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Re: Looking for advice on datacenter electrical/generator

  • From: Robert Boyle
  • Date: Sat Apr 05 00:13:49 2003 
At 06:25 PM 4/4/2003 -0800, you wrote:

    > http://electrochem.cwru.edu/yeager/ohiofuelcell/Norrick-Cummins.pdf

You're right, that's really good reading.
It is interesting to see where they think backup power generation is going and the current ratios of operating costs vs. purchase costs vs. fuel availability vs. power outputs and duty cycles.

> interesting unit which uses propane and/or natural gas mixed with the air
> to extend the runtime by adding significant BTUs from the gas. However, it
> can run directly on diesel alone should the gas supply be interrupted for
> some reason. Very neat technology and obvious after the fact, but much more
> expensive.

URL?
http://www.gastechnologies.net/bifuel.htm

This is one manufacturer of the control systems. We currently have enough diesel fuel to run for about 10 days without refueling so I couldn't justify the 2-3 times higher expense of a bi-fuel genset. Apparently, pretty much any genset can be modified for bi-fuel operation without any internal modification. The other advantage to bi-fuel systems is that the slew rate problems of lp/ng gensets are completely avoided. For those who haven't seen or heard of problems with natural gas or propane powered gensets, this is another argument against them. We heard from multiple genset vendors of slew problems and several actually refused to sell us gas gensets when they learned about our application - powering high inductive loads (A/C compressors) as well as UPSes with computer equipment. Apparently as the load changes based on cooling equipment cycling on and off, gas generators (even with electronic governors) have trouble keeping the RPMs constant. Cummings specifically stated that diesel gensets don't have this problem due to the higher slew rate and more accurate RPM control due to the higher energy density of diesel fuel - just another data point. He also noted that the bi-fuel (diesel/gas) systems did not exhibit this problem either.

-Robert


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