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Gas Generator Conversion
By Bigwheel, Section Mechanical Posted on Thu Jan 03, 2008 at 07:24:02 PM MST
Going To Tri-fuel

Hi again everyone,
Here's what I am looking to find out. Back on the 23rd of December we dropped power for over 30 hours. My used high-lo battery lasted 9 of those hours. Not bad for a battery that was brought back from the dead. I was unable to get my old gas genny up and running and know is awaiting sentencing. With company in house and no heat, I was left no choice to head to Home Depot for a new 8kw genny. Would of been nice to put the money towards a lister but oh well. With the heat pump the genny is still small but big enough to run the rest of the loads and then some. A couple of years ago I added a heat broiler heat exchanger to the plentum. I taped into the gas water heater and with the blower on the heat out of it was quite nice. Now to the nitty gritty, Purchased about $50.00 in gas and two trips to the station to get us through. I recently got to thinking about a tri-fuel setup for ease of having natural gas on hand. I'm trying to figure out if it might be cheaper to run than gasoline. So what I did was compair the BTU's of Gas vs Natural Gas to find out a cost per hour between the two. My math is a little rusty so bare with me. I used roughly 1 gal of gasoline per hour.

gal of gasoline=125,00 btu
cubic foot of natural gas=1030 btu
So to find out how many cu/feet of natural gas is in 1 gal of gasoline: 125,000/1030=121.35 cu/feet
I buy natural gas in incriments of 100 cu/feet so 121.35/100=1.21 cu/ft. used per hour. The cost of the natural gas after those pesky surcharges is $1.05 per 100 cu/ft. 1.21cu/ft*$1.05=$1.27 per hour to operate the genny on natural gas. Does this seem right, if so you would think more people would be doing it where it is aviable. Let me know what you all think. A gallon of gas during the ottage was $3.05/gallon. That would transulate to a 58% savings. Mind you this is not for everyone but might work for some of you and me. What I found is that conversion kits run $175-250. If my caculations are right it's a route I will most definetly look into.
Again thanks to OLDF for his link on his propane conversion. Let me know what you think. Chad

Gas Generator Conversion | 14 comments (14 topical)

Re: Gas Generator Conversion (3.00 / 0) (#1)
by wlcoldiron on Thu Jan 03, 2008 at 01:13:08 PM MST

Hi
Tri-fuel mix is ok. If you look at vapor fuels for standby gen sets ng has a lower kw output than propane for the same size genset. You can purchase a lug in vapor setup for the carb then you can get a vaporizer/regulator for the propane.Set up a regulator for ng. Each fuel requires a different jet for proper fuel/air ratio. Better yet would be to bite the bullet and set up a low speed diesel genset and entertain the guests Hopethis helps. Weldon

Re: Gas Generator Conversion (3.00 / 0) (#2)
by Old F on Thu Jan 03, 2008 at 02:13:17 PM MST

Chad for me the main reason for using propane wasn't the cost.

Unlike gasoline propane won't go stale. For most of its live a back up gen will be just sitting there.

A lot of folks will get a back up gen An stick it back out of the way gathering dust with a tank full of gasoline.

A year or more mite go by and when they need it they can end up having to clean up
A gummed up carb by flash light so they can get it to start.

I have two BBQ size tanks I keep with mine in a box just out back of the garage.
This will give me roughly 24 hours run time. If push come to shove I can tie in to
My 300 Gal main propane tank thats about 25 feet away.

I keep the proper hose an fitting in the box just in case.

I all so keep a supply of engine oil in there to. Along with the cord that goes from the gen to the load transfer switch in the garage

The real plus you have with Natual gas
is its all ready delivered ; )

Have fun

Old F

Re: Gas Generator Conversion (3.00 / 0) (#3)
by Old F on Thu Jan 03, 2008 at 02:19:26 PM MST

Here is the link to the kit we are talking about

http://www.propane-generators.com

OlD F

[ Parent ]

Re: Gas Generator Conversion (3.00 / 0) (#4)
by Old F on Thu Jan 03, 2008 at 02:29:12 PM MST

Sorry haveing a brain F here forgot to add this

http://www.fieldlines.com/story/2003/9/1/82526/70829

[ Parent ]

Re: Gas Generator Conversion (3.00 / 0) (#5)
by Rock on Thu Jan 03, 2008 at 02:54:07 PM MST

My system has a DC generator hooked to the batteries. Its much more efficiant than a AC generator that has to run just to power a light bulb. Genset runs when batts need charging and shuts off when they are charged. Saves ALOT of fuel.

Just some friendly advise.
Rock

Re: Gas Generator Conversion (3.00 / 0) (#12)
by highway on Wed Jan 09, 2008 at 01:27:31 PM MST

This is my first attempt at a discussion board so bare with me. I read about you having a DC generator charging a battery bank. I really need some help here. i am building a remote camp and have a natural gas well and no electric. I wanted to use a 24 volt 90 amp generator powered with a 16 hp briggs (used for jump starting heavy equipment)convert it to NG and charge batteries. The local electric supply Co told me they did not think it could be done. Can You help?
Dave

[ Parent ]

Re: Gas Generator Conversion (3.00 / 0) (#13)
by TomW on Wed Jan 09, 2008 at 03:45:01 PM MST

highway;

What you just did is whats known as a thread hijack.
[Attempted anyway]

Thats where someone posts a question that leads the original thread in a different direction to get help with their own question.

It is considered unfriendly and rude.

Just for your information.

The Truth is the Truth, even if no one believes it; and a lie is a lie even if everyone believes it

[ Parent ]

Re: Gas Generator Conversion (3.00 / 0) (#14)
by highway on Thu Jan 10, 2008 at 06:39:34 AM MST

Sorry I tried posting on the board and it did not work. I will read more and try again. I did not mean to start off on the being rude. My apologies.

[ Parent ]

Re: Gas Generator Conversion (3.00 / 0) (#6)
by kurt on Thu Jan 03, 2008 at 05:08:15 PM MST

this is the way my father in law converted gas engines to propane or natural gas before he died a few years ago.

http://www.otherpower.com/images/scimages/8/conversion.html

IRC inst.
just a personal rant carry on.

Re: Gas Generator Conversion (3.00 / 0) (#7)
by Gordy on Thu Jan 03, 2008 at 11:09:08 PM MST

Thanks Kurt,

Interesting link. I think I could scale it up for my twin cyl. Ownan

But what exactly is that poppet regulator and where are they used, so I know what to look for.

Gordy

[ Parent ]

Re: Gas Generator Conversion (3.00 / 0) (#8)
by southpaw on Fri Jan 04, 2008 at 06:29:01 AM MST

Hi Gordy
Try googling maxitrol
These regulators are used on gas burning appliances as a safety device to limit gas pressure into the appliance.
they are often used on propane powered stationary engines and for larger engines they just remove the spring without changing the diaphragm.
If the engine is sitting in the cold (below freezing) the diaphragm may get too stiff to start properly (won't open under cranking vacuum) or for small engines, hence the rubber glove, (more flexible, more sensitive)
Try a junk yard or appliance repair shop to source these regulators.

Southpaw

[ Parent ]

Re: Gas Generator Conversion (3.00 / 0) (#9)
by Bigwheel on Sat Jan 05, 2008 at 12:06:41 PM MST

Hi again and thanks for the comments. I finally got a call back from the supplier that I gave a rang to. Basically, a dual fuel would run $180 and a tri-fuel $240. Thanks Kurt for the pictures. Looking at the web site that OLDF posted and another I found. I'm woundering if building my own would be worth the time. I would have to buy the regulator and fittings. Making the new carb is the easy part but figuring out the orifice sizes may require some R&D. For how often we loose power around here which isn't often, I'd like to give it a try. It would take alot of gallons of gasoline to recoop the cost of the retrofit. Anyone got an idea were to find any specs. I could google for something just figured it be quicker to ask. Let me know what you think. Chad

Re: Gas Generator Conversion (3.00 / 0) (#10)
by Waterlogged on Sat Jan 05, 2008 at 07:08:00 PM MST

Hi, Bigwheel. I should mention that switching from gasoline to propane, may reduce the power output of the engine by about 20-30%. Switching from Propane to Natural Gas, may reduce the power output of the engine about 20-30% again. You may want to look for specific ratings for your generator before spending too much time and money converting this unit. Make sure it will still meet your needs.
Rod.

Re: Gas Generator Conversion (3.00 / 0) (#11)
by Bigwheel on Wed Jan 09, 2008 at 11:35:04 AM MST

Ya, I remember seeing that info found under those standby back up's made by Generac. After, talking to a relative about the topic I was able to reconfirm that my caculation was the right approach and was done correctly. I' didn't factor in any efficencies. So inorder to get the same 8Kw output I would have to upsize the engine to run on natural gas. I don't plan on changing it out but I would be interested to do a comparison test just to see Input VS Output. Thanks again for your comments and give it some thought but will put this one on the shelf for the time beeing. Chad

[ Parent ]

Gas Generator Conversion | 14 comments (14 topical)

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