CAFE stds on the chopping block

Turtle n Peeps wrote:

ShinerBock wrote:

LIKE2BUILD wrote:

I took several graduate classes in Environmental Studies and one of the professors always talked about SLOT Efficiency....SLOT= Second Law of Thermodynamics. The second law deals with entropy (chaos) in a system, the transfer of heat (energy) and that all inputs of energy into a non-reversible system interact until it reaches equilibrium.

Basically, it means exactly what you just said. You can't just look at the EPA rating on the sticker and assume you're more efficient. You have to look at SLOT efficiency, or the entire system required to make the car plus the efficiency of each individual vehicle. Does it take more energy to create the parts of a hybrid car? Maybe. Will it last as long as a diesel or gas powered car? Does it need the same, fewer, or more inputs (replacement parts) than an equivalent combustion powered car. What are the sum total pollution outputs of each piece of the manufacturing pie to make each car, the fuels (electricity of petroleum), and the replacement parts.

A diesel locomotive is a great example. If you look at the fuel they guzzle it will boggle your mind. But, if you compare fuel useage in terms of gallons/ton/mile the locomotive is vastly more efficient than an equal number of semis needed to carry the same load the same distance. Also, when you compare vehicle maintenance, road/track maintenance and all other pieces in the puzzle the locomotive still wins. So yes, a locomotive burns a LOT MORE fuel than a semi, but when you compare how much work it does for the same amount of fuel it's a huge advantage. The road surface? concrete and asphalt can be sort-of recycled. Steel train tracks? Melt them down and get almost all the steel back into new tracks.

KJ

Very solid points. A good friend of mine were talking about this very same thing the other day with the 2010+ diesel regulations of .01 g/HP-hr PM and .2 g/HP-hr NOx and what it takes to get there compared to the 2004 emissions regulations of .2 g/HP-hr PM and 2.5 g/HP-hr NOx and what it takes for that.


We were debating whether the considerable drop in fuel economy in the truck itself, more fuel needing to be transported since more is being used, DEF manufacturing and transport logistics that come with it, the manufacturing of the plastic jugs for DEF along with their environmental impact, special catalysts that require more rare earth mining, and DPF's along with their cleaning equipment worth the difference in emissions standards. From what we gathered, it would probably be better to go back to the 2004 emissions standards, but that was based on what we know and not any hard data.

2 very, very good posts that make one go; hmmmmmm! :)