What are most people doing for back-up power these days?  It seems a little unfortunate to set up a house for high efficient electric then  have to install a very large propane generator to handle backup needs.

Maybe that is still the best option given how little it will be used?

Well, we use onsite hydro (cross flow turbine) and PV for our primary electric power. Our first backup is an old style Lister diesel engine design that normally uses vegetable oil, but can also use propane/diesel and natural gas. Our second backup is utility power. Heating is via passive solar (about 70%) and hydronic radiant floor heating (electric boiler with propane backup). We also have a masonry heater for ambience, backup heating, and bread/pizza-making oven.

Lister Engine Forum Gallery

However, I reckon most folks just use a standard propane generator, LOL!

It doesn't have to be a large propane generator. We divided up the load into critical and non-critical functions so things like ventilation, pumping, control, security and critical lighting goes on one system that is smaller. A wood-burning fireplace supplies backup heat. The fans for that are on the backup system, of course.

Inverter-driven ductless minisplits are easy on generators, so you can even get one of those on the system if you take care to run it so as to not draw full power at any one time. Individual heads are controllable, so you could program the system to deliver heat to bedrooms in turn rather than all at one time.

You can also split up your lighting systems such that you still have light in a backup power situation, just less of it. An example of this would be a room that has 6 overhead lights or cans. If you ran them all at once, the power needs would be 6 X 23W =138W, but if they were split up on two switches, with one light on a switch and 5 on the other, you could still have functional light in a room, but for 23W instead of 138W.

Outlets for refrigerators and freezers can be managed by putting individual circuits on a timer That way, you can make sure that they won't both run at the same time.

We specify many and have one here since they are common, reliable and relatively efficient. As ICF suggests, load management is the key and the incidental use the excuse.

Also think about an overall integrated plan/design. The first step is to reduce your electrical footprint which reduces both your primary and secondary power requirements and can also create other opportunities. For example, if you use a propane or natural gas range in lieu of an electric range, you reduce your electrical footprint, make available propane or natural gas for backup electrical power system usage, and have a more desirable range (assuming you prefer gas over electric burners).

The reason we went with the Lister engine was low cost and supreme reliability and efficiency. Folks use these engines for their off-grid homesites as their only source of power and sometimes as their heat source too (Google "micro co-generation"). These single cylinder, simple engines run at only 600 RPM nearly forever with minimal maintenance. If there is a failure, they can easily be DIY repaired at low cost. They only burn 1/12 gallon of fuel per KWH. However, they are certainly a DIY project as you will never find anyone who will sell, build, or install one for you. For anyone interested in pursuing this, there is a dedicated forum of people who will help:

Lister Engine Forum

We also use a lister for backup power. It is 6HP and can sustain just a little over 3KW of electrical load. As mentioned, when it comes to "get by" mode, you can setup so you only power the necessities. With a little thought you can get by with very little power. For instance, with 3KW available, electric hot water is off the menu, but the lister is liquid cooled so we harvest the waste heat from the engine to maintain the hot water tank at 120-130F. This setup has a recovery time of about an hour, but you can do a lot with a tank full of hot water, load of laundry, shower, dishes. No electric dryer, but a cloths line works well in the garage With 3KW I can run any light combination I wish,(CFL lights) the entertainment system, the pellet stove, microwave or any two burners on the stove. I make sure the well pump is disabled when we cook, but other than that not a lot of managment is required. We have a freezer and reefer running also. This setup burns about 1/8 gallon per KW per hour or a little under 1/4 gallon per hour average. 55 gallons of diesel can last a real long time running 10-12 hours a day. Diesel also keeps pretty well and since we have a diesel tractor the fuel gets rotated regularly thru the storage tank.

If you have propane appliances well that is the natural choice to power the backup generator. Anyone who is trying to sell you a backup generator however is going to try to get you to buy a generator that will power everything silmultaneousely and will typically only be using 15-20% of it's capacity. THis is a very wastefull way to get a little bit of average power. Remember when you need it, so does everyone else, so getting the propane truck to deliver every 2 days might be a problem to get an appointment when everyone else is needing the same thing in a sustained power outtage. Nor will it be any fun to have to drive abroad foraging for a gas station who has power and can pump gasoline to power a thirsty oversized generator.

Less is really more in these type situations when you need to think in terms of sustainability...
Good Luck.

Exactly. When they think they are going to sell a generator, they tell you to go figure out how much power you are currently using, add some margin and let them know.

The best way is to figure out how to reduce the usage, first.

Diesel is the greatest. In a pinch, you can even make it. Not sure what the readily available gasoline or propane substitute would be. Methane?

Yes, that's another advantage of the Lister engine. In a pinch you can burn waste automobile motor oil, waste fast food vegetable oil, natural gas, etc. Diesel engines like to be loaded down, so 6 HP (or about 3.5 KW) is a nice size for average household backup electrical power needs.

And for completeness and posterity, we recommend building these Lister engines on an isolation stand that uses resilient mounts and operating a robust and heavy duty 4-pole generator at 1800 RPM (i.e., to create 60 Hz power) by transferring the mechanical power from the engine flywheel to the generator pulley.  Here's the isolation stand and pulley drive system design software:

Borst Isolation Stand Design Software

Borst Pulley Drive System Software

Anyhow, perhaps something to think about if preparing for SHTF scenarios, LOL!

Where did you get your Lister(s)?

We built ours from parts procurred from various places about 10 years ago. We purchased the lower crank case group from a company in Portland OR that is no longer in business. We purchased the upper valve head group from a company in Kansas that is no longer in business. We purchased the generator from this fellow George in Kent WA that imported them from China at the time.

There was a time when you could purchase a fully completed Lister engine/generator setup, however, the EPA slammed that door closed many years ago. So people had to build them as a "kit" as I described.  These days I imagine you would have to find someone selling their setup or seek out the parts to build it as a "kit". The engine parts come from India and are essentially clones of the original British Lister engine design. This is a very serious DIY project (e.g., dangerous open valve rods and open flywheels, etc.) and it certainly helps to be an "engine head" and know how to turn a wrench!  If you do some research or post at the Lister Engine Forum that I previously mentioned and provided the link, you can get more current information about all this if interested.

Ronmar, Bob said to say hello!

Yeah we're not pulling a lot of juice except if I go with a heat pump mini split and/or heat pump water heater then it means I need to be able to power 240v. We'll have a wood stove so that is always an option when we're home.

Here's a thought, if we went up with propane heat and hot water then a TriFuel Honda eu2000i (about .1 GPH of propane at 50% load) could be used to power:
Lights (all LED)
Fridge (EnergyStar)
Some computer stuff (about 50 watt in total)
Heat - either the pump or fan, ignitor, etc.
Blower for water heater exhaust, ignitor
ignitor for oven

The 240v well pump would have to go on a battery/inverter that would be charged by the Honda. I can't see running 120v on such a long run and the eu2000i probably wouldn't start it anyway.

The next option I can think of would have to be a bigger 240v generator and run it all off that, skipping the battery. Could probably power heat pumps too (Water heater and/or mini-splits), just might have to run well pump manually so it's not all running at once. Honda eu7000i or so. The generators are bigger/heavier (harder to maneuver) more expensive and less efficient. So it's a little over the top and almost seems reasonable at that point to go to a Generac Guardian so you get the automatic startup and transfer too. Even the smallest Generac would probably power most of the home simultaneously, although it's not really necessary.

Here is a ready built lister engine FWIW

http://www.generatorsales.com/order/Vegetable-Oil-Lister-Generator-6600-Watt.asp?page=L09989

This is the same place that sells the Propane converted Honda and Yamaha inverter generators.

I've never seen them vibrate quite so much. Is that a problem with yours?

Yes, some of these Lister engines can be real hoppers! However, there are ways to improve the balance if needed. Our engine is relatively smooth, but we took the time to make sure all the components were within design tolerances.

Very smart Ronmar.

I don't think "everybody" sizes backup generators to the potential load. In fact the factory training suggests the very things you do with the notable exception of civil emergency generators, a class onto themselves.

Waste oil in a Lister...riiiight.

OK, so what's the speed of dark?

If you look up the efficiency (BSFC) of a Lister diesel, you will find that they are less efficient than more modern diesel designs. The piston speed is too slow.

1/12 gallon per KWH way more than meets our needs. Engine wear and associated maintenance is proportional to the square of the engine RPM. So a 3,600 RPM engine wears 36 times faster than a 600 RPM engine... Listers also sound much better too...

Some one is pulling numbers out their arse.... 36 times.... Engine wear is by design, not by the square of RPM.... Just because your Lister can't survive very long at anything over 1000 rpm. Doesn't make high rpm bad.

Planned obsolescence is by engineering design. However, engine wear is proportional to the square of the engine RPM. Just ask any mechanical engineer who specialized in machine design (like my husband) or consult Joseph Shigley, Mechanical Engineering Design sometime.

Lister engines were designed to run at low RPM expressly for the purpose of increased longevity…like decades of continuous 24/7 operation. This is only a 6 HP engine that weighs about 700 lbs! It all comes down to the purpose of the design and accepting the tradeoffs. High RPM is for high power…and that doesn’t make high RPM bad...but the tradeoff is significantly increased wear and reduced longevity.