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INFORMATION SHEET 12

SOURCES OF ENERGY

As described in Information Sheet 3 you can choose between energy basedtargets or CO2based targets. One of the advantages of CO2 based targetsis that it gives you additional flexibility. This is because different fuels havedifferent carbon contents and by switching to one with a lower carboncontent you will contribute towards a CO2 based target without changing theenergy intensity of your process.

For example, by simply substituting electrical heating with gas you wouldreduce carbon dioxide emissions by around 50% per unit of energy used.Similarly, conversion from heavy fuel oil to gas reduces CO2emissions by

about 25% per unit of energy. Another example is replacing electricalpower from the grid with electricity sourced from renewables. Renewablepower could either be provided through the grid or via local generation. Inthis case using renewables would provide two benefits: a) a 100% reductionin CO2 emissions in proportion to the amount of renewable energy used,and b) a reduction in the amount of Levy paid, again in proportion to theamount of renewable energy used.

Calculating CO2Emissions

When any fuel is burnt, energy is produced and carbon dioxide (CO 2) andother chemicals, mostly water, are produced. The ratio of energy produced

to CO2 differs according to the type of fuel used. Table 5.1 shows thecarbon emission factor of different fuels, expressed as kg Carbon/kWh.

Table 5.1 Carbon Intensity of Different Fuels

Type of fuel kgC/kWh primary

Electricity (from grid) 0.0453

Natural Gas 0.0518

Gas Oil / Diesel Oil 0.0680

Heavy Fuel Oil 0.0709

Coal 0.0817

Liquid Petroleum Gas 0.0627

New Renewables 0

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

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Electricity is generated from a range of fuels including nuclear, gas, oil and coal. The figurefor grid electricity in Table 5.1 reflects the current mix of fuel sources used in UK electricitygeneration. 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 renewablesources such as wind or landfill gas. New renewables have a zero CO2emission.

To calculate the carbon dioxide emissions associated with your energy use, simply multiplyyour primary energy use by fuel type by the appropriate factor from Table 5.1. If youmeasure your energy used by weight or volume rather than directly in energy terms, thenyou should first convert your fuel use to energy units using the conversion factors shown inTable 5.2.

Table 5.2 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

Medium Fuel 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.

The following table of unit conversions may be useful.

To convert Operation Constant

From To

ft3 m3 multiply by 0.02832

therms kWh multiply by 29.31

MJ kWh divide by 3.6

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Example: Lovely Lollies Ltd annually uses 1 million litres of heavy fuel oil in its boiler

house. What are the annual carbon emissions associated with this oil use? By howmuch would the emissions be reduced by converting the boiler house to natural gasfiring?

Step 1. Refer to Table 5.2. The calorific value of heavy fuel oil is 11.4 kWh/litre.Therefore the energy used in Lovely Lollies boiler house is given by:

1,000,000 litres x 11.4 kWh/litre = 11,400,000 kWh.

Step 2. Table 5.1 shows that 0.0709 kg of carbon are emitted per kWh of energyderived from heavy fuel oil. The annual carbon emissions associated with this energyuse is:

11,400,000 kWh x 0.0709 kg/kWh = 808,260 kg of carbon.

Step 3. Refer again to Table 5.1. The carbon emissions per kWh of energy fromnatural gas burning are 0.0518 kg/kWh. Hence if the same amount of energy were tobe derived from natural gas rather than heavy fuel oil, the carbon emissions would be:

11,400,000 kWh x 0.0518 kg/kWh = 590,520 kg of carbon.

Step 4. The emissions saving is (808 590) or 218 tonnes. This is 26.9% of currentemissions from combustion of boiler fuel.

Note that this calculation assumes unchanged combustion efficiency, which might notbe the case in practice.

Renewable Energy

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

Wind Energy Geothermal hot dry rocks

Hydro power up to 10 MW Geothermal aquifers

Tidal power Municipal and industrial wastes

Wave energy Landfill gas

Photovoltaics Agricultural and forestry wastes

Photoconversion Energy crops

Renewable electricity is available from many electricity supply companies and can be bought

in the same way as conventional electricity.