<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div>On Oct 24, 2010, at 11:49 AM, Keith Henson wrote:</div><blockquote type="cite"><div><font class="Apple-style-span" color="#000000"><br></font></div></blockquote><blockquote type="cite"><div>The power output from a turbine is the product of the RPM and the torque.</div></blockquote><div><br></div>I know, so the faster the RPM the weaker the torque. Gas turbines have very high RPM's.<br><div><br></div><div><blockquote type="cite"><div>you can use any RPM for an AC generator.<br></div></blockquote><div><br></div><div>Provided you have something with enough torque to turn it.</div><br><blockquote type="cite"><div>It just changes the frequency.</div></blockquote><br></div><div>Electrical frequency is not the problem.</div><br><blockquote type="cite"><div>Reduction gears reduce the speed and increase the torque while introducing loses.</div></blockquote><div><br></div><div>That's the problem.</div><div><br></div><blockquote type="cite"><div>At the time I worked in the EMD plant, locomotive engines ran at 900 RPM.</div></blockquote><blockquote type="cite"><div>It would be no problem to replace one with a equal power 9000 RPM turbine. </div></blockquote><div><br></div>And some gas turbines have an even slower RPM than that, but they tend to be HUGE, the sort found in power plants, more typically they operate between 10,000 and over 100,000 RPM, the smaller the faster, and the one in a car would be a lot smaller than the one in a locomotive.<br><div><br></div><blockquote type="cite"><div>The point is that after you have electric power you can<br>drive electric motors over a wide speed range.<br></div></blockquote><div><br></div><div>But to get that electricity you need a gas turbine and they operate most efficiently under a constant load. That's not the sort of load you expect from a car, it's constantly accelerating and decelerating.</div><div><br></div><div> John K Clark</div><div><br></div></div><br></body></html>