Diesel versus Natural Gas Generators
Diesel versus Natural Gas Generators
(OP)
I am a Civil Engineer looking at providing information to one of my clients on selecting a large stand-by generator for a critical water well installation (200 Hp). I would like to provide the pro's and con's to my client on selecting either a diesel powered generator versus a natural gas (NG) generator. I have gotten some input from some of the generator manufacturers (Kohler, CAT) but I would like to find out other peoples experiences in dealing with both generator types.





RE: Diesel versus Natural Gas Generators
Diesel will normally have longer life (not usually a big deal for standby use), acquistion cost will be more, running cost for fuel will be less. The provision and maintenance for diesel fuel can be a real problem, as the client will likely need a fair amount for unattended use, and it will need to be rotated/changed more often if it is not consumed for its periodic run.
Natural gas units are usually more problem free in this regard, as fuel supply & maintenance are a no brainer.
If standby power is needed often and for long periods of time, then diesel usually is the way to go.
If it is rarely off and for short periods of time, NG is much more cost effective.
RE: Diesel versus Natural Gas Generators
I am getting different answers from the generator mnfr's. They indicate that NG generators (at least in the 400 kW range) are two to three times more expensive to purchase then diesel generators becuase they are a rare breed.
As for diesel fuel going bad, I have been told that there is some type of fuel additive that can be placed in diesel fuel that will reduce the effects of age on the fuel. Are you familiar with this additive?
Currently, in comparing the energy costs of diesel fuel with that of NG the cost to ship diesel fuel to the site is consiberally more then NG. This does not include the cost to "pipe" the NG to the site.
Again JW, thanks for your input, I hope we can prompt a few more threads on this subject.
RE: Diesel versus Natural Gas Generators
If this back up generator is that much of a necessity, I think it should be a maintenance person's job to run it every once and a while to ensure it functions. This should alleviate fears that people may have of allowing a diesel engine sitting for long periods of time.
Check out this link if you are concerned about diesel storage.
ww
-Reidh
RE: Diesel versus Natural Gas Generators
RE: Diesel versus Natural Gas Generators
RE: Diesel versus Natural Gas Generators
Gas engines require a spark ignition to fire the charge in the cylinder, diesel relies on compression and as such is deemed to be a little more reliable at starting when called for.
As I said Id go for diesel. Id also be wary about setting up a routine to run your diesels off load once a week or so as well its been shown that running an engine unloaded can cause a build up in the cylinders. Its best to load them up when running them to ensure that they get a fair crack at the whip.
Ive seen diesels that have been run regularly off load fail when run under a load condition. So best to run loaded just to tempt that failure! best to fail when you dont need it rather than when you really really do need it!
Rugged
RE: Diesel versus Natural Gas Generators
Rugged
RE: Diesel versus Natural Gas Generators
Not withstanding that caveat, my vote is for the diesel, but I echo the recommendation to run it loaded when testing.
rmw
RE: Diesel versus Natural Gas Generators
Any critical system you will find that they will run the diesel at the very least every couple of months just to be sure that it will come in and go onto bus no problem. Peace of mind especially if it did fall over the effect could be a lot worse than using a few gallons of diesel.
Can always use a load bank to give it a good run if required and these can be made up pretty cheaply if required.
RE: Diesel versus Natural Gas Generators
My experience is that natural gas and propane engines run cleaner and longer than diesel.
Maintainance is less.
You don't have to worry about ground contamination with a leak.
I love my diesel truck, but some folks think they smell.
AND if it is critical, your fuel supply can be nearly infinite with natural gas.
RE: Diesel versus Natural Gas Generators
Low flamability
Higher btu content of fuel
In the old days simpler fuel system
Less maintenance
Gas Power advantages
No need for fuel tank
Cleaner exhaust
Cleaner engine (combustion process/crankcase etc)
In a bad earthquake if gas lines are disrupted that would cut off fuel supply.
To remedy the diesel degradation use #1 fuel or jet fuel.