In the attached chart, I have plotted the total CO2 emissions of using the Volt as function of the CO2 intensity of the grid for charging it. The chart shows 3 scenarios: 90% or 70% or 50% of mileage is electric. For comparison reference, I have added conventional car (30 mpg) and Prius HV (Gen 3) total emissions. Total emissions for gasoline cars and for CS mode part of Volt drive includes gasoline production emissions (estimated 2540 g/gal) plus combustion emissions (8550 g/gal). Chart is based on EPA data. This post is dealing with CO2 emissions only, surely there are other aspects to consider, like other tailpipe pollutants, displacement of imported oil etc. Giora. (Sorry, but dont know how to embed the chart into the post)
I use GIF because the file size is nice and small, but JPG is also possible. Maybe PNG too ? When you have the graphic on the internet (PC or elsewhere), inline to text is as easy as putting the URL inside IMG tags. Alternatively you can click on the icon of a mountain when you are posting a message. A dialog box will query you for the URL and then insert it into your text at the cursor along with the IMG tags.
Thanks for posting. I can see the chart from PDF on my iPhone. GIF or PNG works great for charts. One suggestion, I think CO2 emission of g/mile would be more meaningful on a Distance vs. CO2 Gram chart.
So this ends up being an apples to oranges comparison. If you want to compare the electricity emissions from generation to the outlet, you have to consider the emissions of getting the oil to the gas station, otherwise this is a worthless graph...
^^ When you consider that Giora is ignoring the emissions involved in coal strip mining and then the half baked effort to put the countryside back together again, transport of petrol to the station hardly matters.
Sorry for not being absolutely clear. The CO2 emissions for producing gasoline (2540 g/gal) include getting it to the gas station, well-to-pump if you want...so apples to apples. As for Coal (and NG) upstream emissions, i.e. all emissions before firing in the power station - go ahead and add them when you estimate the CO2 intensity of electricity in your area. Giora. P.S. I have a nice chart of what is going on in Europe with regard to CO2 intensity of national grids. Oops once again I cannot upload it from my computer, so it is attached.
Just to add for the chart, the average for the US grid is 590 g/kwh. EPRI-NRDC Definitive Study: PHEVs Will Reduce Reduce Emissions If Broadly Adopted
I suppose this is generation emission only, not including upstream emission. 650 g/kWh is the estimate for US average grid emission including upstream emission.
The study that AG just posted is a joint venture of the EPRI, an electric utility lobby group, and NRDC, an environmental lobby group. From my prior readings EPRI spins, and NRDC has an agenda but is honest and knowledgeable. I'll get back after I have read the source article. I admit to starting off as a skeptical reader, in no small part because the headline news is at odds with the recent studies of the US national energy labs.
I didn't see your number mentioned in your post. They both fit in the ball park of the US grid, and I would not have commented if I had seen it. For you graph chart makers out there I would put a dashed line at 650 g/kWh and at the combined cycle gas figure (tesla's benchmark if we build new gas plants as we improve the grid). My number came from the 2010 EPA egrid. It uses 2007 actual estimated co2 from eia for all 50 states divided by total electricity consumed. It doesn't include mining but should include distribution to the plug. Other studies will get higher numbers by using older numbers or averaging differently. Some cut out California, Alaska, and Hawaii. You may want to weight the generation by where the cars will be sold which will give a lower number. 590 also is CO2 only and does not include the other green house gasses with CO2 equivalent. Looking at your graph and suspected volt usage, with either of our numbers the volt will produce slightly higher ghg than the prius. In many places the volt will produce less ghg, in many it will produce more. The difference is small enough that other considerations should be taken. If the fleet moves to cars like the prius and volt we will use less gasoline and produce less ghg. If you look at 2030 and likely trends cars like the phv prius, leaf, and volt should be producing significantly less ghg.
A vertical dashed line for US average mix is a good idea, I have hesitated and decided not to put it in, first because I wanted it to be "international", and second I did not want to start a debate of where exactly to put it drifting away from the main message. For these reasons I did not mention any number in my post. Giora.
