Wednesday, March 13, 2013

Real MPGs Of Plug In Vehicles

After last week’s blog on the Tesla exposing the primary energy needed for producing the humongous battery pack in that rich man’s car, I did an analysis of other plug in vehicles and how green or gangrene they are.  Note I use the DOE Argonne labs value for primary energy needed for lithium ion battery production and the Consumer Reports winter driving scenario in the Northeast USA as the basis for the comparison.

The greenest plug in are the Toyota Prius with 4.3 kwh of batteries and the Mitsubishi I MiEV with 12 kwh of batteries.  The Mitsubishi is a very light car with a curb weight of only 2,579 lbs.   The plug in Prius has a curb weight of 3,165 pounds.  The lighter mass of the Mitsubishi helps it attain the same Green Machine rating.  They each achieve approximately 43.5 MPG equivalent on the thermodynamically correct Green Machine scale.  Also the Mitsubishi has 3 times the range on electric power than the Prius.

The Honda fit which is light at 2,850 pounds curb weight and has a 20 kwh battery pack attains slightly less mileage on the Green Machine scale coming in at 43.3 MPG.  For all intents and purposes one may say that the Fit is as green as the Prius and Mitsubishi plug ins.  Of these three vehicles, the Fit has the longest range on electric power

Ford CMax and Fusion plug ins achieve approximately 40 MPG equivalent on the Green Machine scale.  Both of these Ford vehicles have lithium ion battery packs with 7.6 kwh of capacity.  These cars are quite heavy with curb weights of 3,899 and 3,720 pounds respectively.  Given their larger mass, Ford has done a remarkable job in attaining a respectable MPG equivalent on the Green Machine Scale. 

The Chev Volt similarly earns 40 MPG equivalent on the green machine scale with its 16 kwh battery pack and cub weight of 3,781 pounds.    The Volt has greater range than the Ford plug ins (perhaps twice as much) hence more miles a year can be traveled on battery power than the Fords and hence the amortization of the primary energy to produce the larger battery pack is over more miles.

The Nissan Leaf comes in a little worse than the Volt on the Green Machine scale with 39 MPG equivalent on the Green Machine scale.  Given how cheaply Nissan is selling the Leaf one can pick up a 1 year old Leaf for half the price of a new Volt so folks may be able to get affordable transportation in buying a used Leaf.

The soon to renamed Fisker is a stage 1 gangrene car when rated on the Green Machine scale but is far less gangrene than the Tesla Model S whose CEOs set out to hog all the available lithium on the planet.  The heavy Fisker, 5,600 pounds of curb weight, has a rating of 33.5 MPG on the Green Machine Scale as it only has 22 kwh of batteries and did not need massive primary electrical input that the 85 kwh Tesla battery pack needed.  As reported last week the Tesla Model S wins the Green Machine Gangrene Award on the Green Machine scale for only achieving a paltry 24 MPG equivalent.

Of course in performing these calculations I had to make an estimate how many miles will be driven each year in each car using battery power.  I also assumed that all cars have a battery pack with 8 years of life.

The founder of Fisker Mr. Fisker resigned from his company today.  It is fitting that this dog of a company brought to us by Al Gore and his partners at Kleiner Perkins rename the company now that the founder has left.    I think Bruiser would be a great name for the company given how bruised Dr. Chu Wow Wa became for investing DOE money in this Legally Blond idea of a car company.