Energy Efficiency

[tfol...@earthlink.net]

Most of the discussion is on energy to overcome rolling resistance. For a standard car, energy to overcome aerodynamic drag becomes the more important term at speeds above 35 mph. For a light vehicle, the cross-over point can be as low as 12 mph. The drag factor dominates at high  speed, and it doesn’t care whether the vehicle is ICE or BEV. See https://www.researchgate.net/publication/356194082_Improved_Bus_Service_on_Ten_Times_Less_Energy

 

Tyler Folsom, PhD

Affiliate Professor

School of STEM

University of Washington | Bothell

206.618.7459

 

 

[Jerry Roane]

Tyler  It is possible to overshoot the runway on energy savings.  Once the energy to move people crosses the line from what is converted to electricity from the sun beating down on the system then it does not matter much how much more efficient those vehicles are.  What we all have limited in our lives is time.  We all get 24 hours each day and going slow in and of itself has no particular value.  Your first statement of 35 mph based on "standard car" is too simplified although I understand the teaching problem to the full population.  Many will take that 35 mph figure and run with it and we all know that is filled with error.    Here is a better calculator of that feature of vehicles so although simplified some it still maintains generic accuracy.  http://tritrack.net/horsePower.html  As for energy the bus is terrible as it is so, good paper.  Here is some backup material for buses as they are in the US today:

If you can calculate your rider percentage adjusted BTU per served passenger mile I can add it to this chart for comparison.

Jerry Roane

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[Burford Furman]

Jerry,

Do you have larger version of the graph? I can't make out the text along the bottom edge. Thank you!

Buff