DIY Power and Load Leveling

The general ideas in this posting have been spread around in several other postings, some in comments. I’m mostly pulling things together here just to make it easy to find.

I’ve had an interest in Do It Yourself electric power production for, well, many decades. I was always fascinated by electricity and related, and was building radios and motors at about 9 years old. (Those ‘toy motors’ made from a battery, some nails, and a bit of wire). As a natural outgrowth of that comes the notion that a generator and a motor are largely the same thing, just a question of which force is driving whom… Then the ’70s happened. Between the “back to the Earth” folks (yes, I had a subscription to Mother Earth News for a while ;-) and the Arab Oil Embargo encouraging a lot of folks to find “alternatives” and my having an adventure prone soul, well, I learned a lot about power production. (At one time I had a couple of “motor generators” that were military surplus, and dearly wish I’d kept them. Crap power in, nice power out.)

In the ’80s I was prepared for the Loma Prieta Quake (sometimes also called the Superbowl Quake). A 7.1 quake (the wiki still recognizes that rank as the ‘surface wave’ but then quotes the later 6.9 rating. Me? I’m claiming my 7.x Merit Badge ;-) I had two generators and a load of other gear. Along the way, we had lived through the rolling blackouts and brownouts of the Democrats running our power system. (Eventually Governor Grey “Out” Davis was replaced by Governor Arnold “RINO” Schwarzenegger and blackouts / brownouts ended… so I sold one of my generators).

I’ve also installed a heck of a lot of computers and built a couple of computer rooms ( at one time had dual titles of “Director of I.T. and Director of Facilities” at a small tech company – about 200 folks at peak.) One of those computer rooms was for a Cray X-MP-48 that sucked down 750 kVA through a set of 3 motor generators. They turned the 60 Hz wall power into 400 Hz so that all the power supply gear would be much much smaller. (Inductor size is inverse with frequency).

Basically, the point is that I’ve been around the block on electrical power. Dad worked as an electrician for a while after W.W.II and I helped him rewire a few very old houses he bought. At 7 I was “wiring hot”. That is, working on 110 Vac power lines while the power is still in them. Something basically forbidden today, but not that unusual then, and sometimes unavoidable. Dad had done bomb disposal as a Combat Engineer and from that point of view, ‘wiring hot’ is a very minor level of risk. It does teach you to be very careful. The “litany” is now built into my brain. Rubber shoes, check. Rubber handle tools, check. Not touching any walls, check. Gloves or one hand in pocket, check. … (Yes, I’ve ‘been bit’ across the hand… it hurts, but not as bad as the 400 Vdc I took through a class ring working on an old tube radio. I now wear NO jewelry… ) From pulling wire to installing fixtures to doing a ‘field expedient repair / rebuild’ on a VW generator 100 miles from nowhere.

So “making electricity” is, to me, an easier task than making a loaf of bread.

Some Basics

Prime Mover – A machine that makes mechanical movement, usually a rotating shaft, to power the generator head. A gasoline engine, Diesel engine, water wheel, wind mill turbine, steam turbine or steam piston engine. All are example prime movers.

Generator Head – Sometimes just ‘gen head’. The coils and magnets that, when rotated, actually makes the electricity. Usually connected to the prime mover with a single shaft, or with a variety of belts, pulleys, or gears. Most generation setups consist of a prime mover and a gen head. Some, like solar panels and thermocouples, use direct creation of electricity.

DC – Direct Current. The stuff you get from batteries that only has electrons going one direction. Common generators in old cars also made direct current. It can not be changed in voltage with a transformer and has very limited things you can do with it in inductors (coils of wire).

AC – Alternating Current. The stuff in the wall that has electrons changing what direction they go. First one way, then the other. So in Europe, most of it is 50 cycles per second. ( I like the older Cps better than Hz has Cps is self explanatory). In the USA it is 60 Hz (or cps) while in aviation they like 400 Hz as that uses lighter weight smaller transformers and motors. Were I designing things from scratch, I’d likely use the aviation frequencies. It would save tons of copper and other materials.

Nicola Tesla was the guy who invented substantially all of the AC power equipment. AC power dominates global power systems, outside of those that depend on batteries. Even there, the use of AC systems is constantly encroaching on the battery / DC world. Today, most cars use an AC alternator then rectify the AC to DC for use in the vehicle.

Conductor – Stuff that carries electrons well. Copper, silver, aluminum, most all metals.

Insulator – Stuff that does not carry electrons well. Glass, most plastics, ceramics, dry air gaps.

Semiconductor – things that can change state from conduction to insulation to some degree and let us make neat things like radios and computers.

Inverter – A device that takes DC power from a battery and turns it into AC power. Can be done mechanically (with ‘choppers’ or switches driven by a vibrating coil – as in very old cars with tube radios), with a motor generator (DC motor on one side of the shaft, AC generator on the other. At one time many folks distinguished the AC Alternator from the DC generator, but that isn’t really needed. Just be aware of it.), or with electronic circuits.

Rectifier – A device that turns AC power back into DC power. Also many kinds, from motor generator sets to tubes and diodes.

Voltage – How much “pressure” is pushing those electrons along. High Voltage can jump larger gaps of free air and need more insulators to keep it in place.

Amperage – How many electrons are moving. High amperage (or high current – same thing) needs fat wires to carry it.

Watts – Amperage (amps) X Voltage (volts) = Watts. So a 100 W appliance might use 10 Volts at 10 Amps, or 100 V at 1 A. The Watt is a unit of power. So Volts alone or Amps alone do not tell you how much power you have.

Watt-Hours – The W-hr tells you how much work you can get done. It’s fine to have 1000 W of power, but if it only lasts 1/1000 second, you don’t get much done. So for things like starting motors, you may need a big surge of power, lots of Watts, but once it is turning, will find a much lower Watts used over time. The need to have high Watts in “surge” and then lower Watts as ongoing W-hr figures in to sizing a lot of power systems.

Inductor – Things like coils of wires or motors (that contain coils of wires).

Capacitor – Things that are like two plates of metal with an air gap between them. The original Layden Jar was a capacitor.

Inductors have one behavior with respect to power flowing into them, capacitors the opposite behaviour. As many things have chunks of metal hooked to the two different wires feeding in power, there is always some capacitance between them. Similarly, even a straight wire has some inductance. Much of electronic design is balancing that inductance vs capacitance behaviour between parts. Electrons rush into a capacitor at low voltage to start. Current (Amps) leads the build up of pressure (Volts). For an inductor, the voltage builds first as the electrons are not keen on going through the windings, then current builds later. Volts lead Amps. This matters rather a lot, yet most folks outside electronics and power pay no attention to it.

kVA – Kilo Volt x Amps. Due to that difference in how inductors and capacitors behave, there are often different values for the total Watts that can be delivered as actual power, and the specific values of Volts and Amps that can be delivered (as the phase between them shifts with different inductance vs capacitance loads). Mostly you can ignore this, other than to realize that often power equipment may say “1000 VA or 10 kVA” and have a very different W or kW rating) Typically, the kVA is larger than the kW rating. (To go more into this gets into a lot of messy phase diagrams and isn’t worth it for our needs).

3 Phase – Most electric power in the home is single phase. There are two wires, one with electrons coming in, one with them going out, and the flow halts and reverses periodically. (There can also be couple of kinds of ‘ground’ that we are ignoring. This isn’t a class in doing home wiring… those wires are not for carrying power, but for keeping it from getting where it doesn’t belong. They can literally be connected to the ground via a ‘ground rod’.) For some very good reasons, if you use 3 wires and have the electrons flowing in 3 different time periods relative to each other, it is a lot more efficient. Taking any 2 of those wires relative to each other gives you the “single phase” power in your home. For large power distribution or consumption, it’s all pretty much 3 phase. That’s why there are 3 wires on the major power lines. The also can act as self shielding for lower power leakage via radiation and as all 3 are carrying active power, more power is shipped per ton of wire. Mostly you can ignore this for home use, but realize that large generators may say “408 Vac 3-phase” but you can still get ‘house single phase’ out of it with the right wiring and plugs. OTOH, if you have a shop with 3 phase motors in it, you need 3 phase power.


I tend to look at things from a ‘what can be done if a disaster happens’? That is a very different mind set than “What can be done now, under normal conditions, and in keeping with all laws, regulations, permits, and inspections?”

The local laws and regulations vary dramatically around the world. What is allowed, or not allowed, will depend on where you are and your local government. I can’t address in any way what is OK for you to do, what is allowed, permitted, etc.

So everything I’m going to talk about is in the context of “things the laws of nature let you do”, not “things the laws of man forbid”. In some locations, doing anything with electrical power requires a license. I may think that stupid and largely a matter of graft, but that doesn’t change what law applies to you. So check your local laws, codes, etc. before doing anything.

During disasters, the “rules” are often relaxed, and / or you just don’t care if what you are doing might get you arrested if the alternative is to be dead. It’s a very different mind set. As one example: I’ve made a ‘jumper cable’ that has a “male” plug on each end. Horridly dangerous. Plug it into the wall, you have 3 prongs with power just really wanting to move between them. 1500 W of power looking to zap you to death. So why have it? I can “flip the breakers” to isolate the house from the mains and a particular circuit from the house switch box, plug that little monstrosity between the generator and the house circuit, and energize that whole sub-circuit quickly and easily (though at very high risk).

Now I’ve never had a need to actually use this, but it is “in the kit” so that if I ever need it, I have it. In particular, there is a seed archive on my patio and some external yard lights (LED / CFL). All told, it takes about 100 W of power. A circuit with it’s own ‘breaker box’ and with a Ground Fault Interrupter and with 2 breakers between it and the mains. But so spread out it is very hard to put it all on a ‘drop cord’ to the generator. After the quake, if we are living in the back yard in a tent, I can ‘triple isolate’ that sub-circuit from the mains, house, interior; then use my ‘jumper’ to power it. Keeping the seed archive intact, the refrigerator working, all the exterior lighting working, and with outlets left available on the generator. For that, I’m willing to accept the “risk” of triple checking the power status, the several breaker statuses, the depowered status of the sub-circuit,etc. I’ve also ‘wired hot’ for decades so having a powered end of exposed conductors is something I’m trained to handle. Not the kind of thing for the average person, though. And certainly not something to use in any condition other than emergenecy / expedient circumstances. It is highly recommended NOT to do it. Yet it can have a use in extreme conditions.

(Odds are, in that bad a quake, I’d be ripping out the ‘uplink’ to the rest of the house so the ‘breakers’ would be out of the loop – litteraly – anyway. Just to assure no risk of a ‘spark’ lighting the interior on fire. At that point, I’m just powering the external loop under the eaves and some outlet boxes on the end of metal conduit. But for $10 and some time, I’ve got a 2nd level fall back to give area lighting and refrigeration out doors post quake when the house is askew… and we’re living in the tent.)

So that kind of thing is “not for you”, OK? If you are skilled and know all this stuff already, you can figure it out for yourself if it is right for you.

I will fairly freely be moving between 3 different scenarios.

1) Post Disaster. My “model disaster” is a Great Quake – since that is what we had, and will get again, here. You will need to customize for your type of local disaster. We “don’t do snow”, nor tornadoes, for example. I can leave a generator sitting on the patio for a few years and nothing bad happens. Can’t do that in tornado country and can’t find it under 20 feet of snow in Snow Country. It’s up to you do do that adjustment of scenario. Oddly, on the news it was just announced that some idiot shot out a major substation power transformer in the area, so we’re being told to expect “issues” as they fix it. So I may suddenly need to start my generator and finish this another day!

2) I’m a cheap SOB. So my “Patio Kitchen” is just a bypass of the use of electrical power. Avoidance is just as good as generation in most cases. Making my own power via a modest solar collector system is likely in the next year or two. (To power that external loop circuit that is on its own sub-panel). Just pruning off a few hundred Watts of hobby and yard lights while getting some practice at making an ‘out in the boonies’ power system.

3) Regulatory Stupids. We’ve had our share here. So I have ‘drop cords’ ready to power emergency needs inside the house while following all code requirements. (i.e. NOT using my ‘jumper into the house wiring’ that is for Apocalypse only). Just so that WHEN blackouts return, I’m ready. Now we have a ‘smart meter’ and folks are sending me “nag notices” about how I choose to use the product I bought from them. Well, ‘easy fix’ is to put some demand on an energy storage system. A UPS “Uninterpretable Power Supply”. Then put that on a timer for when it charges. Charge it at ‘off cycle’ and use it at peak cycle. Lets me ignore the Regulatory Stupids. (Frankly, moving the cooking off of the AEK All Electric Kitchen and onto kerosene and charcoal on the patio takes care of most of it…)

I may not always flag which scenario is in mind, partly because they often overlap. So, for example, during Gov. Grey “out” Davis years, I had small portable (computer scale) UPS boxes on the outlet clusters in the living room (entertainment cluster) and in two bedrooms (lighting, clocks, VCR). WHEN the power would fail (as it was doing about once / month or two) we’d get some “cheep cheep cheep” from the UPS boxes, but otherwise didn’t really notice. If it took more than 5 minutes to come back on, I’d start the generator and then just unplug the UPS boxes from the wall, and plug them into the pre-placed drop cords. All told, took about a minute to “swap over”. It if took more than 1/2 hour, I’d unroll the drop cord to the kitchen and plug in the refrigerator. If it was at night, I’d light the small kerosene lamps ( 1/8 inch round wick mini-lamps) that acted as night lights in the bath and kitchen and pass out the LED flashlights for any area NOT on a UPS / normal house light. So is that “regulatory stupid” or “prep for disaster”? Some of each since the same thing works the same way during a quake that doesn’t damage my house, but knocks out local power (or the times some idiot drove a truck into a power pole….)

Similarly, I can put that little generator and the drop cords and a couple of the UPS boxes into the trunk of the car, drive off to a remote cabin, and have a stand alone power system. (Though I’d pull the wires off the “cheeepers” so the UPS can be used as a battery box without driving me up a wall ;-)

How you use things depends on you, your circumstances, and what you need to achieve. I can’t address that. In short: YOU need to do some of your own thinking, and are responsible for your own decisions. At most I can tell you what I am doing, and you can choose to laugh at me, or not. ;-)


I tend to design things in layers. Defense in depth and variable ‘scale’. So I have a Minimal Emergency Power Kit. It lives in a backpack that travels with me most of the time. I also have the above mentioned generator for the house. I also have kerosene lanterns and a kerosene stove stored outdoors so if the house collapses in a quake, I’m still warm, fed, and can see in the night.

This means you can choose how many layers you like. Maybe more, maybe less. My Florida Friend has a “Neighborhood Generator” as part of his gated community. They have hurricanes and frequent power failures. He takes a 10 second outage, then power returns. I’d put UPS boxes on the clocks and electronics and call it done. He just resets all the clocks… It was interesting to have the house go dark, then hear a Diesel power up in the distance, and have the lights come back on. Would have been better, IMHO, to have not had the TV need to reboot in the middle of the game ;-)

So you might choose to just have that minimalist style kit, and a long drop cord to put a few hundred Watts into the house for emergencies. More than enough for lights. Not nearly enough for heat or cooking. Yet you don’t need to cook on electricity. So a small propane camp stove and the minimal kit is “enough” for many (most?) emergency needs.

So which are you? A “whole house Diesel with UPS” or a “minimal lights and camp stove”? Or some of each?

Up to you. I can show the layers, what you think of them is up to you.

Community / Coop

The largest scale is “Community / Coop”. In a comment to Gail in another thread, I pointed at a preferred solution at that scale.

Mostly just mentioning this scale as it is of interest to Gail. In reality, it isn’t a DIY scale. It will be done by licensed electricians and with a load of permit applications, reviews, etc. etc. Yet it is ‘kind of a DIY’ in that you are not just calling up the Power Utility and asking them to install a power line.

IMHO, the best options are either a stand alone Diesels generator set, or the Capstone Turbine micro-turbine solution (especially good for Combined Heat And Power situations).

The Diesel solution can be bought at very small scales too, so we will see them showing up as low as 4 kW size. They also can be as large as flat bed trucks (or even small houses…) Until recently, the world’s most efficient engine was a giant ship Diesel at over 50% efficiency. Diesel Electric is used in most trains in the USA for the same reasons. It is highly efficient.

From that comment to Gail:

E.M.Smith says:
28 March 2013 at 6:41 am

@Gail Combs:

Were I looking for industrial sized generation, I’d get the Capstone Microturbine. Comes in units of 30 kW, 60 kW, or 200 kW and can be ganged together up to 1 mW. If you need more that that, get a nuke ;-) . Also suited to “rough environments” (used at sea on oil rigs), will burn ‘crap gas’ such as from landfill recovery sites, flare gas from rigs, or “pig poo”, Diesel, Kerosene, or Propane. It has an air bearing system so doesn’t need oil changes (nor wear much).

Local high school was heating the swimming pool (large…) with natural gas. BIG expense. Installed one of the 30 kW with the cogeneration kit. Same gas use as before, but 30 kW of “free” electricity… That was several years ago. Whenever I’ve gone by the “shed” next to the pool, it’s just quietly whirring away… about like the pool pumps in sound level.

They also have an absorption AC option if air conditioning is what you need… I just wish they made one that was closer to 3 kW in size ;-)

I especially like the ones that are ruggedized for use on oil rigs. Salt spray. Flammable atmosphere risks. Crappy fuel. No problem.

Capstone MicroTurbines reliably power onshore and offshore operations using unprocessed wellhead gas (economic or flare, sweet or up to 7% sour) to generate 3-phase, load-following continuous power.


Perfect for both manned and unmanned platforms, Capstone MicroTurbines can be fueled with unprocessed wellhead gas to provide continuous load following power down to an idle and up to a few hundred kilowatts in easily manageable, redundant 30 and 65kW models.

Capstone’s offshore C30 and C65 models are UL Certified to meet Class 1, Division 2 NFPA 496. For non-hazardous-area placement, a more affordable stainless steel package is available for each model. Non-hazardous units are UL-certified to meet the new UL220 and UL1741 category for engine generators fueled with “raw natural gas.”

Capstone MicroTurbines use no oil, lubricants, coolants, other hazardous materials, or even water. This eliminates transporting, storage, and costly hazmat spill/leakage issues associated with engine gensets.

You’ll also find that a Capstone platform power solution dramatically reduces scheduled maintenance to mere filter changes twice a year. The first minor scheduled maintenance is at 20,000 hours, an overhaul is suggested by 40,000 hours.

That’s the kind of rugged, low-cost, dependable, set-it-and-forget-it operation you need to maximize platform performance and minimize downtime risk.

If you are an “island” of power consumption, that “load following” matters… That 20,000 hours is 2 1/4 YEARS to the first scheduled maintenance. At 4.5 years you get an overhaul…

Beats the pants off a Diesel, IMHO. (And I dearly love Diesels…)

But why do I say that? Well, first off, experience. The local high school installed a Capstone 30 kW Cogeneration system. They have a swimming pool. The same natural gas that was used to heat the pool, now makes electricity first, then the “waste heat” heats the pool. In effect, the school makes their own electricity at competitive rates AND gets free pool heating.

The unit was rapidly installed, turned on, and just runs. Over several years, there were no issues. It is left, untended, for almost all the time. It sounds about as loud as the pool pumps and is in the same kind of ‘shed’ as the pumps. ( I think it is the old heater shed, reused.) The thing just works.

Then there is this article, with this graph to which I’ve linked, that finds them to be the most efficient option at all but very large scales. ( I would only add that the ‘low end’ is 30 kW, so not something for the average single home owner).

Relative Efficiency of power generation microturbines

Relative Efficiency of power generation microturbines

This chart only goes down to their 200 kW unit, but they also have 60 kW and 30 kW units. I’d expect them to be about the same (note the very flat efficiency curve from 200 kW up to several MW scale). A 1/3 efficiency of turning just about any flammable gas into electricity is quite a trick. These things work on well head gas, fermentation / sewage / land fill gas, Gobar Gas from manure fermentation, propane, butane, natural gas, Diesel, etc. etc.

So for “just install and change filters for years”, it’s a darned good solution. Diesels take much more down time for maintenance and much more “overhaul” time per 3000 hours of run time. Still, if you need intermittent power, or don’t need ‘walk away running’ for months on end, a Diesel can be a great choice. I’ve used them to bring up computer rooms when the power company was unable to deliver power for a week, and during various ‘bad things’. Generally, just start them up and keep adding fuel for a week or three. The fuel is also very safe compared to flammable gasses and gasoline. (A lit match tossed into a puddle of it will go out.)

Minimal / Emergency

Minimalist Portable Power Kit

Minimalist Portable Power Kit

This is my “minimal kit”. It fits in a pocket of a backpack. I’ve used it, by the side of the road, for hours on end. Reading a book. Setting up a camp. Recharging the cell phone. The small white thing is a 100 W inverter that also has a USB power / charging spigot on it. The larger blue one is a 300 W inverter that lives in the car and works better for the newer laptop that wants over 200 W when discharged.

The little one cost me $14, and the larger one was something like $30 IIRC. I would likely buy an LED bulb now instead of that CFL bulb, as they are more durable to shock / handling. Still, this has ‘traveled well’. I did cut the ‘tab’ off the end of the power cord so that I could plug in ‘3 prong’ plugs in the last socket of the extension cord. It would likely be a bit better to have a real ‘3 prong’ extension cord, but they are a bit heavier and this is my minimalist kit ;-)

Hopefully, at this point, it’s pretty clear that you have no good excuse for NOT having some kind of “DIY” power generation kit. The “entry point” is about the same as 3 nice coffees at Starbucks or about 1/2 the cost of a nice dinner out. For that, you have light, and ability to keep the communications working. Add the cost of an entire dinner out and you get into the ‘few hundred’ Watt range. That lets you keep the laptop running, and likely a TV set (depending on size), and more light than anyone needs (if LED or CFL). As your car has a built in generator / battery system, you can keep this running for days (weeks?) just by starting the engine every so often.

A typical car alternator puts out about a kW, so 1/2 hour of run time means you can use that 100 W inverter at full output for 5 hours. A typical car battery has about 30 to 60 Amp-hours, or about 300 to 600 W-hours, so if you use that 300 W inverter at full output, expect to start up the engine every 1/2 hour or so of usage and run it for about 1/2 an hour.

Now, if you were out in a cabin somewhere, adding some ‘deep cycle’ batteries lets you spend more time on the inverter, and less time on the generator (or running your car with jumper cables to the battery pack). For example, this RV battery, a small one, has a 66 A-hr rating:

I usually use 10 V as my ‘figuring number’ instead of the 13.2 V of a fully charged, or the 12 V of a ‘being discharged’, and close to the “nearly dead” figure for lead acid batteries. It gives about a 15% to 20% safety margin. So figure that as about 660 W-hr. The “Smart Meter” on my house reports that most of the time I run about 300 W and up to 600 W other than the power hog AEK, the heater motor (it’s a gas heater), or the washer / drier motors. So one of these batteries would run the whole house (minus those large appliances) for about 1 to 2 hours. Longer at night when the lights and TV are off and folks are in bed. A “battery box” of about 10 to 15 of these would let me run the house for 24 hours (and perhaps longer) without any generation / recharge capability. IFF I was careful about what was running (i.e. not leave 2 TVs running in both ends of the house, replace the “big heavy Tube Display” TVs with LED / LCD TVs, not indulge my penchant for 1/2 the lights being incandescent, not have 2 refrigerators and a freezer, etc.) I could likely get that ‘base power’ down to 200 Watts and the number of batteries down to 4 for a day length of run. (The seed freezer and seed fridge are small ones. Combined about 200 Watts when running, about 100 W continuous as a guess.)

Having such a ‘minimal kit’ and using it gets you comfortable with the ‘parts’ of a basic system. A generator of some kind (i.e. my car). A battery box (that can also be the car). An inverter. A distribution system (that power cord). When it is time to make a ‘house sized’ system, you are just making each of those things larger. And maybe changing what kind of generator. Or, in some cases, making the generator large enough that no battery box is needed. Conceptually the same as always having the car running when the inverter is connected.

Mid Scale / Whole House

So one quick “take away” from this is that making a ‘whole house’ UPS for “the basics” could be as small as four to 1/2 dozen car sized batteries in a box, and a couple of fairly small inverters. Another is that looking for “electricity hogs” and finding an alternative can dramatically reduce the size of a ‘DIY solution’. Moving my cooking to a Patio Kitchen on a propane grill / Smoker, Kerosene stove / oven, Gasoline camp stove, whatever; removes THE largest electric power consumption appliance from my power bill. The AEK has an oven that sucks down about 4 kW, and then 4 burners of 2 kW, and 4 kW each, IIRC. If it all is turned on at once (say, starting Thanksgiving Diner) that’s 16 kW of “suck”… That battery would last about 2.5 minutes. 4 of them would last 10 minutes. Which leads to the point that “Doing the math matters. A Lot.”

If you are the kind of person who likes to just plug things in and pay what shows up in the mail and not care, then buy stock in the power company and marry someone rich… (Though I’d still suggest a camp stove and LED lights for your emergency kit…)

But if you are looking to make your own electricity, the first, and best, thing to do is look for power hogs and shoot them.

IMHO, the second thing to do is move the “very efficient and frequently used” gear onto your own system as a stand alone. Leave the “only used rarely and takes a lot then” on the Grid Power. So, for example, a clothes washer used once a week for a couple of hours. Why put out all the money to build generation capacity that will be used 2 hours a week? (IFF, for some reason, you can’t do that grid connect, then at least you can spend a week charging the battery to run that big suck for those 2 hours).

A typical home consumes between 1 kW and 4 kW average / continuous, but it comes in lumps for the big loads. With some care, you can get that down to 500 W to 2 kW average. At that point, having the “big lumps” on the grid means a very small batter pack, or not on the grid means a larger battery pack, and not much more than that.

Many folks who live “off the grid” live on a modest battery pack / inverter for most of the time, but “fire up the generator” once a week to run the major appliances and top up the batteries. Having a 4 or 5 kW generator lets you run things like a washer / dryer and related heavy power using equipment on an intermittent basis, while having most of the ‘regular stuff’ on a battery box with 4 or 6 batteries in it, and a 500 W solar panel for daily ‘top up’, with maybe a 2 kW inverter. All for “pretty cheap”. Under $2000 for the kit. Most of the ‘day to day’ will be silent operation. Once a week the generator makes sure the batteries get a deep full charge, while all the very heavy electric usage appliances are used. It’s a nice solution. Just don’t expect to to it with an AEK or without thinking about what you are doing.

If you want a ‘brainless’ solution, just plug in anything and everything and it goes, you can do that. Just apply money.

So a ‘whole house’ generator (one that even comes on, all on it’s own, as needed) can be purchased and installed and all you need to do is write checks. It needs to be sized to feed your max house breaker (often 100 Amp / 240 V, so about 24 kW) and will cost a fair amount, require some permits, and will need fuel. Most of the time it will be running way under capacity, so will not run at optimal efficiency either. But if you can afford one, you don’t care about the cost all that much.

Several folks make these. Onan, for one.

They have a selection that ranges from a few kW up to several dozen.

Greg Hall liked this one in a comment on a prior thread

The perfect, whole home generator requires no complicated gas hookup or complete electrical panel rewiring. Generators like this work independently and are self contained. Built in fuel tanks, transfer switches and control systems make it easy to install and maintain. Modern diesel engines used today, produce more power, make little noise, and have no visible smoke. People are quickly abandoning the air cooled, fast turning natural gas or propane engines of the past and switching to longer lasting environmentally friendly diesel.

They have a 6 kW unit on their home page.

An important point here is about “standby” vs “continuous” power production and about relative engine life and fuel costs.

In another comment on another posting I’d figure out some cost of fuel numbers. These are based on California fuel prices, you you would need to adjust them for where you are. Still, the relative performance is clear. Diesels make power for about 2/3 the cost of gasoline, but the generator costs about 10 times as much. (For house sized units). Diesels can also run for years on end, where gasoline units often are worn out and need an overhaul at about 2000 hours of operation. Fine if used 8 hours a week for 5 years. Not so good if used 20 hours a day…

I just “did the math” on a typical Honda gasoline generator (gasoline generators are not nearly as efficient as Diesels) and it gets a 1.56 more consumption than the old Honda Diesel (that I think is no longer made). I used the EU2000i that is max 2 kW and continuous rated 1.6 kW.

At the present gasoline prices here of $4.10 / gallon for regular, you can “make your own” electricity at 64 cents / kW-hr fuel costs. That means it is economical to put a transfer switch (or even just a large plug…) on your Air Conditioning and during those $1 peaks, swap it onto a gasoline generator. Crazy, I know, but that’s what the costing says.

That comment goes on to look at ‘peak shaving’ the crazy rate structure in California with a generator. Not so relevant here.

If, instead of $4 gasoline, you use the (roughly) $1.5 / GGE (gallon of gas equivalent) natural gas (conversion kits for generators are available) that drops it to 24 cents / kW-hr which starts to be something of a ‘no brainer’… It covers everything but your baseline low price tier.


Have a 4 kW w/ Honda engine propane / nat gas unit for about $1k (would need to provide your own sound dampening enclosure) and a portable one using Yamaha and 2 kW (or so) in the $1100 to $1500 price range. (with sound dampening built in)

At peak, it would save about 70 cents / kW-hr AFTER fuel costs. So 1400 hours run time to pay for the capital cost of the DIY one. I think that’s likely “doable”, though you end up in “overhaul land” somewhere in there. Then again, if you don’t run it flat out at 4 kW it will likely last longer.

The same folks have Diesels that are small, too, so a 4 kW with enclosure at $1.6 k and one without enclosure for $1.2 k.

No idea what brand or quality. It is possible to put some nat gas into a Diesel, but it takes a certain understanding of some complex stuff. Not for the feint of heart… So likely need to keep it on Diesel for most folks.

OK, two easy DIY solutions. One on Nat Gas with lower capital appliance life at 24 cents / kW-hr that will show up on your PG&E bill as more nat gas usage. One on Diesel at about 41 cents / kW-hr and you buy fuel wherever you want. (Likely one could get ‘off road’ Diesel for about $3.40 / gallon or 34 cent / kW-hr costs…) Capital cost about $1500.

Well. Looks like PG&E is pricing themselves out of the market and DIY is being priced in.

If I lived on a farm, in the country, or anywhere I could run a semi-quiet generator and not wake the neighbors, I’d be exploring it. (And finding out MTBO and overhaul costs).

I note in passing that you can get more expensive commercial Diesel generators that have the natural gas option built in.

But that brings up another point: What fuel is available and reasonably cheap where you live? For us, here in California, natural gas is plentiful, cheap, and comes from a pipe already in the wall of the garage. For folks elsewhere, it is expensive, and may not be already on premises. Propane is common in rural areas and at reasonable prices. Generally, though, it is Diesel that is cheap and delivered out to farms in the countryside. So what fuel is common in an area makes a big difference.

In general, my preference would be for a small Diesel with a natural gas option, run for about 8 hours a week, and with a battery box / inverter for day to day things. Then add a small solar panel for ‘base load’ level of consumption, and even your fuel costs are minimized. ( A 10 kW solar installation is crazy expensive. A 1 kW instal is very affordable and small.)

But do realize that even the “low cost” 24 cents / kW-hr electricity from a generator using natural gas fuel is expensive compared to what electricity ought to cost from a major industrial utility. They can create electricity for down in the 5 ¢ to 9 ¢ / kW-hr range. Electricity ought to cost in the range of 7 ¢ to 15 ¢ / kW-hr. It is only due to stupid policies, or living way out in the middle of nowhere and being charged for expensive power poles, that we have any price above that. So in any real world situation short of being away from the grid, or having incredibly stupid political electricity prices, any DIY electric production isn’t profitable.

But still “do the math” with your fuel costs and your utility rates. We have PG&E here charging “time of day” rates in the Central Vally of nearly $1 / kW-hr in summer. Simply crazy. At those rates it makes sense to put your A/C on a gasoline generator and “just say no” to PG&E. So YMMV as you may have idiots setting your rate structure rather like we have here.

Not So Conventional

OK, that’s the “broad view” of the usual and customary solutions. A standby generator, maybe on nat gas, or with a tank of fuel. Battery boxes and inverters. Some ‘portable inverters’ for emergency use. UPS boxes to let you ‘float’ though glitches and have time to swap to the backup generator. For some, the automatic cut over generator, professionally installed. (For others, like me, a ‘lay the drop cord during outages’ manual system). In any case, just moving onto fuel driven appliances and off of electric ones.

But what about the “edge cases”. What if you live on a farm at the end of a long road? Perhaps where the power company is just such a PITA that you don’t want to deal with them? Are there things, other than a Diesel generator, that could be done? Or what about if you live in a place that hands out $12,000 subsidy for solar panels?

Well, if you live near a stream, even a 1 meter or so ‘drop’ or ‘head’ can give you several hundred Watts with a simple DIY rig.

These folks in India are making about 1 kW from a water wheel made from scrap.

If you have running water nearby, even modest amounts, micro-hydro is a very nice solution.

Though a bit more fancy a prop design would get more…

One of my favorite generators is a Lister Diesel. First designed long ago, these run at very slow RPM, so are physically large for their horsepower, but also tend to run for decades. There are folks who sell these already set up to run on vegetable oil. (Heated, the viscosity becomes low enough that it works well. Left cold, it’s not so good. So these have built in fuel heat). If you can grow your own vegetable oil cheap, or get nearly free used cooking oil from local restaurants, this can be a very cheap and very effective solution. Besides, they sound cool ;-)

A very nice page of what it’s like to actually make one of these go on a real DIY basis, with lots of pictures:

If I had a farm, I’d have one of these. There are also plans for a Lister powered seed press kicking around the web (used in India a fair amount) and then you just grow corn or soy beans or whatever, press the oil, and use it for power. (Alternatively, use the steam engine and burn corn stalks and cobs for power… but I’d really like to do both…)

If the 1800’s call to your spirit, or you like things that have been shown to work for time units of 1/2 century or better, that’s the one…

Honda has a nice home co-generation unit. Lets you make your own power, while also using the heat. The kind of thing you can have professionally installed, even in the suburbs, and get combined heat and power. Hooks up to the natural gas line, but I’d expect a propane version can be made / bought.

Honda thus has been expanding its household cogeneration unit business in Japan, but has also been making efforts to establish a market presence in the U.S. and Europe.

In March 2007, Honda began retail sales of the freewatt™ household cogeneration system—which combines Honda’s cogeneration units with heating units produced by ECR International, Inc.—in Massachusetts, since then expanding sales to Rhode Island and New York.

In summer 2011, Honda and Vaillant of Germany began installing their co-developed micro-cogeneration system, ecoPOWER 1.0, in Germany. In November of the same year, ecoPOWER 1.0 won first place in the “Germany’s most sustainable products/services” category of the German Sustainability Award of 2011. The award recognized ecoPOWER 1.0, which produces heat and electricity with extreme efficiency, for its high economic value and environmental performance.

So on the East Coast USA, or selected parts of the EU plus Japan.

Here is a nice article about a semi-DIY whole home solar panel solution. Anthony Watts of WUWT installed it.

How much did it cost? About $25,000 and change, fully installed, plus shipping and tax on the hardware portion.

So only really a solution in places like California with $1/kW-hr punitive summer rates and lavish graft and crony socialized capitalism subsidy programs.

Personally, I’d use a smaller “kit” like this one:

A 500 W kit with everything in it for under $2k ( $1900 as I type). At 6 hours of sun a day, that’s 3 kW-hrs. Enough to run basic lighting and TV and a small fridge for 10 hours, which is about what folks use each day. So put that on the roof and hook up a battery box. Now your generator needs to run about once a week to ‘top it up’ (more in N.H. winters, less at the equator) and when you are running major appliances like the washer / drier. At that point, having something like the 1.5 kW steam engine (see below) running on solar / wood aux and you are set. You get a 1.5 kW base, 2 kW during daytime hours, and any ‘surge’ up to 2-5 kW can come from a big inverter and some batteries. (So, say you had a big Fridge that sucked 2 kW, but only ran 1/4 of the time – they do cycle – that’s only 500 W average, but you need to meet the surge, so a battery / inverter fixes that.)

Yes, actually sizing things takes personal attention to YOUR appliances. What is the peak draw at motor start? What is the surge demand into things. What is the average draw over hours. Then you size the average generation and the peak inverter and apply batteries to fill the gap.

If you have a lot of wood, and live in a rural place, consider a steam generator. There are even folks selling them ‘ready to go’:

This steam engine is capable of putting out enough power to drive a 500-watt generator, depending on the pressure from your boiler. When the neighbors run out of gasoline and diesel fuel you will still have power from wood, trash, coal or whatever else is available.

The exhaust of this engine will also provide 40,000 BTUs of heat, ideal for steam heating your cabin, providing a heat source for the alcohol still described in our junkyard still book, heating hot water for cooking and other uses.

Our 2-cylinder 3 horsepower steam engine will provide 1500 watts of electrical power and over 100,000 BTUs of exhaust heat.

As we’ve seen, a 1.5 kW generator runs most of the ‘typical’ household power. Use that 100,000 BTU of heat for home heating and water heating, and just put wood in the boiler. Steam engines tend to run nearly forever, so this can be ‘tick tocking away’ in a shed for a long time. Again, I’d likely add a battery box / inverter for some things, and have a major gasoline or Diesel generator for emergencies and outages. (So, for example, a 4 kW Honda gas generator for ‘when all else fails’ or the steam engine was being worked on… or when I forgot to chop some wood ;-)

I could easily see a 1 kW solar “basic lights” system, this steam engine running most of the time for heating and major appliances, and a gasoline generator ‘on the side’ for if / when something breaks or I want to have a big band party and they want 5 kW for the band ;-)

The steam unit can be shut down for a few hours of maintenance and things run from the battery box. The Fridge can cycle on / off with a 2 kW demand to start-up from the inverter / battery box; and the 1.5 kW average more than covers it.

One cylinder 1 hp Steam Engine $1,195.00

Two cylinder 3 hp Steam Engine $2,395.00


Fun to watch, too:

But say you don’t want to be chopping wood or burning things. What if you have nice regular daily sun for, oh, 5 hours a day, and wanted to use it. Solar heat of 180 F or so (about 80 C) isn’t hard to come by in sunny places. So if you have room to set up some black boxes with pipes in them, you get a load of hot water cheap. But what to do with it? How about an organic Rankine cycle generator?

This is a ‘way cool’ micro-turbine:

Don’t know the prices for an ‘all up’ system. They sell those, along with DIY kits and parts.

So you can easily power a place that needs 3 kW average from 10 kW for 8 hours a day.

Personally, I like the idea of a DIY “kit” using a microturbine that can run on solar heat during the day, or biomass heat from a fire in the evening. So a valve (perhaps solar operated? ;-) that connects it to the solar panels when the sun is out, or to the wood firebox when the sun is hiding.

This one is steam, but also claims solar / biomass as options. I’d expect the organic fluid one to be more efficient, and easier to use low temperatures, though.

GREEN TURBINEtm is a very small (slightly larger than a football) steam driven turbo generator that converts (waste) heat into electricity. This makes the Green Turbine an excellent choice in applications where both heat and electricity is required (combined heat and power). The part of the energy, not converted to electricity, is available for heating or cooling.

Green Turbine powered heaters will enable any homeowner or small business to produce 100% of their heating and hot water needs at a huge savings while generating up to 80% of their electricity needs, free of charge. It will also reduce their CO2 emissions by a staggering 50%.

Green Turbine can use the heat energy from solar thermal boilers to generate electricity. Little ships with Green Turbine have clean emissions. Green Turbine can also be used to extend the range of current hybrid automobiles by 20%.

They say the 1.2 kW is shipping now, larger size to come.

Precious little in the way of specs and no mention of boilers at all. But it is often that way. In many cases, getting a decent boiler made is the hard part. But they are available commercially, including wood fired ones.

If you have an engineering bent, it looks like a decent ‘part’ around which to build a steam system. Though, just for the pleasure of watching steam pistons, I’d rather have that steam piston engine with the ‘waste heat’ driving that organic Rankine turbine as a bottoming cycle… (Damn the cost, I want fun! ;-)

In Conclusion

I may add some interesting bits to this over time as I run into them. But the obvious question is “Why are folks not doing this?” Mostly it comes down to cost and “Fuss With Factor”. Most folks don’t want to fuss with things, and as long as the Utilities were cheap, were happy to just pay up. With political driven crazy power policies, more folks will start doing this kind of thing.

Yes, the posting is a bit vague on specifics and wanders a bit. That’s because so much depends on personal options and choices. How much you love the sound of a Diesel, or hate it with a passion and want silence. Do you need 500 W for a cabin in the woods? Or 5 kW for a business -retreat with industrial refrigeration and well lit dining room? Do you like chopping wood? Or writing checks? So it’s up to each person to decide what they like, and what makes money (or sense) for them.

Heck, just letting my Diesel car idle in the garage and hooking a 1 kW inverter to it will make me 60 ¢ / hr in the Central Valley of California at peak summer rates. It doesn’t take long for folks to figure that out. Anyone with a farm has a lot of Diesel equipment, often their own ‘off road’ Diesel tank, and a Power Take Off. Just need to run a belt to a generator head and call it a day. For other folks, signing the “Subsidy Solar” contract is what they like.

So it will happen, in bits, and likely pick up speed. There are the “approved” approaches, like Subsidy Solar, and the less approved, like a DIY Diesel rig, and the very unexpected, like solar thermal / Rankine cycle. The problem is not lack of power; the problem is too many sources to choose between.

Local costs for materials and labor, local sun and wood. Lots of individual moving parts to sort out.

For me, I just start with the smallest simplest layers and “add them on” until it isn’t worth it.

The “minimalist power” kit, for my backpack and for the car. A 2 kW inverter and battery box (that needs installation, now that we’ve gone back to crazy power policies and tariffs in California). A ‘fuel driven’ patio kitchen and deprecate the AEK. Eventually a “few hundred Watts” of solar and the whole patio / external lighting goes ‘off grid’ along with the seed archives and maybe things like the electric lawn mower. Maybe, someday, the rest of the house.

Had I a farm, I’d likely order up a Lister and one of those Steam Engines and get to hacking iron. If I were in a place with consistent year round sun, that solar thermal Rankine Turbine and just add a solar panel a month until it reached full capacity. (And an added ‘wood fired heater’ if I had lots of scrub to burn and no CARB on my neck ;-)

Or maybe I’d just buy one of these folks “power pallets” of 10 kW to 20 kW. Runs on wood.

The Full Solution: 10kw and 20kw

The GEK Power Pallet is a complete biomass power generation solution that converts woody biomass to electricity, heat, and PTO shaft power. It is a compact, integrated and fully automated system –from wood chips in, to power out – delivered at the breakthrough price of $1-$2/watt.

The Power Pallet is comprised of the GEK Hot TOTTI multi-stage gasifier, spark fired industrial engine, generator head, and electronic controller. The system automatically adjusts syngas/air mixture via a wide band Bosch oxygen sensor, shakes the grate when needed, and removes ash via a mechanical auger. The Gasifier Control Unit (GCU) monitors and responds to all internal reactor, filter and engine conditions, displaying the results on an LCD screen.

Power Pallets are available in 10kw and 20kw sizes, using Kubota or GM industrial engines. Genheads are configurable to single, split or three phase, at 120/208/240vac, 60hz or 50hz.

Fire it up for an hour or two, ever other day or so, and coast on the batteries in between. Spec sheet here:

The also have full docs for the DIY sort to make their own (and several other variations):

(CARB Is California Air Resources Board. They own all the air in California. So far, they still let us breath. Barely…)

Oh Well. As it is I get to play with the minimal bits and dream of a farm… some day…

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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29 Responses to DIY Power and Load Leveling

  1. jim2 says:

    I’ll just toss this in. It is probably too expensive, but what the hey. These are used in industrial applications to clean up dirty power.

  2. jim2 says:

    Hey – check this out. Smart meters for water and nat gas. What will they think of next?

    Click to access ElectriSense_Journal.pdf

  3. E.M.Smith says:


    I’m rather fond of a motor and generator bolted together for power conditioning. Other than a direct lightning strike arc-over, they pretty much clean up the power ;-) The physical inertia covers fast sags well, and the electrical impedance of the input plus inertia tends to absorb spikes. About the only thing it doesn’t do is fix significant drops (brownouts) but a tiny bit of circuitry can fix that… (motor automatic speed control).

  4. Peter Offenhartz says:

    For what it’s worth, my summer house (in Maine) is off the grid, powered entirely by solar with a gasoline generator for backup. We have three solar systems: (1) one that pumps well water to a tank when the sun shines (2 x 100 W panels, no batteries);(2) one that powers the 16 cu ft SunFrost fridge (3 x 100 W panels; 4 kW-hr storage; no backup needed so far [5 years]); (3) 3 x 100 W house panels; 3 kW-hr storage. We also have a Sears gasoline generator (3 kW?), which is rarely used except for power tools and vacuuming, and cost under $500. Typical daily load in summer is less than 1 kWhr, which covers computers, wifi, cell phones, CFL lighting, and radios. Sometimes we have a dozen people overnight. Except for the fridge, this is not an expensive system, and since the fridge would otherwise run on propane, I can make a case for the economics of solar (and the SunFrost fridge is BIG and easily freezes to 0F). We cook with propane. My neighbor, who lives on our island year-round, has a similar (but larger) system.

    My point is simple: Don’t overbuild. A cheap Sears generator will get you through most emergencies if you can keep ca. 15 gallons of gasoline on-site. Propane can provide cooking and hot water for a month on a 100 lb tank. A few panels and the equivalent of three or four car batteries can give you all the electricity you really need for light and laptops. I’m assuming, of course, you have sunshine: Coastal Maine has it, in summer, but we also have fog and rain.

  5. E.M.Smith says:


    Interesting that the three solar systems are disjoint. Would be pretty easy to run ‘intertie’ connections between them. ( I presume they are physically isolated, at least for the water pump).

    Still, something to be said for not having the lights go out if the fridge gets left open ;-)

    I’m looking at about 500 W as “about right” for what I need to leave on electric power (after getting the kitchen stove converted to natural gas) as ‘enough’ solar panels. But leaving the large motor driven things grid connected until proven to have enough excess to support them.

    The 1 kW Honda generator runs the whole house, during blackouts, other than those large motors, A/C, and the AEK. So I sold my 4 kW generator. Just didn’t need the ability to do the laundry during disasters. ;-)

    Were I not ‘stuck in the city’, I’d have a large propane tank, propane appliances, and a propane powered generator. With solar / storage / inverters for the typical load so the generator was rarely used. ( i.e. in winter when we can get overcast / fog for a few weeks…)

    Part of why I like the “incremental” approach is that you stop when the sizing is just big enough. What I learned from my “2 generators” time… Bought the big one after figuring all that was needed to run everything. Bought the little one when the spouse could not start the big one… Found the little one was ‘enough’ 95% of the time… Realized it would have been better to start at the smaller end and go larger as needed. Then again, the Honda cost 2 x as much as the big one, but is about 1/2 as many dB so worth 4 x as much ;-) The Briggs & Stratton powered one was horrific to hear. The Honda is 56 db and hardly heard at all. I’ll gladly pay the extra for the quiet.

    But yes, over designed and overbuilt for “6 9’s” availability is just kind of silly, really. Put $700 into a good quiet generator and if you are short of power, go hit the “START” button…

  6. p.g.sharrow says:

    @EMSmith; fairly good short, dissertation on electricity and generation systems. Like you, my father started my training very early. I also was a ship board, 3-wire ( 3phase) electrician.
    Every prime mover has good points and drawbacks. Maintenance is the big thing to think about for any type of prime mover. Very short emergency use can be best filled with a cheap engine. Long term needs would best be filled with a mover that is long lived with little maintenance needs, even if at a high price. Fuel needs are the often the determining factor.due to availability and cost. In your case Natural Gas would be cheapest available fuel except in case of major earthquake caused interruption. This is also very kind on engine internals.
    I my case wood fuel is the cheapest and most available but is also a dirty fuel that requires the most management in it’s use. I kind of lean toward a steam system as it is the most versatile and long lived but requires a lot of management. Balancing all the needs may require a hybrid system of generator and battery feed inverter. As needs run from hundreds of watts to thousands. I fear that the Peoples Republic of Kalifornia is rapidly headed to third world status. Public Graft and Extortion Has gone insane in their pricing structure as well as set things up for rolling blackouts that also will cause usage spikes to increase the rates charged for reduced amounts delivered.
    20 years ago I helped a friend convert his communication trunking system over to Solar charged battery power. After conversion to the battery power, that was still charged by the grid, his bill dropped by over 1/3rd. The installed Solar provided more power then we needed to keep the battery to full charge except during heavy use in dead of winter, Not much sun above the snowline in January. pg

  7. Another Ian says:


    A friend had a fairly large Lister unit on his ranch before he got our SWER rural power (single wire earth return).

    It had racked up around 58,000 hours by then.

    He reckoned it was worth the fuel and maintenance.

  8. Bloke down the pub says:

    I worked for Hawker Siddeley Power Plant Ltd, the company making Lister gen-sets, in the 80’s. Changing regs at the time meant they were developing more efficient models, but they were still sending out spare parts for engines that had been running in the middle of Africa since the days of Noah, usually with minimal maintenance.
    I have a solar pv system which is connected to the grid. For most applications in the UK it is the only way to make it pay. All such systems are required to shut off in the event of a power outage to prevent some engineer getting zapped by power coming back down the line. As a jury rig system, I should think that once isolated from the mains it could be fooled into working by connecting to an inverter on the car battery. So long as the sun shines (not guaranteed here by any means) it would meet most requirements including keeping the battery charged. I just hope that whatever caused the emergency in the first place didn’t also blow the panels away.

  9. tckev says:

    Old Lister engines I’ve seen them all over the place. The most amazing Lister I saw was an ex-boat engine of 1930 vintage, running on locally made palm oil and kerosene mixture in a village in North Ghana. It was running, through a locally made/modified vehicle gearbox, a ‘recovered’ generator from broken and much younger Honda. It sure did stink but the engine just thumped along as if it were made for this strange diet. Apparently they had it running like that for two years or so with no major problems. I wish I had a picture as it sure was a sight. It kept the (tiny) refrigerator going and the lights on though, and that was all that mattered.

  10. Reblogged this on The GOLDEN RULE and commented:
    A wealth of information about home power generating choices and ideas.

  11. A C Osborn says:

    Chiefio, this might interest you, I am not sure if it was in your other post on Generation.

  12. E.M.Smith says:

    @A C Osborn:


    has a more production version. The big problem is mostly just availability of commercial things. Both the free piston and the Sterling have the ‘taint’ of always being Real Soon Now and not making it to volume products. I saw a free piston combustion design once, loved it. ONE moving part (two cycle with ports) and the generator was used as a linear motor to get it started.

    There are generally issues with holding a constant frequency (less of an issue now that AC to rectifiers to inverter are common in high efficiency generators) and startup (as a free piston isn’t connected to much…). For the Stirling designs, they often want to use Helium, that is not in large supply. This paper goes into the control problems a little:

    Click to access 2007_076_01.pdf

    but you saw some of them in that video of the drink can engine where it was a bit, um, sporadic in power levels and frequency.

    I’d love to have one, but only once they are available in a store somewhere… Until then, you are taking on a “project” to develop a product that has had decades of effort soaked up, and with little to show for it.

    The combustion design had a combustion source at each end, so no need for ‘springs’. Those spring / diaphragms are not going to last forever, so I’d be worried about longevity. For most things, an air bearing microturbine will last a heck of a lot longer.

    But it would be a neat gizmo to have working…

    Free piston compressors are more common, likely due to the control being inherent in the power input to the driven part. Well, and the easier thermal problem to deal with ;-)

  13. p.g.sharrow says:

    IIRC this Sunpower device has been in R&D since before 1973. Popular Mechanics magazine used it for a cover story in the mid 70s. Wonderful in theory, 60 cycle by design, solar driven. Never made commercially, as far as I know. I’m kind of leaning toward the Brown steam engine above. 200 year old technology and it actually is available. ;-) pg

  14. Paul Hanlon says:

    Here’s a link to a nice commercial scale stirling engine. 127cc’s displacement giving out about 800Watts. I’m pretty sure I saw another video where the chap adapted two scrap air compressor heads. It didn’t take much adapting either as air is the working fluid in both.

    Apologies if this is a repost of this link, but I love the way this guy was able to literally stick the gas outlet from this gasifying stove straight into a generator.

    Imagine putting the hot end of a stirling engine into the fire and then running coiled pipes around the cold end of the engine, and passing water through it to heat a cylinder. The bigger the divergence in temperature between the hot and cold end, the better the bang.

  15. Wow! Once again I am awestruck. On arriving in the USA I was astounded to find that electric power fails frequently in sharp contrast to my experience in the UK where local power distribution lines are underground. One power failure lasting less than four hours in 20 years.

    My planned solution to the problem of unreliable electrical service involved finding a property with a decent stream or lake that would enable me to generate modest quantities of electricity to cover at least a week long interruption of electricity from the power compay. When this idea failed I looked into less satisfactory solutions based on solar power and wind power but never built any of them.

    Eighteen years later I built a house in North Carolina with a 1,000 gallon propane tank to supply an internal combustion engine driving a 5 kW generator. I could have managed with a smaller generator but for the 4 kVA starting load that my well pump (200′ lift) needed.

    This proved to be an excellent choice. While it would not have been enough to keep my air conditioning going during a power interruption caused by a hurricane it was more than sufficient to cover the ice storm that caused a four day electric power interruption. We lived in a small sub-division of 10 homes and all of our neighbors were able to enjoy warm showers and cook their meals using our propane.

  16. E.M.Smith says:

    @Paul Hanlon:

    I was trying to clean up the links in your comment and deleted the Stirling one before verifying that the replacement was right. It wasn’t. I’ve fished around and found one that seems similar, but if you can repost that link, I’d appreciate it.

    You had posted the “Embed” code (used in postings, but not in comments) and really just need to paste in the “share” choice (that just looks like an html link without the square brackets).


    It really is easy to make your own electricity these days. Frankly, I’m surprised at how few folks do it. Maybe it’s my computer room experience, but it just seems natural to have your own power source for when The Bad Thing happens…

  17. Graeme No.3 says:

    Free Piston Stirling Engines – Nice Technology for Tinkerers
    Posted: April 19, 2013 by tallbloke in solar system dynamics …I’m looking into new ways of generating power in the backwoods. What we need is a robust system like the free-piston Stirling engine pictured here.
    Discussion has animation and leads to U-tube tin can version.

  18. Paul Hanlon says:

    @Chiefio, sorry to give you that work. Won’t happen again :-).

    That looks like the link I posted, but I hunted around for another one, which comes after, showing a 500W generator attached and some other improvements. I couldn’t find it, but I did find this, a full description of the work that went into making it and its current progress. Well worth a read.

    One thing that did jump out was the 25-27% thermal efficiency of it, so one would need to either use a heat source generated for something else as well, and/or find a way to use the excess heat afterwards. So not a one stop solution – yet, but the nicest implementation of a Stirling Engine I’ve seen.

  19. Paul Hanlon says:

    Sorry to double-post.


    Any chance of a run-down on your setup, along with the issues and costs involved in doing it? With the disparity in gas to oil prices atm, that sounds like the perfect setup. And with that many neighbours, it can’t be that intrusive.

  20. E.M.Smith says:

    @Paul Hanlon:

    It’s not a lot of work. One click puts me in the editor, I’ve usually got the video open in another window (having watched it), then just click ‘share’ and pick up the default text (instead of the ’embed’ text that goes into articles – why WordPress uses both in different contexts is a mystery…) and paste it over the original link. Click save. Faster than typing this description ;-)

    Works great, too… unless one pastes over the wrong link and hits save before noticing ….

  21. J Martin says:

    The U.S. Department of Energy in Washington, NASA Glenn Research Center in Cleveland, and Stirling Technology Co. of Kennewick, Wash., are developing a free-piston Stirling converter for a Stirling Radioisotope Generator. This device would use a plutonium source to supply heat. There is a potential for nuclear powered Stirling engines in electric power generation plants. Replacing the steam turbines of nuclear power plants with Stirling engines would greatly simplify the plant, yield greater efficiency, and provide above all, a much greater margin of safety, while reducing radioactive by-products.


    But is it possible to get sufficient power density from a Stirling engine, it might mean that the average size of Nuclear power stations would have to shrink.

    So every house or housing estate or small town could one day have it’s own Thorium powered Stirling engine. That would be what people in the future would call off grid.

  22. E.M.Smith says:

    An interesting paper on Solar Trough Organic Rankine Electricity Systems:

    Click to access 39433.pdf

    Solar thermal ‘micro generator’ being built by students in Lesotho.

    Solar powered A/C:

    Combining solar thermal with absorption refrigeration:

    Parabolic dish solar thermal

    Click to access 301-ferreiro.pdf

    Fig. 7. Thermal efficiency of the for the cited working fluids
    While thermal efficiency for a dish/Stirling engine
    approaches 30%, in the proposed case studies, for ethane
    and ammonia as working fluids, the efficiency is
    significantly higher. As consequence of such results,
    power converters based on RC, could be implemented
    rendering higher efficiency that than of the Stirling

    Where RC is Rankine Cycle. So looks like an organic or ammonia Rankine cycle turbine beats a Stirling engine anyway…

    Useful list of Stirling Engines:

    An interesting page on Ammonia Engines. Along with some old designs, it also looks like the rocket motor on the X-15 was an ammonia engine. Nice picture of it too:


    There is another way to use ammonia for power generation- burn it as a fuel. There is currently interest in using ammonia as a fuel in IC engines. It delivers hydrogen without having any carbon content. There are obvious problems, such as the toxic nature of ammonia, and some less obvious- ammonia burns slowly compared with a petrol-air mixture.

    A notable example of ammonia as a fuel was the XLR-99 rocket engine, which powered the famous X-15 manned research rocketplane. It was the first big man-rated throttleable and restartable liquid propellant rocket engine. The thrust was 262.400 kN (58,990 lbf) in a vacuum and 227.300 kN (51,099 lbf) at sea level. The throttle range was from 50% to 100% thrust, and the restart capability allowed it to be shut off in flight and started again if needed.
    The XLR-99 was developed and built the by Reaction Motors Division of Thiokol Chemical Company. The propellants were liquid oxygen (LOX) and anhydrous ammonia, fed into the engine by turbine pumps at a flow rate of more than 4500 kg per minute.

    Left: The XLR-99 rocket engine, fueled by LOX and anhydrous ammonia.

    So “minimum” was about 2250 kg / minute (though a bit unclear if that is ‘each’ or ‘both’) or about one ton / minute. On “slow”… I’m sure they must have had a good reason to use ammonia, but I’d have thought even propane would have had more zip / kg. Then again, I’m not a rocket scientist ;-)

  23. jim2 says:

    I wonder how ammonia would work in a (possibly) modified Lister engine? From what I’ve read, iron and steel are compatible with it.

  24. E.M.Smith says:


    Works well with iron and steel, not with copper, zinc alloys of them. Per these folks:

    The Lister would likely need a spark plug and might be well suited due to the low flame speed needed in a slow engine, but would not ‘tick over’ well at very low speeds like idle…

    Ammonia has a high autoignition temperature of 651°C so it has a high octane rating. This temperature is just slightly higher than the temperatures typically created by the compression stroke in a typical diesel engine with a compression ratio of between 15:1 and 20:1. This characteristic therefore favors a spark ignition regime.

    But ammonia has a relatively low flame speed. Flame speeds are important because at high or even medium revs, the piston can outpace the flame during the power stroke, leaving unburnt fuel in the cylinder to be expelled by the exhaust stroke. This is both polluting and wasteful of fuel. Flame speeds for any given fuel depend on the mix of air to fuel. If the mixture is too lean the flame speed can be so low that energy released by burning cannot match the rate of cooling as the piston descends. If this happens, the power stroke fails and the engine stalls. Ammonia’s low flame speed limits how low the fuel concentration can be and thus limits the range of power outputs of the engine and particularly affects the engine’s ability to tick over. This characteristic therefore favors a compression ignition regime although it can be mitigated by use of multiple spark plugs to each cylinder – an often impractical proposition if you are converting an existing engine.

    Ammonia has a boiling point of -33°C and so unless you are in Moscow in the middle of winter, the fuel can be introduced into the induction manifold where like LPG, it vaporizes without the need of a carburetor. Even in Moscow a little pre heating makes this a very easy way to introduce fuel into the engine. But such a method only suits a spark ignition regime. If you want compression ignition to overcome the limits imposed by the slow flame speed, you could have some fun and games with the injectors. Ammonia has a critical temperature of 132.4°C which means that above this temperature it is a gas no matter what pressure it is under. Since the injector is screwed directly into the cylinder head controlling its temperature and that of any ammonia within it, is difficult to say the least. It will start out cold, warm up to an operating temperature that could be below the critical – but probably not reliably below it. In any event the vapor pressure of ammonia varies dramatically with temperature. This means the most practical method of injecting ammonia into the cylinder is as a gas at all times. But since the pressure in the cylinder at the top of the compression stroke is very high (~100 bar), the ammonia injectors would have to include a pre-heater and be fed using a very high pressure pump. These temperature characteristics of ammonia mitigate strongly in favor of a spark ignition regime.

    Converting existing engines to Ammonia

    From the characteristics of ammonia it is very easy to build an ammonia burning engine if you are starting from a blank piece of paper. We use spark ignition with multiple plugs and take advantage of the high autoignition temperature with a compression ratio of say 15:1 instead of the 10:1 typically used in a spark ignition (gasoline) engine. And that’s it. Job done. You have an ammonia engine.

    But for a conversion we have two choices, none of them quite ideal. If you start with a gasoline engine the conversion is essentially identical to an LPG conversion. The difference being that the tank and fuel pipe must not contain metals such as copper or zinc or any of their alloys as ammonia will corrode these. Steel is used instead. The tank must also be able to withstand pressures of at least 25 bar because of ammonia’s higher vapor pressure. The advance and retard regime will also be different as it will have to take account of the different temperature characteristics of ammonia compared to gasoline or LPG and the different ratios of flame speed against fuel concentrations. This implies a refit of the engine management system (EMS) in many cases and in any event we still end up with limited power range and of unreliable tick over.

    Conversion of a diesel is actually better but a bit more radical. Take out the injectors and replace them with spark plugs and the means to fire them, then perform the same LPG style conversion as you would for a gasoline engine. You should not perform conversions on diesels with very high compression ratios but anything up to 18:1 should be safe.

    The result is an engine that is more fuel efficient than the converted gasoline engine thanks to the higher compression. It also has fewer of the problems associated with the lower ammonia flame speed. This is because the temperature due to the compression stroke gets the fuel air mixture very close to the autoignition point. This then requires less energy to actually ignite and the flame speed is enhanced. Diesels converted to ammonia have better output power range but still fall short of being able to tick over on very little fuel.

    Turbo/Super Chargers, Intercoolers and Variable Valve Regimes

    Turbochargers and superchargers boost an engine’s power by compressing the air in the intake manifold so that each stroke processes more air and fuel. It effectively increases the engine capacity. But it also slightly raises the temperature of the air in the intake manifold. This slight rise in temperature translates into a big rise in the temperature at the top of the compression stroke and the peak flame temperature when the fuel is burned. In a spark ignition engine the elevated compression temperature could cause knocking but even in a compression ignition engine, the higher peak flame temperature could cause other damage. Therefore an intercooler is used to mitigate the rise in temperature in the intake manifold. If you have converted a gasoline engine with a compression ratio of 10:1 or less, there is a lot of scope for the engine to accept elevated temperature in the intake manifold. The intercooler can be either bypassed or set to cut in at significantly higher temperature than for gasoline. But if you have converted a diesel with a 15:1 or higher compression ratio, the ammonia air mixture could pre-ignite without intercooling. Some engines use a variable valve regime to close off the intake valve at some point before the intake stroke is complete. This effectively reduces the compression ratio and the power rating of the engine. But it gives a noticeable improvement in fuel efficiency. As the expansion ratio is unchanged this is now greater than the compression ratio. The exhaust temperature and pressure is lower so the exhaust contains less energy and so less energy goes to waste. Such engines are commonly heavily supercharged to mitigate the reduced power output per unit capacity and frequently have higher would be compression ratios. Ammonia conversions work exactly the same in such engines as they do in engines lacking this regime.

    But you would want to check the compression range of the Lister…

    Might want to find out how much it costs for a gallon of Ammonia liquid too…

    Looks to me like an old farm tractor might make a more interesting conversion. First off, they often have equipment to carry liquid ammonia already designed for them ;-) They are also typically built really heavily so can take abuse. Find one with a very high compression Diesel in it, you might even get it to work as a Diesel (but I’d be worried about the injector temperature hitting the critical point). Still, it ought to be pretty easy to put spark plugs into the head instead and then just run ammonia through an air intake injector instead.

    Don’t know why one would want to do it, though. Not a lot of ammonia filling stations around ;-)

  25. Tom says:

    “Disruptive Generation: Anxious Utilities Ponder the Threats” jogged my memory concerning your experiments. Apparently the combined cycle guys intend to introduce less costly systems using cheap natural gas into residential use and compete with electric utilities.

  26. E.M.Smith says:


    Nice article… Capstone MicroTurbine already has a solution at the 30 kW level. Just needs shrinking to 2 or 3 kW scale and I’m off the grid… (or even 6 kW that can throttle down to 1).

    Nat Gas to the home is THE cheapest fuel available right now. Yes, better to just convert the All Electric Kitchen directly to gas, but I’d be happy to move the A/C and lighting onto gas derived electricity and have room in my garage at the end of the gas pipe to place a generator unit…

    I’m holding off, just because I’m not fond of the cost of the commitment right now, but with $200 electric bills for “not much product”, well, it’s easy to pay for a $1000 generator / kit at that price…

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