Green Building Forum - Micro Hydro from spring water powering GSHP

Micro Hydro from spring water powering GSHP

Pile-o-Stone — Thu, 13 Dec 2012 16:45:41 +0000

Hi,

Opposite our home is a former mannor house that used to have its water provided by a natural spring. The manor house was connected to the mains many years ago and so the outlet was severed and now empties into a stream that is at the rear of our garden. I've been monitoring the outlet for the last 3 years and it seems to have a constant flow regardless of the season. I'm seriously thinking of using the water to power a turbine and was wondering if anyone had information on how this can be done technically?

We currently have a heatbank connected to a woodburning stove and ma9ins gas condensing boiler (solar is an option but due to shading could only provide HW in summer) and I was wondering if the hydro could be connected to the heatbank either by emersion heater or GSHP?

Which would be the better option? I know that GSHP are supposed to have a RHI payment next year and the micro hydro would have a FIT, so would this be the most cost effective solution? What sort of power output would the micro hydro have to produce to power a GSHP?

Micro Hydro from spring water powering GSHP

tychwarel — Thu, 13 Dec 2012 17:36:33 +0000

To work out the approximate power in Watts of a micro hydro use the following formula

Available Head (metres) X flow rate (litres/second) X Gravity (9.8) X efficiency factor (for small set ups assume 0.7)

example:- head 5M X flow rate 20 litres/second X 9.8 X 0.7 = 686watts,

In essence for micro hydro to be worthwhile you either need a lot of water or a big drop, preferably both

Micro Hydro from spring water powering GSHP

Pile-o-Stone — Thu, 13 Dec 2012 20:04:52 +0000

Thanks for that, I'll have to get out there with a bucket and metre stick work out the drop/flow to see how much I could possibly generate.

Assuming it's viable, does anyone know how much electricity I'd have to generate to heat water either with a heat pump or immersion heater? Which would be the better option between the two?

Alternatively, would I be better off remaining with gas/wood/possible solar for space & water heating and use the generated electricity for everything else?

I guess I'm looking for the best payback for the least expenditure, though the heat pump appeals if I can get rid of gas for good (we have induction hobs for cooking, so gas is only used for space/water heating), but not if I'd save more money with an alternative.

Any help/suggestions/comments are very welcome. :)

Micro Hydro from spring water powering GSHP

Paul in Montreal — Thu, 13 Dec 2012 22:44:13 +0000

Posted By: Pile-o-StoneAssuming it's viable, does anyone know how much electricity I'd have to generate to heat water either with a heat pump or immersion heater? Which would be the better option between the two?

How much water do you want to heat? A tank full, or a kettle full? A heatpump will give you about 3x the amount of heat for a given amount of electricity compared to using the electricity directly.

But, I have to say, I think there's almost no chance your stream will have anything link enough power available to do anything more than heat a teacup of water. I'm certain it won't have enough flow to power a heatpump. A 20l/s flow rate is heck of a lot of water - of the order of 140 MILLION gallons per year!

Paul in Montreal.

Micro Hydro from spring water powering GSHP

Pile-o-Stone — Fri, 14 Dec 2012 09:29:44 +0000

The capacity of our heatbank is 350l, plus then the capacity of the radiators as the temperature in the heatbank falls dramatically once the central heating pump kicks in.

The power isn't coming from a stream but from a natural spring that empties into the stream, which is at the bottom of a high/sheer sided valley. I have to say that I find your 'tea cup' prediction, based on not knowing the drop, not knowing the flow, never seeing the stream, never seeing the height of the valley, never seeing the spring gushing out of the exit pipe, is a bit defeatist to say the least!

Micro Hydro from spring water powering GSHP

SteamyTea — Fri, 14 Dec 2012 09:54:50 +0000

Call that 0.5 kWh per Â°C then.

Micro Hydro from spring water powering GSHP

renewablejohn — Fri, 14 Dec 2012 12:38:19 +0000

Posted By: Pile-o-StoneThe capacity of our heatbank is 350l, plus then the capacity of the radiators as the temperature in the heatbank falls dramatically once the central heating pump kicks in.

The power isn't coming from a stream but from a natural spring that empties into the stream, which is at the bottom of a high/sheer sided valley. I have to say that I find your 'tea cup' prediction, based on not knowing the drop, not knowing the flow, never seeing the stream, never seeing the height of the valley, never seeing the spring gushing out of the exit pipe, is a bit defeatist to say the least!https:///forum114/extensions/Vanillacons/smilies/standard/tongue.gif" alt="" title="" >https:///forum114/extensions/Vanillacons/smilies/standard/wink.gif" alt="" title="" >

You do get a lot of defeatist comment when talking hydro. What people forget is that even a small power on a 24/7 basis can turn into a far larger power for a short period of time. We do seem to forget that London before electric motors was powered by hydraulic accumulators. There is no reason why your small stream could not power a GSHP but it might not be as simple as attaching a turbine to the shaft of the GSHP.

Micro Hydro from spring water powering GSHP

Beau — Fri, 14 Dec 2012 13:04:34 +0000

If you do go with a heat pump it might worth considering using a water sourced one and putting the spring water through it instead of using ground loops.

Micro Hydro from spring water powering GSHP

skyewright — Fri, 14 Dec 2012 13:21:00 +0000

Posted By: Pile-o-StoneI have to say that I find your 'tea cup' prediction, based on not knowing the drop, not knowing the flow, never seeing the stream, never seeing the height of the valley, never seeing the spring gushing out of the exit pipe, is a bit defeatist to say the least!

While you haven't mention head, you did say (maybe jokingly) "...get out there with a bucket and metre stick...".

Perhaps Paul was thinking that if a bucket is adequate to measure the flow and a metre stick is adequate to measure the height then that didn't indicate large values of flow or height?

A classic 2 gallon / 10 litre bucket would fill in half a second at 20l/s (if you could catch it all).

If there were, say, 2l/s flow and a 50M head, then maybe you'd be using an OS map rather than a stick to measure the head?

However, not wishing to be defeatist, you can potentially improve matters at least a bit on the flow front if your need is intermittent and the flow is constant by storing up water (as high up as possible) ready for release when you need the power.

You might find the Navitron website interesting, e.g. this page on their high head turbines (especially the table at the bottom of the page).

http://www.navitron.org.uk/page.php?id=50&catId=70

Micro Hydro from spring water powering GSHP

Paul in Montreal — Fri, 14 Dec 2012 13:56:39 +0000

Posted By: skyewrightPerhaps Paul was thinking that if a bucket is adequate to measure the flow and a metre stick is adequate to measure the height then that didn't indicate large values of flow or height?

Indeed, and I was being facetious, too, because the original poster was very vague when he asked how much electricity is required to heat water. How much water, to what temperature and how quickly? Since he'd described the water source as a stream, it didn't sound like there would be much power available. Of course, with a constant flow, it would make the idea source for WSHP (water source heat pump), but as to whether it would be able to supply several kW to run a GSHP (I'm assuming a relatively large one would be required because he stated his house had been a manor house), sounded unlikely as it was described as a stream, rather than a river. Even if a micro-turbine could source several hundred to a couple of kW, it's doubtful it could supply the starting current required by a heat pump's compressor (which can be as high as 90-100A @240V - for a single-phase motor - though if it's an inverter-driven compressor, then maybe there's a chance).

I wasn't being defeatist, I was being a realist.

Paul in Montreal.

Micro Hydro from spring water powering GSHP

Pile-o-Stone — Fri, 14 Dec 2012 14:23:54 +0000

Posted By: Paul in Montreal
Posted By: skyewrightPerhaps Paul was thinking that if a bucket is adequate to measure the flow and a metre stick is adequate to measure the height then that didn't indicate large values of flow or height?

Indeed, and I was being facetious, too, because the original poster was very vague when he asked how much electricity is required to heat water. How much water, to what temperature and how quickly? Since he'd described the water source as a stream, it didn't sound like there would be much power available. Of course, with a constant flow, it would make the idea source for WSHP (water source heat pump), but as to whether it would be able to supply several kW to run a GSHP (I'm assuming a relatively large one would be required because he stated his house had been a manor house), sounded unlikely as it was described as a stream, rather than a river. Even if a micro-turbine could source several hundred to a couple of kW, it's doubtful it could supply the starting current required by a heat pump's compressor (which can be as high as 90-100A @240V - for a single-phase motor - though if it's an inverter-driven compressor, then maybe there's a chance).

I wasn't being defeatist, I was being a realist.

Paul in Montreal.

Heavens, did you even read my original post?

I said that the water was from a natural spring that used to supply the manor house opposite my property but was severed when the manor went onto mains water and now empties into the stream at the rear of my garden.

I'm therefore am not trying to get hydro from a stream and nor do I live in a manor house. I'm happy to have a healthy dose of realism but that realism needs to be based on the facts.

Anyway, step 1 seems to be to discover the energy potential from the natural spring and then see what it can be applied to.

Micro Hydro from spring water powering GSHP

Paul in Montreal — Fri, 14 Dec 2012 14:34:05 +0000

Posted By: Pile-o-StoneHeavens, did you even read my original post?

I said that the water was from a natural spring that used to supply the manor house opposite my property but was severed when the manor went onto mains water and now empties into the stream at the rear of my garden.

I'm therefore am not trying to get hydro from a stream and nor do I live in a manor house. I'm happy to have a healthy dose of realism but that realism needs to be based on the facts.

Yes I did read your post. It makes no difference if the stream is fed from a puddle, a spring, a lake or whatever. It's the flowrate and head that determines the amount of energy you can extract. That you called it a stream made it sound like the flowrate is relatively modest - and being fed from a spring reinforces this notion. Had you said there was a stream that was fed by a lake up a hill, then it would be different. How wide is the stream? What head could you use? Until you answer these basic questions, then we can only guess, though those guesses are coloured by the descriptions you used in the first place.

Posted By: Pile-o-StoneAnyway, step 1 seems to be to discover the energy potential from the natural spring and then see what it can be applied to.

None! The potential comes from the head that you can use and the flowrate, the spring itself is irrelevant (except for the flowrate).

Paul in Montreal.

Micro Hydro from spring water powering GSHP

Pile-o-Stone — Fri, 14 Dec 2012 15:03:31 +0000

Thanks to others who have already responded and to others who may read this in the future and are now a bit confused due to some misinterpretation, the facts are as follows:

1) There is a pipe poking out from the bank of the stream at the back of my garden.
2) The pipe carries spring water that used to supply a manor house with its water.
3) The pipe was severed and now empties into the stream.
4) The pipe gushes water all year round, summer and winter at the same rate (as far as I can see).
5) I'm not doing anything with the stream - it is just a receptacle for the spring water once it has passed through the turbine.
6) I don't live in the manor house, I live opposite it.

As I said, step 1 is to determine the energy potential from the natural spring (based on its flow rate and fall *sigh*) and see what it can be applied to. I'll report back once this has happened.

Micro Hydro from spring water powering GSHP

renewablejohn — Fri, 14 Dec 2012 15:14:17 +0000

Paul

I dont understand this obsession with electric motors and ground source heat pumps. Hydraulic motors are far superior in water environments then electric for obvious reasons with the added advantage of not requiring a high start up current only oil pressure built up in an accumulator.

Micro Hydro from spring water powering GSHP

Paul in Montreal — Fri, 14 Dec 2012 15:23:58 +0000

Posted By: renewablejohnI dont understand this obsession with electric motors and ground source heat pumps. Hydraulic motors are far superior in water environments then electric for obvious reasons with the added advantage of not requiring a high start up current only oil pressure built up in an accumulator.

Hard to find belt-driven compressors for residential applications. Their performance can be lower as well, from what I understand it's to do with the difficulty in making the drive shaft hermetically sealed. Of course, in large scale commercial refrigeration applications, belt-driven (or the equivalent) is the norm as it allows for easier maintenance.

But I agree, if you can find a compressor that you can drive without a motor, it's far better than converting the hydraulic energy to electrical energy first.

Paul in Montreal.

Micro Hydro from spring water powering GSHP

SteamyTea — Fri, 14 Dec 2012 15:54:53 +0000

How about this one

Micro Hydro from spring water powering GSHP

Paul in Montreal — Fri, 14 Dec 2012 15:58:31 +0000

Posted By: SteamyTeaHow about this one

Is that from a car A/C system? Actually, that could be a good way to cobble together a DIY GSHP! Might be a bit tricky with the heat exchangers, TXV and working out how much refrigerant to use, but probably doable.

Paul in Montreal.

Micro Hydro from spring water powering GSHP

SteamyTea — Fri, 14 Dec 2012 16:16:06 +0000

Yes, just googled for one.

The thing about electricity is the controllability. This often makes up for the loss efficiency. It is also easy to redirect to other places.

Micro Hydro from spring water powering GSHP

Pile-o-Stone — Fri, 14 Dec 2012 16:32:15 +0000

Posted By: BeauIf you do go with a heat pump it might worth considering using a water sourced one and putting the spring water through it instead of using ground loops.

This intrigued me so I did a bit of 'googling':

http://www.peakdistrict.gov.uk/__data/assets/pdf_file/0004/90472/peak-district-heating-from-spring-water.pdf

As well as determining the fall and flow of the spring, I might also see if I can determine the temperature of the water.

I was also thinking that if enough flow/water pressure is left after coming out of the turbine, I could possibly link it to my house to provide water for the toilets and washing machines - a lot more cost effective than rainwater recycling via a buried water tank and electric pump.

Micro Hydro from spring water powering GSHP

Ed Davies — Fri, 14 Dec 2012 16:44:43 +0000

http://www.heatpumps.co.uk/types.htm

â€œThe heat pump can be driven directly by a mechanical belt-drive etc. However, this system requires a lot of maintenance. An electric drive heat pump driven from a hydro-electric source is probably the most practical solution, since electric compressors are now so well developed and significantly more efficient than any belt-drive design available.â€

Micro Hydro from spring water powering GSHP

SteamyTea — Fri, 14 Dec 2012 21:10:29 +0000

Posted By: Pile-o-Stonesee if I can determine the temperature of the water.

There are at least two give-aways as to waters temperature, stick to the lower end though.

Micro Hydro from spring water powering GSHP

renewablejohn — Sat, 15 Dec 2012 10:17:54 +0000

Posted By: Ed Davieshttp://www.heatpumps.co.uk/types.htm" rel="nofollow" >http://www.heatpumps.co.uk/types.htm

â€œThe heat pump can be driven directly by a mechanical belt-drive etc. However, this system requires a lot of maintenance. An electric drive heat pump driven from a hydro-electric source is probably the most practical solution, since electric compressors are now so well developed and significantly more efficient than any belt-drive design available.â€

Electric and water do not mix. The heat pump can be driven direct by a hydraulic motor without any belts in just the same way as an electric generator can be powered directly by a hydraulic motor. Hydraulic pumps are widely used in agricultural sprayers and can be used in reverse to power hydraulic equipment from a hydro source.

Micro Hydro from spring water powering GSHP

SteamyTea — Sat, 15 Dec 2012 11:08:44 +0000

They mix about as well as a pulley and belt

Micro Hydro from spring water powering GSHP

renewablejohn — Sat, 15 Dec 2012 21:28:28 +0000

Posted By: SteamyTeaThey mix about as well as a pulley and belt

Whats with the pulley and belt.

Hydraulic pump drives hydraulic motor totally closed system just two hydraulic pipes connecting.

Micro Hydro from spring water powering GSHP

Seret — Sun, 16 Dec 2012 08:08:35 +0000

Posted By: renewablejohn
Electric and water do not mix.

Eh? We're talking about a hydroelectric system. By definition, a mixing of electric and water.

Pile-o-stone: You need to take a look at the technology for micro-hydro. It's often used in the developing world, you can get Âµhydro sets that are small enough to manpack up the side of a mountain and give useful amounts of power (eg: Peltric set). I suspect in your case you're not going to have a large head, so you're probably looking at something like a propellor, which will work quite happily with a head of only a few metres. You can obviously create head if you pipe the water from a high to a low point.

What rights do you have the rights to use the spring water? You said that it used to supply another property? Are you able to dam the output, or are you looking at a "run of river" system? Where is the actual source of the spring?

Micro Hydro from spring water powering GSHP

Pile-o-Stone — Mon, 17 Dec 2012 15:28:07 +0000

Posted By: Seret Pile-o-stone: You need to take a look at the technology for micro-hydro. It's often used in the developing world, you can get Âµhydro sets that are small enough to manpack up the side of a mountain and give useful amounts of power (eg: Peltric set). I suspect in your case you're not going to have a large head, so you're probably looking at something like a propellor, which will work quite happily with a head of only a few metres. You can obviously create head if you pipe the water from a high to a low point.

What rights do you have the rights to use the spring water? You said that it used to supply another property? Are you able to dam the output, or are you looking at a "run of river" system? Where is the actual source of the spring?

I'm looking at buying the land that the spring sits on to use as a smallholding, using the spring as a power source was just an afterthought. I'm struggling to measure the head because the spring is underground and comes out of a pipe on the bank of the stream. There is a structure halfway up the hill that seems to be some sort of 'pump house' that has valves and such. A builder working at the manor house told me that it supplied the spring water to the building and that the manor still has huge (empty) tanks up in the loft space that was used to hold the water.

All I can really do is measure the height from the pipe outlet to the 'pumping station' to determine the head, but the spring could come from anywhere.

Micro Hydro from spring water powering GSHP

Jonti — Mon, 17 Dec 2012 15:56:25 +0000

If it has a pump house tht would seem to suggest that the head is below the tank it used to feed.

Jonti

Micro Hydro from spring water powering GSHP

Pile-o-Stone — Mon, 17 Dec 2012 16:43:59 +0000

Sorry, my bad. I used the word 'pump house' very, very loosely. It's basically a concrete structure with rusty valves, there are no pumps. I couldn't really describe it as I have no idea what it does except to channel the spring into a pipe that empties into the stream, so I called it a pump house.

In many respects it looks like the capping on a mine shaft, perhaps its a cap on top of the spring? I'll see if I can get some photos sorted out as it's quite hard to describe.

Micro Hydro from spring water powering GSHP

renewablejohn — Mon, 17 Dec 2012 16:58:31 +0000

Seret

I know its a hydro electric scheme and if you have seen as many failed schemes as I have then you would understand the comment. Professional systems go to great lengths having water proof glands etc to keep water and electrics apart whereas the typical Joe Public puts a paddle wheel onto the end of a car alternator and then wonders why it does not work. The bigger the alternator the higher the potential of killing themselves.

Micro Hydro from spring water powering GSHP

skyewright — Mon, 17 Dec 2012 17:31:11 +0000

Posted By: Pile-o-StoneSorry, my bad. I used the word 'pump house' very, very loosely. It's basically a concrete structure with rusty valves, there are no pumps. I couldn't really describe it as I have no idea what it does

There's something very like that on the hill above the "big house" near here. Seems likely that it's either a cistern of some sort or just something to protect the source (i.e. a cap on the spring, , as you wrote).

except to channel the spring into a pipe that empties into the stream, so I called it a pump house.

From the description I'm not quite clear if the water vents to atmosphere (i.e. is not entirely within pipework) in the structure? If it's vented then it marks the top of your useable head anyway.