[rollei_list] Re: OT - Turbines generating electricity
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Thu, 27 Jan 2005 12:42:58 -0800
----- Original Message -----
From: "David Seifert" <dseifert@xxxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Thursday, January 27, 2005 10:11 AM
Subject: [rollei_list] Re: OT - Turbines generating
electricity
> Ardeshir,
>
> I certainly wouldn't characterize this as a "trend" in
> shipbuilding.
> The vast majority of tonnage is being built with really
> conventional low
> or medium speed diesel engines driving shafts via gearing.
> While gas
> turbines are, indeed, quite efficient in the weight/power
> ratio, weight
> is seldom much of an issue for a large vessel. There are
> a couple of
> issues, first is the cost of fuel. Jet A costs a lot more
> than bunker
> fuel and the prices are much more volatile too! Second is
> a highly
> inefficient conversion of heat to electricity. None of
> the heat in the
> exhaust gasses are converted to electricity and are thus
> wasted unless
> you go to a very fancy system like GE created for Chantier
> and
> Celebrity. In this system the hot exhaust gasses are used
> to heat water
> which, in turn, runs a steam turbine which generates yet
> more
> electricity. This goes a long way to solve the heat
> recapture problem
> without messing with the efficiency of the gas turbine.
> Again, a very
> elaborate (and fairly large) system to improve on the
> fundamentally weak
> fuel efficiency problem of gas turbines.
>
> I have sailed on both diesel (both geared and
> diesel-electric) and
> turbine (both steam and gas) powered commercial vessels
> and I can tell
> you there is a distinct difference. The turbine powered
> ships are much
> smoother and vibration free. Other than the cachet
> Celebrity was
> convinced to go gas turbine not for the fuel efficiency
> reasons (there
> are none) but for space efficiency. The power plant is
> much smaller
> than an equivalent diesel system and thus provides more
> revenue space.
> Completely different economics.
>
> Needless to say, none of this applies to cars!
>
> Best,
> David
>
> Ardeshir Mehta wrote:
>
I was not aware that marine deisels burned bunker oil, I
thought that was confined to boilers. It must need to be
heated to get it volitile enough.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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