Tuesday, June 4, 2013

Tesla Gets Ridden Hard By Dr. P.



I am not talking about the stock dropping from its recent high.  The stock will probably drop further as it simply is overpriced, over hyped, and over promoted as being green.  But who knows the stock has defied gravity and logic before so it could go back up.

A friend of mine who is a MD (Dr. P.) in Southern California bought a Model S with the 85 kwh battery pack and the unlimited mileage warranty on the battery pack.   Dr P. lives 50 miles away from his medical office and has a terrible commute if he cannot use the High Occupancy Vehicle (HOV) lane.  Dr. P. uses his car to travel 25,000 to 30,000 a year.

He was told he was being mighty green buying the Model S and was told he is achieving 89 MPG equivalent.  Dr. P contacted the Green Machine to establish his real MPGs and his real level of greenness.    Dr. P. gave me the following information from his data logger that he is averaging 0.343 kwh per mile (battery energy to the wheels).  He is using grid supplied electricity to charge his car and the losses from the power generation station to Direct Current to the terminals of his battery pack are estimated at 15%.  Therefore Dr. P. uses 0.404 kwh of generated power per mile.

The US DOE has published emissions for the electric grid in California and this is 0.658 pounds of CO2 per kwh of power generated.  The batteries were made in Japan and post Fukashima the average grid emissions for Japan are 1.438 pounds of CO2 per kwh.  The average emissions for the US grid are approximately 1.3 pounds of CO2 per kwh.  It is interesting that power generated in California has less than half the CO2 emissions than power generated in Japan post Fukashima and the closure of all nuclear power stations in that country.


As explained previously I have developed a model for estimating the MPG equivalent compared against gasoline by amortizing the primary energy used to manufacture the batteries plus adding the charging energy to keep car moving.  Dr. P. drives much more than the average Model S owner and will hopefully get 175,000 miles out of his battery pack.  On this basis and the equivalent MPG that Dr. P. will likely experience owning his Model S is modeled at 42 MPG.  This is pretty green as Dr. P traded in his Lexus with 175,000 miles that only achieved 21 MPG.   Unfortunately the 42 MPG is not the 89 MPG he was sold by Tesla.  The real culprit is the US EPA that provides fake numbers to help promote the chosen green policy de jour of the administration. 


Using the Japanese and average US grid data, a US motorist who only travels 80,000 miles over 10 years in the Model S will experience a real equivalent mileage of only 19.73 MPG.  The average US motorist wishing to be greener should have bought a diesel Porsche Panamera rather than a Tesla Model S.  Dr. P. has the unique advantage of driving his Tesla hard (over 25,000 miles a year) and then recharging with greener electrons from the California grid.

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