Carbon Footprint (Life Cycle)
Published: Jan 18, 2011
Updated: Jan 31, 2022
Author: C. Michael Hogan
Topic Editor: Sidney Draggan
Carbon footprint should really consider the full life cycle carbon costs of activities, (Product Life Cycle Accounting and Reporting Standard, 2019) including manufacturing and disposal carbon costs. For example, carbon dioxide emissions from manufacturing electric vehicle batteries is a huge contribution to carbon footprint (Weis et al, 2016)(Notter et al, 2010) ; correspondingly, disposal of electric vehicle batteries and solar panels is a major impact to footprint. Carbon footprint is the measure of the amount of greenhouse gases usually stated in units of carbon dioxide, produced by human activity. A carbon footprint can be measured for an individual or an organization and is typically given in tons of CO2-equivalent per year. For example, the average North American generates about 20 tons of CO2 each year. The global average carbon footprint for one individual is about 4 tons of CO2 per year.
Main Contributors to Carbon Footprint
Travel carbon cost is a principal contribution to carbon footprint, and electricity generation is a major source of carbon footprint. Hydroelectric, wind, and nuclear power produce the least CO2 per kilowatt-hour of other electricity sources; nuclear fusion power is particularly promising, since it produces very litter radioactive waste. Another sizeable component of individual carbon footprint is general maintenance of one's residence; there are considerable annual costs including labor and materials of repairs, landscape maintenance and remodeling. A component generally overlooked in individual contribution is the respired carbon from each person, which amounts to roughly one-half ton per person per year, based upon at rest breathing rates. (Berkow, 1997) Each person in North America consumes food each year that amounts to about six tons of carbon dioxide.
There are immense geographic variations in carbon footprint size. As one might expect, the USA, Europe and Australia have large per capita footprints. The more amazing statistic is that dense urban areas have a widely disproportionate impact compared to their suburban and rural counterparts. For example, not only does New York City have a huge per capita carbon footprint, but also Seoul, Johannesburg and Dhaka and many other dense cities in lesser developed countries. There are five Chinese cities and three U.S. cities in the top twenty.
Criticism of Carbon Footprint
The chief problem with carbon footprint is the narrow focus on greenhouse gases; moreover, some of the main issues with environmental protection should be more accurately focused on deforestation, species survival, water quality and air quality. There are also some technical issues with the way carbon footprint is commonly computed:
- Failure to include full life cycle carbon costs that include not only operational emissions, but also manufacturing, installing and decommissioning.
- Failure to include human respiration CO2 emissions
- Failure to compute electricity wheeling costs when carbon emissions are related to electric grid transmission
- Failure to address impacts of large sporting footprint activities such as golf and basketball
- Failure to differentiate electric vehicle emissions from lower carbon hybrid vehicles
Life Cycle Concept
For most simplistic carbon footprint calculators, the full life cycle greenhouse gas emissions are simply not considered. For some activities this will not cause a serious calculation error, but for some activities such as personal vehicle use, this is a major flaw. The best example is comparison of internal combustion vehicle, versus hybrid vehicle versus electric vehicle. There is also a major calculational outcome from state to state (or country to country). For example, in many USA states the hybrid or plug in hybrid vehicle has superior low carbon performance compared to fully electric vehicles (U.S. Dept of Energy, 2021); moreover, when total life cycle carbon costs are considered as well as wheeling costs of electricity transmission, every part of the USA shows superior low carbon performance for hybrid or plug in hybrid cars compared to electric vehicles.
An electric vehicle battery costs about 17 tons of carbon dioxide emissions in its manufacture. (Dai et al, 2019) Due to this high carbon cost of manufacture and difficulty of electric vehicle recycling, electric vehicles actually have a higher life cycle carbon emissions than a fuel efficient internal combustion vehicie. According to data from the U.S. Department of Energy, an electric vehicle would have to driven about nine years to break even with carbon dioxide emissions from a plug in hybrid vehicle, (U.S. Dept. of Energy, 2021) based upon the large carbon footprint of manufacturing an electric vehicle battery. (This break even point does not include the considerable carbon expense of mining the materials for the electric battery, shipping costs of battery materials and extreme difficulty of properly recycling a lithium ion battery)
Alternative Footprint Schemes
A number of alternative protocols have been advanced; the most important is a protocol that addresses a more true panoply of impacts on the environment, including impacts such a deforestation, habitat fragmentation and species extinction impacts as well as energy consumption. A possible better way to compute carbon footprint (and even better for total environmental footprint) is to begin with using income as a proxy; one would add outstanding credit card and other short term debt, and one would subtract all taxes paid and subtract charitable giving and savings. That would lead to a first order surrogate for consumption, while not having to ask such a plethora of questions for the survey.
- Kimberly Aguirre, Luke Eisenhardt, Christian Lim, Brittany Nelson, Alex Norring, Peter Slowik, Nancy Tu, Deepak Rajagopal (2012) Lifecycle Analysis Comparison of a Battery Electric Vehicle and a Conventional Gasoline Vehicle. Prepared for California Air Resources Board
- Qiang Dai, Jarod Kelly, Linda Gaines and Michael Wang (2019) Life Cycle Analysis of Lithium-Ion Batteries for Automotive Applications. Systems Assessment Group, Energy Systems Division, Argonne National Laboratory, DuPage County, Argonne, IL 60439, USA. Batteries 2019, 5(2), 48; https://doi.org/10.3390/batteries5020048
- Berkow, R., et al., 1997: The Merck Manual for Medical Information: Home Edition. Merck & Co, publishers, 1509 pp.
- Norwegian University of Science and Technology (2018) New Study Estimates the Carbon Footprints of 13,000 Cities. Lab Manager. LabX Media Group
- Product Life Cycle Accounting and Reporting Standard" (PDF). GHG Protocol. Archived (PDF) from the original on 25 February 2019. Retrieved 25 February 2019.
- Weis; Jaramillo; Michalek (2016). Consequential life cycle air emissions externalities for plug-in electric vehicles in the PJM interconnection. Environmental Research Letters. 11 (2): 024009. Bibcode:2016ERL....11b4009W. doi:10.1088/1748-9326/11/2/024009
- Notter, Dominic A.; Gauch, Marcel; Widmer, Rolf; Wäger, Patrick; Stamp, Anna; Zah, Rainer; Althaus, Hans-Jörg (2010). Contribution of Li-Ion Batteries to the Environmental Impact of Electric Vehicles. Environmental Science & Technology. 44 (17): 6550–6556. Bibcode:2010EnST...44.6550N. doi:10.1021/es903729a. ISSN 0013-936X. PMID 20695466
- U.S. Dept. of Energy (2021) Emissions from Hybrid and Plug in Electric Vehicles. USDOE Alternative Fuels Data Center
- Ben Webster (29 July 2019). Electric cars are a threat to clean air, claims Chris Boardman. The Times. Retrieved 3 August 2019.
The government's air quality expert group said this month that particles from tyres, brakes and road surfaces made up about two-thirds of all particulate matter from road transport and would continue to increase even as more cars were run on electric power.
C. Michael Hogan (2011, updated 2022) Carbon Footprint (Life Cycle) ed. S. Draggan. Encyclopedia of Earth. National Council for Science and Environment. Washington DC.