To help us understand our carbon footprint we have broken down our greenhouse gas (GHG) emissions by source.
Our GHG emissions in 2009/10 were 574,912 tonnes carbon dioxide equivalent (tCO2e).
Direct emissions from burning fossil fuels have increased, due to the significant increase in the amount of natural gas we purchased, which is the equivalent of 2,189 tCO2e. This increase is due to the recommissioning of our sludge incinerator. This one site used over 12 gigawatt hours (GWh) of natural gas during the year, our largest use of gas on any site. We expect this usage to increase over the next year as the incinerator gets further use, depending on operational requirements.
Process emissions have increased due to the inclusion of emissions from the generation of renewable energy where we do not hold REGO certification. Process emissions from sludge processing and secondary treatment have decreased due to lower volumes of effluent received from industrial and commercial sources, probably as a result of the economic recession.
Transport emissions have increased slightly. The major reason for this is an increase in vehicle fleet size as a result of bringing various business activities under our control, such as wastewater pumping stations. This increase has been reduced to some degree by a new scheduling tool that improves route planning for our sludge tankers.
Grid electricity The amount of grid electricity that we purchase has increased by 6,710 megawatt hours (MWh) increasing our footprint by 3,627tCO2e. Most of this increase has come in our water business and can be attributed to additional pumping to maintain supply during the cold snap early in 2010 and to maintain reservoir levels in our Lake District supplies in early 2010.
Employee mileage Our emissions from employee mileage, public transport and air travel have increased slightly.
Sludge and process waste Emissions from disposal of sludge to land and grit and screenings to landfill have decreased as the amount of material has decreased.
Carbon intensity of our operations
Carbon intensity is a useful comparison measure used by the water industry and also our economic regulator Ofwat. This is calculated for wastewater by taking our total operational emissions associated with wastewater and sludge treatment and dividing this by the total volume of wastewater treated. The same method is repeated for our water operations.
Our emissions intensity figures based on the UUW carbon footprint boundary for 2009/2010 are:
- 888kg CO2e per million litres of wastewater received and treated
- 243kg CO2e per million litres of water treated and distributed
Our wastewater carbon intensity figure has increased by 7kg on last year’s data and our water figure has increased by 17kg, due to the increases in our carbon emissions explained above and accounting changes explained in the carbon footprint homepage.
The measurement of our carbon footprint is extremely important for us to be able to monitor and reduce our carbon emissions. This is an integral part of informing our carbon strategy.