Skip to Content

A self-powered house?

Last night we had a blackout in our neighbourhood. This in itself is not a big deal, but when you consider that a) I live in a very large city (Calgary, Alberta, Canada), and b) we have had a series of blackouts over the last couple years, well, one begins to wonder. So, let's put on our "pure speculation" hats for now.

While I sat in the dark, waiting for power to be restored, it occurred to me that in this day and age a house should be able to supply it's own power needs. This would remove a lot of drain from the large electricity infrastructure, and lead to larger benefits - such as less impact on the ecology, and the bank accounts (to pay for electricity supplied).

With that I began doing some Google searches once power was restored about an hour later. I began by setting myself some guidelines. I didn't want to pay someone an arm and a leg for hardware that may or may not meet the goal of making a house self sufficient. So I immediately discarded sites that were trying to sell products. Next I also wanted to understand some of the math involved, so that I could determine if it would be possible to meet our needs myself, without relying on someone else telling me "it can't be done", just because they don't see a way. I also wanted to reuse materials if possible to minimize our impact on the garbage dumps. And finally, I didn't want to replace one master for another, so to speak. I don't want to turn to gas powered generators, or hydrogen fuel cells, where I just have to pay someone else other than the electric company.

First thing to determine then is just how much energy would need to be generated. After some very cursory searching, it appears that an average 3 bedroom house uses approximately 1500 KW (kilo watts) of electricity per month. If we assume 30 days in a month, this equates to 50 KW per day. Alright that gives us a goal.

But what exactly is a Watt? According to the math theories (thanks Google - again), Watts are just a power measurement derived form Volts, Amps, and/or Resistance. Here's the basic formula:

  • W = V * I
  • W = I^2 * R (That's I squared)
  • W = V^2 / R (That's V squared)

If we have any two of the values for Ohms Law we can calculate the power used. But in converse we can calculate the items needed if we know the power to begin with.

After a little digging, I came across a site that will do the calculations for us. By applying the assumptions of 120 volts, and 15 amps (what most household circuits are rated for), we can begin to get some ball park numbers. Plugging the data we have into the Calculate Amperes form (120 Volts, and 50,000 Watts) we can see we need to generate 240.847784 amps in a day. Which in turn equates to about 1 amp an hour. Sounds reasonable so far.
(UPDATE: I just had a DOH! moment when I noticed my math was off there... it should be approx 10 amps an hour... This will throw off some of the following discussion.)

Next, we can use the Calculate Volts part of the form to figure out how many volts we'd need to generate a day. Using 50,000 Watts, and 15 amps we get a total of 3333.333 Volts needed a day. And that translates to 138 Volts an hour. This seems a little high, but might still be reasonable.

Ok then. Our targets would appear to be 140 Volts (rounded up), and 1 amp generated each hour. IF this is possible, we should almost be able to take our house off the grid. (Almost because the above doesn't account for those few circuits which need 220 V and 20 or 30 amps - like the clothes dryer.)

Now, we don't really need to generate these numbers 100% of the time. We just need to be able to provide these values consistently throughout the day. If we can store our generated power in a safe manner this storage unit should be able to provide these values to us. Now we're talking batteries. But I'll leave this for further speculation another time. For now let's talk about generating power.

I think it's safe to say there is no "magic bullet" to do the job for us (not until a small home nuclear power plant becomes feasible, but that's not likely for at least a few years). But there are a number of things that can be done to help reach this.

Which brings us to the next topic. HOW does one generate electricity? There are three high level methods I can think of off the top of my head. Solar, Chemical, and Mechanical.

  • Solar - Solar cells have come a long ways in the past decade. However they still are not really useful to an average home (in my opinion). They are too costly, too unstable (i.e. cloudy day, night time, dust buildups, etc.), and just not efficient enough (yet). Sure there's a few cells out there that may be very efficient, but I'm talking about the type us average joes would have access to. Still Solar should be considered part of the overall solution, where it makes sense.
  • Chemical - Chemical reactions in batteries are used to store and generate power. A nuclear reaction is a chemical reaction (with a heavy dose of Physics of course). Fuel-cells use hydrogen reactions to generate power. For our purposes, and budget, we are likely reduced to looking at batteries. This makes a perfect solution to storing the power we generate, but again, the choice of batteries is a different tangent than we're looking at tonight.
  • Mechanical - This covers everything from a generator to friction. If something has to be moved to generate the power, then we are talking about a mechanical method.

Putting some thought into what is in or around a typical house in North America, we can mostly apply a mechanical method to generating power. So we need a generator.

What is a generator? Boiled down to it's core essence, a typical generator consists of coils of wire, and some magnets. When the magnets move pass the coils, the coils produce some power. (It's the electrons in the wire being moved around that is giving us that power.) To go out and buy a good generator can cost some money. And I'm not even talking about the gas powered generators used for emergencies, camping, or industrial purposes. One place to find generators is the local junk yard - pull the alternators out of any car, and you are holding a generator. The problem with these generators is the force it takes to get their shafts moving. The typical household doesn't have anything convenient that can turn that shaft. (I'm excluding people, pet, and hamster power here.)

What does a house have that can be used to turn a shaft? This is the core question I've been pondering for the day. Here's what I came up with:

  • Wind, and
  • Water

Wind is fickle. Sometimes its there sometimes its not. But if wind could be induced to generate some power, and that power was fed into a battery, we have one of possibly many methods for generating power. I've heard folks say that wind power alone cannot power a house. They're probably right. But, if you were to take a number of smaller windmills, connected to smaller generators, rather than one large windmill needing a tower and taking up most of the yard, they can be strategically placed to take advantage of the wind as it hits the house from different angles. The question here is if the generators that these windmills could turn could generate anything worthwhile.

Water. When you think of water being used to generate electricity, one normally thinks of the large hydro dams. I'm picturing something smaller. How does water get to your taps? By pressure. The water needs to be pushed through the pipes. This means there is already a force there. Could we tap into that force to turn a shaft? Probably. But now we're talking about redoing some of the plumbing in the house. I'm still speculating here, but this might turn out to be worth while. Think about how many times you use the tap in a day. Or do laundry. Or use the dish washer. Or have a shower/bath. Every second the water is flowing through the pipes we could be generating some power. How much power? Well, that's still up in the air, and will need some experimentation to find out. But then there's the other side of the water flow - it all has to go somewhere. It goes down a drain. If falls down the drain and pipes. Could we not also plug a generator/turbine near the bottom of those pipes before they exit the house? Or at the bottom of the rain gutters? This applies the same principles the hydro damns use.

At first glance none of the above will generate enough power on its own. But can we add them up? Use say 10 windmills and 4 or 5 generators on the water pipes going to the taps, and one or two on the pipes leaving the house? How much energy can all those produce in a day? I think it'll easily meet the one amp per hour requirement. And put a healthy dent in the 140 V per hour requirement.

I forsee a need for a "collector" circuit of some type. A tool to take an arbitrary number of incoming power feeds to produce a single feed. This single feed should be used to charge batteries. Then the batteries used to provide the power to the house (via a different circuit). Unless there is a large power draw ALL day long, our small generators should be able to provide enough to help top off the batteries, if not keep them topped off. And that's assuming the single feed doesn't just produce enough consistent power without the batteries, thought that's not likely in the scenarios I'm picturing.

So we have work to do on the power generation side of things. Some experiments are in order here. But can we do something about the consumption side of the equation? Of course we can.

If we can reduce our energy usage from 1500 KW per month to something smaller, then we don't have to generate as much power. There's already been much talk in the marketplace about reducing consumption. Everything from turning lights off when not in use, to using energy efficient appliances, and even insulating the home better to make the furnace work less.

When it comes to heating, we have the options of solar passive techniques and Geothermal Exchange systems. By solar passive I mean simple things like putting more windows on the south side of the house than the north side, or using the sun to heat water instead of an electric water heater.

When it comes to lighting, the newer bulbs have come a long ways over the traditional incandescent bulbs. But I think we can go even further. I think the LED lights used in newer flashlights can make a huge difference, especially where the amount of light needed isn't that great (i.e. how many people read books in the hallways of a house?). And even then, using a few LEDs together, with some mirrors and/or refractors could produce a fair bit of light. (Ever get stuck behind a newer car with LED lights in the middle of the night? did you see spots afterwards too?)

Of course this is a huge topic overall, but that's just a few ideas that have been circulating around my noggin. Of all of them, I'm curious to see just how much power can be generated by a small generator, and then maybe making a stack of them. If this works out, I might be able to save a few bucks for the house. At the very least, I'll have fun finding out. :)