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FLEXO Magazine : March 2008
PLANTS & PROCESSES www.flexography.org MARCH 2008 FLEXO 57 raw materials through users and final dis- posal of printed products is complex, dif- ficult to find appropriate data, and beyond the control of the printer. CALCULATING A FOOTPRINT Calculating a facility's carbon footprint does not have to be as aggravating or time consuming as completing your income taxes. It can be broken down into four steps. Select sources of emissions to 1. include. Gather fuel usage data. 2. Look-up emission factors. 3. Make the calculations. 4. In calculating a basic carbon footprint, typically emissions of carbon dioxide are the focus. However, other gases contribute to global warming. The Intergovernmental Panel on Climate Change has published a table of the Global Warming Potential (GWP) of various gases. Some of these are included in Figure 3. To convert the Global Warming Potential (GWP) of one of these gases to CO2 equivalents, multiply the GWP factor by the amount of emissions. For example, if you have 2 metric tons of methane emissions, multiply 2 metric tons by the GWP of CH4 (310) to obtain 620 metric tons CO2 equivalent. Energy-use data during 2007 at the Illinois Waste Management and Research Center is used in this illustration. This facility has 45,000 gross square feet, of which about half is administrative offices and the rest is research laboratories. The building is heated by natural gas-fired boilers and is on the public power grid. A breakdown of the sources of electricity for this facility is shown in Figure 4. Carbon emissions from coal generated electricity are quite different from nuclear or hydro, for example. The mix of sources of electrical power varies widely from re- gion to region across the U.S., as do the resulting carbon emissions per 1,000 kilo- watt-hours. It is best to use emission fac- tors for the power used in your area. In this case, average emission factors from known sources were supplied by the Illinois Waste Management and Research Center's power company in an insert in a recent bill. These factors are shown in Figure 5. The first step is to determine which emissions to include in the calculations. In this example, emissions from our natural gas-fired boilers, emissions from company vehicles and emissions from generat- ing electricity are included. The first two sources are direct emissions from our activities. Electricity generation emissions are indirect because we use the electric- ity but we do not consume fuel to make the electricity. The power company does that through a variety of means including coal-and natural gas, nuclear and others as shown in Figure 4. Each source of electric- ity has a different carbon emission rate. So the emission factor for electricity should be specific to each area. Fortunately, most utilities can provide average emissions data for their customers. Carbon emissions can be either mea- sured directly or calculated. Only very large facilities are likely to have direct measurements. The majority of facilities use emission factors for various operations such as gas-fired boilers. Indirect carbon emissions are those produced by others. Typically this is the electricity used for lights, presses, and computers. The general equations for this calculation are: Annual electricity usage x electric emis- sions factor = carbon emissions In the case of the Waste Management facility, in 2007 it used 1,594,500 kWhs of electricity. Using the emission factor for carbon dioxide in Figure 5, of 1,770 pounds per 1,000 kilowatt hours the calcu- lation is as flows. (1,594,500 kWhr) x (1.77 lbs CO2 / kWhr) / (2,000 lbs / ton) = 1,411 tons / yr Direct carbon emissions from a facility are from the use of, for example, natural gas in the boilers. For this calculation the basic equation is: Annual natural gas usage x natural gas emissions factor = carbon emissions In the case of our facility, in 2007 the Waste Management facility used 96,850 therms of natural gas. A therm is equiva- lent to 100,000 btus. The Climate Registry draft protocol provides an extensive table Biomass power 0% Coal-fired power 68% Hydro power 1% Natural gas-fired power 18% Nuclear power 1% Oil-fired power 3% Solar power 0% Wind power 0% Other resources 0% Unknown resources purchased from other companies 9% Total: 100% FIGURE 4. SOURCES OF ELECTRICITY SUPPLIED FOR ILLINOIS WASTE MANAGEMENT AND RESEARCH CENTER DURING THE 12 MONTHS ENDING SEPT. 30, 2007. Greenhouse Gases 100-Year GWPs Carbon Dioxide (CO2) 1 Methane (CH4)2 1 Nitrous Oxide (N2O) 310 Sulphur Hexafluoride (SF6) 23,900 HFCs Range from 12 to 11,700 PFCs Range from 6,500 to 9,200 FIGURE 3. THE GLOBAL WARMING POTENTIAL OF VARIOUS GASES. Carbon Dioxide 1,770lbs Nitrogen Oxides 2.96lbs Sulfur Dioxide 7.43lbs High-level Nuclear Waste <.0001lbs Low-level Nuclear Waste <.0001ft3 FIGURE 5. AVERAGE AMOUNTS OF EMISSIONS AND AMOUNT OF NUCLEAR WASTE PER 1,000 KILOWATT-HOURS PRODUCED FROM KNOWN SOURCES BY THE ILLINOIS WASTE MANAGEMENT AND RESEARCH CENTER FOR THE 12 MONTHS ENDING SEPT. 30, 2007.