SOURCES OF ENERGY

As described in Information Sheet 3 you can choose between energy based targets or carbon based targets. One of the advantages of carbon based targets is that it gives you additional flexibility. This is because different fuels have different carbon contents and by switching to one with a lower carbon content you will contribute towards a carbon based target without changing the energy intensity of your process.

For example, by simply substituting electrical heating with gas you would reduce carbon dioxide emissions by around 50% per unit of energy used. Similarly, conversion from heavy fuel oil to gas reduces carbon emissions by about 25% per unit of energy. Another example is replacing electrical power from the grid with electricity sourced from renewables. Renewable power could either be provided through the grid or via local generation. In this case using renewables would provide two benefits: a) a 100% reduction in carbon emissions in proportion to the amount of renewable energy used, and b) a reduction in the amount of Levy paid, again in proportion to the amount of renewable energy used.

Calculating CO₂ Emissions

When any fuel is burnt, energy is produced and carbon dioxide (CO₂) and other chemicals, mostly water, are produced. The ratio of energy to CO₂ produced differs according to the type of fuel used. Table 12.1 shows the carbon emission factor of different fuels, expressed as kg Carbon/kWh.

Table 12.1 Carbon Intensity of Different Fuels

It may be seen for example that the carbon emissions per unit of energy from burning natural gas are much less than those from the high carbon-content fuels such as coal and oil.

Electricity is generated from a range of fuels including nuclear, gas, oil and coal. The figure in for "grid" electricity in Table 12.1 reflects the current mix of fuel sources used in UK electricity generation. The carbon figure stated is per kWh of primary energy – for electricity primary energy is 2.6 times the delivered energy. Some power is generated from "new" renewable sources such as wind or landfill gas. New renewables have a zero CO₂ emission.

To calculate the carbon emissions associated with your energy use, simply multiply your primary energy use by fuel type by the appropriate factor from Table 12.1. If you measure your energy used by weight or volume rather than directly in energy terms, then you should first convert your fuel use to energy units using the conversion factors shown in Table 12.2.

Table 12.2 Fuel Conversion Factors

Fuel	Usual Units	Conversion Factor	Conversion Factor units
Natural gas	00 ft3	Depends on local conditions. See bill.
Electricity	kWh	1.00	kWh/kWh
Gas Oil	litres	10.6	kWh/litre
Light Fuel Oil	litres	11.2	kWh/litre
MediumFuel Oil	litres	11.3	kWh/litre
Heavy Fuel Oil	litres	11.4	kWh/litre
Propane	kg	13.89	kWh/kg
Butane	kg	13.69	kWh/kg
Dry steam coal	tonnes	8,500	kWh/tonne
Anthracite	tonnes	8,236	kWh/tonne
Coke	tonnes	7,750	kWh/tonne
Nitrogen	hcum		kWh/hcum
Carbon dioxide	hcum		kWh/hcum
Steam	kg	Depends on conditions. Check with supplier.
Hot water	kg	Depends on conditions. Check with supplier.
Condensate	kg	Depends on conditions.

To convert		Operation	Constant
From	To
ft3	m3	multiply by	0.02832
therms	kWh	multiply by	29.31
MJ	kWh	divide by	3.6

Renewable Energy

Energy derived from "new renewable" sources are defined, for the purposes of the Climate Change Levy and energy reporting to have zero carbon dioxide emissions. "New renewable" sources are listed below:

Renewable electricity is available from many electricity supply companies and can be bought in the same way as conventional electricity. Definitions regarding what is truly renewable are being developed, with a view to establishing a green accreditation scheme in time for the introduction of the Climate Change Levy in April 2001.