Performing even a basic carbon footprint analysis can help businesses understand the impact of their processes in order to move towards sustainable strategies.
With dozens of carbon footprint calculators available online, individuals can quickly and easily assess their basic carbon footprint by entering a few simple numbers. Businesses, however, are typically forced to purchase software or hire an expert, even when they are small and even when only a simple process needs to be evaluated. The problem is that those who are just beginning to adopt environmentally sustainable practices do not typically have team mates who already know how to perform such an analysis manually.
An in-depth analysis is time-consuming and software is recommended for complex processes, but here are some guidelines for a basic analysis to get your business on the right track. Let’s begin by establishing that the carbon footprint of a product or process comprises only a small component of the ecological footprint, focused not on total impact, but on greenhouse gas (GHG) emissions exclusively. Carbon Dioxide (CO2) is a widely recognized greenhouse gas, but there are others that should be taken into consideration, particularly Methane (CH4), Nitrous Oxide (N2O) and perfluorocarbons. The three latter substances can be converted to equivalents of CO2, referred to as CO2e and to clarify why equivalent CO2 calculations are important, consider that over a 100 year period, Nitrous Oxide has 298 times more impact per unit weight than carbon dioxide. Buildings and transportation are primary sources of GHG emissions, but you can calculate product specific emissions as well.
Let’s look at transportation: Diesel produces 12 kg (26.4 lbs) CO2e/gallon, gasoline produces 10.5 kg (23.1 lbs) CO2e/gallon, propane produces 8.5 kg (18.7 lbs) CO2e/gallon and natural gas produces 1.5 kg (3.3 ibs) CO2e/meter3. If you would like to know how much of the total is derived from CO2, please refer to the following table:
The best way to get started is by creating a process flowchart. For example, if you are using intermodal transport to get supplies from A to B, you can chart each stop and calculate the mileage between stops. If you want to be exact, consider the fuel used by mobile cranes at Intermodal Container Transfer Facilities and if you are really dedicated, consider that those facilities also use fuel in operating their facilities (i.e. overhead). Next, you will need to know the fuel economy of your transportation mode. A fully loaded 80,000 lbs semi-truck uses diesel fuel at approximately 4-5 mpg. Rail moves a ton of freight at an average of about 400 mpg. If you load 45,000 lbs (22.5 ton) of freight on a train, you’ll end up with fuel economy of about 17.78 mpg. Now simply apply the emission factors noted above, in the case of rail and truck, those of diesel fuel.
Here’s an example: You have a semi-truck moving 45,000 lbs of freight over 2,000 miles with optimistic fuel economy of 5 mpg. You are calculating equivalent carbon dioxide. Let’s assume your 45,000 lbs consist of 17,000 individual products weighing 2.65 lbs each.
2,000 miles / 5 mpg = 400 gallons
26.4 (factor of CO2e for diesel per gallon) x 400 = 10,560 lbs of CO2e
10,560 lbs of CO2e / 17,000 = 0.62 lbs of CO2e per individual product
The following graph provides a general comparison of transportation modes and the results should come as no surprise:
If you are wondering why water transport shows higher emissions than rail, remember that these calculations include equivalents and the low-grade bunker fuel used in cargo ships emits significant amounts of nitrous oxide.
Let me reiterate that carbon footprint is only a small compononent in the assessment of overall environmental (and social) impact. Maritime transport offers an excellent example once more. Consider that each year, ocean-faring vessels from overseas discharge enough ballast water in US waters to fill 20,000 Olympic-sized swimming pools. This process introduces invasive species into local waters and causes concerns regarding reproduction of domestic fish and an increase in pathogens that may affect human health. Clearly, if you were to consider water transport, lifecycle assessment would provide a much more accurate picture than carbon footprint alone.
The same basic process we have just applied to transportation also applies to buildings and processes. If you are evaluating energy that is derived from a typical coal powered utility, you’ll need to know that 1 kg coal emits 2.93 kg CO2, and that the direct CO2 emissions from coal power are 1.47 kg/kWh, or about 0.407 kg/MJ. For natural gas, you can use the numbers mentioned above. Your utility bills can help you determine your monthly and annual emissions.
The point of this post is to provide you with a very basic overview of carbon footprint analysis, one that will yield more accurate calculations than those we have retrieved from various free online tools for businesses. It is certainly adequate for the assessment of straightforward processes. Feel free to contact me for additional information or to submit suggestions for improvement of this article.
