Simply put, carbon emissions generally occur as the result of energy consumption in one form or another. More specifically they emanate from the combustion of fossil fuels, though there are certain industries, like concrete production, that give off CO2 as a byproduct of different kinds of chemical reactions.
Figuring out the carbon emitted by various fuels is straightforward. The Energy Information Administration (EIA) created a chart that provides the number of pounds of CO2 emitted for a variety of common fuels.
So, for example, it tells us that a gallon of gasoline emits 19.6 pounds of carbon dioxide when burned. It doesn’t tell us that, based on each vehicle’s efficiency, the amount of carbon emitted per mile will vary. For example, a Prius will emit 0.39 pounds per mile, while something like a Jeep Grand Cherokee will emit 1.03 pounds per mile. Still, a company that owns a fleet of vehicles can simply add up the amount of fuel purchased, from which the carbon footprint can easily be computed. Diesel fuel emits 22.6 pounds of carbon per gallon. There are other considerations, such as where the gasoline came from, how the oil was extracted and refined and how far it was transported, but these are generally ignored since it would be extremely difficult to track.
Some companies may want to offset the carbon footprint of their supply chains. This could include shipping raw materials and value-add assemblies along the supply chain, or shipping finished products to retailers or directly to consumers. Other companies might offset the footprint of their employees as they commute to work or provide an opportunity for the employees to do so.
Electricity is also difficult to track for similar reasons: Most people today receive electricity from a variety of sources, which could include wind, solar, gas, coal, geothermal, hydro and nuclear. Most utilities will provide an estimate of the mix that they provide -- some in real time and others on a monthly-average basis.
Here are some of the carbon values for various fuels, which can help companies estimate their carbon impact and reduce their footprints. Values per million Btu are included (in parentheses) for comparison purposes.
Similarly, a company could provide offsets for employee travel. Jet fuel emits 21.1 pounds of CO2 per gallon, about midway between gasoline and diesel. A Boeing 747 burns approximately 1.2 gallons of fuel per second, during which time it covers approximately 5 miles. Of course, what an individual’s actual travel footprint will be depends on the type of aircraft flown and how full it was. Based on the numbers I just gave you, if the 747 had 100 passengers on board, it would emit 0.05 pounds per passenger mile -- about as much as eight Priuses or 2o Jeep Grand Cherokees. A Boeing 737 is far more efficient, burning through a gallon of fuel in 4.5 seconds.
Finally, there are servers, which are an increasingly substantial source of energy consumption to any company doing any kind of e-business, whether they do it directly or contract it out.
I checked a couple of different carbon footprint calculators online to see the footprint of a one-way trip from New York City to London. The total distance is 3,443 miles. ClimateCare, a U.K.-based company that offers carbon offsets and calculators, gave a total of 0.77 metric tons, which is equivalent to 1,698 pounds.
TerraPass gave the same answer, provided I selected the 'refractive forcing' option. Refractive forcing is the effect of emitting certain gases and particles at high altitudes, which directly impacts the greenhouse effect, otherwise known as radiative forcing. Without that option, the footprint is only 737 pounds. Clearly, ClimateCare used that option as the default.
I asked Jeremy Richardson, senior energy analyst at the Union of Concerned Scientists (UCS), about the equivalency of buying offsets versus investing directly in the energy efficiency of your own business. While he has no problems whatsoever with buying offsets, as long they are verifiable, he sees a number of advantages in doing what you can in your own facilities first.
For one thing, most investments in energy efficiency will continue to pay back, year after year. You get to see it actually being done, and in some cases experience intangible benefits like a more comfortable workspace. It also provides the opportunity to communicate your values to your customers and employees and perhaps inspire to carry the ball forward in their own worlds.
Image credit: Flickr/pagedooley
RP Siegel, PE, is an author, inventor and consultant. He has written for numerous publications ranging from Huffington Post to Mechanical Engineering. He and Roger Saillant co-wrote the successful eco-thriller Vapor Trails. RP, who is a regular contributor to Triple Pundit and Justmeans, sees it as his mission to help articulate and clarify the problems and challenges confronting our planet at this time, as well as the steadily emerging list of proposed solutions. His uniquely combined engineering and humanities background help to bring both global perspective and analytical detail to bear on the questions at hand.
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RP Siegel, author and inventor, shines a powerful light on numerous environmental and technological topics. His work has appeared in Triple Pundit, GreenBiz, Justmeans, CSRWire, Sustainable Brands, Grist, Strategy+Business, Mechanical Engineering, Design News, PolicyInnovations, Social Earth, Environmental Science, 3BL Media, ThomasNet, Huffington Post, Eniday, and engineering.com among others . He is the co-author, with Roger Saillant, of Vapor Trails, an adventure novel that shows climate change from a human perspective. RP is a professional engineer - a prolific inventor with 53 patents and President of Rain Mountain LLC a an independent product development group. RP was the winner of the 2015 Abu Dhabi Sustainability Week blogging competition. Contact: email@example.com