Central Air and 15kW Genset

[pigseye]

Hi All,
Great forum, already received some help on an non lister engine.

I live in Wi and am considering building a 15kW genset with a 24/2 lister. 

One concern I have is that our home really heats up on hot summer days and our AC runs for a long time.  But generally this is only for a few weeks a year.  The rest of the time the AC is used very intermittently and we could manage it better to use it less.  But there is no way i can talk my wife into going off grid if we don't have simple and easy AC like she is used too. She loves it.  So i'm willing to accomodate since it means a bigger engine!  woohoo!

But does it really make sense to spin a 15kw gen head, with a 24hp Lister, 365 days a year, so you can meet the needs of 2 central air systems for 30 days a year?  I like the idea of hybrid boost set ups, but the complexity and cost really worry me.

My questions: 

Is a lister 15kw genset over kill for my needs? 

What are your throughts or recommendations?

Thanks
Pigseye

[BoldtsWagon]

Double your fun, buy a second 6/1 with a 5 kw head for daily operation.  Tie the 15 kw unit into a separate circuit for the air conditioning with circuits to the shop for welders, compressors, etc.

[solarguy]

Another idea that has been kicked around is to use two engines (like two tens for example) to drive a single big generator.  When you have heavy loads, run 'em both.  Light loads, slack the belt for the second engine.

Either scheme would give you some backup capability, which you really really want if you're off grid.

Good luck and have fun!

troy

[rgroves]

Hi All,
Great forum, already received some help on an non lister engine.

I live in Wi and am considering building a 15kW genset with a 24/2 lister. 

One concern I have is that our home really heats up on hot summer days and our AC runs for a long time.  But generally this is only for a few weeks a year.  The rest of the time the AC is used very intermittently and we could manage it better to use it less.  But there is no way i can talk my wife into going off grid if we don't have simple and easy AC like she is used too. She loves it.  So i'm willing to accomodate since it means a bigger engine!  woohoo!

But does it really make sense to spin a 15kw gen head, with a 24hp Lister, 365 days a year, so you can meet the needs of 2 central air systems for 30 days a year?  I like the idea of hybrid boost set ups, but the complexity and cost really worry me.

My questions: 

Is a lister 15kw genset over kill for my needs? 

What are your throughts or recommendations?

Thanks
Pigseye

Do you know the continuous draw and starting load of your a/c?  That's sure where I would start, because it would suck to put that amount of bucks and work into a big genset and then find out it couldn't run everything or start the a/c while running other loads.

Russell

[pigseye]

Yikes 2 engines that would cost some bucks, but it sounds like fun.

Well here's what I was thinking.  I would stay on the grid and run the generator during the day and only at night when it's very hot.  If we only use the grid at night and if the AC isn't running, I doubt we would burn enough electricity go much beyond the monthly connection rate of $10.

That gives me back up.

We do have 2 central air conditioners, but it's not because we live in a huge house but because of ductwork limitations in remodeling.  The plan here was to have the AC units on relay circuits so both ACs are not running at the same time.  Neither AC unit is huge but they still take a lot of juice.  Unfortunately I don't know the start up and operation draw of either unit.  I'm hoping that a 15K gen head is able to power at least one at a time under typical load.

One thing I'm worried about is we have an electric oven we really like.  This is one appliance that we won't replace and I'm thinking I'll have to plan to use the oven only when I'm connected to the grid.  It's good thing we don't bake very often.

Here's the embarassing part, on average we use more than 2200 kwh per month.  I'm figuring we could lower our electricity consumption with basic conservation by about 30 to 35%.  But that's still ~1500kwh per month.

I'll figure out the startup and coninuous operation current draw on the AC units and work from there.

Out of curiosity, how bad is 2200kwh per month?  Seems real bad to me.



 

[WWIProps]

USe net metering to bank electricity over the winter.  Use the Listeroid to provide electricity and heat in the winter, build up an excess credit with the utility and burn down the credit over the summer.  This way you only have to size for an average load and the utility can take care of the peak load.

Here is a summary of the WI net metering rules:

Wisconsin Net Billing Order
Net metering in Wisconsin is authorized by Public Service Commission of Wisconsin (PSCW) Order 6690-UR-107, effective January 1, 1993. The order applies to all utilities under the jurisdiction of PSCW (investor-owned utilities). Rural electric cooperatives in Wisconsin are not rate-regulated by PSCW, but they often follow Commission’s rulings voluntarily, and several rural electric cooperatives are preparing to offer net metering to their customers. Wisconsin’s net metering applies to customer-owned electric generation facilities that are rated at 20 kW or less, regardless of energy sources.

The utility’s electric meter is permitted to run backward when the customer is generating electric power to feed into the utility grid. If the amount of energy supplied to the utility exceeds the amount of energy consumed, the customer will receive a credit on his monthly bill equal to the net excess kilowatt-hours of energy received by the utility multiplied by the Energy Credit Rate, including any applicable adjustment for cost of fuel, or the customer will receive a check for this amount issued by the utility. Any credits to the customer shall be reduced by the monthly customer charge of the standard applicable rate schedule. Actual issuance of a check payable to the customer shall not occur until the amount due the customer exceeds $25. If a customer-generator operates a renewable energy facility, then the utility pays the retail rate for net excess generation. For non-renewable generation sources, the utility pays their avoided cost for net excess generation.

For further information, refer to Public Service Commission of Wisconsin (PSCW) Order 6690-UR-107.

Contact: Paul Helgeson
Public Service Commission of Wisconsin
Fax: (608) 266-3957
E-Mail: paul.helgeson@psc.state.wi.us

Look for my other posts on Cogen and use of an induction generator for more info.  The only downside is that you do not have back up generation when the grid is down.

By the way, you have to run WVO.  Dino diesel will break the bank!

I hope this helps.

Regards,
Scott

[Jim Mc]

OK.  I gotta ask.  What is the resasoning behind going, as you say, "off-grid?"  If it's for the sheer joy of engineering a diesel power plant, then by all means, carry on!

If it's to have back-up power for times when the mains go down, then carry on!

BUT, if you think you're going to save money, beware.  The only way I see it working is if you operate in cogeneration mode, where the engine is run when you need the heat, and the electricity is sold back.  Running the system in the summer when the heat isn't needed is probably going to cost more than just buying utility power.  Could be wrong, but let's see the math...

Net metering is a wonderful thing, but as I read the info just posted, there's a devil in those details.  Find out what the utility's "avoided cost" is in your case.  When I checked into it with my REMC, it was about a penny a kW-hr.  It's not worth earning a monthly credit if all they are paying is avoided cost.  You might be able to drive each month's bill toward zero, but the idea of banking credit from one month to the next might need a bit of investigation.

[WWIProps]

"If a customer-generator operates a renewable energy facility, then the utility pays the retail rate for net excess generation. "  That is why it has to be veggie and absolutely not diesel.  Some states won't buy off on veggie as a renewable fuel, you will have to check. 

If you were runnig diesel then "For non-renewable generation sources, the utility pays their avoided cost for net excess generation." would apply.

Scott

[solarguy]

2,200 kwh per month is so bad it's amazing.

When I fiirst bought my 1,200 sq ft house, I thought it was bad because we used 700-800 in the summer with AC on all the time.

Once we "fixed" the house, our monthly use dropped to 100 to 200 kwh.  The "fix" consisted of:

Buying a "kil-a-watt" meter to find out where all that electricity was going.  This lead to:

1. Replace electric water heater with gas
2. Replace electric stove/oven with gas (much nicer to cook with by the way, all the real chefs use gas)
3. Replaced all incandescent light bulbs with compact fluorescent, except those bulbs that are only on for 10-15 minutes at a time, like the bathroom.
4. Put in a ceiling fan in our bedroom and use the central air less
5. Put all phantom loads on power bars so we could turn them completely off, the TV and VCR are the most common culprits for using electricity even when they are "off".
6. If you're not in the room, the lights must be turned off.
7. Insulate that attic more to reduce heat gain in the summer, so we need less AC

Even if you don't save any money, which is unlikely, it's waaaay better for the environment.  It will also make it a lot easier to set up an alternate energy supply that could actually be more affordable and run your whole house.  Conservation is always a good first step before you jump into any alternate energy schemes.

Good luck and have fun!

troy

[pigseye]

Hi Troy,
I gotta tell using that much electricity is just embarassing.  I hadn't been paying attention because we;ve been so busy and it has really gotten away from us over the last couple of years.  Just being careless and lazy.  We do have 3 daughters and an electric water heater and what I listed above, but still.  At one point we were leaving on all of our computers (5 of them)  24/7.  I've replaced half the bulbs with flourescent and working on the other half and turned down the down the water heater.  But that's just a start.

Everyone else,
To answer some of the other questions, I'm very interested in running WVO and have a friend on a farm who is making biodiesel and has access to 1000s of gallons of WVO.  He said I could have all I want.

i do want to run cogeneration for the hot water needs and for my radiant floor system that I'm in the process of installing.  That should lower my gas bill and limit how often one of the furnaces runs.

My main interest is to have real back up power and the thought of running a diesel engine is just plain intriguing.

Thanks for all the input.
Pigseye

[GuyFawkes]

At one point we were leaving on all of our computers (5 of them)  24/7. 

boom boom

you got 60-70 percent of my electric bill right there, oh yeah, don't forget the UPS, power conditioner, all the itty things like routers and so on.

[hotater]

I think 'daughters' count for about 700 Kw each.         More if teen-agers. 

[ceiii2000]

.

[DirtbikePilot]

I will probably figure out how to run my 20/2 at 650rpm and 1000rpm. During low months I will change the pulley and run it as a 12/2 at 650.
   It isn't a perfect solution but I will probably be on and off the grid a lot anyway as I tinker and play with it.

Now, that sounds like a good idea to lower costs.

[GuyFawkes]

I will probably figure out how to run my 20/2 at 650rpm and 1000rpm.

a ratio of 1:1.538, gotta be able to find that in a motorcycle gearbox...