Unicorns, Bigfoot, Nessie And Now T H I S...

jharrell wrote:

RSD559 wrote:
I understood that all modern locomotives are electric powered. The big diesels are to charge the batteries. The torque required to start a train rolling is immense. Electric motors are about the only thing that can produce that kind of torque.

There are no batteries, the electric drive train just replaces the transmission. You can get all the torque you want from gears, but a modern train needs very precise traction control to prevent wheel slippage. Much easier to do with electric motors than gears, however efficiency suffers. Mechanical transmission with gears is 95+% efficient, the double conversion from mechanical to electric back to mechanical in a train is under 80% but the trade-off is worth it to be able to get the thing moving properly. Also dynamic braking is useful too, just using motors to brake and electricity dumped to heat strips on roof.

OTR trucks and MH's are different, they dont need precise traction control they do need maximum efficiency at highway speeds though. Standard semi has 300 gallons of diesel and 2000 mile range. To do that with batteries your talking a 4-5 Megawatt-hour bank. That's a million dollar battery that weighs as much as your cargo.

So maybe do a 500 mile range with a 1 Megawatt-hour battery weighing 10k pounds for a days driving, then 10 hours to charge on a 100kw charger. What trucker would go for that? Will be interesting to see what Tesla shows in Sept.

Diesel-electric semi like a train? Why at highway speeds Diesel mechanical is more efficient, whats the point? Hybrid? Only helps in the city, nearly all hybrids connect engine to wheels directly on the highway for efficiency.

I like electric cars, perfect for commuting, decoupling fuel from vehicle is great. Today it runs off coal tomorrow solar, power plants are more efficient than small engines and can and do have more extensive emission controls. However its a long way off before we have batteries that make sense in long haul highway applications such as Semis and MH's.

There is more efficiency to be had in diesel mechanical, Cummins is showing a prototype with a secondary heat recovery turbine like a power plant, they tried driving electric with the turbine, found it was more efficient just to mechanically feed it into drivetrain.

Good and interesting post. I agree with moving the pollution problem to the grid and away from personal vehicles and city busses. As the grids get cleaner the pollution is less and the air gets cleaner. Many countries already get most or all their power from renewable or low polluting sources. Others not so much but I don't think anyone doubts that the trend on a world wide basis will be towards a cleaner grid. Some countries will lag behind but as the technologies get cheaper it won't make any sense to produce power from coal and at some point even natural gas. It will be like it always is, a question of economics.