This briefing paper discusses the potential for introducing an efficiency based measurement to categorise advanced Energy from Waste (EfW) processes. Biomass, whether specially grown or originating from wastes, is a limited resource and it is important to maximise the value extracted from each tonne processed. In power generation, this means maximising the amount of power exported to the National Grid per tonne of biomass processed. Hence, DECC’s policy aims look to drive energy efficiency and value. However, measuring efficiency of an ACT on a consistent basis from plant to plant is challenging and complex. A one size fits all efficiency measure will not be straight forward to set up and will be complex and expensive to implement and manage.