Examples

Example 1 - Energy efficiency
Example 2 - Electricity generation

The following hypothetical examples demonstrate how emissions reductions can be estimated according to the DEFRA guidelines, both for an energy efficiency project and an electricity generation project.

Example 1 - Energy efficiency
A project has been proposed to the Carbon Trust which could radically increase the efficiency of a heating system. The proposed technology promises to make better use of the energy going into the heating system, allowing the system to operate with 20% less energy input whilst still providing the same service. Firstly, the emissions attributable to the heating system before the addition of the proposed technology must be calculated, this is known as a baseline:

Baseline calculation
The heating system requires an average of 500kWh of electricity per day to heat a factory to a required temperature, the CO2 emissions (tonnes) due to this heating requirement are:

CO2 emissions (tonnes) = Energy Consumption (kWh) x emission factor (kgCO2/kWh) x 0.001

CO2 emissions (tonnes) = 500 x 0.43 (this is the factor for electricity from the grid) x 0.001

CO2 baseline emissions = 0.22 tonnes CO2/day

With the addition of the new proposed technology, the heating system can provide the same average heat output for 20% less consumption of fuel, this requires a calculation for the proposed technology:

Proposed technology calculation
CO2 emissions (tonnes) = Energy Consumption (kWh) x emission factor (kgCO2/kWh) x 0.001

CO2 emissions (tonnes) = 400 x 0.43 x 0.001

CO2 emissions = 0.17 tonnes CO2/day

The emissions saving due to the technology is therefore the difference between the baseline and the proposed technology:

Emissions saving per day = 0.22 - 0.17 = 0.05 tonnes CO2saved per day.

This simple calculation allows the applicant to make further calculations which would give some indication of the possible emissions savings over the lifetime of the technology and the possible extent of the adoption of the technology throughout the UK. The applicant would be expected to comment on assumptions used in such calculations and would be expected to address all significant issues surrounding the calculation, these may include:

1. The utilisation rate of the technology (i.e. would it be working
   24 hours a day, 365 days a year or less)
2. Whether the efficiencies of the technology were dependent upon other factors (e.g. the ambient temperature, this may make the technology less efficient in the summer than the winter)
3. Whether there are additional emissions resulting from the new technology (e.g. does it need much greater servicing, resulting in greater transport related emissions)
4. Are there any disadvantages to the system which may make it undesirable or more desirable for the consumer (e.g. does the new technology require the heating system to take longer to warm up to operating temperature?)
5. An example of the further calculations which could be done to extrapolate the potential of the technology are shown below:

Further calculations
In this example the same heating system is used in 100 factories around the UK and the estimated lifetime of the heating systems is 10 years, in which case the total possible emissions reductions due to the technology would be given by:

Total theoretical emissions reductions (tonnes CO2) = Number of heating systems (100) x number of days of use (years x operating days (365 x utilisation rate)) x emissions reductions (0.05tonnes CO2/day).

The heating is used for 70% of the day and the utilisation rate is therefore 0.7.

Total theoretical emissions reductions (tonnes CO2) = 100 x (10 x (365 x 0.7)) x 0.05

Example 2 - Electricity generation 
A project has been proposed to the Carbon Trust which would generate electricity from a renewable source in a new and innovative way. The total emissions reduction in this case would be given by the emissions resulting from a counterfactual case (i.e. what could be expected to happen if the project did not go ahead). In this simplistic example it is assumed that the new renewable technology has no emissions (however, most renewable technologies have some emissions attributable to servicing, manufacture etc, which should be discussed by the applicant).

The counterfactual case in this example is simply use of electrical power from the grid, in this example the renewable technology has a unit generating capacity of 1000kW, 10 possible sites in the UK where it could be installed, and a lifetime of 10 years. The total theoretical emissions savings are therefore given by estimating the total possible electrical output of the technology multiplied by an emissions factor for the counter factual case (electricity from the grid):

In this case, the applicant would also be expected to comment on assumptions used in the calculations and any issues related to the technology which may mean additional emissions would result above those described by the simple calculation (e.g. from increases in transport or manufacture).

Power generation
CO2 emissions saving = total predicted electricity production from the renewable technology (kWh) x emission factor (kgCO2/kWh) x 0.001
 
Total predicted electricity production from renewable technology = 1000kW per unit x 10 units x number of hours of use (10 years x operating days (365 x utilisation rate (0.7) x 24).

Total predicted electricity generation from renewable technology = 613million kWh

Emissions saving (tonnes CO2) = renewable electricity generated (kWh) x emissions factor (kgCO2/kWh) x 0.001

Emissions saving (tonnes CO2) = 613million kWh x 0.43 (grid average) x 0.001

Total emissions saving = 0.3 million tonnes CO2