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CO2 Emissions & Chevy Volt vs Honda Civic EX-L

Willem Post's picture
President Willem Post Energy Consuling

Willem Post, BSME'63 New Jersey Institute of Technology, MSME'66 Rensselaer Polytechnic Institute, MBA'75, University of Connecticut. P.E. Connecticut. Consulting Engineer and Project Manager....

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The purpose of this study it to determine the CO2 emissions of plug-in hybrids and high-mileage gasoline vehicles. The Chevy Volt and the Honda Civic EX-L were chosen for comparison. 


The CO2 emissions of the Chevy Volt in EV mode are based on the emissions from: 


– Extraction, processing and transportation of the fuels

– Conversion from thermal to electrical energy

– Power plant self-use energy

– Transmission and distribution losses to user’s meter.


The CO emissions of the Honda Civic EX-L are based on the emissions from the tail pipe, adjusted for the upstream CO2 emissions of extraction, processing and transportation of the fuel.


The comparison includes annual operating costs, annual CO2 emissions, and cost of CO2 emission reduction per metric ton. As Chevy Volts will be driven all over the US, basing its emissions on the 2011 US grid CO2 emission intensity (latest available) is rational. 


In addition to the above comparison, this article also presents an analysis of two alternatives to show there are much less costly ways to reduce CO2 emissions than with plug-in hybrids and plug-in EVs.


Popularity of Chevy Volts in California: It is not surprising, Chevy Volts are popular in California, because:


– People want to do something about air pollution and global warming

– Federal and state subsidies reduce the $40,000* price to about $30,000

– Gasoline prices are among the highest in the US.

– Nighttime charging is available from utilities at about 6 c/kWh

– Numerous workplaces provide low-cost, or free, daytime charging 


* The $40,000 would be even greater, if not for the federal subsidies given to GM to set up production facilities and GM foregoing profits to increase sales to meet future CAFE standards.


Whereas, NON-plug-in hybrids sales have rapidly increased the past few years to about 45,000 in July 2013, of which Toyota Prius 23,294, the monthly sales of plug-in hybrids, such as the Chevy-Volt, are about 4,000/month, and of all-electrics, such as the Tesla, also are about 4,000/month.


Currently, there is a price war among manufacturers to increase sales of plug-in hybrids and all-electrics, to ensure they sell enough such vehicles to meet legal requirements under California zero-emission vehicle rules.




– The average Chevy-Volt owner has an income of  $170,000/yr.

– Some states offer incentives in addition to the $7,500 federal cash grant. California adds up to $2,500, Colorado adds up to $6,000, West Virginia adds up to $7,500, PLUS up to $10,000 for a personal charging station.

– Ten U.S. states open the high-occupancy-vehicle, HOV, lanes, of their highways to EVs, even if the car carries a lone driver.   

– Numerous stores offer VIP parking for EVs—and sometimes a free charge.


This article ignores the subsidies, because the aim is to compare the economics of reducing CO2 emissions. The future costs of reducing CO2 will be an enormous burden on the US economy; it would be wise to first use the lowest cost, most effective  methods, such as increased energy efficiency.

Plug-in Hybrid and EV Production Past 5 Years; excludes non-plug-in hybrids:






Alternative No. 1 compares the continued operation of a fully-paid-for, 40-year old, 35%-efficient, base-loaded, 500 MW coal plant versus replacing it with a new, 60%-efficient, base-loaded, 500 MW CCGT (combined cycle gas turbine) plant built on the same site to minimize any impact on grid systems.

Alternative No. 2 compares the current US corporate average fuel efficiency, CAFE, standard of the 27.5 MPG to the enacted 35.5 MPG by 2016 and the enacted 54.5 MPG by 2025.

Alternative No. 3 compares a Chevy Volt traveling 12,000 miles in electric vehicle, EV, mode versus a Honda Civic EX-L traveling 12,000 miles in gasoline mode. 



Summary of Alternative No. 1: CCGT Plants vs Coal Plants


                                                                      Metric ton CO2/yr*   


Coal plant CO2 emissions                                     3,478,896

CCGT plant CO2 emissions                                   1,305,330  

CO2 emission reduction                                       2,173,566


* Includes coal and gas plant upstream CO2 emissions.


NOTE: If, by magic wand, the US had instantly replaced all its coal plants with 60% efficient CCGTs, it would have reduced its 2011 CO2 emissions of 6,027 million metric tons to about 4,150 million metric tons. 


Coal plant amortization payment           $0/yr

CCGT plant capital cost                         $625 million

CCGT plant amortization payment          $31,581,607/yr, or 0.901 c/kWh

Cost of CO2 emissions reduction            $14.53/metric ton 


NOTE: Recent market prices of CO2 are $8, $12 and $20 per metric ton in Europe, California and Australia, respectively.


                                   Energy Cost; c/kWh

                             New CCGT Plant    Old Coal Plant


Amortization               0.901                     0.000 

Fuel                            2.275                     2.340

Plant O&M                   1.000                     2.000 

Total                          4.177                     4.340   


A profit is achieved by selling the energy to utilities under long-term contracts at about 5.5 c/kWh. 


NOTE: In Europe, Japan, etc., gas prices are about 2 – 3 times US prices.


NOTE: CCGT plants can be arranged for district heating with an (electrical and thermal) efficiency up to 85%, as practiced in the Netherlands, Denmark, etc., for about 40 years. The hot water send-out temperature could be as low as 130F, if the distribution piping is well insulated and the modern, multi-story, well-insulated, well-sealed buildings have in-floor space heating, for a system efficiency of up to 90 – 95 percent.


Summary of Alternative No. 2: High-Mileage Vehicles

In May 2012, the US finalized new standards to increase the corporate average fuel economy, CAFE, standard for light duty vehicles, LDVs, from the current 27.5 MPG to 35.5 and 54.5 MPG EPA Combined by 2016 and 2025, respectively. Europe is well ahead of the US. Already millions of LDVs are sold each year that get 35 MPG or better.

Below is a comparison of the 27.5 MPG and 54.5 MPG standards:

                               Travel              Mileage     Gal/yr                  Emissions*                                            

                               mile/y                MPG                            lb CO2/y    g CO2/km                              

Present CAFE          12,000                27.5         436             10,647          250.36          

2025 CAFE              12,000                54.5         220               5,372          126.33

* Includes upstream CO2 emissions.

Whereas the higher-mileage vehicles would be more expensive, the amortizing of the cost difference over 10 years (the average life of US LDVs) would be more than offset by the significant reduction in annual fuel cost, i.e., there would be a net reduction in annual owning and operating costs.

NOTE: Earlier CAFE standards were rife with loopholes which resulted in a difference between test MPG and real-world MPG of up to 20%. Maybe Washington’s “constituent service providers” will be less lenient in the future.


NOTE: Increasing the mileage of cars, SUVs, minivans, and 1/4-ton pickups, which would decrease their fuel consumption per mile and reduce their CO2 emissions per mile, must be high on US car producer’s agendas, if they want to stay relevant in the future.                  


Summary of Alternative No. 3: Chevy Volts vs Honda Civic EX-L


                                         Cost          Travel      Energy/yr    Cost           Emissions**

                                           $            miles/yr                       $/yr      lb CO2/yr  g CO2/km


Honda Civic EX-L              22,105     12,000        364 gal       1,309       8,873        208.63

Chevy Volt, EV mode        39,145     12,000    4,200 kWh+    3,161*     5,818        136.80

Chevy Volt, Gas mode                       12,000       324 gal        3,763*     7,914        186.07


*   Includes capital cost difference amortization of $2,531/yr

** Includes upstream CO2 Emissions.

+  Energy at the meter


See “US Grid CO2 Intensity” section below.


Volt CO2 emission decrease, EV mode, lb/yr                             8,873 – 5,818 = 3,055                             

Volt operating cost INCREASE, EV mode, $/yr                           3,161 – 1,309 = 1,852 


Volt CO2 emission reduction cost, EV mode, is $1,852/(3055/2204.6) = $1,336/metric ton             


Note: If a higher-priced, gasoline-powered vehicle with the same mileage were selected to reduce the amortization payments by 50%, the EV mode annual cost increase would be less.




Coal and Gas: CO2 adjustment factor for emissions for extraction, processing, and transportation of Coal and Gas are 4.4% and 23.4%, respectively. See URL, page 10. 


Fuel Oil and Other: CO2 emissions for refining Fuel Oil and Other are 2.5 lb CO2/gal. See URL cleanskies.


CO2 Emissions from well to pump: 

                                                               lb CO2/gal

Exploration/Production, 8%                         2.00   

Transport, 1%                                            0.25  

Refining, 10%                                             2.50

Distribution, 1%                                          0.25   

Total                                                          5.00 


CO2 adjustment factor for Fuel Oil and Other: (19.4 + 5)/19.4 lb CO2/gal = 1.2577

See accenture URL, page 3.




2011 energy production was 4,138.7 TWh, of which Coal 1733, Gas 1025, Nuclear 790, Hydro 260, Wind 120, Other 211 


2011 energy-related CO2 emission were 2,166 metric ton, of which Coal 1718, Gas 411, Other 36


2011 US grid CO2 intensity = (2,166 million metric ton CO2)/4,138,700,000,000 kWh) x 2,204.6 lb/metric ton = 1.154 lb CO2/kWh 


2011 US grid intensity intensity, incl. upstream CO2 emissions = (1,718 x 1.044 + 411 x 1.234 + 36 x 1.2577)/2,166 = 1.250 lb CO2/kWh, for an 100 x 1.250/1.154 = 8.36% increase due to upstream emissions. 


NOTE: 2009 US grid intensity was 1.216, about 5.4% greater than the 1.154 in 2011, mostly due to more gas and less coal combustion, and more renewables.




The below numbers give an indication of the number of years to break even on CO2, based on life cycle emissions.


The production of hybrids and EVs have CO2 emissions of about 25,000 lb vs an average conventional gasoline vehicle about 14,000 lb.


– Mining and processing lithium ore is a dirty business, mostly performed in China with inefficient CO2-emitting coal plants.

– At least 40% of the 25,000 lb is due to the battery system and the added complication of a second power source. 


Assuming no changes over 8 years:


At present, a Chevy Volt in EV would cause emissions = 8 yr x 5,818 lb CO2/yr = 46,544 lb CO2

At present, a Honda Civic EX-L would cause emissions = 8 yr x 8,873 lb CO2/yr = 70,982 lb CO2


………………………………………….Chevy-Volt……….Honda Civic EX-L

Production Phase…………………….25,000…………………14,000

Driving Phase; 3.60 yrs…………….20,951…………………31,951                Total……………………………………..45,951…………………45,951

Breakeven period………………………………..3.60 yrs


Assuming design improvements by 2025:


– Production Phase CO2 emissions in 2025 of a high MPG vehicle 15% greater and of a Chevy-Volt 15% less.

– Driving Phase CO2 emissions in 2025 of a high MPG vehicle 5,372 lb at 54.5 MPG (2025 CAFE) and of a Chevy-Volt 25% less.


In 2025, a Chevy Volt in EV would cause emissions = 8 yr x 4,364 lb CO2/yr = 34,908 lb CO2

In 2025, a high MPG vehicle would cause emissions = 8 yr x 5,372 lb CO2/yr = 42,976 lb CO2


………………………………………………Chevy-Volt……..High MPG Vehicle

Production Phase………………………….25,000…………..14,000

Adjusted due to assumptions…………21,250…………..16,100                          

Driving Phase; 5.11 yrs………………….22,254…………..27,397                


Breakeven period……………………………………5.11 yrs



The US-DOE has backed away from the target of one million plug-in hybrids and plug-in EVs on the road by 2015, in favor of reducing battery costs to $300/kWh by 2015 ($650/kWh at present; Chevy Volt battery cost = $650/kWh x 16.5 kWh = $10,725). 


This seems dubious, given the American Physical Society symposium’s view that “only incremental improvements can be expected” in lithium-ion batteries. 


GM made an incremental improvement that increased the Chevy Volt battery storage capacity from 16.0 kWh, 2012 model, to 16.5 kWh, 2013 model.


If new battery inventions were to occur during the next 20 years, AND the cost of such batteries would be at least 50% less than at present, AND the US grid CO2 emission intensity were to have a much lesser value, due to gas displacing coal, then plug-in hybrids and plug-in EVs will significantly reduce CO2 emissions. Whether such reduction will be cost-effective remains to be seen.


Until this happens, for reducing CO2 emissions, higher-mileage vehicles would be much quicker and more cost-effective, and gas replacing coal extremely quick and cost-effective. See Alternatives 1 and 2.


Plug-in hybrids and plug-in EVs are more costly than gasoline vehicles, say on average about $4,000  – $10,000, depending on battery kWh (DC) capacity


NOTE: Technically, it will be less challenging to improve the MPG of gasoline vehicles and quicker to implement their mass production, than to improve the battery performance of plug-in hybrids and plug-in EVs and implement their mass production, per American Physical Society. 


Therefore, it would be more prudent for the US to allocate more funding to gasoline vehicle improvements than to plug-in hybrid and plug-in EV vehicle improvements, especially because competitors, such as Europe, Japan and China, are already doing this.


Note: Regular hybrids, i.e., non-plug-ins, such as the Toyota Prius, that do not draw energy from the grid, ARE reducing CO2 emissions.




The above table indicates, the Chevy Volt is more efficient in EV mode than in gas mode, on a gram/km basis, but here is no physically valid method that would yield the 100 MPG-equivalent values published by the EPA.


A rational approach is to use each nations’s grid CO2 intensity, gram/kWh, to calculate the EV mode CO2 emissions, g/km, of the energy drawn from the grid. 


This will provide a common international basis for comparison of CO2 emissions, as Europe, Japan and China are already using g/km. The below article explains all in detail.




Natural Gas vs Coal for CO2 Emissions Reduction: For the past 30 years, US utilities have been using less coal and more NG to generate energy. The annual percentage contribution of NG energy to the US grid has increased from a few percent to about 30%. This trend will accelerate for at least the next few decades. 


Because of advanced drilling techniques, invented in the US, domestic NG has become an abundant energy resource that is low-cost, has about 1/3 the CO2 emissions of coal, and has no particulate emissions.


US CO2 emissions (in 1,000 million metric tonnes) decreased from 6.145 in 2010 to 6.027 in 2011 (a 20-year low), a decrease of 0.118, which was 4.92 times greater than Germany’s expensive ENERGIEWENDE (renewable energy) reduction. The decrease was mostly due to:


– increased use of gas, i.e., CCGT build-outs 

– decreased use of coal, i.e. retiring older coal plants or running them fewer hours

– economizing due to the Great Recession

– CO2 emission reduction due to renewable energy was minor by comparison


It is clear from the above, maximizing the installation of low-cost, relatively CO2-free, natural gas-fired, 60%-efficient CCGTs, as supplied by Siemens and GE, would be the fastest, least-visible, least-costly, most-effective way to reduce CO2 emissions. The levelized cost of CCGT energy is about 6.5 – 7.0 c/kWh; per EIA/US-DOE.


A later version of EIA estimates of energy costs; April 2011 


High Mileage Vehicles vs Chevy Volts for CO2 Emission Reduction: The above tables indicate higher mileage vehicles significantly reduce CO2 emissions AND people would reduce their annual expenses by switching to high-mileage vehicles.     






Assume the replacement of a base-loaded, 40-year old, 35%-efficient, 500 MW, coal plant with a new, base-loaded, 500 MW, 60%-efficient CCGT plant:


– the coal plant is paid off

– the CCGT plant capital cost is 500 MW x $1,250,000/MW = $625 million

– useful service life of CCGT plant is 40 years

– amortization factor at 4%/yr over 40 years is 19.79

– the O&M of the coal plant is about 2 times the CCGT plant.

– gas price, on long term contract, is $4.00/1,000,000 Btu

– coal price is $48/ton

– coal heat content is 20,000,000 Btu/ton

– capacity factor of both plants is 0.80


NOTE: The capacity factor used in the calculations is less than 1, due to:


– scheduled and unscheduled outages; about 7% of annual hours 

– the plant output varying from 60 to 100 percent of rated output, even though both plants are classified as “base-loaded”; the plant annual average output would be [(3,504,000 MWh/yr)/{(1 – 0.07) x 500 MW x 8,760}] x 100% = 86%; efficiency decreases due to part-load operations were omitted to simplify calculations.


NOTE: Operation above 60% avoids instabilities of combustion control systems and air quality control systems.


Annual energy production = 500 MW x 8,760 hr/yr x capacity factor 0.80 = 3,504,000 MWh/yr. 


Coal plant CO2 emissions = 3,504,000,000 kWh/yr x (3,413/0.35) Btu/kWh x 215 lb CO2/1,000,000 Btu x 1 metric ton/2,204.6 lb x 1.044 = 3,478,896 metric ton CO2/yr.


CCGT plant CO2 emissions = 3,504,000,000 kWh/yr x (3,413/0.60) Btu/kWh x 117 lb CO2/1,000,000 Btu x 1 metric ton/2,204.6 lb x 1.234 = 1,305,330 metric CO2/yr. 


CO2 emission reduction = 2,173,566 ton/yr 


Annual amortization payment = $625 million/19.79 = $31,581,607/yr.


Cost of CO2 emissions reduction = $31,581,607/(2,173,566 metric ton/yr) = $14.53 metric/ton. 




An effective CO2 emission reduction policy would be to subsidize development (not production) of light-weight, higher-mileage, standard vehicles, including non-plug-in hybrids; the less energy used from the “dirty” US grid to charge vehicle batteries, the better. 


In May 2012, the US finalized new standards to increase the Corporate Average Fuel Economy, CAFE, standards of cars and light trucks from the current 27.5 MPG, to 35.5 MPG by 2016, to 54.5 MPG by 2025. See table in SUMMARY OF ALTERNATIVES


Assuming the increase in cost of a high-mileage vehicle will be $5,000, then from 27.5 to 54.4 MPG and assuming a life of 10 years, will yield a net annual cost = amortization – fuel cost savings = {$5,000/6.733; amortization at 4%/yr over 8 yrs – (436 – 220) x 3.60/gal; fuel cost savings} = -$162/yr; i.e., a negative value means people would reduce their annual expenses by switching to high-mileage vehicles AND have a zero-cost way to significantly reduce CO2 emissions.


Higher-mileage vehicles are being produced by the millions in Europe, China and Japan, whereas EV/Hybrid plug-ins were 53,172 in 2012, of which Chevy Volt 23,461; Toyota Prius 12,750; Nissan Leaf 9,819; Tesla model S 2,400.


Europe currently enforces 43.3 MPG, 50 MPG by 2016 

China currently enforces 35.8 MPG. 

Japan currently enforces 42.6 MPG.


Using a different metric than the US, the EU requires the corporate fleet average CO2 emissions of an average weight car be reduced to 130 g CO2/km by 2015, equal to 42 MPG. Fines for breaching the standard are 5 euro/gram/vehicle. Again, Europe, China and Japan vehicle producers are well ahead of the US regarding high-mileage vehicles.


Increasing the mileage of cars, SUVs, minivans, and 1/4-ton pickups, which would decrease their fuel consumption per mile and reduce their CO2 emissions per mile, must be high on US car producer’s agendas, if they want to stay relevant in the future.






General Motors is marketing its 2013 plug-in hybrid Chevy Volt, a 4-dr sedan, 16.5 kWh lithium-ion battery, using a 220/240-V, 40 A outlet, charging time about 4.25 hours by the 3.3 kW on-board charger, electric range about 38 miles (EPA) after which a 1.4 Liter, 4 cylinder gasoline engine provides power for another 340 miles. The battery cells are produced in South Korea by LG Chem. The cells, etc., are assembled into battery packs in the US.


The 2013 Chevy Volt uses about 65.5% of the stored energy, kWh (DC), or about 10.8 kWh (DC) for its 38 mile EV range. Climates, road surfaces, driving habits, etc., will affect performance and battery aging rate. The battery discharges to about 20 – 25 percent and charges to about 85 – 90 percent, to reduce battery aging.


GM warrantees the battery for 8 years/100,000 miles for manufacturing defects. This is not a performance guarantee, i.e., the performance will be less as the battery ages. 


By 8 years/100,000 miles, GM expects the car’s range to be reduced by 10 to 30 percent, in the worst case, due to aging of the batteries. Some customers will experience less degradation. The car can continue in EV mode beyond 100,000 miles , but range will continue to contract. Reduced performance during hot summer months and cold winter months is in addition to the 10 to 30 percent.




Vehicle Cost Difference: The Chevy Volt is designed to be a more upscale car (to appeal to the upscale “green” buyer and to increase GM revenue/car) than the Honda Civic EX-L. Some of the significant capital cost difference between the Honda Civic EX-L and Chevy Volt in this article is due to that. The more equipped and upscale a vehicle is, the more CO2 emissions to produce it. 


According to some comments, the Honda EX-L is not “equivalent” to the Chevy Volt, which is a valid point. If a more “equivalent” car had been chosen to reduce the capital cost difference by 50%, the amortizing cost would have been $2,531/2 = $1,266/yr. 


The truly “green” person would likely not select a Tesla, Chevy Volt or Lexus 450 hybrid, but a Toyota Prius, the most popular hybrid in the world.   


EV Range: At the end of 8 years, the above-mentioned EV range would vary from 26.6 to 34.2 miles, in the worst case. As the Volt ages, it would become more sluggish, especially with some passengers and some cargo, going uphill, on cold days. Unlike owners of 8-year-old gasoline-powered vehicles, Chevy Volt owners would have a relatively little-used gasoline engine as back-up. The increased back-up operation will add to CO2 emissions.


Colder Climates: In colder climate areas, such as New England, hybrids may not require much in terms of heated garages or curbside chargers/heaters, because they can be started and operated on just the gasoline engine, but for pure EVs, such support systems would likely be required. The building of such support systems would add to capital costs, O&M costs and CO2 emissions. The batteries would be less efficient in colder climate areas. Instead of 38 miles, one may get only 34-35 miles in EV mode, when the temperature drops to about 35F, and about 30 miles at 20F. The increased back-up operation will add to CO2 emissions. 


Warmer Climates: According to a 2012 Chevy Volt owner in Arizona: “The Volt starts by battery. The AC cools the cabin and the TMS cools the battery. The gasoline engine starts when the battery charge drops to about 30%, where it remains until the next time it is plugged in. EV range drops to about 35 miles in June, July & August, but stays above 40 miles the rest of the year. The net result is a shorter EV range in summer, due to energy consumed by the AC and TMS.”


Charging Energy Input and Losses: According to the owner of a vehicle testing company in Santa Monica, CA: 


“The charging energy, kWh, depends on the ambient temperature and the charging voltage of 120 V or 240 V. On average, it takes about 12.2 kWh (AC) to fully charge the 2012 Chevy Volt battery using a 240-volt charger in Santa Monica, CA, about 13.0 kWh (AC) using the 120V GM-supplied power cord.” 


The 12.2 kWh provides a range of about 35 miles, or 34.86 kWh/100 miles.


The 2013 Chevy Volt uses about 65.5% of the stored energy, kWh (DC), or about 10.8 kWh (DC) for its 38 mile EV range. 


Charging losses @ 240 V = ((12.2 – 10.8)/10.8) x 100% = 13% 

Charging losses @ 120 V = ((13.0 – 10.8)/10.8) x 100% = 20.3%


Calculations using EPA energy consumption data: As a result of its improved battery chemistry, the 2013 Volt increased its EPA rated EV range to 38 miles with an energy consumption of 35 kWh (AC) per 100 miles, or 13.30 kWh (AC) per 38 miles, as measured at the user’s meter. See “Range” in URL.


The CO2 emission of the energy drawn from the grid = 1.05, Self-use x 1.05, T&D x user meter reading. The primary energy is based on the conversion efficiency of 0.33. Amortization is assumed at 4%/yr over 8 years.


                                                    2013 Chevy Volt  Honda Civic EX-L 


US grid CO2 intensity, incl. upstream, lb/kWh = 1.246

US grid CO2 intensity, incl. upstream, g/kWh = 608.81

km/mile = 1.609

gram/lb = 454

lb/metric ton = 2,204.6

CO2 emission, incl. upstream, lb/gal = 19.4 + 5.0 = 22.4        

Energy, $/kWh = 0.15


EV mode/Gas mode, miles/yr                            12,000                   12,000

Fuel cost, $/gal                                           $3.80 premium         $3.60 regular                                                                                                                                                                                                   


EV range, miles                                                   38

EPA mileage, EV mode, kWh/100 miles                 35

EPA Combined mileage, hybrid mode                     37

EPA Combined mileage                                                                      33

Battery rating                                                   16.5


Energy at user’s meter, per EPA, kWh/m         0.3500

Energy to grid, kWh/m                                    0.3684

Energy produced, kWh/m                                0.3878

Energy to plant, kWh/m                                  1.1634

Energy extracted from mine/well                    1.2646

Energy from mine/well, Btu/yr                   51,993,642            52,604,342


Energy at user’s meter, kWh/yr                       4,200

Energy cost, EV mode $/yr                                 630 utility bill

Amortization, $/yr                                          2,531 

Total cost, EV mode, $/yr                               3,161


Fuel, hybrid mode, gal/yr                                    324                       

Fuel cost, hybrid mode, $/yr                            1,232                    

Amortization, $/yr                                          2,531 

Total cost hybrid mode, $/yr                           3,763


Fuel, gasoline mode, gal/yr                                                               364

Fuel cost, gasoline mode, $/yr                                                       1,309


Operating cost increase, EV mode, $/yr            1,852

Operating cost increase, hybrid mode, $/yr       2,454


CO2 emissions, incl. upstream, lb/yr                 5,818                   8,873

CO2 decrease, incl. upstream, lb/yr                  3,055


CO2 emission, incl. upstream, g/km                 136.80

CO2 emission, incl. upstream, g/km                                            208.63


Operating cost increase, 1/2 amortizing, $/yr    586


T&D Systems: A house without AC uses about 25 kWh per day. Widespread plug-in hybrid and EV adoption, each using about 13.3 kWh/day, with 1 or 2  such vehicles per household would almost double the usage per day, reduce T&D system design margins, and may overload local transformers, etc., if charging occurs during daytime/evening hours. Future such vehicles may have batteries of greater capacity. 


House wiring would need to be modified for charging plug-in hybrids and EVs, and the capacity of grids would need to be enhanced and the US power system would need to produce more power. The increased use and modifications/replacements of T&D systems would add to capital costs, O&M costs and CO2 emissions.


Increased Energy Production Due to Plug-in Hybrids and EVs: The US power system would need to produce a significant quantity of additional energy. It would need enhancements of fuel production systems, fuel supply systems, generation systems and T&D systems. The increased use of existing systems, plus enhancements, would add to capital costs, O&M costs and CO2 emissions. 


NOTE: The Chevy Volt charging controls can be set to begin charging around midnight and end charging around 5 AM; utilities would be wise to encourage it with lower rates during nighttimes, to avoid daytime overloads of local grids.


As the nighttime unused energy generating capacity is used more, there would be increased generating units in operation, increased staffing and fueling, increased wear and tear, increased O&M, and more frequent replacements, just as when a car is driven more often.


How much more? Say after some years, 100 million plug-in hybrids and EVs would draw 13.3 kWh from the grid/day, or 1,330 million x 365 d/yr = 485 TWh/yr, an increase of 21% over current US annual consumption of about 4,000 TWh/yr. That nighttime supply would be generated from about 12 at night to about 5 in the morning, i.e., about 5 hours for charging.


The current supply during those 5 hours is about 13% of the total US supply, or 4,000 TWh/yr x 0.13 = 520 TWh/yr, i.e., an almost doubling of energy production during these hours, most of it in the densely-populated East and West Coasts.




Most “early adopter” Chevy Volt owners likely are more upscale and more careful drivers, as, by my observation, are Toyota Prius owners; one hardly ever see Prius owners “gunning it”. With widespread adoption of Chevy Volts, there will be an assortment of drivers.


2013 Chevy Volt: battery capacity 16.5 kWh (DC), discharge 10.8 kWh (DC), electric range 38 miles (EPA), or 0.284 kWh (DC)/mile.


The 0.284 kWh/mile value would need to be increased to at least 0.30 kWh (DC)/mile, due to: 


– an aged population of Chevy Volts; some new, others more than 8 years old,

– a mix of Chevy Volts charging at 120 or 240 Volt, 

– driven in various climate and road conditions, 

– by an assortment of drivers; some careful, others not so, 

– plus accounting for the above extra CO2 emissions, usually glossed over or not mentioned.




This section was added, because a significant number of comments indicate some clarification is needed regarding how and in what form energy enters the grid, and how it travels on the grid.


North America has three major grids, the Western Interconnection, the Eastern Interconnection and the Electric Reliability Council of Texas (ERCOT) grid, often referred to as the Western System, the Eastern System and the Texas System. These grids have minor connections with each other. Recently, ERCOT has been increasing the capacity of its connections to the other two grids to enable it do deal with excessive variable wind energy on windy days.


ALL generators on these three grids are synchronized and spin at 60 revolutions/second, i.e., their electromagnetic waves enter the US grid in a synchronized manner and at 60 Hz; chaos would ensue, if the waves were not in sync.


The speed at which energy travels down a power line is actually the speed of the electromagnetic wave, not the movement of electrons. The waves move from higher to lower voltage areas. The waves do not travel inside the power line, but in the air near its outside surface.


Drawing energy from the grid lowers the voltage at various points, but the continuous energy supply, as electromagnetic waves, from the large number of generators “fills in the voltage dips” to the desired levels. 


Energy “mixing” from various energy generators takes place at near-lightspeed, as the waves move at near-lightspeed on bare copper power lines, at somewhat lesser speeds on insulated wires and coaxial cables. Wave travel time for 1,804 miles would be 1,804 m/(0.97 x 186,000 m/s) = 0.01 sec. Typically, a wave dissipates “filling voltage valleys” well before traveling that far; chaos would ensue, if the waves did not travel at such high speeds.


If a DC voltage is applied, as with a battery, the electrons will increase in speed proportional to the strength of the electric field. These speeds are on the order of millimeters per hour. 


If an AC voltage is applied, as with a generator feeding the grid, there is no net movement of electrons; they oscillate back and forth in response to the alternating electromagnetic waves.



Grids are interconnected and energy, as electromagnetic waves, “flows” back and forth between them, and between time zones (such as from the Midwest to the East Coast), depending on demand. Wave flows between grids could be up the rated capacity of their connections. So-called “exports” and “imports”, MWhs, between grids are merely the DIFFERENCE during a time interval (minute, day, month, year) of the back and forth wave flows. 


Thus, it would be invalid, based on the physics, to claim “I am getting my Chevy Volt energy from a ‘clean’ grid, or from hydro, or from my solar panels (which are likely grid-tied), or from nuclear, or from wind, etc.” The correct statement is “I am getting my energy (electromagnetic waves) from the US grid.”


Regarding drawing energy from the grid, everyone is equal; it is like drawing water from the ocean. The only, physically-valid, measure for evaluation is the energy conditions of the US grid.




In this article, two Chevy Volt cases were analyzed vs the Honda EX-L base case. Each has its own primary energy. The primary energy consumption of the cases are listed below:


Honda Civic EX-L = 364 gal x 115,000 Btu/gal x 1.2577 = 52,604,342 Btu/yr


Chevy Volt, EV mode = 12,000 m/yr x 1.2695 kWh/m x 3,413 Btu/kWh = 51,993,642 Btu/yr 




All travel of the Chevy Volt is assumed to be electric; annual travel at 12,000 miles/yr, or about 33 miles/day; electricity at $0.15/kWh (includes all fees, taxes, surcharges, etc.); regular gasoline at $3.60/gallon, premium gasoline $3.80/gallon; Honda Civic EX-L mileage at 33 MPG (EPA combined); subsidies are ignored to enable rational decision making; values include upstream CO2 emissions. 


Annual Operating Cost: 


Honda Civic EX-L 


Annual energy cost = (12,000 m/yr)/(33 m/gal) x $3.60/gal = $1,309/yr   


Chevy Volt


Annual electricity = 0.35 kWh (AC)/mile x $0.15/kWh x 12,000 miles/yr = $630/yr 


The Chevy Volt costs $39,145 and the Honda Civic EX-L Sedan $22,105, for a difference of $17,040, which would require annual amortizing payments of $2,531/yr, if borrowed at 4%/yr and paid off over 8 years.


Chevy Volt annual operating cost increase = ($630/yr, electricity + $2,531/yr, amortize extra cost, Chevy Volt) – ($1,309/yr, gasoline, Honda Civic EX-L) = $1,852/yr. 


CO2 Emissions 


Honda Civic EX-L


CO2 emissions = 364 ga/yr x 19.4 lb CO2/gal x 1.2577, upstream = 8,873 lb CO2/yr 


CO2 emission = 8,873 lb CO2/yr x 454 g/lb x 1 yr/12,000 m x 1m/1.609 km = 208.63 g/km 


Chevy Volt, hybrid mode


Energy = 12,000 m/yr x 1 gal/37 m* = 324 gal/yr


CO2 emission = 324 gal/yr x 19.4 lb CO2/gal x 1.2577 = 7,914 lb/yr


CO2 emission = 7,914 lb CO2/yr x 454 g/lb x 1 yr/12,000 m x 1m/1.609 km = 186.07 g/km


Chevy Volt, EV mode


Energy = 0.3500 kWh/m x 12,000 m/yr = 4,200 kWh/yr; at the meter. 


CO2 emission = 0.3878 kWh/m x 12,000 m/yrx 1.25 lb CO2/kWh  = 5,818 lb CO2/yr 


CO2 emission = 5,818 lb CO2/yr x 454 g/lb x 1 yr/12,000 m x 1m/1.609 km = 136.80 g/km


Equivalent mileage (g/km basis) = 186.07/136.80 x 37 MPG* = 50.3 MPG; as the US grid becomes “cleaner”, the 136.80 decreases!

*37 MPG value is per EPA.


NOTE: The above analyses do not account for:


– The extra CO2 emissions due to the greater manufacturing cost of the Chevy Volt

– Any incremental improvements in battery technology, before 8 years have passed.


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John Miller's picture
John Miller on Feb 4, 2013

Willem, another excellent post and analysis.  One data point that caught my attention was the 54.5 mpg CAFE, which overstates actual average vehicle mpg that average owners should expect.  Based on a past analysis (CAFE vs. actual) a more accurate vehicle mpg would be 44.4 mpg.  (Sorry that my post graphs that illustrated ‘CAFE vs. actual’ disappeared again.) 

Keep up the good work.

John Miller

Max Kennedy's picture
Max Kennedy on Feb 4, 2013
Another useless analysis that ignores alternate energy technologies which don't produce carbon emissions nor the increasing use of those technologies for power generation in the future. Funny how future mileage changes can be accounted for but not improvements in generating technologies. Willful blindness in pursuit of promoting the continued use of fossil fuels.
James Hopf's picture
James Hopf on Feb 5, 2013

Trying desperately to keep this short......

This analysis goes into an absurd amount of detail, and effort, when it is obvious that the results are extremely sensitive to several basic assumptions, such as the cost difference (PHEV vs. ICE), the CO2 emissions and cost of input (charging) electricity, and the cost of gasoline.

The largest variable is vehicle cost.  It has been (correctly) pointed out that the Volt is not the equivalent of some basement model car.  It is at least as "nice" as a ~$25,000 car.  But such judgments are subjective.  Others would say it's the equivalent of a small Mercedes or Lexus, i.e., a low 30s car.  I've read that the battery costs ~$15,000, so let's use that as the "extra" cost.

The main point is, if you reduce the battery cost by a factor of 3, to ~$5,000, the Volt reaches economic parity with the Civic (per the Case 1 example presented).  And that's despite the fact that the Case was based on a 15 cent electricity cost which is well over the cost of off-peak (midnight) electricity.  (I'm getting a price of ~6 cents/kW-hr for nighttime charging, in California.)  At that point, the CO2 emissions reduction cost drops from ~$1,000 per ton AAAALLLLLLL the way down to zero!!!!!

Again, suffice it to say that the analysis is extremely sensitive to the input assumptions.  And no, a $5,000 battery cost is not an unrealistic assumption.  Most experts predict it will be achieved before 2020.  Another sign of progress in the EV sector is the huge numbers of companies jumping in and the proliferation of EV and PHEV models.  Not only will this reduce costs through healthy competition, but it reflects a large amount of invesment by (private) industry, which will lead to rapid technology advancement,  Of note is the fact that most car companies are not persuing these vehicles because of the subsidy.  They view EVs/PHEVs as an essential part of the portfolio of vehicles that will be necessary to meet future CAFE standards.

As for what energy source is used to generate the electricity, the all gas case is by far the best assumption.  Applying the electricty mix is not a valid approach.  You have to ask what will be used to meet the *incremental* demand increase from the cars, over the short and long term.  As for the short term, gas plants are what is mainly used for load following.  Over the longer term, EVs would result in additional power plants (baseload plants, if most charging is done at night).  Well, it's pretty clear (based on new EPA regulations and other factors, including the low cost of gas) that the US has pretty much built its last coal plant.  All new plants will be gas, or non-emitting.  Speaking of mixtures of gas and non-emitting sources, how about using the California grid (CA being where most EVs and PHEVs are sold), as opposed to the NE grid?  There are no coal plants in the state.

The EV subsidy will be phased out long before it ever reaches 3.8 billion.  The current subsidy cost of $100 million is pocket change in the grand scheme of things.  It is much smaller than most energy technology federal research budgets.  Would it help if we called the tax credit a (real world trial) research project?  There are several examples of things that get far less bang for the buck, such as trillion dollar wars in the Middle East, as well as ~$60 billion a year for the US navy to patrol and secure the Persian Gulf oil shipping lanes.

Finally, I must point out that the EV push is about far more than just CO2 emissions.  It is about reducing air pollution (especially in population centers where people live, and drive), as well as other environmental impacts from oil production.  It's also about reducing our dependence on oil from unstable/unfriending regions, and reducing our trade defecit (something you'd think even conservatives would agree with).  There is also an energy diversity (and security) benefit.  The fact that our transportation sector can only use one specfic fuel/energy source (oil) is not a good thing.  Electric cars can essentially use almost any primary energy source.

The temporary, small, EV/PHEV subsidy may be one of the best, most strategic investments the US government has ever made.

James Hopf's picture
James Hopf on Feb 5, 2013

BTW, I'm totally in agreement with the author about replacing old dirty coal plants with gas-fired plants.  It is indeed the lowest hanging fruit and those coal plants need to be retired for reasons other than CO2 emissions (i.e., egredgious pollution, that results in tens of thousands of annual deaths).  We need additional policy input that will accelerate, and maintain this process, i.e., further tightening of pollution rules and/or some policy that puts some economic weight on both CO2 emissions and air pollution.

With gas costs as low as they are, we've lost every last excuse to keep old, ultra-dirty coal plants operating, or to build any new ones.  The bleating about "unbearable" economic costs from the "war on coal" coming from the right side of the political spectrum is breathtaking in its intellectual dishonesty.  These are the same people who are extoling the "miracle" of increased gas production and low gas costs!!  Reducing CO emissions significantly, through coal to gas switching in the power sector, will not have any measurable negative economic impact.

James Hopf's picture
James Hopf on Feb 6, 2013

You missed my point entirely!  I was not saying that the Volt has zero net CO2 emissions.  I was saying that once battery costs drop to ~$5,000, the net overall cost of buying and driving a Volt will be no higher than those of the equivalent ICE car.  At that point, there will be no need for any subsidy, and the CO2 emissions reductions from using Volts (PHEVs) vs. ICE cars will come at zero cost.  That is, $0 per ton vs. ~$1,000 per ton.

The fact that car companies are choosing to use EVs and PHEVs in part to meet the requirement of lower fuel usage (per mile), as opposed to relying solely on more efficient standard ICEs (e.g., deisels) or orindary hybrids, shows that they believe in their future viability and competitiveness.  Your statement that EVs and PHEVs should actually be excluded from CAFE is difficult to understand, and points to some deep seated problems (prejudices) you seem to have with the technology.  Even if one includes the (relatively minor) energy input from electricity, the effective mileage of these cars is way over any ICE or hybrid car (i.e., ~100 MPG) and, as I pointed out, there are additional reasons to want to reduce oil consumption, specifically, that go beyond CO2 emissions.  Given all this, they are more than justified for inclusion in any CAFE policy.

As an MIT physics grad who has worked in the energy industry all his life, I understand how electricity (and the grid) works just fine (e.g., how electricity follows Ohm's Law, as opposed to contract law).  How is selecting the (smaller) New England grid any more justifiable than selecting the California grid?  What's simplistic is to just take the generation mix of the national grid and assume that equals the incremental generation increase that would go towards charging EVs.  You seem to have missed, or didn't address, my point about how you have to look at incremental generation.

I undertstand that CA has some contract for power from (relatively distant) coal plants in Western states.  But all its in-state generation is gas, hydro or nuclear, and it also imports a lot of NW hydro.  Gas tends to be used for load following, especially in very gas-heavy systems like CA.  Thus, when I charge my car at night, I'm pretty sure that it's a gas plant that is being throttled up, not a coal plant.  As for the longer term, if and when off-peak demand from EV charging causes new power plants to be built, it's pretty clear that none of the new generation will come from coal.  It will be from gas or non-emitting sources.  Virtually no new coal plants will be built.  Coal is actually declining, fairly rapidly.

$300 million is still pocket change in the grand scheme of things.  Equal to only 1-2 days of the navy's cost for patrolling the Gulf shipping lanes (i.e., subsidizing and stabilizing the cost of oil).  I concur that coal to gas switching is the best option for reducing CO2 emissions over the shorter term (i.e., the next decade).  After that, EVs and PHEVs will probably make a substantial contribution.  The transport sector is ~40% of our emissions (equal to the power sector) after all.

Paul O's picture
Paul O on Mar 11, 2013

Here is an article that supports some of your ideas Willem.

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