Cost of electricity from a gas generator

[Crowz]

A portable generator that you can ride.
Awesome

Next mower that ends up with a rusted deck around here is going to be introduced to one or two 48v alternators

Ive already been eyeing one of my trucks that has an optional 2nd alternator on it now that may end up getting its 2nd one replaced with a 48v model. I haven't driven it in a year so its looking better and better as a candidate.

 

[marionw]

Next mower that ends up with a rusted deck around here is going to be introduced to one or two 48v alternators

Ive already been eyeing one of my trucks that has an optional 2nd alternator on it now that may end up getting its 2nd one replaced with a 48v model. I haven't driven it in a year so its looking better and better as a candidate.

If you have kids, hook one up to a stationary bike and turn it into an exercise machine and make the kids peddle for their dinner....

 

[wattmatters]

If you have kids, hook one up to a stationary bike and turn it into an exercise machine and make the kids peddle for their dinner....

They'll be waiting a long time. The fittest cyclists on the planet are capable of generating an output at the cranks of ~ 400 W for about an hour. A kid will generate perhaps 50 W or less.

 

[Suijkerbuijk]

GAS GENERATOREN

You do know that is on the market.
It works on propene

 

[wattmatters]

You do know that is on the market.
It works on propene

In the US when they say "gas" they are referring to gasoline.

In Australia when we say "gas" we are referring to propane (bottle supply) and/or methane (reticulated supply).

 

[timselectric]

Feed the family beans and make your own methane.
Free energy.

 

[wpns]

My gasoline is $10/gallon, so definitely for emergency use only!

 

[CVCPJared]

I wonder if anyone has found or performed research about the cost of electricity from a gasoline generator.

A google search indicates that it is approximately 0.1Gallons of gasoline for 1 kWh.

That seems really low to me. 1 Gallon of gasoline costs here in California right now $4.60 , so that would be 46 cents of gasoline per kWh.

The utility charges 50 to 70 cents per kWh, depending on time of day and rate schedule.

Has anyone tried to verify the 0.1G estimate?

Generac 26kW states 3.63 gal propane/hr full load. Propane around here (N Cal) is about $2.50/gal. Theoretically about 35c/kWh (less efficient at less than full load though)

But same with NEM 3.0 - PGE claims something like 75% of the cost is in the transmission of the power through the power lines, that's why they give about 1/4th back vs what they charge now for every KWh sent back to the grid

 

[sunsurfer]

I had to run a generator for part of a summer once. Fuel was $4.50. Its like pouring bags of money strait into the tank $$$$

 

[Citlalatonac]

They'll be waiting a long time. The fittest cyclists on the planet are capable of generating an output at the cranks of ~ 400 W for about an hour. A kid will generate perhaps 50 W or less.

So let's assume 75kg untrained rider going for an hour.

75 kg * 2.2 kg/w = 165 Wh

Let's assume you're in most of the world and powered by rice.

How many calories does cycling really burn? And how important is counting them anyway?

We all want to know how many calories we burn while cycling, but while it's easy to make an estimate, it's hard to get an accurate figure. We explore common questions around cycling and calorie burn

www.cyclingweekly.com

Rider weight Average riding speed estimated calories burnt per hour
75kg 13mph/21kph 600kcal/hour

Calories in 465 g of White Rice and Nutrition Facts

There are 600 calories in 465 grams of White Rice. Get full nutrition facts and other common serving sizes of White Rice including 1 oz, dry, yields and 100 g.

www.fatsecret.com

465g of white rice maybe $1-$2/kg for bulk, dry to cooked weight is about 1:3 https://weighschool.com/rice-calculator/

Looking at around $1-2 per kWh for a poor cyclist. (edited for bad math)

That's watts of power at pedal, IKD what kinda losses are going to happen between the pedal and the rice maker I assume you're powering.

 

[Citlalatonac]

More math, my rice maker is rated at 350w, takes maybe 30 mins if full, so 175Wh. I can fit 600g of dry rice, for 1.8kg of cooked rice. which based on my math converts to 638wh of pedal power. About a 25% efficiency loss from the fuel refining.

 

[dougbert]

Since people are throwing wrenches into the calculations don't forget those of us that use chargeverters.

I run my generator for a short time aka 1 or 2 hours and then I run the batteries all day or so. Then repeat.

yes, doing it this way optimizes the generator power production

using a generator to directly power a house usually means the generator is mostly idling or at least not producing maximum efficient power because house load come on and go off all the time

"caching" energy in battery and efficiently charging it via the chargeverter (solar is better and should be 1st priority of production) will maximize production

 

[HarryN]

At one time I spent quite a bit of time on this question.

I don't remember the details, but I remember that a honda 2000 running at ~ 800 - 1000 watts - the tank full, would charge up a 4 kW-hr LiFe battery pack.

That is ~ 1 gallon for 4 kW-hrs.

 

[740GLE]

Generac 26kW states 3.63 gal propane/hr full load. Propane around here (N Cal) is about $2.50/gal. Theoretically about 35c/kWh (less efficient at less than full load though)

But same with NEM 3.0 - PGE claims something like 75% of the cost is in the transmission of the power through the power lines, that's why they give about 1/4th back vs what they charge now for every KWh sent back to the grid

Yeah but what’s its no load consumption? Prob half that, so running one 24/7 will last how long on that 100gal or 500gal tank?

IMO people love to oversize generators cause of hot tubs and such, then wonder why they burnt through a tank of fuel when powers out for 2-5 days and can’t get the propane guy to show up until next week.

 

[olivinelife]

Even that number surprises me. $4.60/7 = 65c per kWh .. Our PoCo charges 50 to 70c.

I realize there's the cost of the generator, oil, effort to stock fuel etc.

Yes, this is why the CA IOUs themselves have realized that they would be in big trouble after one or two more rate hikes. That's why they really want the fixed charge+lower volumetric pricing.

 

[TM48]

In almost every case the cheapest power is utility power. Those who claim there're producing it cheaper are usually leaving out some up front cost.

 

[JRH]

It cost me to run my 12k for 3 days, 1 gal per hour at $3/gal so NOT cheap.

I agree it not cheap but it’s value is relative to what conditions exist outside….
And who is weathering this event inside the house…

I had a gas 12k back in the mid 90s… it severed me well on a couple of occasions when terribly cold snowy weather shut down the mountain with a bunch of family and children visiting at Christmas…

Of course I was the one to have to fuel it , at night at below zero temps…..and that’s why I switched to propane plumbed to it from a large tank… every gen set I have will use propane nowdays… gas is a big mess… and it seems. no one ever has enough on hand to last along time…

 

[CVCPJared]

Yeah but what’s its no load consumption? Prob half that, so running one 24/7 will last how long on that 100gal or 500gal tank?

IMO people love to oversize generators cause of hot tubs and such, then wonder why they burnt through a tank of fuel when powers out for 2-5 days and can’t get the propane guy to show up until next week.

Well, perfect scenario is only run full load (assuming not crazy THD) to load/charge batteries then shut off. OP mentioned pushing excess into the battery bank so I ass-u-me-d

 

[wattmatters]

That's watts of power at pedal, IKD what kinda losses are going to happen between the pedal and the rice maker I assume you're powering.

Cyclists operate at roughly 20% gross mechanical efficiency (17-22% is about the typical range), i.e. of the energy released by the metabolic conversion of glycogen and free fatty acids (sugars and fats), about 1/5th makes it to the cranks of the bicycle.

As it so happens, the conversion of kcal (or Cal) to kJ approximately cancels out that gross mechanical efficiency, such that 1 J of energy put through the cranks requires ~1 kcal (Cal) of food intake. It's really a bit closer to 1.1 times, so 1.1 Cal of food per J of mechanical energy output.

Cyclists have a similar efficiency to a regular gas generator.


Hunter and Andy are friends of mine.

I was once a professional cycling coach (now retired). My wattmatters handle originates from my time spent writing about and helping develop systems for training and racing with (cycling) power meters, as well as aerodynamics testing.

 

[wattmatters]

In almost every case the cheapest power is utility power. Those who claim there're producing it cheaper are usually leaving out some up front cost.

My amortised cost of home solar PV generation is ~AUD 5c/kWh. My utility power costs AUD 32c/kWh.

If we only consider the energy generated so far, our PV system cost A$12,800 and has generated 77.41 MWh over 5.7 years (AUD 16.5 c/kWh). That's half the price of utility power, and it keeps falling every day as it keeps on generating.

 

[robby]

I don't think gasoline generators reach 10kWh per gallon of gas. Maybe some big super efficient industrial one?

Gasoline has 33.7kwh of energy per gallon. Most gasoline ICE engines run about 25% efficient, so there you are at 8.4kWh produced at the shaft. Then you have a conversion to electricity, which maybe is 85% efficient, so you are now have generated about 7kwh from your gallon of gas. This does seem about what I get from a Honda gen.

That is very close to my real world measurements on the Honda EU-3000is.
It runs for about 7 hours on 3.4 Gallons of Gas which clocked in at about 3Kwh power for 7 Hours or about 21KWh total production. So efficiency would be 6.17KWh per gallon of gas.
It is clocking in about 16 hours of runtime when producing 1KW of power or 16Kwh total on a Tank of Gas.
1Kw of average power use is more than enough to run the whole house minus AC units in an emergency.
I like the fact that I can fill it at 6pm and not have to worry about it again until roughly 9am the next morning.

 

[LydMekk]

For some reason I picture a bicycle with a raised back wheel and a Chargeverter ^^
Could be fun and CHEAP!
Fitness comes gratis!

 

[HarryN]

Dont forget the cost of the generator itself, the lifespan, the maintenance, the cost of going to get the fuel 5 gallons at a time, your time and attention....

A few years ago ( 10 I guess) my older son was looking at running a food trailer in FL off of a generator.

The trailer company suggested a decent one - can't remember the brand - and told him it would run about 10K hours.

( 10 000 hrs ) / ( 100 hrs / week of use expected ) ~ 100 weeks ~ 2 years.

vs for a honda 2000 size ~ ( 500 to 1 000 hrs run time life ) / ( 100 hrs / week ) ~ 1 - 3 months

Instead he bought some packs from a wrecked Tesla S and just charged it up at night. Ran it through a V 5000 / 48.

 

[Brucey]

I wouldn't expect 10,000 hours out of an air cooled gas engine. Water cooled diesel? But the little Honda inverters can definitely go for thousands of hours.

 

[HarryN]

I wouldn't expect 10,000 hours out of an air cooled gas engine. Water cooled diesel? But the little Honda inverters can definitely go for thousands of hours.

Maybe you are right and I am off a decimal place.