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FLEXO Magazine : September 2011
remaining 16 percent comes from other energy sources, such as hydropower, biomass, nuclear, wind and solar energy. Energy-related activities from fossil fuel combustion, ac- count for the vast majority of CO2 emissions worldwide. In the United States, electricity generation presents 40 percent of total CO2 emissions. Reducing Scope 2 emissions has the greatest potential to impact total CO2 emissions. CH4 and N2O account for a much smaller portion of emis- sions from electricity generation. In fact, some reporting pro- grams consider CH4 and N2O insignificant and do not require that they are included in the calculation, thereby simplifying formulas presented in this article. If they are not included, be sure to make note of it for future comparisons. To begin to calculate Scope 2 emissions, a facility must know the amount of electricity it uses. Electricity use is typically reported on a facility 's monthly utility bill in kilowatt- hours (kWh). To determine the total carbon emissions from Scope 2, including the emissions of CO2 and the CO2 equiva- lent (CO2e) from CH4 and N2O, it is necessary to know how much of each gas is generated from the production of one kilowatt-hour of electricity by your specific utility. Across the world these numbers will vary as utilities generate power using different types of fossil fuels and cleaner energy sources. Of the most common fossil fuels used, coal combus- tion results in greater amounts of CO2 emissions per unit of electricity generated, while oil produces less and natural gas produces the least. METRIC CONVERSIONS The U.S. Environmental Protection Agency (U.S. EPA) posts regional conversion factors for each of the three GHGs be- ing emitted by utilities. The agency's eGrid emission factors are derived from the mix of electricity fuel sources used in a particular region and are available online. These factors are then included in the calculation of total carbon emission (CO2 and CO2e) in metric tons. Although many companies use eGRID emission factors, they are expressed regionally and the most recent reports available online are three years old. More accurate infor- mation may be available from the local utility and may be indicated right on the utility bill. Also, be aware that eGRID reports output of CO2 in lbs/ MWh and output of CH4 and N2O in lbs/GWh (1 GWh = 1,000 MWh = 1,000,000 kWh). All emis- sion factors must be converted to lbs/kWh in these equations. To calculate total carbon emissions, all GHGs must be ex- pressed as CO2 (or CO2e) using the emission factors provided by the utility or eGrid for CO2, CH4 and N2O and the global warming potential (GWP) for each of them as follows: Usage (kWh) × CO2 emission factor (lbs CO2/kWh) / 2204.62 lbs/metric ton + (Usage (kWh) × CH4 emission factor (lbs CH4/kWh) / 2204.62 lbs/metric ton) × 21 GWP + (Usage (kWh) 54 FLEXO SEPTEMBER 2011 www.flexography.org SYS TEC NORTH AMERICA, LLC. 108 State Street Suite 103 - Greensboro NC 27408 Phone 336-272-5225 - email@example.com www.systecamerica.com INNOVATIVE FLEXO MOUNTING SOLUTIONS WITH VIRTUAL IMAGE SYSTEM