Carbon Emissions

 

Energy use and CO2 emissions

The Mineral Products Association reported energy use in 2009 L0562 as:

Electricity 0.74 MWH
Natural gas 42 m m3
Gas oil 243 m litres
Non-transport diesel 4.1 m litres
Fuel oil 96.9 m litres
Recovered fuel oil 60.0 m litres

The total on-site carbon emissions for aggregates and aggregates products was given as 6.71kg CO2/tonne

The United Kingdom Minerals Forum set up a Working Group to examine carbon and proximity in the UK minerals industry as a whole L0560. The working group found there was a lack of good figures on carbon emissions for the minerals industry and therefore made some cautious estimates L0561 limited to emissions from the point of extraction to first customer and omitting the transport of non-aggregate components of value-added products (e.g. cement in ready mixed concrete). Table 1 provides estimates of extraction emissions and Table 2 sets out estimates of transport emissions.

Table 1: Estimates of extraction emissions for aggregates

Material	Excavated Volume (tonnes)	Operational CO2 emissions (tonnes, estimated)	Assumed non-product ratio to product or feedstock used to calculate total extraction	Assumed kg CO2 per tonne
Sand and gravel	157,143,000	628,572	21:1	4
Crushed rock	94,562,000	378,248	16:1	4
Total	251,705,000	1,006,820
Source: UKMF Working Group on Carbon and Proximity L0561 Assumptions: the average load of aggregates =21.3t, coasted stone = 18.4t and readymixed concrete = 6 cu.metres The average delivery distance for aggregates = 35km, coated stone = 28km and ready mixed concrete 8.3 km

Table 2: Estimates of transport emissions for aggregates from the site to the first point of use

Product	Aggregates - Road	Asphalt - Road	RMC - Road	Aggregates - Rail
Volume ( tonnes)	231,000,000	26,700,000	50,000,000	15,000,000
Average vehicle load (tonnes)	21.3	18.4	12	1726
Average delivery distance (km)	58.5	56	16.6	287.8
Vehicle km	634,436,620	81,260,870	69,166,667
Tonnes km				4,317,000,000
KgCO2 per vehicle km	0.969	0.969	0.969
KgCO2 per tonne km				0.021
KgCO2 Total	614,769,085	78,741,783	67,022,500	90,657,000
KgCO2 per tonne	2.66	2.95	1.34	6.04
Kg Carbon total	167,512,012	21,455,527	18,262,262	24,702,180
Tonnes Carbon	167,512	21,456	18,262	24,702
Tonnes CO2	614,769	78,742	67,023	90,657
Source: UKMF Working Group on Carbon and Proximity L0561 Assumptions and method: Volume is delivery volumes, to internal or external customers. Aggregates volume assumes 25% of aggregates stay on site (for value added processes). Av vehicle load (21.3 tonnes the QPA aggregates average) Average delivery distance includes delivery and return trips (based on Mineral Products Association returns, assumes some back-loading so overall delivery distance per load/tonne is reduced – 35 km delivery, 22.5km "return trip". Vehicle km - volume divided by average load and multiplied by average delivery distance Tonnes Km - volume multiplied by average delivery distance, for RAIL use only KgCO2 per vehicle km - Defra conversion factor for rigid HGVs above 17 tonne gross vehicle weight, with "average" loading KgCO2 per tonne km – Defra conversion factor for RAIL freight KgCO2 Total - vehicle km multiplied by Defra conversion factor KgCO2 per tonne - total KgCO2 divide by total volume Kg Carbon total - KgCO2 divided by 3.67 to convert CO2 to Carbon Tonnes Carbon - KG Carbon total divided by 1000 Aggregates = UK primary + recycling – 25% for aggregates staying on original site Asphalt = assume UK market 1 mil tonnes higher than 25.7 mt RMC = assume UK market is 1.5 m cu m higher than 23.5 m cu m

 

The total estimate from Table 1 is 1,006,820 tonnes and from Table 2 is 852,000 tonnes giving an overall total of 1,858,820 tonnes for the total extraction of 251,705,000 tonnes of mineral or an average of about 0.7 kg of CO2 per tonne extracted. Given the uncertainties, this is in reasonable agreement with the MPA estimate. However the Working Group noted that their result was likely to under-estimate the full "carbon footprint" of extraction, initial processing and transport. Further work remains to be done to validate the emissions of CO2 per tonne.

However, the estimates are probably of the right order of magnitude so it is reasonable to put these estimates into perspective against overall UK emissions arsing from economic and social activity in the UK. Defra estimates for 2006 were:

		Million tonnes CO2
	Energy generation	232
	Transport	130
	Industry	93
	Domestic energy use	76
	Commerce and the Public Sector	23

 

 

 

 

MPA estimates for 2009 suggested that operational emissions associated with aggregates contributed about 0.46% of UK total emissions or, when transport is added, about 0.62% L0562.

 

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