Generator Running Costs / kWh


S

SabrToothSqrl

Well-known member
The boat my wife and I plan to Great Loop on - has solar panels.
I don't think any of the Formula's do yet?

But, my question to those with a generator:
Are you able to tell how many kWh/gallon of diesel you get?

I've run the numbers 100 ways from Sunday on solar for my home, and in PA, where grid is cheap and sunshine is less plentiful, it's a hard sale...

But on a boat... you have no grid.
And on the loop, you're running heat/ac/internet/cooktop/etc etc etc 24/7/365.

SO... the analytical mind in me wants to know, when you run diesel through a generator, what's the gallon to kWh conversion? it's not 1:1 as no engine is 100% efficient.
I think you're looking at 40% at best...

www.genpowerusa.com

Diesel Generator vs. Gas Generator: Which is More Efficient?

If you're considering a commercial backup generator for your business, you'll have a lot of decisions to make. One of the first things to consider is the fuel source. One common question is, are diesel generators better than gas? The answer is, it depends on the needs of your business. To...
www.genpowerusa.com www.genpowerusa.com

1 gallon is about $5 on the water, so that's 37.95 kWh* 40% = 15.18 kWh
/ $5 = $1 = 3.036 kWh
1 kWh = $0.33

at $0.33 kWh, and with 'limited' filling stations, not to mention smoke, CO, noise, vibration, etc. Solar + battery starts to make some appealing arguments.

Anyway, just thinking out loud, and wondering what people see out of real world marine generators. thanks!

Gasoline gallon equivalent - Wikipedia

en.wikipedia.org en.wikipedia.org
 
There are way too many variables to provide a blanket answer. I don't think you'll find real-world data because not many will have a flow-scan hooked up to their generator's fuel line for logging consumption. It's going to vary by generator make & model, but my little 3kw westy is supposed to use 0.4gph (gas) at full load (3kw) from the literature I got with it. So, in my case, 1kwh would cost roughly 0.4gph/3kwh*$5gal=~$0.67/kwh. You should be able to find similar marketing literature on a diesel genset of your choice and do the same calculation.
 
Interesting! thanks for the data!

If, for the sake of comparison, we look at (first one I could find at random, for 3kW).

3kW. $3100. and "free" power. vs. $0.67/kWh.
so, this system, would make (about) 8 hours/day = 24kWh/day, from the sun. or you'd have to spend $16.08/day on diesel, which if you use 24kWh/day, works out to: $482/month = $5800/year. ouch.

the panels pay for themselves in no time, with that electric 'rate'.
less than 6 months vs. fuel costs. Even if you could just offset some of the fuel costs, seems like a win/win.

we plan to live-aboard, and between HVAC, electronics, cooking, electric tender, etc. I figure that adds up. I wonder if anyone's invented a heat pump oven/stove yet. Pump the heat out of the cabin or body of water, use it to low power heat up the oven. (Moving heat is 3-4x more energy efficient than making heat).

Right now our house has a heat pump water heater.
Not sure I've seen marine ones of those yet.

Panels on a boat seem like a huge win vs. diesel costs, no?
Obviously to omit the generator you need a big battery too, which raises the cost, but with the cost of diesel electricity, I think you'd be in the black in no time.

Of course if you only use the boat once in a while, and don't use that much power, the numbers wouldn't show as favorable, and you'd just use fuel.

Going to be exciting to see what develops in the next 10-15 years!
 
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