<i>In the turbine train,........ the alternator needs to be spinning to provide enough DC link V, otherwise the HEP inverters won't play ball. What isn't said, however, is that as long as a certain amount of burn is taking place, the turbine will spin as fast as the load allows. In this turbine, there's two separate shafts- the compressor shaft, and the PTO shaft... and they're not connected by anything other than aerodynamics. Once the compressor shaft is running, exhaust pressure drives a turbine stack downstream of the compressor's driven turbine. If the alternator load is low, exhaust pressure will spin the PTO shaft pretty fast, so you'll have link voltage. SO, the net answer is that it doesn't take full throttle to push the turbine shafts to full speed... it just takes a minimum amount of exhaust gas pressure and a light load." </i>
This isn't anything new - turboshafts operate like this. But, it STILL doesn't mitigate poor part throttle economy.
<i>I hope all can see that full turbine rpm does not equate to full throttle fuel consumption in this system. Here is where it effectively beats a diesel in providing HEP. </i>
No, it doesn't beat a diesel.
<i>"To make for an even larger mess, don't forget that of all the energy which a turbine converts (from chemical, to thermal, to kinetic), almost 75% of it is used simply to sustain itself. Seems like a shocking number, but reciprocating piston engines are right behind... requiring just over 50%."
Seems like your fuel efficiency stats are a bit off. </i>
Not really - the best diesel in the world achives over 50% therodynamic efficiency. That's far better than the best simple cycle gas turbine.
<i>1) you can't throttle down an HEP-providing diesel; and </i>
Whoops. You can, and they do. Ther'es zero need to run a HEP generating diesel at a constant RPM or throttle setting.
<i>2) the turbine has much less mass to accellerate. </i>
But it's also gotta accelerate more.
<i>Passenger locomotives use a large chunk of their HP simply to make the train comfortable. Same goes for airplanes. </i>
Only 200 or so HP.
<i>Such a comparison to JetTrain is a major stretch of logic and patently unfair.</i>
No, it's not. All the JetTrain is, is yet another different transmission attached to a gas turbine engine. There have been plenty of attempts at this, they've all failed because gas turbines are simply poorly suited for constantly varying loads.
<i> Besides, once again, the goal was to not prove it better than diesels in fuel consumption. It was, rather, to prove it better than diesels in acceleration and sustained top speed.</i>
And that gap no longer even exists, since Talgo has demonstrated 150mph diesels. The gap never really existed overseas anyway - 125mph diesels have and continue to exist in Europe.
<i> And, yes, even though there were no Acela cars available to pull, performance data pulling Amfleet and Horizon cars in CO and LRC cars in Canada strongly suggests that it would have/will pull Acela cars in parity with electric Acela power cars. </i>
That's actually not what I've read. The time to 150mph in the studies I've seen is considerably slower than an electric. Amfleets are considerably lighter than Acela cars. AFAIK, there has been NO straight up A/B tests Vs the Acela.
<i>The FLHSR debacle supports your point. However, competing contractors stating that their cost of electrification is significantly lower than projected seems suspicious to me because they are the only ones so far who have claimed so.</i>
Electrification isn't a big expense in HSR projects. This is standard experience throughout the world.
The rest of the world doesn't live in a freefall of rail funding (indeed, SJ has been teertering on Bankruptcy for a while now). If turbines were truely less expensive, they would have developed eleswhere. They haven't. Electrification is still standard for HSR lines everywhere. You can debate theoreticals all you want, but practical experience has shown that electrification costs aren't a big deterrent to HSR.
<I> And we must take into account that the Republican administrations both in FL and D.C. are vehemently opposed to HSR expansion and COULD have influenced those contract bids/estimates in ways we cannot yet imagine. </i>
Oh please. That's just tinfoil hat conspirancy thinking. There's absolutely zero evidence of it. It was no secret, however, that the FRA was pressuring Florida to select JetTrain, though, which, given the money they've dumped into it, isn't a surprise.
HSR in FL failed for a simple reason - there's no supporting locoal transit. Without any local or regional lines to feed HSR lines, the potential ridership is so seriously constricted that the economics just aren't there.
I'd say Texas or California would be where the first true HSR lines get built, as California has plenty of local transit, and Texas is currently experiencing an LRT explosion. Florida has so little local transit that HSR makes no sense at all right now. It's not partisan politics that killed it.
Yeah, I lost the war, but I fought a GOOD fight.
