Further to @Prashanta nice analysis of comparison Prime to Volt with respect to CO2e emissions on a nationwide scale (i.e. using US average electricity mix) in this post I would like to take the subject one more step in creating a tool that can be used in any region. Attached is a spreadsheet for calculation and visual presentation of the comparison for any region, just type-in the carbon intensity of your regional grid (in gCO2e/kWh) to see results in your region. I have included Prius ECO to the comparison for reference. Values bolded can be user changed. All calculations are based on EPA scores of the cars. Emissions shown are 'total emissions' including up-stream emissions of the fuels. For gasoline 20% were added to the combustion emissions (per EPA). For power plants 8% were added to the combustion emissions. I have also added 7% for electricity transmission and distribution. The second attachment is a pdf snapshot for a region with clean electricity of 300 gCO2e/kWh (California?) as an example. Enjoy
Very cool! A couple suggestions for the excel page, already done in the PDF... Identify what year of grid data is being used, or a link to the EPA site (which should list the year). Round off the CO2 emission numbers for the Volt and Prime in the second table. Change the scale of the graph to 100 miles to make it more readable
Good formatting suggestions, I cannot make any changes for coming 3 days as my current computer has an older version of Excel. I have left the sheet intentionally unprotected so you can make the changes you think beneficial I left grid data to be used to the user to define and type in.
Giora, this is excellent. Is there a EPA site that allows one to quickly look up this information for one's state?
Thank you. I am sure there are databases but I am not aware of one. Maybe Americans can chime in with references. I am doing it indirectly with the EPA fueleconomy site>find a car home>compare side by side. I am choosing a BEV (any BEV) say 2017 Nissan Leaf. Choosing energy and environment tab and then in greenhouse gas emissions section I am choosing 'show: tailpipe and upstream GHG' and then 'calculate emissions'. Typing in zip code (example: 14611 Rochester NY) then I am here: Beyond Tailpipe Emissions: Results Estimating US average mix today to be 580-590 gCO2e/kWh I am calculating for the region, in this example: Rochester NY region is 258-262 grams. Hope it is clear.
I don't understand why the axis is gCO2e (grams of carbon dioxide equivalent). The equivalent is important for MPGe because of the way the EPA chose to normalize electric cars with traditional gas cars. But for electricity the carbon, as for gas consumed, the footprint is straight forward - CO2 produced per kWh generated. What does the 'equivalent' stand for?
It mostly comes into play when methane is released to the air as part of NG production. And if you are inclined to be picky, NOx emissions are GHGs CO2e is meant to say: GHG, in CO2 equivalents
To complete @EV-ish answer above. Some greenhouse gases have greater impacts on climate than others. Scientists have developed relative global warming potential numbers for each gas that gives its impact on global climate relative to that of carbon dioxide. We use the global warming potentials developed by the Intergovernmental Panel on Climate Change to combine the three gases into tons of carbon dioxide equivalent. We believe this gives the most complete and accurate reflection of the impact of each vehicle's energy use on the global climate. Numerous assumptions and calculations are necessary to estimate full fuel-cycle greenhouse gas emissions in carbon dioxide equivalents. So, estimates from different sources will vary. Our estimates are taken from the U.S. Department of Energy's GREET Model developed by Argonne National Laboratory. Frequently Asked Questions
