Making my own 20 KW Genset

[3930dave]

Thanks BT !

I like your holistic approach to the engineering .

Rgds, D.

 

[rockinmywaypa]

Just in case anyone is interested in the math on this, it is very easy to convert some known calculations into how this will work.

For instance we know that this is a 55 mechanical Horsepower engine. Since we know that 100 hp equates to 7.5 boiler horsepower, this engine is the equivalent of 4.15 boiler horsepower. Since we know a boiler horsepower is equal to 33,000 btu's...it would be around 139,000 btu's...but that is BEFORE some losses.

We know an engine consists of 75% heat energy, and 25% mechanical energy.

That means the engine has about 104,000 btu's...but about 10% of that energy goes up the exhaust stack, so it is in total about a 94,000 btu heater-equivalent.

But we can also do the math backwards too. If our engine consumes about 1.5 gallons of fuel, at 131,000 btus per gallon, we get about the same amount of btus per hour, based upon throttle position and load!

there's no reason why he can't build a tube within a tube to run the exhaust through and heat the water some more after it has passed through the water jackets of the motor

 

[BrokenTrack]

there's no reason why he can't build a tube within a tube to run the exhaust through and heat the water some more after it has passed through the water jackets of the motor

That is true, but I am not really sure that it would be worth it. The gains made would only be 10% or so.

From the numbers we can see that for my home, which requires around 700,000 btu's on the coldest days, would only need to have the cogenerator operating for 8 hours per day to get the amount of heat needed, if prioritizing for heat. Since it is a radiant floor heating system, it can store that heat in the concrete slab so that heating the home does not have to be proportional with operating time.

Most likely I would operate the genset for four hours in the morning, and four hours in the evening, when family life means we are consuming the most electricity. If I put my large electrical loads on timers, like say freezers or refrigerators, and set them at their coldest temps, it would net me 100% of my domestic heat, and probably 75% of my electrical power. The rest of the time I would just pull what little power I need, off the grid.

Assuming a consumption rate of 1.5 gallons per hour of diesel fuel, that would be a $30 day per cost. Grid electricity and propane would be pretty close to that, at about $25 per day. So it is pretty comparable.

I do not think it would be cheaper to heat and power my own home, but the fact that if I ever had to, I could...is reason enough to do it.

 

[shooterdon]

Wow your energy costs are high. $750/mo. My electrical cost is about $120/mo. Propane is $1.40/gal and I run about 200 gal per month if not burning wood...$280. Cost $400/mo or about $15/day.

It shows how all power/heat decisions are local.

During an outage, I burn wood in the winter and run the generator 8 hours a day. Total cost about $15/day. If I ran the generator 24 hrs...cost is $40/day. (BTW, I cannot justify running the generator non-stop for more than a few days) "Cheap" propane is not a given though.....what seems OK now may be prohibitive in the future...one reason I like your system.

Nice job.

 

[BrokenTrack]

Wow your energy costs are high. $750/mo. My electrical cost is about $120/mo. Propane is $1.40/gal and I run about 200 gal per month if not burning wood...$280. Cost $400/mo or about $15/day.

It shows how all power/heat decisions are local.

During an outage, I burn wood in the winter and run the generator 8 hours a day. Total cost about $15/day. If I ran the generator 24 hrs...cost is $40/day. (BTW, I cannot justify running the generator non-stop for more than a few days) "Cheap" propane is not a given though.....what seems OK now may be prohibitive in the future...one reason I like your system.

Nice job.

I just got propane delivered this week, and I am looking at the receipt and it even makes me sick:

03/02/2020: 364.8 gallons of propane delivered, $4.159 per gallon, for $1517.20

I am not sure what power costs, we are "deregulated power" here, s that just means we pay more. I think it is around 18 per KWH delivered.

Our property taxes jumped this year from $4800 last year to $6760 this year...a $1960 jump, and they wonder why so many Maine people are leaving? Which of course, just drives the cost up higher for those that stay. Our school has lost 1/3 the kids in less than 10 years, but their cost is higher to operate.

 

[metalbender]

Wow, the price of propane is high in your area. Just for ***** and giggles, I called a local supplier. Price here is quoted at .57 cents CDN per liter. Translates to $ 2.28 CDN per US gal. Don't know the difference in the US vrs CDN dollar, but ours sucks in comparison. Our home is heated with fuel oil at .97 per liter, should really consider the switch to propane.

 

[BrokenTrack]

Wow, the price of propane is high in your area. Just for ***** and giggles, I called a local supplier. Price here is quoted at .57 cents CDN per liter. Translates to $ 2.28 CDN per US gal. Don't know the difference in the US vrs CDN dollar, but ours sucks in comparison. Our home is heated with fuel oil at .97 per liter, should really consider the switch to propane.

Maybe...

The two things to remember are, the efficiency rate of the furnace or boiler. For instance, a oil fired boiler might be 87% efficient, and a propane boiler 95% efficient, so that has to be calculated in. But the other thing is BTU's per gallon. Fuel Oil has 131,000 btu's per gallon, and propane only has 91,000 btu's per gallon.

Depending on how those two things work, it could mean the difference between being worth switching or not.

What I like about having various forms of heat, is that I can chose which heat I use based upon price. Another thing I find myself doing a lot of, is switching between heating sources. Last year we lived in a tiny house and ended up heating with coal, firewood, oil, and wood pellets. For the most part we used wood pellets, but when it got cold we used firewood, and when it was really, really cold we used coal. When we were not home, we used oil.

 

[hr3]

I just got propane delivered this week, and I am looking at the receipt and it even makes me sick:

03/02/2020: 364.8 gallons of propane delivered, $4.159 per gallon, for $1517.20

I am not sure what power costs, we are "deregulated power" here, s that just means we pay more. I think it is around 18 per KWH delivered.

Our property taxes jumped this year from $4800 last year to $6760 this year...a $1960 jump, and they wonder why so many Maine people are leaving? Which of course, just drives the cost up higher for those that stay. Our school has lost 1/3 the kids in less than 10 years, but their cost is higher to operate.

Sorry Broken, but I'm one of those that had to leave Maine when I retired. I lived there all my life but was taxed out of the state . Ooo and lived in Belmont for the last 20 years so close to you..

 

[metalbender]

Great point on the btu rating, in my haste I neglected to consider that factor. Changes the outcome a lot. The payback time would be longer than I'll be around.

 

[grsthegreat]

I just got propane delivered this week, and I am looking at the receipt and it even makes me sick:

03/02/2020: 364.8 gallons of propane delivered, $4.159 per gallon, for $1517.20

I am not sure what power costs, we are "deregulated power" here, s that just means we pay more. I think it is around 18 per KWH delivered.

Our property taxes jumped this year from $4800 last year to $6760 this year...a $1960 jump, and they wonder why so many Maine people are leaving? Which of course, just drives the cost up higher for those that stay. Our school has lost 1/3 the kids in less than 10 years, but their cost is higher to operate.

HOLY COW.....i just got a quote here in Idaho.....end of winter cost is $1.66/gal.