements and emission limits values to air and water. Disposal of ash is not specifically covered by the WID, however other EU legislation is relevant, such as the Landfill Directive. Waste is defined as either non-hazardous under the WID (according to the European Waste Catalogue) or hazardous, and the technical requirements of the processing plant are different in each case.

The Clean Air Acts of 1956 and 1968 were a response to the smogs of the 1950s and 60s and allowed local authorities to define smoke control areas.  They were consolidated into the Clean Air Act of 1993.

Within smoke control areas authorised fuels, which include gas, electricity anthracite and specified manufactured smokeless fuels, may be used.  Any other fuels, including wood and pellets, may only be burned in an exempt appliance that has been specifically tested and approved under the Clean Air Act.

The Pollution Prevention and Control Regulations in England and Wales are intended to regulate the emission of pollution into the air, water or land, or other forms of pollution including odour, heat, noise and vibrations and also cover the prevention of accidents. Installations are divided up into different classes of industrial processes or activities and three separate, but linked systems of pollution control cover the different classes:

• Integrated Pollution Prevention and Control (IPPC) covers Part A(1) installations, regulated by the Environment Agency
• Local authority Integrated Pollution Prevention and Control (LA-IPPC) covers Part A(2) installations, regulated by local authorities
• Local authority Pollution Prevention and Control (LAPPC) covers Part B installations, also regulated by local authorities

Operation within these regulations is allowed by permits that set operating conditions, based on the use of 'Best Available Techniques' (BAT). Classification as Part A(1), A(2) or B depends on the activity undertaken and sometimes on production capacity.

Part A(1) activity includes burning any fuel in an appliance with a rated thermal input (or aggregated output from all appliances on a site) of 50 MW or more, and also the burning of waste oil, recovered oil or any fuel manufactured from, or comprising, any other waste in an appliance with a rated thermal input of more than 3 MW. It also includes gasification and pyrolysis of carbonaceous material except wood that has not been chemically treated.

Part A(2) does not cover combustion, gasification or pyrolysis activities.

Part B activity includes burning any fuel in an (individual) appliance with a rated thermal input of 20 MW or more, but not covered by Part A(1), and also the combustion of waste oil. recovered oil or solid fuel recovered from waste by an activity involving the application of heat, in an appliance with a thermal input less than 3MW. It also covers the burning of other fuels manufactured from or including waste in an appliance with a rated thermal input of less than 3 MW, but at least 0.4 MW. Part B activity regulations only regulate emissions to air.

If a plant on a site was burning biomass purely to destroy it, it would be regarded as an incinerator, which, if of 50 kg/hr to 1 tonne/hr capacity, would also come under Part B.

If any of these activities are to be undertaken the appropriate permits must be obtained from the relevant regulating authority.

PPC regulations may be in addition to the requirements of the Waste Incineration Directive (WID).