Generating Off-Grid Power: The Four Best Ways
by Collin Dunn, Corvallis, OR, USA on 04.10.08
So, you've thought about whether or not living off the grid is right for you; you know that it means no more utility bills and generating all of your own power, but what's involved in that? It isn't as easy as slapping a few solar panels on the roof and calling it good; when it comes to generating off grid power, there are a handful of methods that can combine to generate all the energy you'll need to live comfortably off the grid.
Plug in to off grid power with solar electricity
Solar power is probably the one that jumps to mind for most of us when it comes to off-grid energy. The sun-powered option, which includes photovoltaic solar panels, an inverter and batteries, can provide lots of electric power (especially if you get a lot of solar exposure where you live) for a long time, without any moving parts and a little maintenance. The downside, at least for now, is the cost: it is rarely cost-effective to power an entire home entirely with solar, even allowing for several decades for a positive return on the investment. Add to that the wide variance of solar exposure by location (see the map for an example) and the fact that solar only works when the sun is shining, and it's easy to see why solar remains a part of the answer, and not the whole thing.
Generating off-grid power with wind electricity
If you get good news after you contact your local weather service to check on the average wind speed in your area, generating electricity from residential-sized wind turbines is another option for off-grid energy. Knowing the average and wind speed ranges, you can estimate how much electricity a given system will produce. Keep in mind, wind speeds on a specific lot can vary significantly from regional averages depending on local topography.
When it comes to picking a turbine, size matters. A 400-watt wind turbine, big enough to account for a few appliances, uses about a four-foot-diameter rotor; a 900-watt turbine uses a seven-foot turbine; a 10,000-watt (10 kW) turbine, enough to power most or all of a house, uses a 23-foot turbine and is mounted on a tower often more than 100 feet tall. Obviously, living in town or on a small plot, the big one isn't going to work as well, but many people have the necessary real estate for an extra seven-foot turbine.
As with solar, there are pluses and minuses to going with wind energy off the grid; the biggest, most obvious one is the need for breeze: if the wind doesn't blow, the turbine stays still and the electricity isn't generated. Wind turbines also have moving parts, which means more things that require maintenance and have the possibility of failure. But if you've got a good consistent stiff breeze blowing through the back yard, you can harvest its energy for years to come.
Using microhydro electricity to live off grid
Probably the least-known of the off-grid energy systems, microhydro electricity uses a source of running water, like a stream, to generate electricity; it's produced from the energy in water flowing from a high level to a lower level that turns a turbine at the bottom end of the system.
Microhydro electricity generation can be the most cost effective of the three, according to Energy Alternatives Ltd., "Our experience with micro hydro systems has demonstrated that water power will produce between 10 and 100 times more power than PV or wind for the same capital investment." If your source is good, it runs 24 hours a day, 7 days a week, providing lots of off-grid energy for a long, long time; because it produces so much more consistent energy, fewer batteries are needed to store the energy because there is less (or zero) time that the system isn't harvesting energy. Of course, as with the other two, it requires pretty specific on-site conditions; if you don't have a stream in the backyard, you can't use microhydro.
Conservation: addition by subtraction
Even though this doesn't technically generate electricity or transfer energy, we have to mention this; as was noted previously, one dollar worth of energy conservation can save three to five dollars in energy generation equipment costs; if you can use what you have more efficiently, there's no reason to spend more to make more. While designing for efficiency is the best way to achieve high levels of energy conservation, there are lots of retrofits in insulation and efficiency upgrades that can help cut back on demand.
See also: ::Inexpensive DIY Solar Kit: The $600 Kit, ::Mag-Wind Vertical Axis Turbine for your Home, and ::Is Living Off the Grid Right For You?
This is an excellent post and I appreciate that you called out the notion that conservation will always be the more efficient path to the larger goal. Still, I've been doing some poking around about my options and have struggled to find great product specific data. These guys are trying to pull together the right stuff, but definitely have a ways to go.
Gotta applaud the effort though and I love the site in general:
Solar , Wind and Hydro Options
Keep up the great work TH!
As the publisher of "The Renewable Energy Handbook" I live (and work) in my off-grid century old farmhouse in Eastern Ontario.
For us being off-grid is a no-brainer... the grid is 8 kms away which would have meant about $100,000 to hook up. We use solar and wind and, as described above, ABOVE ALL energy efficiency is key! There are many challenges but more than anything else, a wonderful sense of satisfaction! I highly recommend it!
Unmentioned is the use of partially off-grid technologies. For instance, using an off-grid micro-wind and small-solar powered 12-volt fridge to keep the food chilled/frozen. These setups will be smaller, cheaper and harder to be opposed by the neighbors/city building commissions.
i think the bit about turbines is a bit off. a 400-watt turbine may only run a few appliances, but 400 watts being consistently produced over a 24 hour period adds up to 9.6kWH a day which is a lot.
that being said, a turbine won't be producing all the time.
however, a 10KW turbine is waaay more than a small house needs. if that thing is running at that power for an hour and a half its producing more power than my place uses in a day.
you can take the fuel motor off a home generation system and replace it with an electric motor and the only adjustment will be the low turn on switch. add solar/wind for optimal performance.This information is free to all.
@chopper - for micro wind systems, that 400W (or 10kW) rating means that it'll produce that much at steady rated wind-speed, usually around 28mph. The 400W unit will only produce about 50 Watts at 12-13 mph. About the same ratio for the 10kW unit. Also they need to be located well above surrounding structures/trees as turbulent air-flows drastically reduce their performance.
@ jesse - I believe you're talking about a perpetual motion machine -- sorry, not going to happen. Where does the power to run that electric motor come from? Although there are some very interesting and relatively unexplored technologies out there, this one is snake oil. You'd be better off trying to find a leprechaun to grant you wishes than spending your money on this.
Keep up the good work Collin & TH.
this is a great site i love treehugging!!!!!!!!!
Great Reading.
My freinds and I are building a GREEN VILLAGE in CT. We have 25 acres on a waterfront site.
We are rebuilding a 225Kw Hydro that was on site in the basement of an old mill. The mill is gone but the hydro will live on. We have an actice FERC Permit for the hydro also.
We plan on tying in Geo-Thermo into the electricity we have. We will have electric heat.
I believe we will have the Greenest Village that there could be.
Any other great ideas from anyone would be welcomed.
Several house sites are still available for those who want to live carbon free!
This is a great post! Thanks for all of the valuable information!
would a water turbine work in residential water supply or sewer lines? I can guess the sewer lines would need to be filtered before it would work properly but the water supply seems to us a constant flow and pressure. this if applied locally (per neighborhood) sounds to me like it could work.
but I am not a hydrologist or anything like that, I'm just reading this enjoying a beer.
thanks.
Residential water supply and sewage energy: Water supplies and sewage are (should be) designed to consume minimum of energy: minimal slopes, sufficient pressures. Every turbine in the way is the brake
So all microturbines do: Cannot make twenty turbines on one creek.
So the wind dings do: consider what energy u steal it was there for years
Solar is origin of all above. solar, wind and water. If not solar then geothermal and nuclear.
Conservation? What's this?