1. The current method of CO 2 accounting is to calculate the CO 2 emissions using the an emission factor for complete combustion of the fuel (CO 2 /J) and then apply the efficiency of combustion or electrical generation process EF = EF f *  This allows, for instance nuclear generating capacity to be computed as zero carbon electricity i.e. EF f = 0 A central question that should therefore be asked is whether the total CO 2 emissions associated with the delivery of the energy that provides the ultimate service (i.e. heat or electricity) should be assigned to its production EF = (EF f *  +EE f This would therefore include mining of uranium in Australia and subsequent transportation and could also include storage of radioactive waste after use. It could also include the mining of coal in Russia or South Africa and its subsequent transportation

2. Where the UK gets its Coal from - Imports

3. Where the UK gets its Coal from

4. A further complication arises with assigning emission factors to electricity consumption. This can be summarised as: The fuel mix used to generate electricity on the national grid varies with time. This variation occurs for the existing network at a minutely, daily and seasonal level In the future it is dependant on decarbonisation of the grid – what technologies and when The way the grid operates to maintain supply and demand balance is that fossil fuel plants are kept in a state of readiness to allow them to come on stream to meet load perturbations. This has an impact on CO 2 emissions If the energy saving technology that is being investigated increases perturbations on the grid then this may therefore result in both an increase a reduction in network scale CO 2 emissions. The saving in CO 2 emissions is therefore net not gross Unless the energy saving technology can be controlled in such a manner to prevent exacerbation of load perturbations There is an absence of certainty