Generator Fuel Tank Sizing (diesel)

[Npstewart]

I don't typically get into generator fuel tank sizing but I did on this particular project. Does anyone have any good references on how much fuel (diesel) a generator uses. Preferebly a table showing KW values and the respective fuel consumption per hour or per day.

I have a reference that says a 225 KW generator (diesel) uses 16.6 Gallons per hour. I need the generator to run for a week continuously at full load.

(16.6)(24)(7) = 2789 gallons total including the day tank.

Im only using this for preliminary design purposes. Someone from another company said it would require about 3 times that amount or upwards of 10,000 gallons.

Obviously this will be properly designed with manuf. actual specs but I need to have a preliminary.

Thanks for the help

 

[eric9822]

I found this:

http://www.dieselserviceandsupply.com/diesel_fuel_consumption.aspx

Disclaimer - I always ask the supplier of the generator to provide the fuel consumption data.

 

[renosteinke]

You definitely need to have a thorough chat with the generator supplier.

Even diesel fuel has a limited 'shelf life.' Likewise, every generator benefits from a reqular 'exercise' program, where it is regularly operated under full load.

Your goal is to have the exercise program use up the fuel before it 'goes bad.' Too much fuel, too large a tank, can be an issue.

I was fortunate that the last diesel I installed was also associated with a tank used to fuel the company vehicles. I was able to pipe things such that fresh fuel was circulated through the 'prime' tank on the generator every time someone ran the fuel dispenser.

Also note that I mentioned operating the generator under full load. Again, most folks size the generator far too large- but that's a topic for another day.

 

[Npstewart]

Yea, I definitely agree. We dont have a generator supplier yet. Im sure generators are pretty typical, the client was asking me if I had a rough idea.

 

[hurk27]

I'm liking NG more and more, no on site storage which can lead to EPA regulations and inspections.

You might want to see if you can go with Natural gas if you can get enough available supply? also generators will be derated if on NG.

Here we have plenty of NG and almost all our generator systems are NG

Even propane can be a good choice if long term fuel storage is a problem, as propane can sit in a tank for a long time, and there is no derating of a generator.

 

[tesi1]

Fuel tank sizing

Fuel tank sizing

Just do not take the gallons per hour and multiply by hours needing
to operate, by law you can only fill a fuel storage tank to 90 % & the
fuel pick up is usally off of the bottom of the tank a lttle bit in order
as not to pick up water or trash.

 

[__dan]

Your preliminary number looks pretty close, 225 kW / 16.6 GPH = 13.55 kw per hour per gallon of diesel.

I have an actual number for you from running with load, 2.6 mW loaded on four 1 mW units uses ~ 165 gallons / hour or 15.76 kW per gallon per hour running.

The good reference will be the one provided by the manufacturer.

 

[G._S._Ohm]

134,000 BTU/gal heat of combustion for #2 diesel x 16.6 gals = 2.2 MBTUs = 645 kwh.

100 x 225 kwh/645 kwh = 35% efficient for the engine/generator set.

If the diesel is 50% efficient then the generator has to be 70% efficient to meet this 35% number.

These numbers and efficiencies look reasonable but as a crosscheck you could ask for engine/generator efficiencies for this power range. In view of these numbers 10,000 gallons seems pretty pessimistic.

 

[Open Neutral]

I'm liking NG more and more, no on site storage which can lead to EPA regulations and inspections.
...
Even propane can be a good choice if long term fuel storage is a problem, as propane can sit in a tank for a long time, and there is no derating of a generator.

I just went through this. If you are not in earthshake territory, NG is a clear winner. Propane stores easily as well, but it's Tornado Alley, please bury the tank. [NHK had horrifying pictures of the waves heaving burning propane tanks inland; starting large fires we here have not even read about. Think monster-sized Molotov cocktails...]

Diesel has 2 advantages. First, it's not spark ignition so there's less to fail on the generator. Second, it's far easier to get a refill than with propane -- worst case, dispatch a crew with a truck of drums to somewhere selling it. Post-disaster, just try and get Jimmy's Propane to come by.

That said, at the OP's power demand, he may have no choice.

 

[Npstewart]

I wish I could use NG. I live in Florida, and around here NG lines are kind of a rarity.

As far as LP goes, it wasn't my decision to go with diesel however given that we live in a Hurricane area, I would rather go with Diesel because its easier to get a re-fill during emergencies.