Bus or Trucking Using Gas-Turbine-to-Pneumatic-to-Wheel Drivetrain

http://www.nrl.navy.mil/techtransfer/fs.php?fs_id=ENE03

Not exactly the same thing, but...

"The Naval Research Laboratory (NRL) is developing a small recuperated ceramic turboshaft engine with the fuel efficiency of a diesel. The four horsepower engine will weigh less than nine pounds complete, including an integral three kilowatt generator and power electronics. It will be about twice as efficient as a typical gasoline engine, and will achieve ten times the life and reliability while producing less noise and no vibration. This will be the first reliable, efficient miniature engine that complies with DoD 4140.43, which requires all future military engines to operable on "heavy fuel" (JP5/JP8/Jet-A). The fuel-flexible design can also be operated on biodiesel, gasoline, ethanol, and other liquid hydrocarbons without compromising efficiency, performance, reliability, or emissions. This novel design uses low cost ceramics for the turbomachinery and heat exchanger components. The recuperated design enhances efficiency, and allows operation with a very lean fuel-air mixture that reduces emissions. Scalable in the 1-10 KW range, this engine is suitable for any small turbogenerator application, including small unmanned air vehicle (UAV) propulsion, turbine-electric hybrid drive, and portable field generators."

Exact thermal efficiency info not given, but claims efficiency of diesel and I'm of the understanding that bigger g-t's will naturally have better efficiencies and this one is only 4hp.

hi given you a GA for that it is linked to the main topic

Ha ha - thanks for that! .... Any further thoughts???

Clearly the average bus company doesn't have the money to buy a Navy-issue g-t. However these things (esp. smaller g-t's) have come a long way since the widespread use of FEA modelling and ceramic blades.

I am encouraged by the articles mention of recuperating the exhaust heat - a method that is not directly workable in a piston engine.

I worked on some micro-turbine gensets, they were used for their small foot print and light weight, usually in high rise buildings, they were 100 to 125 KW and you could move them with a pump jack in a freight elevator, they burned almost twice as much fuel as a comparable diesel and cost about 5 to 6 times as much as a diesel. When they broke there was nothing left. But installation cost was low and it took very little real estate

I can only assume that the art of micro-gt's has come a little way since then (?).

I admit that the idea of a device 'blowing' at 100s of thousands of rpm is a bit more worrying than a few thousand, but Capstone have put a micro-turbine in a 'plastic' sports car so, who knows?

(replying to myself again!)

I especially like the simplicity idea of the first stage of gas compression being intricate with the g-t's compressor stage....

C'mom tell me why I'm wrong