Is hydro a practical possibility here? - Page 1
Forum section: electronics / general

author: Mechanical Menace
author_rank: Super Contributor
timestamp: February 08, 2016, 06:02:15 pm
content: I have a pond fed by a small brook at the top of my garden, the outlet is piped to the bottom of the garden about 5 meters below the bottom of the pond. The minimum flow rate is 20L/s (roughly 43cfm) and is often an order of magnitude greater. Is this enough to get a usable amount of power from? If so has anyone got any suggestions for suitable turbines?Thanks

author: HAL-42b
author_rank: Frequent Contributor
timestamp: February 08, 2016, 06:12:29 pm
content: Power = Head x Flow x Gravity5m x 20L/sec x 9.81 = 981 WOr something around 580 W with 60% efficiency.

author: mtdoc
author_rank: Super Contributor
timestamp: February 08, 2016, 06:20:33 pm
content: There is anice calculatoron the Powerspout website that will let you get good estimate of the potential for your site. In addition to head and flow, you need to take into account frictional losses in the pipe run which depend on pipe diameter and length.Even though gravity is obviously the source of potential energy here, it's force (9.8 N/kg) is not part of the equation.BTW - Powerspout makes very nice microhydro turbines that will work with your site.

author: Mechanical Menace
author_rank: Super Contributor
timestamp: February 08, 2016, 06:27:55 pm
content: Quote from: HAL-42b on February 08, 2016, 06:12:29 pmThanks, that's what I worked out too but it justfeltmore than a bit high for such trickle lol.But now I can hit Google with a bit more confidence to try and find suitable turbines and their reviews.EDIT:Quote from: mtdoc on February 08, 2016, 06:20:33 pmI'd most probably use new pipe for this, maybe even just a heavy duty hose depending on how things work out and keep the existing setup for dealing with overflow. I have checked if I am allowed to do this and as long as I don't majorly disrupt the flow to downstream, or start introducing nasty chemicals, I can do whatever I want between where the water enters and leaves my property.QuoteThanks! Just having a decent recommendation will give me moire of an idea of what to look for.

author: mtdoc
author_rank: Super Contributor
timestamp: February 08, 2016, 06:53:28 pm
content: Quote from: Mechanical Menace on February 08, 2016, 06:27:55 pmI think there is some slight difference in frictional losses depending on the pipe material but the major factors are pipe diameter and length.QuoteI would go with Powerspout if I were you. I have one of their Pelton turbines that I'm hoping to install this summer. You can find Youtube videos of Powerspout installations. They are a Kiwi company.Harris Hydro here in the states and Energy Systems and Design in Canada also make well regarded microhydro turbines.Also - their is a fairly active Yahoo microhydro group with good info and advice available.

author: helius
author_rank: Super Contributor
timestamp: February 08, 2016, 07:18:42 pm
content: Have you seen this project? Really inspirational.http://ludens.cl/paradise/turbine/turbine.html

author: mtdoc
author_rank: Super Contributor
timestamp: February 08, 2016, 07:25:18 pm
content: Quote from: helius on February 08, 2016, 07:18:42 pmYeah - I've seen that. It is a very nice but very large system! As Dave would say - you could fly to the moon with 4kW of power!There's a nice gallery of photos from smaller systemshere

author: IanB
author_rank: Super Contributor
timestamp: February 08, 2016, 07:52:34 pm
content: Quote from: mtdoc on February 08, 2016, 06:20:33 pmAbsolutely it's part of the equation.We can work out the available power as (volumetric flow) x (pressure difference).Volumetric flow (20 L/s) is 0.02 m3/s.Pressure difference (5 m head) is (density) x (gravity) x (elevation difference) = 1000 kg/m3 x 9.81 N/kg x 5 m = 50 000 N/m2 = 50 kPaHence power is 0.02 m3/s x 50 kPa = 1 kWBut of course efficiency losses in the system mean you would not get all of that.

author: mtdoc
author_rank: Super Contributor
timestamp: February 08, 2016, 08:16:24 pm
content: Quote from: IanB on February 08, 2016, 07:52:34 pmI guess my language wasn't precise enough (Ha ha! I should have known better on an engineering forum!). Of course it is part of the underlying calculation. What I was referring to is the point that people who design microhydro systems do not generally use 9.8 kg/N in the standard equation used to estimate potential power production at a site. Obviously you can do it that way as you have (though you need to include the density of water as you have and which the previous poster left out).Some people just use weight (instead of gravity and density), others just use a constant since density (at a given temp!) and gravity are constants (at least here on earth with a water based system!). This greatly simplifies it for those of us in countries not using the metric system!For example here in the US the equation most people use is [net head (feet) × flow (gallon per minute)] ÷ 10 = Watts. (this equation includes typical efficiency losses due to pipe friction).I was just speaking from the perspective of practical experience versus theory. Sorry for the confusion.

author: station240
author_rank: Unknown
timestamp: February 08, 2016, 08:50:20 pm
content: A few people have made water turbines using a Fisher & Paykel motor as a generator.http://www.thebackshed.com/forum/forum_posts.asp?TID=4221Other varieties of BLDC motors could also work. All depends if you want to do DIY or not.

author: IanB
author_rank: Super Contributor
timestamp: February 08, 2016, 08:50:57 pm
content: Quote from: mtdoc on February 08, 2016, 08:16:24 pmWell, quite. Sometimes customary units are simpler. For example, if you want to raise 160,000 lb/hr of water through a height of 16 ft the power requirement is simply 160,000 x 16 = 2,560,000 ft-lb/hr. Now you are simply left to converting ft-lb/hr to whatever unit of power you are interested in, e.g. 1.3 hp or 1 kW.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 08, 2016, 09:03:45 pm
content: Using the us units for such a calculation is just stupid - its hard to remember how to convert things like ft*lb/hr to Hp. There is a good reason science uses metric units.In many coutries you may need a permit to use natural hydroelectric power.

author: mtdoc
author_rank: Super Contributor
timestamp: February 08, 2016, 09:11:04 pm
content: Quote from: Kleinstein on February 08, 2016, 09:03:45 pmI'm not gonna disagree with that in theory. Personally I wish we would have fully converted to the metric system long ago. I have been using it for decades in my professional life.But .. For practical purposes - feet on the ground, real life work - it makes things more difficult in this case. It is not easy to find a metric tape measure or metric volumetric tools. Besides - in this case it turns out that the equation that provides a very good estimate is trivially simple using feet and gallons.QuoteYep, that is generally true here in the US.

author: mtdoc
author_rank: Super Contributor
timestamp: February 08, 2016, 09:15:21 pm
content: Quote from: station240 on February 08, 2016, 08:50:20 pmYep. Standard car alternators as well.

author: apelly
author_rank: Unknown
timestamp: February 08, 2016, 10:03:55 pm
content: Quote from: helius on February 08, 2016, 07:18:42 pmAwesome! That guy has a lot of time on his hands!

author: John Heath
author_rank: Frequent Contributor
timestamp: February 15, 2016, 05:00:03 pm
content: I have a email friend Manfred who I share a fondness for antique radios with. One day Manfred decided to build his own paradise in the mountains of South America. Being a clever fellow he made sure there was water higher than the house he planned to build. The end result was a self made hydro system , 5 K watt if memory serves , to heat and cook in the house. I know you are going to like this from what I am reading which is why I am making this post. He is an excellent photographer so the complete construction from beginning to end is well documented. Try to imagine you are doing this not him to live a life that could have been. Enjoy.http://ludens.cl/paradise/paradise.html

author: mtdoc
author_rank: Super Contributor
timestamp: February 15, 2016, 06:34:04 pm
content: Quote from: John Heath on February 15, 2016, 05:00:03 pmCool that you know him! His project pictures were already posted and discussed. See above. Yes very nice, large! microhydro system. 5kW = 120kWh per day - enough to power 10 homes! WHat does he do with all the extra power? He must have a large diversion load..

author: John Heath
author_rank: Frequent Contributor
timestamp: February 15, 2016, 10:05:52 pm
content: Yes I can see now from an earlier post that this has already been brought up. It puts a smile on my face that such a esoteric detail from myself in Canada and a Mr Manfred on some remote mountain is south America would strike a common cord with a group half way around the world in EEVblog in Australia. My connection would be a yahoo group called antique radios. How cool is that. It shows the power of the internet. I can recommend that you tax Mr Manfred on the finer details of the center of gravity of a Wankel engine at high RPM. If you thought the 5 K watt hydro power project was cool his precise understanding of a Wankel engine will knock your socks off.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 15, 2016, 11:55:13 pm
content: Beware that federal, state and local regulations may come into play: look up anything and all about waterways, watersheds, ponds, dams, water rights, ground water supplies; the list goes on.Tim

author: cdev
author_rank: Super Contributor
timestamp: February 16, 2016, 12:04:23 am
content: Definitely.. Decades ago I spent a summer living at a place that had a setup like that, feeding into a pipe pointed at a pelton wheel. I forget what the power output was in watts but it was enough for a (open from the top) refrigerator and lighting and similar. All 12 volt stuff. It was fun living like that for a bit.Quote from: Mechanical Menace on 2016-02-08, 13:02:15

author: bills
author_rank: Frequent Contributor
timestamp: February 16, 2016, 02:38:49 am
content: Quote from: John Heath on February 15, 2016, 05:00:03 pmI liked the photos.But as he has built it I don't think it has a chance of working for long.How is the frequency controlled ? The generator is designed to run at around 1500 rpm to output 220v @50hz.The home made transformers are they variable frequency?Maybe he has some one controlling the water flow.sorry nice photo shoot .bill

author: bills
author_rank: Frequent Contributor
timestamp: February 16, 2016, 03:03:23 am
content: Before we go any further.1. can it work? yes but not very well.2. How would i do it (not is if that matters)3. how should it be done? (or how would you do it)4. Before responding please go to the link and read it.http://ludens.cl/paradise/turbine/turbine.htmlthis is an interesting topic we see a lot of these (how should i say it BS ?) links.Don't take this the wrong way but I loved the idea.

author: IanB
author_rank: Super Contributor
timestamp: February 16, 2016, 04:31:25 am
content: @bills: not sure of your point?He built it, it apparently works, and it produces 4 kW at 50 Hz (regulated as explained in the link you disparage).To call detailed explanations and documentation in the link BS is quite rude. Did you get out of bed on the wrong side this morning?

author: RobertBG
author_rank: Regular Contributor
timestamp: February 17, 2016, 03:00:56 pm
content: I feel that small scale hydro power is often overlooked these days and for the longest time I was part of that group.That was up until I visited a mountain hut in Bulgaria that was powered by a old cobbled together micro hydroelectric station.It was a amazing place that was off the grid long before that term was coined,everything comes in by foot or horseback and the power is from a small hydroelectric plant on a stream fed by snow melt.They really dont show or mention much about the hydro plant but nonetheless here are a few links,it's a truly gorgeous place nestled in the Rila mountains and worth the hike to get there.http://www.ivanvazovhut.info/history_en.htmlhttp://gowhere.bg/en/guide/mountains/rila/ivan-vazov-hut/ivan-vazov-hut.htmlI say go for it and it isnt too hard to make a DIY pelton turbine although if you have enough flow I'd look into commercial options too as you'll probably see more power in the end.Also one thing I see mentioned too often by people arguing against small scale hydro is they'll say you only have "X" amount of flow so it's only going to make so much power and I just love when they compare a 4kw hydro setup to a 4kw solar setup.The part of the argument they neglect is that you dont have to go too far down stream to collect more power and that it runs nonstop (for the most part)granted a lot depends on the setup but I saw a neat install where the outflow and bypass overflow from the main pelton turbine fed a old fashioned water wheel that was geared down to spin another generator.Granted the secondary wheel wasnt always on but it added capacity when flow allowed.Good luck and if you go for it you'll probably be pleasantly surprised with the outcome no matter if you buy a commercial setup or go DIY with with as little as a bunch of spoons and a bike wheel attached to a alternator or 2 from a car.Once you have it setup and running it's going to quietly produce for you nonstop 24/7 365

author: G7PSK
author_rank: Super Contributor
timestamp: February 17, 2016, 03:24:38 pm
content: You could dam the water supply and create a lake to use for your hydro power when you need it. I once did some restoration work on a Victorian water turbine that worked a saw mill. The lake or pond would fill over night and then the turbine would work the saw for about 6 hours during which time the lake would drain to abot half full at which time the head was to low to do much work. I have some photo's some where but as the work was quite a time ago the pictures are film, I will have to look them out and scan them. The turbine was fed with a 16 inch pipe as I recall and about 4 meters of head, the stream was very small and fed to the lake in a cast iron conduit that was about 800mm by 150mm.

author: John Heath
author_rank: Frequent Contributor
timestamp: February 20, 2016, 01:05:13 am
content: Quote from: bills on February 16, 2016, 02:38:49 amHi BillI wrote Mr Manfred and told him of the interest in his home made hydro plant along with a link to this thread. It is my hope he will join in and give precise answers to your questions.I can tell you what I know.The hydro station is not a car alternator with a fan on it. It is a top down design housed in solid concrete. Frequency control is not easy if there is not a grand grid to sync lock with. If memory serves a sudden drop in power demand leads to a fast triac power dump to a dummy load followed by a slower trimming of the water valve. Knowing Manfred the critical damping of this feed back system is probably as close as possible. As to a hand wound transformer. I will venture a guess that the educational system in Chili puts an emphasis on the fundamentals of electrical engineering. Theory is one thing but can you build it with your own hands? Iceland and Japan is the same where engineers walk around with tools in their hands not laptops.

author: bills
author_rank: Frequent Contributor
timestamp: February 20, 2016, 02:43:52 am
content: Please don't miss understand me I think that the project is great!i am concerned as to how the water flow is controlled?NO I DON'T think it is BS Sorry if I gave that impression .My question was how do you control the flow? I must be missing something.regardsbill

author: IanB
author_rank: Super Contributor
timestamp: February 20, 2016, 03:14:39 am
content: Quote from: bills on February 20, 2016, 02:43:52 amFrequency control is described in some detail in the web pages you linked to.Gross control of power input is regulated by hand, by admitting flow to one or more water jets feeding the reaction turbine. This sets the available power and maximum power output according to expected demand.Frequency is regulated by adjusting the load on the generator electronically. If the frequency is too high the load on the generator is increased (by dumping power), thereby slowing it down. If the frequency is too low the load is reduced. Clearly the base load must be lower than the maximum available power for this to work so there is headroom for the regulation.Regulation can be controlled cycle by cycle at the zero crossing point, or it can be controlled at high frequency within each cycle. The former approach gives a cleaner waveform but slower regulation with occasional frequency dips. The latter approach tends to produce a noisy and irregular waveform that needs filtering. It is also possible to regulate frequency by automatic control of the water flow, but this is even slower to react and is rarely used.At the system in question it seems the constructor settled on per cycle regulation since small transient frequency variations are not important for the loads connected to it.

author: onlooker
author_rank: Frequent Contributor
timestamp: February 20, 2016, 03:35:25 am
content: The Powerspout's power calculator looks to be specific to their products. Comparing to the theoretical power, their products have an efficiency about 40%. The modern hydropower is about %90 efficient in hydro-to-electricity conversion (wiki).

author: mtdoc
author_rank: Super Contributor
timestamp: February 20, 2016, 04:32:31 am
content: Quote from: onlooker on February 20, 2016, 03:35:25 amTheir calculator takes into account pipe losses and gives a similar number to several other calculators I've compared it to. Also, you need to be sure to set the proper type and number of turbines for the head and flow.Their turbines are well regarded.QuoteReference? Perhaps that is referring to turbine efficiency only?No micro hydro system is 90% efficient when all losses are accounted for - not even close - more like 50%.

author: onlooker
author_rank: Frequent Contributor
timestamp: February 20, 2016, 05:20:24 am
content: Quote from: mtdoc on February 20, 2016, 04:32:31 amI was trying to explain the difference between you and IanB (and others). The 40% I estimated was the turbine conversion efficiency assuming zero pipe loss (using their calculator).QuoteI did not dispute this in either way.QuoteI mentioned wikipedia.QuoteI do not know enough to say something specific about a system at kW level. My feeling is that hydro systems are very scalable. I could be wong.Edit: according to wikipedia under "micro hydro", the typical efficiency of various systems is about 80 to 85 % with Kaplan being around 90%.

author: mtdoc
author_rank: Super Contributor
timestamp: February 20, 2016, 06:30:50 am
content: Part of the problem is that the term Micro Hydro is commonly used to describe a broad range of power system sizes. Anywhere from systems generating 100 W from small streams, to systems generating 100 KW from rivers.The Wikepedia Micro Hydropage calls anything below 5kW "pico hydro" but I can tell you from personal experience researching and following this topic over many years that no one uses that term for the small, usually 100 W to 1kW systems that individuals use for single homes. Micro hydro is the term commonly used - even for very small systems.The Wikipedia article states:QuoteIt then goes on to discuss 6 specific turbine types - none of which are the - commonly used for small systems - pelton and turgo turbines. Those are what the leading small turbine manufacturers, PowerSpout, Harris Hydro, and Energy Systems and Designs manufacture and sell.Regardless of the turbine type, I think you'll find that the various calculators for all turbines you find online will give you very similar results once you control for the inputs and the factors used to do the calculations.

author: onlooker
author_rank: Frequent Contributor
timestamp: February 20, 2016, 01:26:56 pm
content: Yes, I have noticed the typical conversion efficiency for microhydro systems varies from about 50% to 90% by different info sources. The below is a quote from DOE resources (http://energy.gov/energysaver/microhydropower-systems)"Microhydropower systems usually generateup to100 kilowatts of electricity....Pelton wheel -- uses the concept of jet force to create energy. Water is funneled into a pressurized pipeline with a narrow nozzle at one end. The water sprays out of the nozzle in a jet, striking the double-cupped buckets attached to the wheel. The impact of the jet spray on the curved buckets creates a force that rotates the wheel at high efficiency rates of70–90%. Pelton wheel turbines are available in various sizes and operate best under low-flow and high-head conditions."Presumably, 70% is for systems under difficult design parameters (e.g. small, low budget, non-optimal water conditions,...).In fact, all such discussions are secondary to my original main point: that is to explain why the number that PowerSpout's calculator gives is much lower than the theoretic value by the power fomula. It is due to that the calculator already figured in the about 40% efficiency of their products.As to whether 40% is too low or to high, apparently there are many different angles to look at it as we have already seen.

author: G7PSK
author_rank: Super Contributor
timestamp: February 21, 2016, 02:54:27 pm
content: For low heads an Archimedes screw turbine is probably better, a piece of old grain auger might make one.https://www.renewablesfirst.co.uk/hydropower/I think the owner of the Homo Ludens site used to be on this forum. But I cannot remember the name he used here.

author: _Andrew_
author_rank: Regular Contributor
timestamp: February 21, 2016, 05:34:00 pm
content: Having fun trying to convince the Environment Agency that they should allow us to take over the operation of the wears that are in place of an old lock gate and Mill. But there being very resistant to the idea in favor of putting in a fish walk.It is also proving difficult to to get the annual flow rate data out of them. For a Archimedes screw turbine 250 liters per second is probably about the lowest flow rate practicable for a 1m turbine.Guess it is coming to playing poo sticks to try and determine the flow rate and measure the aria to work out the volume. Fortunately there is a channel down stream of the site thats safe to wade into when it is not in flood. Should be able to gain a good estimate.The site lends its self for a Archimedes turbine as two of the four weer gates were installed in place of the up stream lock gates leaving the concrete walled lock channel open and plenty of room for the 22 degree angle needed for the Archimedes turbine channel to be installed, and there is also a good 4m drop. Extraction rights not an issue.It is very appealing the idea of producing energy more or less 24/7 in comparison to solar.In theory an Archimedes screw turbine will be better for the over all health of the river as fish ect can pass through the turbine ether way with little or no harm. Tests have already shown that Archimedes screw turbines cause less harm to fish that fish walks.They are also less susceptible to water borne debris clogging them up so less screening is required in comparison to pelton wheel water turbines that can require screens for objects down to 2mm in size.They also can have a very long life span.

author: mrpackethead
author_rank: Super Contributor
timestamp: February 21, 2016, 05:52:43 pm
content: Quote from: Kleinstein on February 08, 2016, 09:03:45 pmAnd maybe you even need a permit to use metric units.

author: mtdoc
author_rank: Super Contributor
timestamp: February 21, 2016, 06:02:48 pm
content: The best low head turbine for small - single home sized projects I've seen is thePowerspout LHHere's a nice video of a largish installation using 2 of these in Romania I saw posted on the Midnite solar forum:Powerspout

author: G7PSK
author_rank: Super Contributor
timestamp: February 22, 2016, 01:44:14 pm
content: Another solution would be this floating wheel design, easy to make and very robust.https://youtu.be/p4scG3cuL7IA good site for renewable energy is.http://www.fieldlines.com/

author: Mechanical Menace
author_rank: Super Contributor
timestamp: February 22, 2016, 04:50:21 pm
content: Seeing as there seems to be a few distributors for them over here I'm looking into Powerspout's offerings around the 200wh mark but while I'm doing that I'm going to get some practice in with a welder and repurpose an alternator just to play around with and get more of an idea of the actual practicalities of getting something like this up and running.I'm also going to have to look into some sort of storage mainly to fulfil my peak power requirements. But, even though something like this should produce more than enough power to run my home, I would like to have a couple of days backup just in case. I can't see me needing it with micro-hydro and a small solar setup but I'd rather have too much and never need it than not enough and be having to upgrade. Such a shame I have zero chance of being able to put up a small wind turbine as well.Thanks for all the suggestions, links, and just general nattering about the subject. It is much appreciated.

author: tszaboo
author_rank: Super Contributor
timestamp: February 22, 2016, 05:23:08 pm
content: Dont forget, that you have probably now a constant heat source, that can be used to heat or cool the house if you slap a heat pump on it.I would ignore the storage systems. If you have net energy metering, it just doesnt matter.

author: mtdoc
author_rank: Super Contributor
timestamp: February 22, 2016, 06:02:26 pm
content: Quote from: NANDBlog on February 22, 2016, 05:23:08 pmIt depends. If he is off grid or has frequent extended grid outages he will need to be able to meet peak loads. Unless one has a very large hydro system - it is unlikely that it will be able to supply peak loads without battery storage and inverter.

author: Mechanical Menace
author_rank: Super Contributor
timestamp: February 24, 2016, 11:58:08 am
content: Quote from: NANDBlog on February 22, 2016, 05:23:08 pmGiven that I'm in the UK I have no real need for cooling and very rarely use my heating. Last year it was on maybe 4 days in total and that was only for the benefit of guests. Good thought for others but not worth it for me.Quote from: mtdoc on February 22, 2016, 06:02:26 pmI have no real need to go off grid but want to. I also at worse use 6kWh in a day and on average 3*, with peaks under 3.5kW. With such low usage a hydro system large enough to provide my peak power would be total overkill.*And hopefully I can get that down.

author: tszaboo
author_rank: Super Contributor
timestamp: February 24, 2016, 02:59:05 pm
content: Quote from: Mechanical Menace on February 24, 2016, 11:58:08 amI always forget that the average thermostat setting in the UK is a freezing 18 degrees.

author: mtdoc
author_rank: Super Contributor
timestamp: February 24, 2016, 05:07:26 pm
content: Quote from: Mechanical Menace on February 24, 2016, 11:58:08 amWell done!.BTW, I've been meaning to ask: Ishmael, is that you?

author: Mechanical Menace
author_rank: Super Contributor
timestamp: February 25, 2016, 06:29:39 pm
content: Quote from: mtdoc on February 24, 2016, 05:07:26 pmWell thanks but that wasn't bragging, just context. But I will admit the fact I don't do without my gadgets or conveniences is a bragging point lol.QuoteOk I know that's going to be a reference to something, it's even firing up that "I know that but don't know why" part of my mind, but I'm having a thick moment and can't pull it together

author: mtdoc
author_rank: Super Contributor
timestamp: February 25, 2016, 07:54:00 pm
content: Quote from: Mechanical Menace on February 25, 2016, 06:29:39 pmHighly recomended!

author: leo_r
author_rank: Newbie
timestamp: February 25, 2016, 10:30:31 pm
content: My dad recently built a micro hydro scheme on his land in Scotland. Peak power is 8.6 kW, but average is more like 4 - 5 depending on season. Head is maybe 20m or so, coming from 2 intakes (2 streams merge into one on the property).He used a turgo wheelfrom these guyscoupled to an induction motor (rated to 10.8kW) running in reverse through some control electronics supplied (I believe - this is from memory) bysustainable control(not that there's much on that site). I think the person who runs that company also wrotethis book, which I imagine covers the electronics in some detail.He's got 4 quarter turn valves being electronically controlled to control the flow rate. Essentially the generator is brought up to speed with no load, and then when it reaches 50 Hz its connected to the mains. The control system then adjusts the valves based on the water level at the intake to the pipes (measured using current loop pressure sensors). As his setup uses 2 intakes and 4 quarter turn valves (rather than the 2 that the original control system is designed to work with) we had to implement a custom control system using a Crouzet CPLD. It reads the 2 intake depth sensors and controls the 4 valves, providing spoofed depth information to the control system to keep it happy.I think the total cost of installation was about £30k. I'm not sure exactly where that went - work included building 2 intakes using pre-cast concrete planks, obtaining and getting delivered the plastic pipes, burying them, building a wooden hut for everything, buying the control system/generator and getting the necessary permits. He hired an environmental consultant to sort out the permits and a builder did most of the larger installation work. I think he did most of the rest himself.In the UK the government pays a tariff of around 21p/kWh for all electricity generated by hydro schemes, on top of the 5.4p/kWh that they'll buy it from you for. That means the scheme will hopefully break even in 3 - 4 years.