Calculating Consumption for a Diesel Generator

There are three reliable options for you.

1) Buy or hire two inline flow meters (either mechanical or electronic) and run the generator at different loads.
One for the Fuel intake, one for the return...the difference is what is burnt by the prime mover.

2) If it has one, check the generators electronic management system.

3) Check the Generator Manual or contact the manufacturer.
The Manual will have either a fuel consumption graph or consumption @ 25%, 50%, 75% & 100% loading.

Regards,
Sapper

diesel consumption measured using flow meters will not give you correct fig.correct method would be you need to weigh diesel calculate consumption in Grams/HP/Hour thats the method specified by ISO and followed by every engine manufacturer world over Volumetric methods will give you approximate fig which is misleading unless you apply corrections for temperature of return line diesel to the tank which is cumbersome.

crm

True, Volume is not the best way, but depending on your accuracy requirements this is easiest to perform onsite.

Options 2 or 3 are prefered options, but require outside assistance.

Best is to contact the Manufacture.

Regards,
Sapper.

Hi guys,

Not being one to argue, especially with a fellow Sydneysider, but I have a couple of small points, (said the actress to the bishop). Firstly we should get a concept of the order of magnitude and accuracy desired by our Guest. If he/she is simply comparing for domestic use on one house, then don't bother, unless you are high on a very difficult site where poles and cables need to be installed, then grid power seems always to be very much less expensive. Continual power failures might be an added cost, but lets not go there.

Secondly, the engine manufacturer will have a set of curves, but not for fuel consumption in gallons or litres, but for Specific Fuel Consumption, ie, grammes per killowatt hour (or lbs/hp/hr)., for various engine loads. To this you need to add the inefficiency of the generator itself, usually about the 15% mark for smallish sets up to maybe 300kW.

Dont forget that temperature increases cause the volume to increase ( but dont start me going on the fuel companies twaddle about temperature constant allowances), so 0ne litre/gallon really reduces by 0.05% per one degree c increase.

To this, add the lube oil consumed and changed, here again the engine manufacturer will give a max oil consumption figure. (usually about 1.5% of the fuel consumption)

Finally add a little maintenance, mix it all in together and you will probably find that silly old Skippy has been rabbiting on in far too much detail, and you will simply get the mains connected. Anyway the exercise was good for me. If you want more accurate stuff, reply to this forum,,,many hands make light work

You are wasting your time & money if you think you want to generate your own power using this system. Home generators are for back up only. The efficiency of a powerplant is always greater than that of any home generator !!!

1. Powerplants buy their fuel in bulk, you'll be in retail - economy of scale
2. Powerplants buy their fuel more often, you'd probably buy when you're running on fumes - velocity of money.
3. Most powerplants operate their diesel generators only during peak hour needs, and these generators operate on a much higher working temperature than the home use generators - Carnot cycle.

Remember the fundamental laws.

I guess I fell in to one of those Ass-u-me(tion) traps.

Assumptions:

1) This information is required for a stand-by\emergency generator.

2) The information is calculate run times based on onsite fuel storage for capacity planning.

3) No-one is would have a generator as prime power anywhere near a grid feed.

For the Gensets (2 X 2.5MVA) we have onsite for the Data Centre within 10litres per hour is good enough regardless of temp.

Regards,
Sapper.

I suggest you visit India you may not believe it we were operating a factory 18hours a day on prime duty generators 1000kvax3 and 125Kvax2 .In India by and large generators are part of plant and machineries Diesel engine manufacturers and Gen set builders are having a field day for last 30years.I had experienced 75% demand cut from the grid during peak summer ! situation is going bad day by day To day New Gen sets are to be booked one year in advance if you any one is planing a new building.

crm

A rough rule of thumb when working out how much fuel we need for a mobile diesel gen.set is 0.35 litres per hour for each kW of load [0.35 Lt per kW/h].

So if you have a 60kVA gen.set (48kW) running for 2 hours at 1/2 load :

2(24 x 0.35) = 16.8 so approx 17 liters of diesel

a 1kW diesel gen.set will use just over a 1/3 litre an hour

Add 10% for reserve / inaccuracy, it will vary between engine manufacturers but they are not that far apart.

We use this on sets up to 500kVA.

Note: it will obviously be different for petrol or turbines engines & even if you are using a replacement fuel (e.g. paraffin / kerosene)

Engine manufacturers will easily give you fuel consumption for 1/2, 3/4 & full load.

Our John Deere 80kVA set fuel consumption is

Fuel Consumption – l/h 1500 rpm
Prime = PRP Standby = LTP
25% Power ..... 5.0 .................. 5.5
50% Power ....10.0 ..................11.0
75% Power ....14.0 ................. 15.5
100% Power.. 19.5 ................. 21.5

I may have some insight on this question .

I run a 100kw generator that burns about 5 gallons per hour .

To buy power from the local utility I would have had to commit to a $2000 monthly charge regardless of my consumption as the utility had to allocate that power at all times .

It was an easy decision for me as I would never use that much power on a monthly basis I would usually consume less than 200 gallons of fuel for my application or about 40 hours a month.

I have run that way for over ten years and for me it was by far the best thing to do.

At one time I calculated my costs and compared it to buying power and it came out to be about the same although I needed to accept the maintenance and long term replacement costs but in the end ,for my application, it has worked out by far to be the best to generate my own power .

Out of interest Trad. is that US or UK gallons? What power are you supplying; ~70% load I guess; any idea of the amps / volts? [should work our ~1/3lt /kW]

In a 'straight fight' one won't generate power (in quantity) for less than the RECs (Regional Electricity Company) sell it - unless there are special circumstances: like strange load as Marcot pointed out, isolated spot where it costs lots to run in a power line or very low usage with high standing charge.

We quote all the time for such applications. Gen.set prices have dropped considerably in the last decade, the secondhand market is very active but it's the price of the fuel here in the UK, even using 'red' (lower tax for non transport use)

That would be in US gallons .

I am running a sawmill with a 125 hp electric motor I use a step starter (home made) to get it going .I am intermittently at full load but as I said the power company charges for that startup required and I believe with my use it was the best decision .

I simply looked at my consumption by refilling my tank and reading hours.

I use home heating oil as I do with all my off road equipment.

Buy the way I have an old 671 Detroit motor as power for the generator I found it cheap reliable and maintenance free that I purchased over ten years ago with about 1000 hours for $5000 not glamorous but very functional

125hp ~ 90kW (93.2)
With a saw it is a short time intermittent full load, so say load profile 40-90 kw with average <60kW & with 5 US-gallons ~19 Lts (18.9)
20 / 60 = 1/3 Lts per kW

With kerosene you get about 3% less power on the same consumption as diesel.
As I say it's a rule of thumb but works.

Dear Sir,

This is Kumar, i have 45 kva gen.set, HP/ RPM : 56/ 1500. Engine type HA 494 TC.

Full load R.P.M. : 1500.....

Now, How can i calculate per hr consumption and standard consumption.

here i have to use 2 to 3 hr per day..only, and one day...it's run 9 hr's.

I need to your guidance regarding this. if any formula for this..???

I want to proper formula..., so, Kindly help me.....

this is my id: urfriend1311atlivecom.

Thanks and Regards,

Kumar

If the load power factor is below 0.7 and or the current harmonics content is above 20-30%, you might need to oversize the generator which cost more and will reduce the efficiency. The only way around this is to add an automatic filter bank. Contact me if you need more info.

If the Genset has a day tank, Just fill it and run under full load for an hour. Fill the day tank with x amount of gallons and you have a rough estimate. Do the same for light load.

If you have no day tank you can just use a 5 or 10 gal. bucket as your fuel test.

My question kind of relates to this forum because I want to find out if it is feasible to buy a diesel generator, convert it to run on soy and waste oil, and use it to heat my house. That is take the latent heat of the generator and turn my base boards in my house into the cooling system for the generator, and then obviously the electricity wouldn't have to be comparable to grid prices, and the price to operate the generator would have to be less than the cost of my heating oil the electricity would just be a by product.

Think of it as a furnace that produces electricity.

dear you

attached your pannel a ccb in your output. and one energy meter.

take reding of goverment supply. and minus your energy meter reading.

then calculate your disel consumption per hour,

like this:- A=b+c

a= energy meter reading

b= goverment power supply reading

c= d.g unit.

i hour conyunue run your d.g unit come-20

then oil cost into hour

dived by unit come you per unit cost.

if i have 1275 kva and runs at the laod of 1317 what will be the fuel consumsion

The general rule of thumb is 4 ltrs an hour for every 17.75 hp used at any given time/load. This is right out of the Detroit Diesel repair manual. I've heard that John Deere makes a 4cycle diesel that gets 18.25 hp out of every 4 ltrs an hour.

Dear Guest,

The Diesel Consumption depends upon the Efficiency of the Engine and Generator. An efficient and GOOD set/system will have a Diesel Consumption of 206.28 gms/kW.Hr. as SPECIFIC FUEL CONSUMPTION at FULL LOAD.

At 75% FULL LOAD the same good DG SET will have a SPECIFIC FUEL CONSUMPTION of 205.9 gms/kW.Hr.

At No-Load the Diesel Consumption will be 10 to 10.2% of the Full Load consumption. Adultered Diesel will not fit in to this band, which will be less in CALORIFIC VALUE.

We should always try to run the set at Full Load or near Full Load in order to achieve best Fuel Economy.

A similar question appeared in this Forum about 6 months back and you can search in this Forum and many CR4 Members responded with their comments. In that Forum you will find that the Specific Fuel Consumption in FPS unit as 0.28 Lb/H.P.Hr (since I studied in FPS SYSTEM) posted by me.

Thanks,

DHAYANANDHAN.S