Knowing the flow.

Putting a numerical value on the flow being delivered to your turbine isn't important to most Powerspout owners; it's sufficient to open a valve, one or two of them for a pelton, or up to four for a turgo, and let the turbine spin; the business of knowing what flow is actually being delivered in litres per second, or gallons per minute, doesn't really matter; all that matters is that the flow delivered is not greater than what is available.

In the last diary entry I suggested I know what flow each of my nozzles delivers; that the figure for each can be calculated from a formula; that the accuracy of the result given by that formula depends rather too much on the value assigned to two inputs: the nozzle discharge coefficient (Cd) and the net Head (Hn).

Today, I've been doing an experiment to check the accuracy of the figure for Cd that I've been using in the formula over the past three years, - and I've found it's way out; the true flow from each nozzle is significantly less than I've been supposing; for me, and perhaps for some other operators of Powerspouts, this has important implications as I'll go on to show, - but first the experiment:

It involved measuring flow rate by stopping the inflow to the header tank and measuring the time it took for the level to drop a measured amount; with knowledge of the dimensions of the tank, the depth dropped and the time it took, calculating the flow rate was easy. Small errors enter because the flow will change as the water level drops (but change only to a tiny extent), and because the internal dimensions of the tank are complicated by internal flanges (a 'best-guess' correction was incorporated).

To get a precise measurement of the drop in water level, two 3 mm knitting needles were mounted in a bit of wood, rigidly fixed to the tank; the tips of the needles were at different levels, a difference which could be measured to 0.02 mm with a vernier caliper; timing started when the falling water level broke the 'grab' on the tip of the higher needle, - the 'grab' being the attachment to the tip of the needle caused by surface tension, - and ended when it was broken on the lower placed needle:

Three runs were made and all provided near identical results: for the nozzle I was using it took 5 mins and 46.7 secs for the water level to drop from one needle tip to the other; calculation gave the flow rate as 1.25 litres per second whereas before I had thought it was 1.29 l/s.

Now you might think this difference to be small but its effects are big; using the figure for flow rate measured today and using it in the formula to do a 'back calculation' of Cd, instead of Cd being 0.91 as I had previously been assuming, it comes out at under 0.88.

Re-calculating the flow for each of my nozzles using a Cd of 0.88 makes each have a flow less than I had been reckoning on; what does this mean in the real world? - it means two things:

• when I thought I was delivering the maximum flow my abstraction licence allows (3 l/s), in fact I was delivering less than this; for the future, delivering a true 3 l/s will mean more power when operating at the top limit of flow.

• 'whole system efficiency' improves with this new information and this makes to be less the factor used in the annual calculation of the total volume of water abstracted, the so-called Hydro Abstraction Factor (HAF), - used to calculate, from the kWh's produced, the volume of water abstracted;  my HAF drops from 13 m³ / kWh to 12 m³ and the effect of this is to reduce the likelihood of my going over the volume I'm allowed to abstract in a 12 month period.

As carried out today, the test to verify Cd was performed using just one nozzle.  The question remains as to whether the value of Cd changes with nozzles having different orifice sizes; so I'll repeat the experiment as opportunity arises to use nozzles with bigger, or smaller, orifices.

Just at the moment though, it's so dry here that an opportunity to use bigger might be a while in coming.

Bringing order to nozzle changing

The heavens have opened at last !  From the middle of August until last week it has been very dry here with the water available for my Powerspout being less than 0.6 litre/sec; but a deep depression coming in from the Atlantic last week brought copious rain and has abruptly increased flow fourfold.

Although I have been looking forward to the winter rain coming, its suddenness has caught me on the back foot: in order to generate at all on a flow of 0.6 l/s, the SmartDrive had been set up with 18 pole stator and the rotor packed off maximally.  All this had to be changed and changed in the middle of a downpour: the 18 pole stator replaced with a 42 pole, the packing reduced and nozzles upped to match the greater flow available.

Despite my best efforts to have an orderly "take off" into each new water year when the rain comes, I have to admit I've failed this year.  I like to increase the nozzles in a steadily incremental way which matches as closely as possible the increasing flow. I don't like having to 'back track' to a smaller nozzle because I've put in too big a one. But a big element of getting things right is predicting how quickly the flow is going to increase and this year I've got it wrong; I've been beguiled by the torrent of water in the stream into which the turbine discharges (see pic below), and twice have put in too big a nozzle only to have to replace it with a smaller one within 24 hours.  I've been slow to follow my own adage that a source coming from a spring increases its output only gradually as ground water builds up; that I must not be misled by the early 'flashiness' of the run-off which appears in the stream.

In an attempt to bring a system to nozzle changing, I try to bring in a bit of measurement so the process becomes less of a guessing game.

For each nozzle I like to think I know what discharge the orifice will give; but in reality I know the accuracy of the figure will probably not be very good.  The lack of accuracy arises because the way of calculating the discharge involves a formula and that formula has rather too many inputs which are not known with great precision; the formula is:

Q  = CD x Anoz x √ (2g x Hn)

where: 
Q is the flow from the nozzle (m³/s)
CD is the discharge coefficient for the nozzle (dimensionless; I take its value to be 0.91)
Anoz is the cross sectional area of the orifice (m²)
Hn is the net head (m)
g is 9.81m/s²

The term which is easiest to tie down in this formula is Anoz. By using the taper gauge that EcoInnovation supply in their tool kit, or a 'small hole gauge' and a vernier calliper (see here), the diameter of an orifice can be fairly accurately measured, and from that the area calculated. 

The difficulty comes with the other two terms: CD and Hn; as the orifice size changes so will the values of these two terms; but it is too complicated to try to measure them for every size of orifice; it is easier to assume constant values and recognise this will introduce an inaccuracy to the value calculated for Q.

With this limitation in accuracy admitted, my orifices are so arranged as to have a difference in flow between one and the next of about 0.3 l/s.  The smallest orifice, Roman numeral # 1, is cut to deliver 0.3 l/s.  By keeping this nozzle permanently in the top nozzle position and bringing it into use only when there appears to be sufficient water to be able to use it, I can test whether the time has come to increase the bottom nozzle by another 0.3 l/s increment: - if I find that employing # 1 causes the header tank to stop overflowing, the time to up the bottom nozzle has not yet come; but if the header tank still overflows, I can up-size the bottom nozzle.

Intuition might say that employing nozzles of markedly different size in the top and bottom positions is a bad thing.  True, it will produce a vector thrust which has to be born by the bearing on which the shaft is carried; a vector thrust which is cancelled by an equal and opposite force if the two jets are equal in size.  But the size of this thrust when calculated at the bearing is small and is unlikely to be a factor in limiting its life. 

The more important consideration relates to the velocity of the water in the two jets; it may be counter-intuitive, but the velocity is actually the same.  This comes about because jet velocity relates only to net Head, not to orifice size.  So the two jets actually deliver water to the pelton cups at the same velocity even though one is delivering more mass of water than the other.  Having the same velocity, the relative velocity of each jet to the speed of the runner is the same for both jets and this is what is important for good pelton efficiency.

As I finish writing, it has not rained for over 24 hours; all today I've been running on nozzles # 1 and # VIII delivering respectively 0.3 and 1.6 l/s, and giving 448w into the grid; the header tank is still overflowing and the forecast is for no more rain for several days.  With that forecast, the likelihood is my next move will be to turn off # 1.

It's good to have a plan but better still would be to have more rain !

Is it worth it in 2016 ?

If you have a stream with promise, the decision to proceed or not with installing a small hydro usually boils down to money: - will it be worthwhile ? 

Working through to a solution of this question is not very straightforward; the factors which  determine if a scheme will be cost effective are constantly changing. So in this diary entry I thought it might be useful to touch on how things stand in the UK as of now, November 2016, whilst also casting an eye to the future to bring in issues which are already in the pipeline (sorry for the pun) and which will inevitably come to bear on the matter sooner or later.

Income from energy generated

• Feed in Tariff (FIT) payments have dropped colossally; in 2013 when my scheme gained accreditation with OFGEM, the payment per kWh for small hydro was 21.65 p; for new schemes now it is 7.65 p; the rate is due to drop further in more leisurely stages to reach 7.52p by Jan 2019.

• the export tariff has gone up;  this payment is additional to the FIT payment but is paid only on 75% of the total kWh's generated;  it was 4.64p /kWh; today it is 4.91p.

• receiving export payments on 75% of generated units is called 'deeming' and deeming has worked very much to the advantage of Powerspout owners because the output of a Powerspout is so low that in reality most generated power gets used 'in-house'; little or none is actually exported; owners who are canny have been able to go further in ensuring no export happens by installing a diverting device to send excess power to a heat storage load such as an immersion or room storage heater.  But deeming is about to change.  A recent consultation paper made it clear that the government's intention is that homes having renewable generation will need to have a Smart meter recording energy flowing each way, - into and out of the premises; no more deeming; export payments in future will be based only on an actual reading of energy exported.

• to flesh out what these changes mean with real figures: it used to be the case that a Powerspout owner would receive payment of £251 for every 1000 kWh's generated; now the figure is just £113 whilst deeming continues; £76 when it stops and if no power is exported.

The effects of sterling devaluation

• at the rate today, the value of sterling has fallen 16% against the US dollar since the Brexit referendum; as the price of a Powerspout is denominated in US dollars, this is going to make Powerspouts and their spares more expensive; however, the cost of a Powerspout accounts for only about 1/4 of the total cost of an installation so this effect is not particularly off-putting.

• by contrast, the fall in the value of the pound will have a more significant opposite effect which will make turbine installation attractive;  this will come about because of the effect on the cost of electricity; right now as I'm writing, the UK national grid is importing 4.3% of its requirement from France, 2.2% from Holland and is generating 50% of its load from gas; much of the gas is imported now that North sea gas is dwindling; all this importation paid for with a weak pound will soon force supply companies to put up their prices; the effect will be to make it increasingly valuable to avoid buying energy by producing it yourself.  

• the rate at which prices will rise is going to be steep; at the moment the tariff I pay is 18.3p for day units and 7.67p for night (VAT included); these rates have been fixed for over 2 years but are nevertheless nearly double what they were 10 years ago; there is no escaping that the pause of the last two years in the rise of the price of electricity has been an aberration in its otherwise relentless upward trend, and that soon that upward trend is going to reassert itself; as it does so, the case for a Powerspout is made to be ever more attractive.

• to illustrate how much more attractive: in the past two years, for each 1000 kWh I've generated, my electricity bill has been reduced by £152 ( a calculation which assumes I've used everything generated and none was exported); if prices rise by 5% per year for the next 5 years, the saving at the end of the 5 years will have grown to £194 per 1000 kWh generated; at the end of 10 years, it will be £247.

To conclude, I offer no answer to the question "is it worth it in 2016 ?"; the answer is too specific to each scheme, - how great is the promise of the stream; how willing is the scheme owner to rise to the challenge of devising a way of making the scheme work, of tackling the bureaucracy involved, of doing the installation work themselves.  

In all this however, too much should not be made of the strength of the business case in reaching a decision; there is the feel good factor to consider as well; the feeling of becoming a generator connected to the national grid, contributing in a small way to the energy needs of the country in a sustainable way. 

It might not count for anything on a balance sheet but in the bigger picture, the feel good factor is a potent force for making a scheme seem worthwhile.

Sizing turbine to stream

In the planning stages of implementing a small hydro scheme, one of the biggest challenges is to decide what power the flow in the stream will support.  To put in a scheme which under-utilises the available flow is to save money. But it will create a lingering feeling of not making the most of the resource which is available; and having installed too small a scheme, up-sizing is not something easily done at a later time.  Conversely, to put in a scheme which is over-sized such that full power is realised only for a small part of each year, wastes money; what is spent on the cost of a bigger machine, bigger penstock and bigger pretty well everything won't see a commensurately bigger return.

So how does one hit upon the right balance?  

The first thing to know with as much accuracy as possible is the flow in the stream and how this varies through the seasons of a year. Even when you think you have this knowledge however, there is a caveat. By whatever means this knowledge is gained it will not be information that can be wholly relied upon: - year to year changes in wetness happen, and climate change may introduce longer term changes too. "Past performance is not a reliable guide to future returns" is an epithet often applied to financial investments; it applies in hydrology too.

In the previous diary entry, I mentioned that it is possible to purchase information about the flow in any river or stream in the UK, made available in the form of a flow duration curve (FDC); that the accuracy of such a computer generated FDC is questionable for the smallest streams of the kind where a Powerspout is likely to be used; and that purchase is expensive. But purchasing knowledge is one way of getting the knowledge you need about your stream's flow.

An alternative way which is cheap but time consuming is to measure flows oneself; this is what I did: every week for a year I measured the time it took to fill a coal scuttle thrust into the flow at a point where the entire flow fell freely over a rock face and I had arranged for it to discharge from a pipe: 

Not being able to hold a stop watch at the same time as holding the coal scuttle, I simply counted the seconds it took to fill its 10 litre capacity.  The method was probably not very accurate but it gave data which was useable to make the following plot:

Once gathered, this time-sequenced data can be manipulated; such manipulation is how an FDC is constructed. Instead of showing what flow was present in each week, an FDC shows the length of time (i.e.duration of time, expressed as a percent of the recording period) specified flows were equalled or exceeded. There is a lot of number crunching which goes into creating an FDC and it needs to be done using a spreadsheet programme such as Microsoft Excel. The easy to follow description of how to do it which I gave before is given again in this link.  

Once constructed, an FDC is useful because it begins to indicate what size of turbine might be suitable for the flows in the stream.  But it only begins to give an idea; many are the factors which massage the actual flow figure that can be used, foremost of which is the amount of flow the regulatory body in your country will allow you to take.


For the flows I measured in my stream, this is the flow duration curve I constructed; on it I have marked a point which is called Qmean*. As can be seen it is at a flow of 1.86 l/s, a flow which is equalled or exceeded, on aggregate**, for 39% of the year. But, and it is an important but, - 1.86 l/s was the Qmean only in the year in which I took the flow measurements. This one year will not necessarily be predictive for future years and as we will see below, it wasn't.

Qmean is an important term to comprehend; the value of it for your stream is a good first-off guesstimate of the size of turbine that suits your site; a rough rule of thumb is that the Qmean value, or a flow close to it, will be the flow to use in your calculations of the maximum power the installation will be capable of producing. Although flows higher than the Qmean flow will be present during the course of a year, experience shows that sizing the installation to the Qmean flow gives a good compromise between being able to use the higher flows of winter and also the lower flows of the drier months.

The way to calculate Qmean depends on the way you do it.  If you have a series of flow measurements taken at equal intervals over a period of time***, then Qmean is straightforward; it is simply the arithmetic mean (sum of flows divided by number of measurements).  But if you have a flow duration curve without actual flow measurements, say because you have purchased it, then Qmean is the point where the area under the curve to the left of the Qmean point equals the area under the curve to the right of it.  Determining this can be done by overlaying a grid on the curve and finding the point where the number of squares to the left of the point equals the number to the right. 

In terms of reliability, the weight that can be born by the figure for Qmean really depends on the way it is reached.  The figure given above for my stream,1.86 l/s, is not reliable; it was derived from measurements, not very precise measurements, taken only weekly, over only one year. To illustrate how unreliable it was, the plot below shows the FDC for that year, 2008/9, together with the FDC for the year just ended (2015/16); in the latter year, the flow measurements were calculated from power generated each day****; seen together, the two years give very different Qmean values: 2.43 l/s vs 1.86 l/s:

Only when the period upon which a flow duration curve is based is long enough to represent the long-term picture can the curve be considered reliable and begin to be used in a predictive way. Even this reliability will not be guaranteed if climate change is having an effect, for then even a historical long-term record will not hold true for the future.

To conclude and to emphasise the importance of Qmean, let me relate how abstraction is adjudicated here in Wales. Since the time, 3 years ago, when I applied for my abstraction licence, there has been a complete overhaul of the guidelines for the abstraction of water for micro-hydro. The new recommendations attach great importance to the value of the Qmean measurement; by relating it to the type of stream under consideration, a formula is employed which determines what amount of abstraction will be permitted.  The guidelines can be seen in full here (especially page 5) but in summary either Qmean or a small multiple of Qmean (a factor of 1.3) is set as the maximum flow which can be abstracted from a water course.

The change in the guidelines is a welcome simplification of what existed before; but the pivotal place given now to Qmean in fixing the size of the installation, and take note, fixing it so that future change can scarcely be considered, makes it a very important parameter to get right; the difficulty is that it's a parameter which doesn't lend itself easily to precision.

*Q is the symbol for flow; mean is the average; so Qmean is the point signifying average flow.

** by "on aggregate" it is meant that within the year the time where 1.86 l/s was equalled or exceeded in total came to 39% of the year; this 39% of the year will not be a continuous stretch of time during which 1.86 l/s was equalled or exceeded.

*** only complete years of flow measurements should be used and the records for partial years discarded; otherwise the flow data may be skewed by seasonal wet or dry periods.

****by using power data, the flow duration curve is 'capped' by the design flow of the turbine; the effect of this will be to under-estimate Qmean; in this year, Qmean would actually have been higher than 2.43 l/s.

Productivity viewed 3 ways

The ending of September brings to a close the 12 months I have chosen as my hydro 'accounting year', a period I have come to call a 'water year'.  In previous diary entries I've speculated as to whether I would reach the total I was hoping for of 4000 kWh; now the answer can be revealed !

There is an old saying which goes: "If you ask a man with a watch what the time is, he will tell you; but if you ask a man with two watches, he can't".  Something of the truth in this applies to my ability to reveal the answer; having two ways of measuring the energy total inevitably gives two different figures.

Below is a plot of the cumulative energy output of my turbine for the three water years it has been running; the data is captured automatically from the inverter; as can be seen it gives a total of 4,032 kWh:

But an inverter is not designed for the very accurate capture of data; there is an Elster energy meter also in the circuit which is more accurate, - as it must be for determining FIT payments on energy generated; and the total it gave was 4,168 kWh.

So, as the graph shows pictorially, even with its less than accurate total, the year just finished has exceeded both previous years.  A consequence will be that I'll probably exceed the amount of water I'm licensed to abstract in a twelve month period (it is calculated from the figure for energy generated); but since the accounting period for that twelve months is April 1st to March 31st, the matter will not arise until 2017.

Another way of presenting the data in the above graph is shown below.  Here, instead of plotting the cumulative total reached at each date, what is shown is the actual energy generated each day; this relationship gives an idea, not seen in the above graph, of the variation as the year's seasons come and go:

From this plot it will be seen that peak generation in 2015-16 (18.9 kWh/day) was higher than in the previous two years and also that generation continued throughout the water year, the first time this has been possible.  Both of these improvements resulted from gaining a better grasp of the science behind a Powerspout, the first by squeezing from the system a small improvement in efficiency and the second from using, in the drier months, a modified stator in the alternator.

The third and final way of looking at productivity is rather different from the above graphs but it uses exactly the same raw data.  People familiar with hydros are usually familiar with flow duration curves (FDC's), that type of curve called an exceedance curve which depicts what percent of a period of time, usually a year, a given flow in a watercourse is recorded as being present. 

These days, rather than measured flow data being used to construct an FDC, rainfall data and catchment area are used to compute the flow; computer calculated FDC's can be purchased for any watercourse in the UK, at a price, without the tedium of taking any actual measurements of flow; their accuracy is questionable, especially for the small streams a Powerspout might be installed on; yet the authorities responsible for licensing water abstraction in each of the national regions of the UK often insist on applicants providing them.

A curve called a power duration curve can be constructed in the same way as for an FDC but using power data rather than flow data.  Here is such a plot for the output of my turbine over the past three water years:

Such a plot is rather useful. Whilst it has all the same features evident in the two plots above, it shows in addition something not evident in those plots; it shows a characterisation of the annual flow in the watercourse, just as if it was a flow duration curve.  

For a site like mine where no 'hands off flow' is required, a provision which allows me to take as much flow as I can up to the design flow of the turbine, the shape of the power distribution curve will be almost identical to the flow distribution curve, at least in that part of the curve below the maximum power level. It will only be 'almost identical' for two reasons: because the system efficiency is reduced at very high and very low flows, thus making the relationship between output power and flow to be non-linear; and second because I don't always manage to take all the flow. But notwithstanding this limitation, it will be a far more accurate characterisation of stream flow than any FDC could possibly give, based as it is on daily electrical readings which are so much more precisely captured than water flow readings.

The usefulness of plotting a power duration curve each year will come over time.  If, as we are led to believe, Wales is going to get wetter as climate change happens, successive year plots layered over previous years should show clearly whether greater wetness is indeed happening.  It'll be a very, very, local investigation into the effects, if any, of global warming !

For anybody interested in learning how to construct exceedance curves, I found this pdf document on Phil Maher's Hydromatch site to be much the most helpful.

Rotor packing - the sequel

Early September and I'm well into the driest time of year.  In actual fact, there has been quite a bit of rain but at this time of year it does little to augment the flow from a spring, - which is the source for my Powerspout; I'm presently running on my second to smallest nozzle and generating 136 w into the grid; I've needed to install the reduced core (i.e. 18 pole) stator to achieve this output, something which I was hoping keeping with the 42 pole stator but using rotor packing would avoid.

Dropping down through my nozzle sizes in the past months has given plenty of scope to experiment with rotor packing at each flow level and collect data about its effects. I have written before of how it increases rpm and thereby keeps the pelton operating at nearer its 'sweet spot' speed; I thought this would make for better power output but reviewing all the data has cast doubt on such an assumption.

Below is the plot of watts output to grid vs dc operating voltage.  Remember I am using a WindyBoy inverter which does not use MPP tracking; it simply draws a current from the turbine which is determined by the dc operating voltage; the magnitude of that dc current is reflected in the ac watts output to grid (LH vertical axis); the dc operating voltage varies with the flow delivered to the pelton (horizontal axis).  The plot shows a polynomial curve on which all the data points sit with remarkably little spread. This was something of a surprise.

It was a surprise because the data points were the result of very different operating states for the turbine; some were with rotor packing and some were not.

For each of the data points on the graph above, I also measured rpm; and for the data points arising from the lower flows, I used rotor packing to keep rpm up to above 900.
With rpm data superimposed on the above graph, using the RH vertical axis for rpm, this is the picture:

As can be seen, for those data points where rpm was kept above 900 by rotor packing, there seems to have been no obvious improvement in ac watts over the trend established by there being no packing. 

But perhaps I'm being unduly negative; perhaps without rotor packing the polynomial curve would have been a straight line relationship between dc volts and ac watts, making for less output than I actually got at the low end of the plot.

What counts for me is that to the eye and the ear the turbine undoubtedly appears happier with rotor packing.  I will continue with it.

Sun and water

The end of August sees the completion of the first full year of having both hydro and solar generation being harvested here where I live. In this brief post, I want to present the data.

The synergy of solar with hydro is well recognised: of benefiting from hydro in winter and solar in summer; so the pattern of yield for the two as seen in the graphs below comes as no surprise.

In the UK, the total amount of generation that can be contributed to the grid at one meter point is restricted, and although my Powerspout could never generate at its maximum at a time of the year when the solar panels were also generating at their maximum, the sizing of the solar array had to be limited to keep the sum of their peak outputs within the permitted total.

For this reason the array is less than the maximum normally allowed; it is a 3.42 kWp installation and its yield is reduced by being in a location which is not ideal, facing east-south-east (S60degE), on a roof pitch which is rather flat (30deg).

Nevertheless it does the job nicely of keeping the energy generated each month in summer up to the peaks the Powerspout reaches in winter.  Totalled over a full year the hydro generates more which, considering its design rating is just 0.75 kW vs the 3.42 kW of the PV, says much for how productive small hydros working 24/7 can be.

A finishing thought: the sun does it all ! - energy from the sun is the source of both solar and hydro generation; were it not for the sun taking water as vapour from sea level up to the sky so it can drop on the hilltops as rain, not a hydro installation in the world could work.

A post script to my last blog post: I have had much interaction with NRW since writing about my 'grievances', all of it good and positive.  Having been decidedly critical in that post, I just want to put on record my thanks and appreciation to all those, from the member of the board downwards, who tolerated with good grace what I wrote and are looking into some of the points I raised. Diolch yn fawr.

Grievances with NRW.

In the past couple of weeks I've been having a dialogue with a very nice lady at NRW. NRW stands for Natural Resources Wales.  It is the body in Wales responsible for issuing and regulating licences for water abstraction.

In the UK, we call such a body a "quango", - an acronym for quasi autonomous non-governmental organisation.  A quango has power to set and enforce legislation. The disconcerting thing about the power possessed by a quango is that where such legislation is later shown to contain glaring anomalies amounting to abuses which arouse protest, yet can the quango close its ears and say that such abuses are in the nature of things so must be accepted without demur.

Ordinary people like myself, coming into contact with NRW for the purpose of getting an abstraction licence, may perceive these wrongs; may perceive that an injustice is being imposed; and this creates a feeling of resentment at being unfairly treated.  Yet the deafness of the organisation makes it impossible to get even a hearing, let alone redress.

The particular matter which has been the subject of my dialogue concerns the imposition of a charge for the water I abstract.  Water abstracted for the generation of electricity does not attract a charge. Neither does water abstracted for domestic use, so long as the volume is less than 20 m³ per day. Yet if these two abstractions come from the same place, the way NRW has written the rules makes it compulsory to 'aggregate' the two volumes and aggregating inevitably brings the total daily volume to greater than 20 m³. Such a volume now triggers a charge; in effect: two abstractions, each on its own free yet together being made not to be free !

There have been other injustices in NRW's self written rule book which I have drawn attention to before. Let me mention two again:

1. - in this third year of operating my Powerspout I am going to generate over 4000 kWh of energy.  The volume of water I have abstracted to generate this is calculated by applying a 'hydro-abstraction factor' (HAF). For my site this is 13 m³ per kWh; To have generated 4000 kWh I will thus have abstracted in excess of 52,000 m³. This is more than the limit set by my licence (49,982 m³) and yet I have generated this number of kWh's, an exceptional number for me, only because it has been an exceptionally wet year;  the instantaneous flow abstracted and the daily volume abstracted, figures for both of which are also stipulated on the licence, have not been exceeded.  

The injustice here is that it is inconsistent for a licence to set both a daily limit and an annual limit; there is no knowing when one applies for a licence how many wet days there will be in future years, so making prediction of an annual limit impossible. All that should matter to NRW with its concern for harm to the watercourse is that the daily limit is not exceeded. It ought to matter not at all to them if a year happens to be so wet that water is plentiful enough to allow people like myself to generate an exceptional number of kWh's.

A subsidiary point to be made about the yearly volume, if indeed there has to be one, is that it is mathematically amateurish to stipulate a figure which purports to be more precise than the accuracy possible from the method used to calculate it.  My licence, instead of saying 49,982 m³ would better have said 50,000 m³, and better still from a mathematical standpoint, should have added an error allowance of, say, 10%, acknowledging the calculation method can sustain no greater accuracy than this. By allowing some measure of flexibility then at least licence holders would be saved the anxiety of overstepping their limit in occasional years.

2. - in describing the way to calculate one's HAF, NRW say that the component efficiencies of the different parts of the installation at maximum power must be used.  To say this is unscientific and subtly over calculates the HAF by the effect of two linked factors: 

• 'run of river' hydros in Wales will never operate at maximum power throughout a year
• efficiency, at least for a pelton, is not very good at maximum power

It would be better to calculate the hydro abstraction factor either from the efficiency at the flow which predominates through a year (the mode flow value) or, and this would be being generous to the licence holder, at the flow where the installation is most efficient.

These points of grievance are highly specific.  They refer to arcane detail which is not for everyone. There is however another matter of grievance, which requires no knowledge of obscure detail, is relevant to all hydro owners and reaches to the deepest level. It has been the subject of a long running argument between NRW and the two organisations in the UK which represent owners of small hydro installations, the British Hydropower Association and the Micro-hydro Association. 

It is the argument about how abstraction for electricity generation should be treated; the proposition that abstraction for the generation of electricity should not be treated as abstraction for other purposes because the one permanently removes water from a watercourse whilst the other does not; that the principles, right and proper principles as they are which guide NRW in wanting to restrict and have control of the removal of water from Wales' water courses, need to be modified when applied to abstraction for electricity.

Unfortunately for hydro owners, the response of NRW so far has been characteristic: the organisation has been unwilling to engage on the issue.  In like manner I have had no real engagement on the particular grievances I have put forward. Such is the typical quango stance.

Who in an organisation like NRW are those responsible for the conduct of the organisation ?
Certainly it is not those like the lady I have been corresponding with or the two NRW field workers who paid me a visit two years ago, all of them open and approachable people but people who are necessarily constrained to work within the legislation that NRW has itself devised. What needs changing is the legislation itself.

The people at the top who sit on the board are the ones who carry the responsibility for the image the organisation conveys.  As it happens, I am familiar with a few of them ! One is a micro-hydro owner who lives near to me and whose installation I have visited. With two others I share the experience of having been a senior employee of the Welsh Health Service. 

Come on you board members ! - ensure NRW puts in place mechanisms for real consultation on matters of grievance concerning your legislation.

Why not have a board member who acts as an internal 'ombudsman', to whom grievances about your legislation can be addressed ? Your complaints procedure specifically excludes using the complaints route for legislative change.