I’m looking at buying a house which has a river running in front of it. It would be a fairly extensive redevelopment, and I’d like to make it as off grid as possible.
The previous owners have already set it up with a reed bed system for waste treatment. I’m curious as to whether I can use the river as a source for energy and domestic water.
So far, the searches I’ve done seem to indicate that’s not possible - the power systems all seem to require a separate water channel, which would not be possible for planning reasons. This surprises me, as I’d have thought it’s possible to make a simple, relatively low power domestic system, similar to the domestic wind turbine kits that are now available.
Domestic water purification also seems to be unavailable. Again, this surprises me.
Sure it’s possible. It’s probably more of a do it yourself project, but I’d imagine the easiest way to do it would be to get a propeller. Put the propeller in the water and hook it up to gears to get the proper speed to run a generator.
Solar purification is probably going to be your best bet here, especially if you don’t need running water. These work by evaporating and then condensing the water. Googling solar water purification yields a number of websites.
Paddle wheel power doesn’t really work well when converted to electricity as the wheel turns too slow, and gearing it to the speed that generators like incur a lot of losses. What you really need for small scale hydro power is a hydrolic drop so you can use a water turbine,
I forgot to add, the reason you generally have a separate channel is that the height of the river is going to change throughout the year. If the river drops 2 feet, suddenly your propeller that was underwater is now above it. I found this propellor/generator which produces DC. I’m assuming that you want to be running AC, so that won’t work, but it gives you an idea of how much energy it can produce. They say 2.4 kwh, which looks to be on the low end of home power needs.
If you want cheap water purification you can put water in a clear plastic bag and keep in in the sun for a couple of days. Make sure you have enough sun.
What’s the matter with drilling a well? The water will probably be good and can be filtered. Use a hand pump if your worried about electrical use.
You can also use the river as a heat source. I’ve heard of heatpumps in streams and rivers used to extract heat for either pre-heating water for hotwater, or for central heating and even for cooling in the summer.
They’re not cheap though, around £4-5K for set up.
In Nepal I saw a converted inflatable dinghy tethered to a bridge, with an outboard propellor generator on the back of it. The flow of the river generated enough electricity to light a few light bulbs and a TV in the nearby village.
Getting the water to the purification unit should be simple enough: I have seen places that use the river to create electricity to drive a water pump. How stupid is that? Far better the great old Victorian invention that uses the flow of the river mechanically to drive a small archimedes screw.
Thank you, that’s just about exactly what I was looking for. Your point about changing river depth is good caution, but the stretch of river I’d have access to fortunately goes through a narrow, rock banked “pinch”, where it becomes fast flowing and deep. I think I’ll contact the company from your link and ask whether these generators can be used in combination to charge a large bank of batteries.
Now, anyone got any ideas for a clean water supply? Solar purification is not really a workable solution in north Scotland, I’m afraid.
Step one is to determine if you are legally allowed to take water from the river. Just because it flows through your land, and there seems to be plenty of it, doesn’t mean you have any right to use the water. This varies greatly according to location. In the Southwest U.S. we have an expression: "Whiskey’s fer drinkin’, water’s fer fightin’. "
Step two is to determine how much treatment the water needs. County extension agents, or Ag and Engineering Colleges may offer low cost or even free testing services.
Google “ram pump” This will provide you with pressurized water using the river flow directly. Once you have pressurized water, there are many treatment options.
At a minimum you will need to use some sort of biological control. Even if it is clean today, a bear or deer could defecate in it tomorrow. This can be chlorine injection (either bottled gas, or bleach) Miox ™, or UV. Bleach injection is probably the most cost effective in your case.
Beyond that you may need some filtration…This can vary from cheap (bag filters) to pricey (reverse osmosis systems) to in between.
I hope that you have checked to make sure that the home is either out of the floodplain, or is sufficiently elevated above the base flood. Flood maps for the U.S. can be viewed at www.msc.fema.gov .
If you’ve already checked it out, then nevermind.
Also, Kevbo has a good point; for example, in our state one must fill out a ‘permit to withdraw waters of the state’ before diverting river flows.
Depending on the location, solar energy might also be a good fit. Solar energy gets knocked around a lot on these boards, with the chief complaint that the technology has yet to produce a surplus of energy. That said, the technology is well developed, and with batteries and inverters it can produce a reliable supply of AC house current.
You mentioned living off of the grid, but my local utility is providing fairly generous incentives for customers to install solar panels on their homes. Besides the whole "green is good sentiment, I think that this is so that they can put off building conventional plants for peak power. It gets hot around here, and air conditioners mean that peak residential use tends to happen when the sun is shining the brightest.
Why do you want to take water from the river and purify it instead of drilling a well, which uses the ground as a natural filter? Both can be powered off the grid.
www.demotech.org , my dad’s site, offers for free some high-tech designs for pumping water and waterwastetreatment. All designs can be made DIY style and are very ceahp, as they are meant to be made by Third World poor farmers.
It’s generally not a good idea to run two or more generators on the same circuit. If you get a difference in rotation speed, then one generator is going to try and accelerate the other. At best this means you just waste a bit of power, at worst it can make things go boom. All you would need to do to make that generator supply more power is to stick a bigger propeller on it, assuming the components can handle the additional wear.
I can go into more detail about how a generator works if you’d like.
I would think you still need some sort of environmental certification from the sate or even federally if you plan on trying to use the stream for power gen.
There is a charge controller listed on the page that has two inputs and one output. That should allow you to have two of those generators going. I guess if the company says it’s ok to do, it should be fine. They must be confident enough in their voltage regulating circuitry to ensure that no negative consequences will result. Two of those hooked up will give 5kwh a day, which is probably not enough.
Thanks for all those points. I will contact the local environment agency to find out if water can be taken from the river (and also to check out their position on the turbine systems).
