Once these high waste density areas are identified, a local WtE facility can be sized according to a reasonable catchment area. For a major town, the size of the facility can be about 60,000 tonnes per year, for a smaller town about 30,000.

If a county needs to divert 180,000 tonnes from landfill to WtE for example, the capacities of the multiple local plants can add up to meet the overall 180,000 target - in this case, say two 60,000 and two 30,000 tonnes per year facilities. Point is they can take waste from a local area, and no one town is lumbered with the whole county's waste problem.

An advantage of sizing WtE plant to meet local needs is that transport distances can be significantly reduced and the associated problems such as pollution and congestion can be reduced with it. It also saves money. The project identified that collection catchments of local plants can be as small as 12 kilometres radius for a 60,000 ton plant and 3 km radius for a 30,000 ton plant.

As well as the local waste arising, the size of any WtE plant should be dictated by a local demand for the heat, say by a factory, shopping mall or swimming pool. It is also often easier to use smaller plants to supply heat. This is the heat energy that is left over after electricity has been generated. Typically this is wasted to the atmosphere, but in an age of increasing concern about climate change, using the left over heat energy from a WtE plant could save us using gas, oil or coal - and provide an additional revenue.