Diesel vs gasoline portable generator efficiency

[Cujet]

Originally Posted By: IndyIan
I would never have guessed that the 3600rpm generators ever get close to the inverter models in efficiency except at full load. I guess our usage with an EF3000is has been mostly intermittent loads like the fridge and freezer, which are off probably 75% of the time, or in construction projects where its unloaded 95% of the time, so I guess that's where it shines and seems to sip fuel. We have no real constant loads at our house except the window AC, but that's pretty optional really.
I don't even really bother to keep a specific jug of gas for the generator as you can keep the fridge and freezer cold running the generator for 2 hours, two or three times a day, and in that usage a gallon of gas last for a couple days.




That's the thing, they are advertised as more efficient. However, here in FL, where you WILL be running high loads all day, multiple AC units, or central AC, or water heater, inverter units lose the advantage.

I neglected to mention, if you are just running a fridge and a few lights, (or similar) inverter generators are absolutely the way to go. Clean power, quiet, and very low fuel burn during periods of minimal draw.

Please don't think I don't like 'em, I do and I own one. I also have a Listeroid 6/1 (and a 20/2) and it's (the 6/1) the ideal "disaster" generator. VERY Low fuel consumption, easy to fix and 4400W under max load. It will run my entire house. This is the exact one I have.

 

[UncleDave]

The Lister 6/1 is the king.

That and a 55 drum of diesel will take you a loooooong way.

Cujets on a rolling cart is killer.

UD

 

[blackgolds]

Originally Posted By: blackgolds
Hi, portable generator fuel efficiency question. What is the best type of fuel for portable generator fuel efficiency? All, fuel types are accessible so that is not an issue for me, maybe for others. But I just want to save some cash on fuel and keep the gene going. This article suggests that diesel is the most fuel efficient but produces lower wattages compared to gas-powered generators. Seems that there a diesel generators with enough wattages. My question is why do most people have gas powered generators? I was thinking to get a diesel one but just not sure if there is something I am missing.


Thanks everyone for your responses. I should have also mentioned what I want to use it for

. I want it as a backup for when the power goes out at home (happens more than it should) but also to take it with us on our 1-2 week camping & fishing trips.

 

[CrAlt]

My Eu2000i is almost 20 years old now. Tons of hours and never an issue.
The problem is the E10 fuel we are forced to use here. The generator can not be stored with ANY fuel in it.
So after every power outage I have to deal with draining the tank and the carb. Storing lots of fuel was also a PITA. I had to make sure I rotated it ever 6months.

My primary back up power source now for short term usage is a 4500watt duel fuel (gasoline/propane) that I only use on propane. When the power goes out I wheel it out, hook it up and go. When the power comes back I unhook it. Let it cool and put it away. No messing with gasoline anymore. Propane stores indefinitely. It is LESS efficient then the eu2000i but the convenience factor out weighs that.

The EU2000i is in dry storage as a backup now.

 

[dlundblad]

Originally Posted By: Cujet
Originally Posted By: IndyIan
I would never have guessed that the 3600rpm generators ever get close to the inverter models in efficiency except at full load. I guess our usage with an EF3000is has been mostly intermittent loads like the fridge and freezer, which are off probably 75% of the time, or in construction projects where its unloaded 95% of the time, so I guess that's where it shines and seems to sip fuel. We have no real constant loads at our house except the window AC, but that's pretty optional really.
I don't even really bother to keep a specific jug of gas for the generator as you can keep the fridge and freezer cold running the generator for 2 hours, two or three times a day, and in that usage a gallon of gas last for a couple days.




That's the thing, they are advertised as more efficient. However, here in FL, where you WILL be running high loads all day, multiple AC units, or central AC, or water heater, inverter units lose the advantage.

I neglected to mention, if you are just running a fridge and a few lights, (or similar) inverter generators are absolutely the way to go. Clean power, quiet, and very low fuel burn during periods of minimal draw.

Please don't think I don't like 'em, I do and I own one. I also have a Listeroid 6/1 (and a 20/2) and it's (the 6/1) the ideal "disaster" generator. VERY Low fuel consumption, easy to fix and 4400W under max load. It will run my entire house. This is the exact one I have.





Is this a 2 stroke diesel?

Very interesting contraption. They have these sort of things in varying sizes at the 4H fair every year.

 

[Nick1994]

It'll likely never pay for itself. The fuel savings is pennies.

Kind of like hybrid cars. If you do the math, it often takes 10-12+ years for a hybrid car just to break even on costs due to higher purchase prices. This doesn't even include the cost when it needs a new battery.

 

[Rmay635703]

Originally Posted By: UncleDave
There arent really any "portable" diesels.

UD


http://www.centralmainediesel.com/order/yanmar_4kw.asp?page=yanmar_4kw

http://www.subarupower-global.com/engines/dy-series/dy23

Kinda sort of


Also the hybrid doesn’t pay argument falls flat with me,
Sounds like debunked nonsense from 2005

My 80mpg 2001 Honda Insight was cheap enough that it’s gas savings did pay for its purchase price
Further if the battery dies 5 minutes to unplug a few things and the car drives on as a very efficient gas car, no battery needed

 

[Cujet]

Originally Posted By: dlundblad


Is this a 2 stroke diesel?

Very interesting contraption. They have these sort of things in varying sizes at the 4H fair every year.


It's a conventional 4 stroke, 2 valve, diesel engine with indirect injection.

As clunky as it looks, it's not like the hit and miss "fair" engines you see. It has Bosch-Mico fuel injection (very precise) and it's 44% thermally efficient. They last a very long time between overhauls.

 

[UncleDave]

Originally Posted By: Rmay635703
Originally Posted By: UncleDave
There arent really any "portable" diesels.

UD


http://www.centralmainediesel.com/order/yanmar_4kw.asp?page=yanmar_4kw

http://www.subarupower-global.com/engines/dy-series/dy23

Kinda sort of


Also the hybrid doesn’t pay argument falls flat with me,
Sounds like debunked nonsense from 2005

My 80mpg 2001 Honda Insight was cheap enough that it’s gas savings did pay for its purchase price
Further if the battery dies 5 minutes to unplug a few things and the car drives on as a very efficient gas car, no battery needed


that's a stretch.

One of those weighs 165 and has no wheels or handle

The other is just an engine not even on a frame and has no tank or exhaust.

My yamaha weighs 150LB but at least I can roll it around.


What are you talking about in terms of hybrid? Not sure I remember that "argument"?
Fuel? or something else?


UD

 

[Rmay635703]

Originally Posted By: UncleDave
Originally Posted By: Rmay635703
Originally Posted By: UncleDave
There arent really any "portable" diesels.

UD


http://www.centralmainediesel.com/order/yanmar_4kw.asp?page=yanmar_4kw

http://www.subarupower-global.com/engines/dy-series/dy23

Kinda sort of


Also the hybrid doesn’t pay argument falls flat with me,
Sounds like debunked nonsense from 2005

My 80mpg 2001 Honda Insight was cheap enough that it’s gas savings did pay for its purchase price
Further if the battery dies 5 minutes to unplug a few things and the car drives on as a very efficient gas car, no battery needed


that's a stretch.

One of those weighs 165 and has no wheels or handle

The other is just an engine not even on a frame and has no tank or exhaust.

My yamaha weighs 150LB but at least I can roll it around.


What are you talking about in terms of hybrid? Not sure I remember that "argument"?
Fuel? or something else?


UD


http://gens.generac.com/generaccorporate...eet_xd5000e.pdf

Portable diesel gensets, wheels optional are about 70lbs on up with head and frame depending on output
Trouble is that all 3600 rpm portable generators (gas or diesel) wear out relatively quickly if used anywhere near their rating.
The statement above applies to inverter style gensets also, though Honda makes a good motor I can vouch that they are problematic with certain electronic equipment and also wear out if you run them hard continuously.

Slow turning gensets, whether gas, diesel, lpg are all much larger weight wise but they can be run continuously at full load for many years with simple maintenance.

So it depends on how the op plans to use the generator,
If it runs occasionally at part load, why worry about fuel cost?

, I have lugged around heavy non portable stuff for decades as if it were portable so if he has a valid reason to need something that can run hard, efficient and continuously
I think he can figure out how to make it portable.

Depends what he is doing with it.

 

[JHZR2]

Originally Posted By: Cujet
Originally Posted By: IndyIan
I would never have guessed that the 3600rpm generators ever get close to the inverter models in efficiency except at full load. I guess our usage with an EF3000is has been mostly intermittent loads like the fridge and freezer, which are off probably 75% of the time, or in construction projects where its unloaded 95% of the time, so I guess that's where it shines and seems to sip fuel. We have no real constant loads at our house except the window AC, but that's pretty optional really.
I don't even really bother to keep a specific jug of gas for the generator as you can keep the fridge and freezer cold running the generator for 2 hours, two or three times a day, and in that usage a gallon of gas last for a couple days.




That's the thing, they are advertised as more efficient. However, here in FL, where you WILL be running high loads all day, multiple AC units, or central AC, or water heater, inverter units lose the advantage.

I neglected to mention, if you are just running a fridge and a few lights, (or similar) inverter generators are absolutely the way to go. Clean power, quiet, and very low fuel burn during periods of minimal draw.

Please don't think I don't like 'em, I do and I own one.



Why would anyone run multiple AC units, or central air, for extended periods off of a generator? It's just silly logistically, rather wasteful, and Im not sure I'd want to expose expensive equipment to the power quality of most smaller portable gensets.

Running luxuries long term after a major outage is going to be a hassle if you can find fuel. Running luxuries after a calamity or societal breakdown is going to get you killed.

I agree with you that inverters don't necessarily do as well at full load. This is very obvious. Thermal efficiency / SFC of an engine isn't going to vary much at full load (assuming roughly similar ratings and sizes). Each power conversion step loses 3-5%, so since there's two (rectification to dc then conversion back to AC), there's quite possibly a 6-10% loss in those steps.

Industry is going there for generation as well though, because they can also run the generator higher than 60Hz, with higher engine speed, and get greater power density on the high end, as well as much better sfc on the low end.

The other reality is that generator sizing is tricky business for a residence, and so they are typically oversized by a good amount, making much of the comparison difficult to accept. The sizing margin necessary to support starting load often drives a 50% oversize. Not saying it's right, but most dot understand load management or what their loads actually are, so use some rule of thumb that gets a marginal success.

 

[Shannow]

Originally Posted By: Cujet
200,000W JD turbodiesel generator
200KW, 15.5KWH/gal
100KW, 15.5KWH/gal (or roughly 20c/KWH at $3/gal) (still double the local utilities price, and the unit's capital costs are enormous)


US gallon of diesel 131.8MJ, That's a heat rate of 8.5MJ/KWh...42.4% efficient.

DICE is being investigated in Oz...
https://www.csiro.au/en/About/Our-impact/Our-impact-in-action/Industry-and-defence/DICE

I really think that's something that will help the energy future...rapid start peakers with thermal plant efficiencies

 

[UncleDave]

Rmay-

That's a 240+ LB genset (dry) - Although it can be bought with a wheel kit that's a stationary generator that can be wheeled around.

I'm still not sure what you mean by "Also the hybrid doesn’t pay argument falls flat with me,
Sounds like debunked nonsense from 2005"

Can you explain what you were talking about or referring to?



UD

 

[henni]

Originally Posted By: Cujet
.. here in FL, where you WILL be running high loads all day, multiple AC units, or central AC, or water heater, inverter units lose the advantage.


We've run through a few hurricanes last 30 years and have used Honda inverters in the 5kw and up range.

Last 10 years we've ran simultaneously five(5) 12,000 BTU heatpumps, pool pump, water heater, 3 refrigerators, TV, modem, routers and repeaters, lights etc.

All motored systems are 240v inverters running DC motors (pumps, compressors).

Water heater has a 3-way switch that allows it to run in 240v mode (4,500 watts) or 120v mode (1,125 watts).

Last experience was Irma a year ago, we had no power for about 10 days and our average power use was around 2,200 watts which the Honda handled just fine and quietly.

 

[Cujet]

Originally Posted By: JHZR2

Why would anyone run multiple AC units, or central air, for extended periods off of a generator? It's just silly logistically, rather wasteful, and Im not sure I'd want to expose expensive equipment to the power quality of most smaller portable gensets.

Running luxuries long term after a major outage is going to be a hassle if you can find fuel. Running luxuries after a calamity or societal breakdown is going to get you killed.


Because we can. It's too hot n humid after a hurricane to needlessly suffer. That's why I have the generators!

Plus, my well pump and fridge run on electric power. I like safe food and water as much as the next guy. I also have multiple generators for backup and periods of low load.

I have 500 gal Jet-A on hand. Burn about 8 per day running everything. Not horrible.

The power quality is good enough to run everything. Sine wave looks really good, but certainly not stunningly perfect like the power company. I've not had any failures due to generator power, and neither has anybody else around me. Contrary to popular belief computers and TV's are insensitive to imperfect power. They have power supplies that can handle any worldwide power input voltage or frequency and convert it to DC to run the circuits.

 

[hatt]

Originally Posted By: Cujet
Originally Posted By: JHZR2

Why would anyone run multiple AC units, or central air, for extended periods off of a generator? It's just silly logistically, rather wasteful, and Im not sure I'd want to expose expensive equipment to the power quality of most smaller portable gensets.

Running luxuries long term after a major outage is going to be a hassle if you can find fuel. Running luxuries after a calamity or societal breakdown is going to get you killed.


Because we can. It's too hot n humid after a hurricane to needlessly suffer. That's why I have the generators!

Plus, my well pump and fridge run on electric power. I like safe food and water as much as the next guy. I also have multiple generators for backup and periods of low load.

I have 500 gal Jet-A on hand. Burn about 8 per day running everything. Not horrible.

The power quality is good enough to run everything. Sine wave looks really good, but certainly not stunningly perfect like the power company. I've not had any failures due to generator power, and neither has anybody else around me. Contrary to popular belief computers and TV's are insensitive to imperfect power. They have power supplies that can handle any worldwide power input voltage or frequency and convert it to DC to run the circuits.
Way too many people plan on running everything in the house with their monster portable but then realize after a short time the little bit of fuel they have stored isn't going to do much. I plan on running a small window unit(it can keep the main living area under 80 in summer), fridge, and small freezer. My 2K inverter can handle it without a lot of noise and gas.

 

[UncleDave]

When it comes to gensets and usage during a power outage too many think "cruise ship" when it comes to gensets when the the correct approach is " lifeboat".

Im not sure I agree a honda 2K running an air conditioner is "not a lot of noise" - you can't run them on eco because of the start surge, and under the big load it becomes a roaring little [censored]. It can work- sure - quiet - not really.

UD

 

[hatt]

Originally Posted By: UncleDave

When it comes to gensets and usage during a power outage too many think "cruise ship" when it comes to gensets when the the correct approach is " lifeboat".

Im not sure I agree a honda 2K running an air conditioner is "not a lot of noise" - you can't run them on eco because of the start surge, and under the big load it becomes a roaring little [censored]. It can work- sure - quiet - not really.

UD


I have a Champion. It's pretty quiet running the A/C. I'm sure the Honda is similar. Sure you can hear it but you can be 20 ft away and carry on normal conversations. I also have a 5K Powermate I picked up for nothing. When it's running you want ear pro on.

 

[UncleDave]

They are always quieter than open frame gennies for sure.

From that perspective - sure, totally agreed.

When I can hear a honda 2K running an AC 3 rigs over - above the 8KW diesel im standing next to it seems loud.


Anybody thinking of doing it should hook up a 1500 watt hairdryer and see how it sounds.
Depending on how and where you arrange it and your head at night it may be golden or a nasty little thing.

UD

 

[fdcg27]

As many others have noted, a diesel genset will be more efficient in its use of fuel than any other fueled genset, with those relying upon piped NG not really qualifying for emergency use.
Whether they are as economically efficient is another matter.
There are no cheap small diesels while there are multitudes of cheap small carbureted gas SI engines.
A small gas engine is also easily started with a rope while this isn't true of any diesel.
For real emergency use over some considerable period of time, a diesel powered genset would be the gear of choice for those who can afford them, but a gas powered genset is a lot more economically feasible for most users.