http://www.triplepundit.com/2007/04/askpablo-well-to-wheel-efficiency-part-i/ Business, Better. Since 2005 Tue, 16 Mar 2010 13:45:56 -0700 http://wordpress.org/?v=2.9.2 hourly 1 http://www.triplepundit.com/2007/04/askpablo-well-to-wheel-efficiency-part-i/comment-page-1/#comment-14669 Daryl Oster Mon, 01 Jun 2009 02:20:24 +0000 http://www.triplepundit.com/wordpress/2007/04/askpablo-well-to-wheel-efficiency-part-i/#comment-14669 Actually any transportation system that uses energy has zero transportation energy efficiency! The reason is that for true efficiency measure one must divide into the energy used by the best theoretical alternative -- and the best alternative uses ZERO ENERGY for transportation. The earth is one such approximation -- all 6+ billion humans have spent their entire lives moving at 67,000mph in orbit around the sun. And our solar system orbits the milky way galaxy at 200,000mph, and our galaxy orbits the apparent center of the known universe at about 400,000mph. Therefore the average human travels more than 250 billion miles in their life time yet uses no energy to do so! -- by comparison, any earth bound vehicle has almost zero TRANSPORTATION efficiency! So we can only compare energy USE (not efficiency) to travel a given distance. Of course thermal efficiency effects energy use, as does aerodynamic drag, and rolling resistance. And it is proven that both of these terms can be practically reduced to almost zero in the case of Evacuated Tube Transport (ETT) tm. Actually any transportation system that uses energy has zero transportation energy efficiency!
The reason is that for true efficiency measure one must divide into the energy used by the best theoretical alternative — and the best alternative uses ZERO ENERGY for transportation.
The earth is one such approximation — all 6+ billion humans have spent their entire lives moving at 67,000mph in orbit around the sun. And our solar system orbits the milky way galaxy at 200,000mph, and our galaxy orbits the apparent center of the known universe at about 400,000mph.
Therefore the average human travels more than 250 billion miles in their life time yet uses no energy to do so! — by comparison, any earth bound vehicle has almost zero TRANSPORTATION efficiency!
So we can only compare energy USE (not efficiency) to travel a given distance. Of course thermal efficiency effects energy use, as does aerodynamic drag, and rolling resistance. And it is proven that both of these terms can be practically reduced to almost zero in the case of Evacuated Tube Transport (ETT) tm.

]]> http://www.triplepundit.com/2007/04/askpablo-well-to-wheel-efficiency-part-i/comment-page-1/#comment-14668 William Hertling Sat, 05 May 2007 21:02:16 +0000 http://www.triplepundit.com/wordpress/2007/04/askpablo-well-to-wheel-efficiency-part-i/#comment-14668 Hi Pablo, First off, let me commend you on an excellent job with these calculations. I think they are very educational in that the various elements of the calculations help you see how different aspects of driving style and vehicle choice affect vehicle efficiency. However, the point of driving anywhere is generally to get you from Point A to Point B (as you also point out in next week's column. But note that the purpose is to get YOU the driver (or the driver and passengers) from Point A to Point B, and not the vehicle. We rarely drive just to move our car from one place to another. So to get a true efficiency calculation, we need to add in the factor of the driver's weight compared to the vehicle's weight. I couldn't find gross vehicle weight for the Matrix XR online, but let's assume that it is 2500 pounds. Then let's assume that the average driver is 175 pounds and that, for the sake of this calculation the overwhelming majority of trips are single occupancy trips. With those three assumptions, we see that the driver makes up only 7% of the total mass being moved from one place to another. So I think the true efficiency of your vehicle is closer to 19.9% * 7% = 1.3% total system efficiency. Hi Pablo,
First off, let me commend you on an excellent job with these calculations. I think they are very educational in that the various elements of the calculations help you see how different aspects of driving style and vehicle choice affect vehicle efficiency.
However, the point of driving anywhere is generally to get you from Point A to Point B (as you also point out in next week’s column.
But note that the purpose is to get YOU the driver (or the driver and passengers) from Point A to Point B, and not the vehicle. We rarely drive just to move our car from one place to another.
So to get a true efficiency calculation, we need to add in the factor of the driver’s weight compared to the vehicle’s weight. I couldn’t find gross vehicle weight for the Matrix XR online, but let’s assume that it is 2500 pounds. Then let’s assume that the average driver is 175 pounds and that, for the sake of this calculation the overwhelming majority of trips are single occupancy trips. With those three assumptions, we see that the driver makes up only 7% of the total mass being moved from one place to another.
So I think the true efficiency of your vehicle is closer to 19.9% * 7% = 1.3% total system efficiency.

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