BIG generator questions

Okay, I know this is dumb (maybe).....
But, fairly large 3-ph genny's, say? 80-100KVA, what would be cheaper to run? Propane or diesel?
I used to work for a guy that powered his machine-shop with a CAT 3-ph genny for a while. I seem to remember needing to fill the 100ish gallon tank once a week?
It has been many years, and it wasn't my job. But, I'm pretty sure that is about how much fuel he was burning in 40-50hrs.
I wish I knew how big the unit was! But, I just don't know (and the numbers would have meant nothing to me then).
But, I know what machines he was running. I am going to assume it was at around 60KVA. It was a CAT genny with ironically a Deere 4cyl diesel, I know that much.
Right now, off-road diesel is under $3 most places. So, if a genny used 150gal/wk? We're looking at roughly $1800/mo in fuel costs.
This isn't too far off what I'm paying the power company. I assume the diesel is more efficient than propane. But, I honestly don't know?

I have a couple different generator. one a 50Kw with 4 bt cummins Burns about 30 gallons in 10 hours running 40 horsepower Worth of electric motors
100 kw burns about 40 gallons in 10 Hours Under load About 60 horse on that one

Have you looked at these 50 to 100 hp single phase motor driven generators? Yes, that is a 100 hp single phase motor driving the 3phase genny.
https://singlephasepowersolutions.com/2019/03/18/1to3-power-source/
Solar panels can help offset the electric costs.
If I had the choice of propane or diesel I would go propane unless diesel was WAY cheaper. Cleaner running so less oil contamination, let it sit almost forever and it will start right up. Just get a big 500 gal tank and the guy will fill it on a regular schedule, That should be available with diesel also, but what delivery charge? If you have to fetch the diesel then, HELL NO.
Do you have Natural gas? NG is cheaper here than propane.

We rented a cat 250 kw diesel gen running 24 hrs a day at about a 160 k load it would burn about 500 gals in two days. Give or take 50.
We then bought a natural gas 250 kw prime power it has a 430 hp series 60 Detroit runs at about half the cost of diesel. Only thing is when it is cold it has to be heated to start quickly. Payback on purchasing was only about 6 months if rental. Depends on hrs too. If you use it 2000 hrs a year , your probably going to need some maintenance too.
Buy a bigger unit than you need. if your not using the full power it burns less fuel, and you have reserve if needed. Also if it is a big enough unit some electric utilities will buy power from you at high demand times.


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Knowing you, you have already answered the questions I would pose such as neighbors, restrictions, etc. Is this proposal for short term use (6-12 months) or continuous? You buy or rent? What do suppliers of this type of equipment say in terms of fuel usage.

Tom

Rob F. said:

Have you looked at these 50 to 100 hp single phase motor driven generators? Yes, that is a 100 hp single phase motor driving the 3phase genny.
https://singlephasepowersolutions.com/2019/03/18/1to3-power-source/

Click to expand...

I'm not impressed, just based on what I read at that website.

The website is full of spelling and grammatical mistakes.

Plus, they say, "[FONT=&quot]The 1-to-3™ allows weak single-phase lines to deliver strong thre-phase power with excellent voltage regulation and precise 60 Hz frequency. "

What the hell does that mean?[/FONT]

TDegenhart said:

Knowing you, you have already answered the questions I would pose such as neighbors, restrictions, etc. Is this proposal for short term use (6-12 months) or continuous? You buy or rent? What do suppliers of this type of equipment say in terms of fuel usage.

Tom

Click to expand...

I haven't gotten that far yet Tom. Would rather ask up here and glean some real-world numbers (such as idacal, and turbo's) than that which a salesman spews at me.
But.......there would be no neighbors to worry 'bout. This would be centralized in 150 acres.
Where it will be over $200k to get the needed juice from the poles to where I need it (according to the "neighbor" who just done it).
Buy or rent? Buy. Temporary? Probably. For how long? No clue.

propane does not produce as much power as diesel or gas.

I would go diesel.

I inquired about that single phase stuff a year or two ago and after a short conversation they asked me if I was interested in becoming their west coast dealer. That gave me a bad feeling and I didn't follow up.

Turbodiesel should be 30-40% more efficient than Propane, but propane and natural gas can be real cheap in some areas. If propane is half the cost of diesel then it wins.

You really don't want to oversize too much. You really want the average load to work the generator, but peak not to go over max ratings. If you aren't loading the engine enough the engine won't last.

Isn't solar a big deal where your at? I'd think solar could really kick butt where you have sun all the time.

I don't think I'd be too thrilled if my neighbor decided to run his machine shop on a generator. That would get old quick.

Garwood said:

Turbodiesel should be 30-40% more efficient than Propane, but propane and natural gas can be real cheap in some areas.

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Yea, I am well aware of how much more "energy" there is in diesel than other combustible fuels. It is all the other things that are already getting mentioned I am curious about. Price/unit, and delivery, being the big ones. If diesel is $3/gal. And propane is $1.25/gal? Even if diesel is twice as efficient, you are still $.25/gal ahead with propane (just a hypothetical, I have no clue the real numbers yet).

Garwood said:

Isn't solar a big deal where your at? I'd think solar could really kick butt where you have sun all the time.

Click to expand...

Not much sun pacific north west.

Garwood said:

I don't think I'd be too thrilled if my neighbor decided to run his machine shop on a generator. That would get old quick.

Click to expand...

Nobody would hear nothing, including me (that part I can handle).

If you need prime power all the time a Capstone turbine may be the most efficient at 60-100KW on either gas or propane. The ongoing maintenance and TBO are factors you may not be considering.

Steve

100 KVA is not large nor even "medium". It is the top end of "small".
Then mediums.
Large start at "Mega".

FWIW, entire 'nam war RAN on Diesels, 24 X 7 X 365 for 15 years.

My unit had 4 x 100 KVA, a 60, a 40, a 15, all trailer mounted, plus a couple of Bogue 3 KVA "cage" ones one or two guys could just lift.

I can get reasonably priced Propane, but its a PITA. There is nat gas at the kerb, but its a PITA.

With the background of "living on and with" Diesels, PLUS the same sort of research you just started, I elected to invest:

- about $4,500 in a 1997 CARB-compliant (as of that year) surplus NATO MEP-803a with well under 1,000 hours on the Hobbes

- two 20 Gal aluminium fuel tanks (Northern Tool)

- a very capable two stage, two pump fuel "polishing" rig.

- "maintainer" battery chargers. Unit has a solar panel, but it is under cover and I haven't rigged a remote one yet.

Fuel needs to be maintained if stored for very long.

Mine being standby/emergency, that needs seen to about twice a year. I alternate DeZol and StaBil preservatives as they are different chemistry.

Run steady, CLEAN fuel delivered regularly, a decent filter and water removal / protection, no need of "polishing" the fuel for your use.

Only 10 KVA (well 12 KVA here near sea level, 15 KVA peak), but..

.. even your 100 KVA needs a sanity check.

Diesels aren't happy at STARTING inrush of heavy load motors.

FWIW-not-much, my personal rules of thumb

1 GAL per hour per 10 KVA fuel burn @ 80% load. Our 100 KVA used 10 Gal/hr.''

1.4 HP per 1 KVA Our 100 KVA had 145 BHP Diesels. My 10 KVA is about 14 HP.

1/2 X the KVA as load motor HP for running electric motors.

EG; My 10/12 KVA is happy with a 5 HP load motor, bogs a bit to start a 7.5 HP, is harder pressed to lift a 10 HP motor.... and that's about all she wrote for what I can do.

BTW..Diesels do not LIKE being run under light load. Turbo is better if you must. Normally-aspirated wet-stack too easily if idled or run lightly loaded.

You want loading to be above 50% for durability, around 75% - 85% the best fuel efficiency range.

If this has to go on for a year or more, and owned not rented, two 60 KVA or a 15 KVA, a 40 KVA and a 60 KVA that you can selectively run to better match to the loads may be worth the extra complexity vs a single 100 KVA that will be under-loaded too often.

There are other sane and easy tricks so I don't need very much for "whole house" gen set and do not have to go without anything much at all:

- My two big 1200 W peak fridge-freezers stay just as cold if a lamp timer gives them each alternate 10 minute time slices, never both running at once.

- water heater and baseboard heat ELSE central air-con are happy with alternate time slices, too. Flywheel effect.

- clothes dryer and kitchen range and ovens need not be allowed to run at the same time. Human does that part. No equipment needed. Same again shop vs cooking & laundry.

- LED lighting, and LED "lanterns", gen set is only needed a few hours a day, not a lot of battery carries even the fridges through the night, doors not being opened. VERY good insulation does the rest.

If you HAVE nat gas? We had our own wells. Didn't have electricity for the first 45 years on the farm. Didn't use MUCH even once we got it since the gas was free.

Gas stove & oven (wood as well). Gas lights. Gas heat. Gas HW. Gas fridge/freezers. Gas dryer. Gas air-con. GASOLINE (Maytag) washing machines run outdoors, Kerosene lamps & lanterns. Gravity water supply from up the hill, septic down the hill.

thermite said:

100 KVA is not large nor even "medium". It is the top end of "small".
Then mediums.
Large start at "Mega".

FWIW, entire 'nam war RAN on Diesels, 24 X 7 X 365 for 15 years.

My unit had 4 x 100 KVA, a 60, a 40, a 15, all trailer mounted, plus a couple of Bogue 3 KVA "cage" ones one or two guys could just lift.

I can get reasonably priced Propane, but its a PITA. There is nat gas at the kerb, but its a PITA.

With the background of "living on and with" Diesels, PLUS the same sort of research you just started, I elected to invest:

- about $4,500 in a 1997 CARB-compliant (as of that year) surplus NATO MEP-803a with well under 1,000 hours on the Hobbes

- two 20 Gal aluminium fuel tanks (Northern Tool)

- a very capable two stage, two pump fuel "polishing" rig.

- "maintainer" battery chargers. Unit has a solar panel, but it is under cover and I haven't rigged a remote one yet.

Fuel needs to be maintained if stored for very long.

Mine being standby/emergency, that needs seen to about twice a year. I alternate DeZol and StaBil preservatives as they are different chemistry.

Run steady, CLEAN fuel delivered regularly, a decent filter and water removal / protection, no need of "polishing" the fuel for your use.

Only 10 KVA (well 12 KVA here near sea level, 15 KVA peak), but..

.. even your 100 KVA needs a sanity check.

Diesels aren't happy at STARTING inrush of heavy load motors.

FWIW-not-much, my personal rules of thumb

1 GAL per hour per 10 KVA fuel burn @ 80% load. Our 100 KVA used 10 Gal/hr.''

1.4 HP per 1 KVA Our 100 KVA had 145 BHP Diesels. My 10 KVA is about 14 HP.

1/2 X the KVA as load motor HP for running electric motors.

EG; My 10/12 KVA is happy with a 5 HP load motor, bogs a bit to start a 7.5 HP, is harder pressed to lift a 10 HP motor.... and that's about all she wrote for what I can do.

BTW..Diesels do not LIKE being run under light load. Turbo is better if you must. Normally-aspirated wet-stack too easily if idled or run lightly loaded.

You want loading to be above 50% for durability, around 75% - 85% the best fuel efficiency range.

If this has to go on for a year or more, and owned not rented, two 60 KVA or a 15 KVA, a 40 KVA and a 60 KVA that you can selectively run to better match to the loads may be worth the extra complexity vs a single 100 KVA that will be under-loaded too often.

Click to expand...

Thanks for the input T! That last sentence says a lot! I don't want to say it was a "concern" (cause I don't know WTF i'm talking about) but it had crossed my feeble mind.

Here is a page where they compare diesel cost (2.60/gal) to elect cost(.11/kwh) on a 75 hp pump:
https://singlephasepowersolutions.com/written-pole-advantages/

Don't discount the solar, I have solar and it puts out 50%-75% when it is is cloudy. Dark rain clouds, if we ever get them stop most of it. Give backwoods solar a look, they are in Idaho panhandle and have been there since mid 70's doing off grid. They should immediatly know what you would need. It is easy to make three phase with solar also, but without a utility service that might need a large battery bank, IDK.
Off-Grid Solar Electric Systems | Solar Panels | Solar Energy Shop
I hope they dont have any typos on the web page....

Here are some diesel fueled Capstone 65KW surplus sets, no matter how you slice it the cost to roll your own is going to be expensive.
Capstone Turbine C65 Diesel Liquid Fueled Top Mounted CHP Hot Water Recovery - Capstone Turbine (used | surplus | buy | sell ) • Energy

wheelieking71 said:

Thanks for the input T! That last sentence says a lot! I don't want to say it was a "concern" (cause I don't know WTF i'm talking about) but it had crossed my feeble mind.

Click to expand...

A(ny) used Diesel that has been "wet stacked" (google it..) can clean itself up, "best case", no real cost...

OR ...it can require a TEDIOUS to do, and costly for even gaskets, tear-down & rebuild.

One run HARD but steady is often in better condition and will prove cheaper. Problem is, how d'you know the difference?

If you wish to become a Diesel mechanic, do your homework. They are NOT just heavier-built gasoline engines.

Stupidity about fuel injection can ruin yer health, cost you a finger, even get you dead.

Otherwise, the "homework" isn't HARD. Just a bit "different". I actually like Diesels! They tend to stay fixed longer!

This 3 phase faclity in UK near London (fog captal of the world?) is off grid and replaced a 70kw diesel with 10kw solar and smaller genny:
Off-Grid, 3-phase, 24/7 | Victron Energy
excerpt:
"The installation was completed in under 2 weeks. Analysed after eleven months of operation they found they had made savings of £25k; placing the project break-even point at 2½ years. Generator run-time has been reduced from 24hrs/day to 3½hrs/day …using a much smaller generator. Using a smaller generator near its peak output extends the life of the generator and is more fuel-efficient. The Quattro has a power-assist feature – if there is a spike in demand which would exceed the generator’s maximum output, the Quattro immediately supplies that demand from the batteries."

An interesting tidbit: I live in an area with PG&E power, and the infrastructure is decaying and undersized. When they aren't shutting off power because it's windy, they're begging people to stop using power or else they'll shut it off.

My dad works for the next city over at a waste water treatment plant. When rolling blackouts are eminent, they run the entire plant off of backup generators to try to save some grid capacity for everyone else. I don't know the capacity of the generators but they burn 150 gallons per hour of plant run time, and they hold somewhere around 4000 gallons of diesel in their tanks.

Strostkovy said:

An interesting tidbit: I live in an area with PG&E power, and the infrastructure is decaying and undersized. When they aren't shutting off power because it's windy, they're begging people to stop using power or else they'll shut it off.

My dad works for the next city over at a waste water treatment plant. When rolling blackouts are eminent, they run the entire plant off of backup generators to try to save some grid capacity for everyone else. I don't know the capacity of the generators but they burn 150 gallons per hour of plant run time, and they hold somewhere around 4000 gallons of diesel in their tanks.

Click to expand...

If its like the sort of sites I once wrote manuals on, those will be in sets of three, synced when need be. Typically one up, two back, two up, one back, and all three online only at peak times. So you might be looking at 3 X 50 GPH for 3 X 500 KVA units.

FWIW - large municipal sewage treatment plants pioneered running pumps and gen sets off the methane the plant itself produced. Or COULD produce.

Been going on since forever-ago, but the choice of bio-processing may have changed that?

thermite said:

If its like the sort of sites I once wrote manuals on, those will be in sets of three, synced when need be. Typically one up, two back, two up, one back, and all three online only at peak times. So you might be looking at 3 X 50 GPH for 3 X 500 KVA units.

FWIW - large municipal sewage treatment plants pioneered running pumps and gen sets off the methane the plant itself produced. Or COULD produce.

Been going on since forever-ago, but the choice of bio-processing may have changed that?

Click to expand...

This particular plant does not synchronize generators between themselves or line power. They have one very large generator and another smaller backup backup generator. Load shedding and plant shutdown/restart/switchover/load shedding is all controlled by PLCs. Supposedly the inconvenience of shutting down the plant and restarting it to switch power sources isn't significant enough to warrant phase matching. However, in the future it might make sense to revamp their backup generator system into a peaker plant and sell off some power.

The power demand is pretty constant but I think they switch to the small generators if the plant is only needed at low capacity, but that is fairly rare.

This plant centrifuges off the solids from the waste and trucks it to a different site, so they can't make much methane. I vaguely remember 2MVA being mentioned for the main backup, but I can't remember for sure.