Propane Generator Question

Since I have a well pump, I am entirely dependent on the grid for even water. In the past, the only disruptions of supply I had to be concerned about were from a fallen tree limb, someone running into a utility pole, or a suicidally curious rodent exploring a transformer. These days there are a few more things to consider that could concievably disrupt supply: an aging electrical grid, increasing demand for electricity without corresponding increased investment in supply, terrorist attacks, and the potential for disruption based on a cratering economy combined with ineffective (if not destructive) political leadership.

Since adopting coal for heat I need little propane (cookstove and hot water only), and given that I already have a submerged (500 gal?) propane tank outside, I am considering getting a propane standby generator to reduce my dependence on an intact grid. For wattage generated, ease of use, and cost I think standby propane is the way to go. I'd still be dependent upon a delivery service for power, but instead of continuous dependence a la the electric company, it'd be only intermittent dependence on a propane delivery service, for which there are numerous local choices/more competition.

I haven't yet tried to estimate precisely how much wattage I'd need, but we used 981 kWh in one month from mid November to mid December. I suspect that summer AC would be the biggest electricity hog, and although I don't have a bill from last summer, our electric bill during the height of last summer was just under 3 times what it's running now--so, maybe 2500kWh for a month in the summer (does this sound about right?).

So, my questions are:

1) Based on the above data on monthly usage, is there a way to estimate how large a generator I'd need? Or do I need to add up the wattage estimates on individual components, which I'm not sure I'd be able to do very accurately anyway.

2) Not that I'd be using it when I had electricity, but I'd like to estimate how much propane I'd be using in, say, one day of continuous use. As an example, this Guardian 14kW generator ( http://www.electricgeneratorsdirect.com ... p1815.html ) states it uses 1.56 gallons of propane per hour at 50% load. Such a load should generate 7000 Watts. Can I assume that, at 25% load, 3500 Watts generated, that I'd use 0.78 gallons of propane? Or, is there not a linear relatioship between propane consumed and power output?

3) General thoughts about using standby propane for generation?

Thanks

Ashcat,
We bought our generator back in '99, two months before Hurricane Floyd hit the east coast. Wow! Timing is Everything! We were off the grid for 7 to 8 days. All power poles on my street were blown over, including two more, delivering power to our house. (Mini tornado, we were told).
Anyway, our generator is a 8000watt continuous, Honda, 13HP gas engine.
Its wired to the main distribution panel with a transfer switch.
It will power:
ALL lights in house.
All outlets in house.
Well pump (240v, 3/4HP)
Oil burner and air distribution fan.
Barn
Garage doors.
Clothes washer
Two refridgerators
Small oven in kitchen over range.
Microwave

Things it is NOT wired to:
Electric hot water heater
Cloths dryer
Large kitchen oven
Kithchen Induction range

We are very happy with its performance. I make sure the tank is ALWAYS full to top, and I mix STA-BIL in the gas to prevent carb varnish issues. To this day (last week) I started it with ONE pull.

most of the high watt energy consumers in the house are 220 volt. so first the BUG( back up gen) should provide that. Biggest question is how deep/ how many hp? is the well pump? 1 hp or so could be run with a 5,000 watt bug.
they typically have a 10 hp engine on them and are the line between fuel efficient and costly bug. Most older gas engine bugs can be converted to LP if the cost is justifyed doing so. Given the choice, for sure go LP. the 5kw/10 hp bugs usually have a 20 amp 220 volt circut. the 115volt side usually has a 30 amp breaker. the 220 volt side requires the bug to run at full throttle so as to supply needed current for the start up load. in 110 mode they often idle down and really conserve fuel. I have a collection of both and run the little honda 2kw all nite on 1/2 gal of gas for PC,boiler,fridge,50"plazma and bose sound. fire up the big guy for well pump as needed.. just my 2 cemts...

p.s. i have the nice electronics plugged into a 1500watt geek squad battery back up then into the bug just to double sure the voltage stabilization and hurtzzzzz! plus i dont miss a thing the devil says when the power goes out!!

Thanks for the replies DVC and PoconoEagle.
Not sure of my well pump power, but the folks who drilled my well told me recently (when I was considering adding a hand pump alongside my regular "supply" pipe) that they started hitting water at 45 feet.

I love Honda products but I don't think they make automatic BUGs, do they? And none on propane that I can find. That's quite a nice list, DVC500, of what 8000W will power. How long does STA-BIL preserve the gasoline?

In advance of electric rate increases planned for Pennsylvania, I'm trying to get my daughters to use the coal stove convection fan to dry their hair, instead of electric hair dryers--no luck yet. Maybe if I mounted a mirror above the coal stove they'd go for it They could use the mantel as a shelf for brushes and make-up

In any event, it sounds like 14,000 W is probably more than I'd need.

Sams Club in Dunmore has a 8kw 13 hp honda gas bug for 999. any of the carbs can be unbolted and a LP retro kit can be installed. That and Amsoil severe service oil and it will never need service,running on LP. the Sta-Bil when added AND run thru the carb, will keep the gas good over a year... The "auto" feature you speak of... auto switching? starting? bug's thats all the deep $$$ in the switching from house to gen. old school method's are much cheaper if your present when power loss occurs.

Hi Ashcat,

We have a Honda 6.5kw gasoline water cooled with electric start generator and a 30 amp sub panel.
This will power the 375' well and the boiler (DHW) also about 3/4 of our house. If I had to do it over, I would get a LP automatic setup... The shelf life of gasoline is less than 60 days before it starts loosing its BTU's.
The last time the power went out the gas station could not pump gas. That was only 18 hours and we had ten extra gallons but what if it was 2 weeks?
I think that 10kw to 12kw is more than enough for your house.
Also for us the LP cloths dryer is much cheaper.
RS

Edit: DO NOT get one fom China!!!! They are very bad for household electronics!!!

The "auto" feature you speak of... auto switching? starting?
Comes on automatically when power to house is lost. Nobody is home during the day to turn on a backup generator. Converting a gasoline engine to LP might be easy for you to do, but you don't have any idea just how good my mechanical skills are These generators come with a transfer switch, and do an auto test run every week. A few other protections as well, like auto shutoff when oil is low, etc.

The 10,000 W from Home Depot is $ 2789, 14,000 W $ 3289, with free shipping/delivery.

PC12-47-E--I'll avoid Chinese. That's quite a deep well you have. Wish we had propane clothes dryer, but it's electric.

Take a look at this small triple fuel inverter style generator:

http://www.generatorsales.com/order/076 ... age=Y07688

For larger propane units look at:

http://01856bc.netsolhost.com/lp_all11.asp?page=1

If you are really serious about getting off the electric grid your most thermally efficient system would be a water cooled propane powered generator in which you use the engine's radiator water to heat your house and/or domestic hot water. In some industrial applications where process heat plus electricity is needed, natural gas powered generators with waste heat recovery can provide large cost savings. Naturally the capital investment is usually substantial.

Poconoeagle wrote: The "auto" feature you speak of... auto switching? starting? bug's thats all the deep $$$ in the switching from house to gen. old school method's are much cheaper if your present when power loss occurs.

Yep, My xfer switch is a manual one, right down by the main distribution panel. I start the generator, which is behind mt barn. The wiring is all buried up to the house, then to Main Distribution panel in house. I just go into house and throw the manual xfer switch. Takes all of 1 second to throw switch , which removes circuits from grid, and connects them to generator.
The only time I complain about this, is when it is 0 degree F. outside, and theres a blizzard or something at 2:00AM, and I gotta go out and start generator. BUT that good ol' generator starts up everytime. Not sure how long the STA-BIL will preserve the gas. We loose power several times a year, so it will last at least 1 year.. I automatically add STA-BIL to every 5 gallon gas jug I have, before I refill them. That way, every gas-powered tool I have, has sta-bil in it. I never drain gas tanks in the fall, I top them off.

You could use a coal fired steam plant.

Yanche said: If you are really serious about getting off the electric grid your most thermally efficient system would be a water cooled propane powered generator in which you use the engine's radiator water to heat your house and/or domestic hot water.
I'm less interested in getting off the grid for its own sake, but in not being too disrupted if/when the grid goes off me. That system that uses cooling system as a source of hot water sounds neat.

DVC500 said: Takes all of 1 second to throw switch , which removes circuits from grid, and connects them to generator.
The only time I complain about this, is when it is 0 degree F. outside, and theres a blizzard or something at 2:00AM, and I gotta go out and start generator. BUT that good ol' generator starts up everytime. Doesn't sound like too much trouble at all. Even at 0* F, a few seconds outside beats the heck out of not being able to run a water faucet, flush a toilet, or stay in touch with NEPA Crossroads.

Paulie said: You could use a coil fired steam plant. Assuming you meant coal, don't think I haven't thought about that. In fact, with all the heat we can generate, you'd think there'd be some way to capture some of that to make electricity--like with a little steam turbine, or something.

One of the things drawing me to a stationary propane back-up system is that I already have the means to store alot of propane next to the house.

Ashcat wrote:Paulie said: You could use a coil fired steam plant. Assuming you meant coal, don't think I haven't thought about that. In fact, with all the heat we can generate, you'd think there'd be some way to capture some of that to make electricity--like with a little steam turbine, or something.

I too, thought about this alot, over the past 10 years. I Found this generator a year ago....
http://www.freelectricity.com/
Read the article. Sounds good? Too good?
Unfortunately, The company is being sued for fraud.
I am amazed they can still be advertising. I guess its just all spam now.

I used a 5kw gas generator for many years for backup. It worked ok but you couldn't run much at the same time and it just wasn't safe or practical to keep a large quantity of gas around. A few years ago I bought a 15kw propane standby generator. It came with an automatic transfer switch but it only had space for 10 circuits so I didn't use it. I bought a 200 amp manual transfer switch and can switch the entire load. The generator starts automatically if there is an outage but I have to throw the switch to go to gen power. It also starts automatically once a week and runs for 12 minutes to keep the unit "exercised."
When I first started looking into it, Generac made a 15kw water cooled model. Water cooled units run at half the rpms (1,800 vs 3,600 rpms) of the air cooled units and are much quieter. By the time I had the money together to do it, they discontinued the 15kw water cooled model. The smallest water cooled unit was 20 kw, really more than I needed. In retrospect, I would have gone for the larger quieter unit.

FWIW when I wired this house for BUG I got a 110v bright red multi led,(out of a EXIT sign the local dollar store makeover crew threw out) and wired it on the power co. side of things so as when they restore juice the led is the signal to shut the bug down. since each Exit sign has 2 of these multi led's in them , I put the second on the input of the main breaker. It gives a almost free lite to the panel and double confirms the power is flo-in.

Coalkirk, what brand is your 15kW air-cooled? When you say you wish you'd have gotten the larger, quieter (liquid-cooled) unit, is 15 kW not enough for your needs? Or is the sound during "exercise" too much?