Looking for advice on datacenter electrical/generator
robert at tellurian.com
Sat Apr 5 05:11:30 UTC 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.
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
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