Tesla co-founder garbage truck tech...

[Shannow]

https://www.wired.com/2016/07/tesla-co-founder-making-electric-garbage-trucks-jet-tech-not/

Quote:
TURBINE ENGINES ARE ideal technology for jets. They cram piles of power into a small, lightweight package, and have revolutionized air travel since their invention in the 1930s. Ian Wright sees them revolutionizing something else: garbage trucks.


Quote:
These 66,000-pound trucks won’t win any drag races (no ludicrous mode), but the innovative drivetrain could reduce fuel consumption by 70 percent. The electric motors provide 400 horsepower and enough torque to happily trundle up a 40 percent grade. The motors double as generators, capturing energy as the truck slows. It’s a seriously beefed up version of what your Prius offers: They provide 1,000 horsepower of stopping power—the kind of might a truck driver with a heavy load on a stop-start route tends to demand.

An overnight charge provides 20 miles of range before the turbine kicks in. At just 250 pounds, about one tenth the weight of a conventional engine of similar power, it’s a featherweight. If you’re worrying about noise, relax: The trucks run on electricity most of the time, and even with the turbine running they are said to be far quieter than diesel trucks.


It's not a bad concept but a small GT sounds ludicrous...the 1/10 the weight of a conventional engine of same power is obviously comparing it to a 1 tonne diesel engine.

 

[JHZR2]

Hybrids are ideal for these trucks. Instsnt torque at low speed and lots of torque to recapture. A lightweight gas turbine would increase load carrying, which is what these are all about. Make it small enough that sfc is in the efficient part of the curve (likely single spool design) and it may not be that bad of an idea... Other than maintenance.

 

[Shannow]

Fair enough, what sort of BSFC numbers to these small turbines pull ?

I've sort of only looked at the Capstan micros, and the power generating big ones, not in the middle.

 

[DoubleWasp]

BSFC is going to rely on how many stages and reheaters they can cram in there. If they can do enough, BSFC should be pretty good with today's modern aerodynamic developments.

 

[Nebroch]

But will turbine have a chance against modern heavy duty diesel? Diesel's efficiency is ~40-45 % these days, that turbine gets maybe 33 %.

 

[Vikas]

where is 1/10 weight claim is coming from? it is very hard to believe. rest of the stuff makes lot of sense. you want to talk about stop-and-go-driving and nothing beats the garbage truck picking up garbage in a town!

 

[JHZR2]

If the turbine is small enough, it could be recuperated. A single shaft at an optimized loading should be able to hit 30%.


You need to consider that a large diesel at 40-45 is at some optimal load point. A garbage truck idles. A lot. The efficiency then is really poor. An undersized and power dense NG turbine with hybrid will allow optimal loading. Thus the real efficiency will be more likely to be realized over time compared to a pie in the sky diesel efficiency for an engine that rarely hits a sustained loading in service.

I'd think a COE tractor design would be prudent for trucks that have to drive long distances to dump the load once collected. For highway runs is think the big diesel is still prudent. But the hybrid would be perfect for municipalities/cities with lots of neighborhoods.

 

[Jetronic]

but you could have a smaller diesel running at it's optimum point charging the batteries, and no mechanical drive

 

[KrisZ]

Originally Posted By: Jetronic
but you could have a smaller diesel running at it's optimum point charging the batteries, and no mechanical drive


I was thinking along the same lines. A turbine will be very maintenance intensive when compared to a diesel engine. Was that factored in during the pitch? I think not.

 

[supton]

What is the emissions out of a turbine? I know they have a "compressor" but I don't think they have high "compression" and thus should not have the NOx that diesel motors have.

Am wondering if a gas turbine has some edge in that area.

 

[JetStar]

Gas turbines can have compression ratios of > 17:1. GE has done work to reduce NOx emissions on their engines starting about 20 years ago. I don't know how they compare to diesels per pound of fuel. The problem with small turbines is the high RPM's and the life of the engine. When you look at costs, and what is available, I think that a small diesel running at it's most efficient constant speed in a Hybrid system is hard to beat. Much like the hybrid mass transit buses I see on the street now.