Micro-hydro power generation

[John Brown]

Here's the downside to solar water heating from my perspective(ours came with the house). I still have to turn the water heating on early morning, as the grandchildren wake up early, and we need HW to be available. Then, if it is sunny, the solar heating doesn't contribute much. We tend to run out of hot water a lot, and it's frustrating, having had a combi for 14 years.
Ultimately, when this boiler reaches EOL, I will look for a combi that can accept pre-heated water. It seems to me to be the only sensible solution.

 

[sunnybob]

Erek, All of the existing solar panels here are mains water (100s of 1,000's of them). Mine has been there for 11 years now and still supplies me all the hot water I need.
A timer on the immersion tank comes on for an hour each early evening during the winter.
The latest system though is this
https://hydrosolar.ca/pages/vacuum-tube ... P8QAvD_BwE
These do not have water in the tubes, just in the steel collector box at the top, greatly reducing weight and possible leakage as well as the amount of water in the actual system. They are fitted as standard here now and the old flat panels are getting replaced with them as and when.
Because of the very low and fluctuating mains water pressure (best day is 2.5 bar- worst day is zero water), the system has a 1000 litre storage tank mains fed. From here to a pump that pressurises the entire household water system hot and cold. The pump feeds mains water though the (old) panels into a hot storage tank (which also has the immersion heater fitted for the winter) and from there straight to the taps. I have my system set at 3.5 bar, which works well for me.

Yes we get some scale, but thats only because I have not paid out and a fitted water filter to the incoming mains.

 

[Trainee neophyte]

Erek, All of the existing solar panels here are mains water (100s of 1,000's of them). Mine has been there for 11 years now and still supplies me all the hot water I need.
A timer on the immersion tank comes on for an hour each early evening during the winter.
The latest system though is this
https://hydrosolar.ca/pages/vacuum-tube ... P8QAvD_BwE
These do not have water in the tubes, just in the steel collector box at the top, greatly reducing weight and possible leakage as well as the amount of water in the actual system. They are fitted as standard here now and the old flat panels are getting replaced with them as and when.
Because of the very low and fluctuating mains water pressure (best day is 2.5 bar- worst day is zero water), the system has a 1000 litre storage tank mains fed. From here to a pump that pressurises the entire household water system hot and cold. The pump feeds mains water though the (old) panels into a hot storage tank (which also has the immersion heater fitted for the winter) and from there straight to the taps. I have my system set at 3.5 bar, which works well for me.

Yes we get some scale, but thats only because I have not paid out and a fitted water filter to the incoming mains.

I also have a solar hot water system(two, actually). They cost €650 plus €100 for a plumber to install. I did mine myself, but it isn't bolted to the roof - I would have wanted someone's insurance policy if I was making holes in the roof tiles. I think SunnyBob and Erik may be talking at cross purposes regarding mains water - the water being heated is mains water, but the water in the panels is separate, and has antifreeze just in case it ever gets cold enough. The hot water tank has an extra jacket where the panel water plus glycol circulates, outside the main tank, encasing the 180litres or whatever of mains water and acting as a heat exchanger. The two systems are separate, and never mingle, unless something has gone horribly wrong. None of this helps Roger decide about his water power project.

 

[Eric The Viking]

Bob, it's different in somewhere like Cyprus that gets far more and stronger sunshine than we do here: in order to work, our panels have to be more efficient, so the channels in the panels are much smaller (I know the sort of systems you describe - they are ubiquitous throughout the tropics too).

It just goes to show that what seems straightforward is a bit more tricky once you get into the detail. That's a common theme across all 'green energy' solutions.

 

[Trainee neophyte]

The amount of water in Roger's video suggests plenty of flow, and then it's just a case of how far up the stream you can run a pipe to give you a good enough head.

OK, This might be a stupid question but why do you need to run a pipe upstream to get enough head? Does the presence of the pipe change the head at all? (If so, how much more head do you get by installing the pipe?) Or is the head already present on account of the water having that much fall even though it is not constrained within a pipe?

A waterwheel works as a low head, high flow system. The weight of the water in the bucket turns the wheel, the speed of the flow is mostly irrelevant. The more water in the bucket, the more power available.

A turbine works by spraying a jet of high pressure water at a paddle - the mass of the water isn't as important as it's velocity which is transferred to the wheel attached to the paddle. To get a high pressure jet, you need pressure. This is done by putting the water in a pipe, which is ideally vertical (in the real world it never is). A vertical pipe full of water has the weight of the entire column of water acting on the bit at the bottom - hence the high pressure, or head. A 10 metre head gives just over 14psi (apparently it is common to mix metric and imperial units for this). Turbines spin much faster than a water wheel, which lends itself better to electricity generation because you don't need gears, which reduce efficiency. A water turbine runs at about 70% efficiency, allegedly. They also run constantly, 24 hours a day, unlike solar, and not intermittently like wind, tide or wave.

 

[sunnybob]

I also have a solar hot water system(two, actually). They cost €650 plus €100 for a plumber to install. I did mine myself, but it isn't bolted to the roof - I would have wanted someone's insurance policy if I was making holes in the roof tiles. I think SunnyBob and Erik may be talking at cross purposes regarding mains water - the water being heated is mains water, but the water in the panels is separate, and has antifreeze just in case it ever gets cold enough. The hot water tank has an extra jacket where the panel water plus glycol circulates, outside the main tank, encasing the 180litres or whatever of mains water and acting as a heat exchanger. The two systems are separate, and never mingle, unless something has gone horribly wrong. None of this helps Roger decide about his water power project.

My system is mains water throughout. I have seen it and been in between it ( :shock: :roll: )
I've also worked on very large solar systems involving a dozen or more panels, using the same water . maybe mainland has more cold than Cyprus? :roll: :roll:

 

[Trainee neophyte]

My system is mains water throughout. I have seen it and been in between it ( :shock: :roll: )
I've also worked on very large solar systems involving a dozen or more panels, using the same water . maybe mainland has more cold than Cyprus? :roll: :roll:

Do you not get any snow? No frosts, ever? Should you have a once in a lifetime cold snap, that would be a plumber's paradise.

It doesn't really matter one way or the other, except that because with my system the panels are at atmospheric pressure, but the water in the tank is pressurised, the panel water will boil but the tank water will not. Allegedly. This would be because the boiling point under pressure is higher.

The coldest we have ever had is -7°C, and all the lemon trees died. This is not normal, but it did happen once. -3°C is not unheard of. On the other hand, we never get over 45°C, and over 40° is unusual, and only happens once every few years.

 

[sunnybob]

We had hailstones last week, big enough to break some car windscreens :shock:
the pool level went up 4" in a couple of hours.
Minus temps are extremely rare, lowest in the 11 years I've been here was minus2.
summer usually peaks at 40, but we had one august at 43 for over a week (the pool water went to 38c =D> =D> 8)

we're kind of sidetracked now, but I repeat how extremely sceptical I am that a single household could be electrically self sufficient without a significant investment.I knew a man who ran his entire house on 24 volt, but unfortunately did not know him well enough to go visit. Think what it would take to get all your appliances in 24 volt!

 

[Trainee neophyte]

We had hailstones last week, big enough to break some car windscreens :shock:
the pool level went up 4" in a couple of hours.
Minus temps are extremely rare, lowest in the 11 years I've been here was minus2.
summer usually peaks at 40, but we had one august at 43 for over a week (the pool water went to 38c =D> =D> 8)

we're kind of sidetracked now, but I repeat how extremely sceptical I am that a single household could be electrically self sufficient without a significant investment.I knew a man who ran his entire house on 24 volt, but unfortunately did not know him well enough to go visit. Think what it would take to get all your appliances in 24 volt!

Fully off grid ishard! Having some extra power to save you money is better. If Roger can get a constant supply of anything approaching 1kW, then he has all sorts of exciting possibilities open to him.

 

[Cheshirechappie]

Unless you want a fun project for the hell of it, forget micro hydro. You'll be lucky to get enough juice out of it to make a 40W bulb glimmer. A back-up diesel generator set would be a lot less bother; I gather quite a few out-of-the-way hill farms and the like have them, just in case, what with supply lines coming in on lines of poles and being vulnerable to 'extreme weather events' an' all . Just remember to top up the fuel tank occasionally.

Or, if you insist on being green, an exercise bike with a dynamo.

 

[RobinBHM]

Waterwheels seem to be a good way to generate with low heads.

This site says upto 20kw versions are possible

http://www.british-hydro.org/waterwheels/

It would be great project -it could be a rival to Steves mammoth workshop build thread.

 

[RogerS]

Waterwheels seem to be a good way to generate with low heads.

This site says upto 20kw versions are possible

http://www.british-hydro.org/waterwheels/

It would be great project -it could be a rival to Steves mammoth workshop build thread.

I like that ! You could have a waterwheel at the top and a turbine at the bottom.

 

[RogerS]

Interesting project here

https://www.smith-eng.co.uk/hydro

And in my neck of the woods. And what looks like a good academic link....project for the students perhaps ? Trouble is it would become a bloody feature on the walk trail. Had enough with bloody walkers as it is :twisted:

 

[Trainee neophyte]

Unless you want a fun project for the hell of it, forget micro hydro. You'll be lucky to get enough juice out of it to make a 40W bulb glimmer. A back-up diesel generator set would be a lot less bother; I gather quite a few out-of-the-way hill farms and the like have them, just in case, what with supply lines coming in on lines of poles and being vulnerable to 'extreme weather events' an' all . Just remember to top up the fuel tank occasionally.

Or, if you insist on being green, an exercise bike with a dynamo.

From one of the links above: Lydia Mill: 3.86m diameter steel wheel, 70 litres/s, 1.8kW, up to 10,000kWh per year.

That's one or two lightbulbs. According to https://www.renewablesfirst.co.uk/hydro ... m-provide/ the wholesale price for electricity is about 6.5 pence per kWh, so the above example would earn the astonishing sum of £680per year. If you use all the power yourself, you can double the value as a saving. An amazing woodwork build, followed by free money! Let's all have a go.

 

[sunnybob]

But.... it makes £680 of electric.
Are you seriously trying to tell me that very large all wood wheel does not need £680 worth of parts and labour maintenance every year?
And if youre trying the "green" argument, how many trees had to be chopped down to make it?

If there is no possibilty of mains power, then this kind of thing has to be considered, but if its about saving a small amount of money, the sums just dont add up because nobody EVER counts the costs of install and maintenance. :roll:

 

[RogerS]

... nobody EVER counts the costs of install and maintenance. :roll:

Similar argument can be applied to the'PCs are cheaper than Macs' argument. No-one actually looks at the TCO (total cost of ownership)

 

[MikeG.]

..... And if youre trying the "green" argument, how many trees had to be chopped down to make it?......

If no-one bought wood, then no new trees would be planted. If there was no market for woodland products, then woodlands would not have an economic value and would soon be turned into something more valuable......such as wheat fields. If no-one used their products, managed woodlands wouldn't exist, taking with them hundreds of species found only in managed woodlands.

 

[sunnybob]

..... And if youre trying the "green" argument, how many trees had to be chopped down to make it?......

If no-one bought wood, then no new trees would be planted. If there was no market for woodland products, then woodlands would not have an economic value and would soon be turned into something more valuable......such as wheat fields. If no-one used their products, managed woodlands wouldn't exist, taking with them hundreds of species found only in managed woodlands.

If Nelson hadnt had a navy, there would be a 100,000 oak tress still alive. :shock:
Circular arguments are great, arent they? =D> =D> 8) 8)

 

[MikeG.]

If no-one ate beef or lamb, there would be no cows or sheep. There is nothing circular about that argument.

 

[Dibs-h]

If no-one ate beef or lamb

Then we could be overrun by sheep & cattle. :lol: :lol: :lol: