As I thought about the launch of the Chevy Volt, a plug-in hybrid electric vehicle expected to be in full production at the end of 2010, I wanted to analyze the advantages or disadvantages of owning such a vehicle in the state of Kansas. The Volt will run up to 40 miles on a single charge of the on-board battery system. Anything beyond 40 miles will automatically start the gasoline generator capable of running the vehicle at 50 MPG. The following analysis considers the MPG rating, the cost to operate the Volt, and the CO2 emissions compared to the leading hybrid engine vehicle.
I. MPG Rating
Miles Per Gallon (MPG): The average number of miles a vehicle travels on one gallon of fuel (gasoline).
2010 Ford Fusion Hybrid: 39 mpg
2010 Honda Civic Hybrid: 42 mpg
2010 Toyota Prius: 50 mpg
2011 Chevrolet Volt: 230 mpg (General Motors’ own estimation)
An Edmunds: InsideLine Magazine article titled, “‘Start Over’ on MPG Rating System,” states directly what the online car magazine thinks should be done with the Environmental Protection Agency rating system. Edmunds’ CEO challenges the U.S. Government to reconsider what he calls the “misleading” MPG rating. In fact, according to the article, “The advantage of EVs over traditionally fueled vehicles is “nowhere near as great as the proposed EPA ratings would imply.” For example, the 2009 Mini E, an all-electric vehicle, is rated by the EPA at 99 mpge (equivalent), and Edmunds estimates it costs $49.39 per month to operate. The Chevrolet Volt plug-in hybrid is rated at a much higher 230 mpg, but Edmunds estimates it will cost $53.55 per month to operate.” Therefore, the MPG rating system does not provide an accurate picture for the operating costs of each vehicle on which the consumer relies when considering the purchase of a hybrid or electric vehicle.
| Abrevs.: | kWh (Kilowatt Hour), mi (miles), mpge (miles per gallon equivalence) |
| GM Claim: | 25 kWh / 100mi => 4mi / kWh |
| Therefore, 40mi = 10 kWh of energy | |
| Assumption: | 37.5 kWh / 1 gallon of gasoline (on average) |
| Equivalence: | 10 kWh / 37.5 kWh = 0.2667 gals of gas / 40mi |
| Therefore, (running on electricity) the Volt gets approx. 150 mpge |
If I were to drive 40 miles round trip to work every day in a fully charged Volt, I would be getting the equivalent of 150 MPG. Considering the Toyota Prius provides 50 MPG for the same drive to and from work, the Chevy Volt greatly surpasses anything else currently out on the market. However, how does the Chevy Volt perform at longer distances? Consider the 230 estimated MPG that GM claims the Volt would reach — this is where the MPG Rating system falls apart:
| GM Claim: | 230 mpg |
| Question: | If I were to drive from Lawrence, KS to Lincoln, NE (approx. 230 miles) in a Chevy Volt, |
| what would my gas mileage be? | |
| Answer: | 40mi @ 149.98 mpge |
| + | 190mi @ 50 mpg |
| = | 4.0667 gals / 230mi = 56.56 mpge |
Therefore, the MPG rating falls dramatically as the distance of travel increases without recharging the vehicle. Nevertheless, 57 MPG is still equivalent to or better than enything else on the road today.
II. Cost of Operation: Volt vs. Prius
Now what about the operating costs of the vehicle? Again, it depends on the driving habits of the owner. Using the same two examples as above we will calculate the approximate cost for each of the trips compared to the Toyota Prius.
| Consider 40 miles: | Kansas residential kWh costs 10.4¢. |
| fully charging the battery uses 10 kWh. | |
| => | 40mi would cost $1.04 in the Volt |
| 40mi in a Prius: $2.09 | |
| Consider 230 miles: | 40mi @ $1.04 |
| + | 190mi @ 50 MPG @ $2.61 per gallon |
| 230mi would cost $10.96 in the Volt | |
| 230mi in a Prius: $12.01 |
III. CO2 Emissions
General Motors claims that the Volt produces zero emissions when in electric drive mode. This is true if one calculates the emissions from just the tail-pipe of the vehicle. However, the Volt needs to be plugged into an outlet, likely one in your garage, to be recharged. Electricity production at a power plant (and therefore the use of that electricity) emits CO2 and other harmful chemicals into the atmosphere. So, let us consider the emissions of electricity production specific to the state of Kansas.
| Source | Percentage* | CO2 Emissions (lbs/kWh) |
| Coal | 74% | 2.095 |
| Natural Gas | 3% | 1.321 |
| Petroleum | 5% | 1.969 |
| Nuclear | 18% | 0** |
| Renewables | <1% | 0 |
| Gallon of Gas | 19.4 lbs CO2 | |
| *Kansas energy statistics can be found here **Near zero CO2 emissions, but other negative environmental impacts exist | ||
Although the consumption of electricity while driving the Volt produces zero emissions, the generation of that same electricity in Kansas emits CO2:
| GM Claim: | Running the Volt on electricity is emissions free. |
| Calculations: | 0.74*2.095+0.03*1.321+0.05*1.969+0.18*0 |
| = | 1.69 lbs CO2/kWh in Kansas |
| Consider 40 miles: | 40mi per 10 kWh |
| 10 kWh * 1.69 lbs CO2 | |
| => | 40mi would generate 16.9 lbs CO2 in the Volt |
| 40mi in a Prius: 15.52 lbs CO2 | |
| Consider 230 miles: | 40mi @ 16.9 lbs CO2 |
| + | 190mi @ 50 MPG @ 19.4 lbs CO2/gal |
| => | 230mi would generate 90.62 lbs CO2 |
| 230mi in a Prius: 92.96 |
As you can see above, the Volt does NOT produce significantly different levels of CO2 emissions when considering the source of the electricity. While Kansas produces 74% of its electricity by burning coal, the United States, on average, produces only 50% of its electricity using coal (Missouri is 86% coal). So the Volt may indirectly produce less CO2 emissions in states that use nuclear or non-fossil fuel (wind, solar, etc.) electricity generation modes.
In summary, the current MPG rating system fails to provide a useful or accurate estimation of the operating costs of vehicles like the Chevy Volt. In addition, GM’s claim that the Volt will be rated at 230 MPGe is supect even when attempting to “fudge the numbers” to achieve such a rating. However, the Volt will cost less to operate on average and still maintain a higher MPGe (on short and long-distance trips) than that of the leading green vehicle, the Toyota Prius. But, when considering the emissions that result from electricity generation, the Volt does not emit significantly different levels of CO2 when compared to the Prius.
The estimated price for the Volt ranges from the mid-30s to $40,000. However, the US Government passed a tax incentive of $7,500 for new plug-in hybrids detailed here; making the Volt more competetive. The 2010 Prius rings in at $21,000 to $27,250. Unless the Volt can produce significant savings in operating costs, it may not be an economical purchase. However, according to AutoblogGreen, as the average cost of gasoline increases the Volt becomes more desirable.
-Joshua Foster
