Carbon Footprinting: Scope 2

[This Tip continues a series of “Carbon Footprinting” tips that started in the January 2015 issue of Plastics Engineering.]

Scope 2 emissions are the emissions resulting from electricity use, and the size of these emissions depends on the method of generation. Nuclear, thermal, or hydroelectric generation results in low CO2e emissions (amount of equivalent CO2), whereas coal, gas, and other fossil fuels result in high CO2e emissions. The driver is the total number of kWh used in the year and the relevant emission factor for the supply. The best source of emission factors is direct from the supplier because this will reflect their specific generation profile (most suppliers should be able to supply this on request). If the supplier cannot supply the emission factor, then it is possible to use the country emission factor (see, for example, www.ukconversionfactorscarbonsmart.co.uk, instead of www.defra.gov.uk/publications mentioned in last month’s Tip). In the USA, the diversity of generation capacity means that a single value is not relevant for most of the country. It is possible to use the eGRID data produced by the EPA (cfpub.epa.gov/egridweb), but try to get supplier data before using eGRID.

Actions:

Quantify the electricity used in terms of kWh.
Use the emission factor for the supply to calculate the amount of CO2e.
Always use the emission factor for the consumption and not for generation.
If getting data from suppliers, then check that it is total CO2e data and not simply CO2 data.
Always use the latest emission factor to reflect changes in generation profiles with time.

Note: Dr. Robin Kent is the author of Energy Management in Plastics Processing, published by Plastics Information Direct, and managing director of Tangram Technology Ltd., consulting engineers specializing in energy management in plastics processing. rkent@tangram.co.uk.