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Old 11-25-2009, 02:11 PM   #95 (permalink)
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Originally Posted by trebuchet03 View Post
So lets say a tractor trailer requires 50hp to maintain 65mph on the road (if you can find documentation for an actual number, I'd appreciate it). So in one hour, it produces 535g... Lets say 10mpg - that's 53.5g/mi * 295 = 15782GWP
CO2 would be 20lb = 9071g = 907g/mi * 1 = 907GWP Those number seem grossly far apart - but the standards of yore are vastly far from the standards today....
You are off by a factor of over 2x. My Jeep Wrangler requires 47 hp to maintain 65. All the big rig drivers I know say they get about 4.0 - 4.5 mpg hauling down the freeway.

Something to consider is the approach Detroit Diesel is taking with their current clean diesels - The DD15. It is a turbo compound that gets 10% free HP (50 hp) and an reduction of 5% fuel burn. It uses the same technology as the panicle in gas piston engines used in the last non-jet airliners - the Constellation - a turbo charger running the usual way, and an additional turbo down wind of the primary. This secondary does not have a compressor wheel to compress air, but rather is connected (serious gear ratio) to the crank shaft to convert lost energy out the exhaust into useful work.

My Dodge Caravan with a VW diesel gets 40 mpg at 70 mph, and 25 mpg hauling a large pop-up camper at similar speeds :-) GO DIESEL !!! Here its only 20 cents higher than low grade. so less than 10% - considering the 40% less fuel burn and 30% less CO2, I think its a bargain !!
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