Written evidence submitted by Powys Hydropower (REW0005)


This  submission is put forward in response to the Committee’s request for submissions on a number of questions:


The following paper describes my response to the questions asked and my recommendations. 

In summary I recommend that a very systematic professional approach is taken to the technical and financial evaluation of potential developments in renewables in Wales.  

The reports on renewables in Wales which I have reviewed have tended to be based on rhetoric rather than on quantified engineering and financial analysis. In some cases critically important parts of the analyses have been wrong.  As result some completely erroneous conclusions have been reached.

David Gayther

Director Powys Hydropower.









Q1 How can the UK Government best support the deployment of renewable generators in Wales? 

Q2 How should the UK and Welsh Governments work together to support the development of renewable energy projects in Wales? 

The overwhelmingly obvious characteristic of renewable energy policy in Wales is the lack of reasoned and rational technical & financial analysis of development opportunities. As a result a number of spurious conclusions have been reached. The most notable of these was the Welsh Government decision to support the Swansea Tidal Lagoon. The following are  examples of unsupportable conclusions which are widely stated and believed at present:


In fact Wales is probably not a competitive location for wind turbines when the full cost of transmission to market is taken into account.  This point was made in the Welsh government publication. Energy Generation in Wales 2019 which states that:

With a supportive planning environment and strong wind resources, Wales has significant potential for further onshore wind development. The major barrier continues to be the geographical disparity between developable areas and suitable network infrastructure

The above statement is slightly self contradictory and can be restated as follows:

Despite having relatively high average wind speeds relative to other parts of Western Europe (see below) the lack of grid capacity means that the delivered cost of wind power from Welsh wind farms is probably uncompetitive with other areas of UK

Turbine design conventions applied to Europe, where 100 m average site wind speeds are supplied by GWA. A 5 km averaging kernel is applied to the GWA wind speeds in order to suppress design fluctuations over short distances.


Nonetheless, politicians continue to say that Wales has major opportunities in wind power.   However, on the good news side, Wales is likely to be a competitive location for wind/hydro combinations which are wind turbines coupled with pumped storage.  This opportunity has not been properly assessed, probably because the prevailing mindset is that there are no opportunities in hydropower (see below).


The belief that Wales is a competitive location for wind turbines is widely held as shown by the following statements:

Wales is uniquely placed to benefit from the energy transition, particularly in wind power and marine renewables.”


Wales has vast potential to be a renewable energy powerhouse. Currently, however, our natural resources are largely untapped – or where they are, as in off shore and onshore wind – it is the taxpayers of other European countries that reap the benefi t. Even the much-vaunted tidal lagoon project was led by a company from Gloucestershire”


Mid Wales is well placed to deliver on Wales’ ambition to capture the opportunities associated with the low carbon economy and clean growth. Grid capacity in Mid Wales is a significant constraint to future growth”



There are very few examples of marine energy having been successfully exploited anywhere in the world despite its theoretical attractiveness as a reliable source of clean energy. The exceptions to this may be the Rance Tidal Power Station near St Malo in France and the yet unproven Morlais tidal stream project off Ynys Mon in North Wales

There seems to be a sustained belief in Welsh political circles that it is a major viable source of renewable energy for Wales.  However, simple international comparison indicates that this is unlikely to be the case.


To quote from a letter received from an official in the Wales Energy Service:

“Although we have many streams and rivers, evidence based assessment of new

opportunities for hydropower indicates the opportunities in Wales to meet a large proportion

of electricity use from hydropower are limited by the size and type of waterways. Where

streams and rivers are suitable for hydro developments, in cases where the electricity can’t

be used on site, the cost of development and exporting the power is often greater than its



The above statement is simply a reflection of the prevailing mindset within the Welsh Govt bureaucracy. In fact there have been no credible ‘evidence based assessments’ of the hydropower potential in Wales. There have been several studies but careful examination of the results and data demonstrates unambiguously that these studies have produced completely inaccurate and/or totally spurious conclusions.


To quote again from the Welsh govt publication Energy Generation in Wales 2019

Hydropower is a mature and proven technology that can provide a predictable source of energy. However, the relatively high upfront cost and a lack of cost reduction potential is likely to limit future growth without support

No evidence or analysis was provided to justify the conclusion that “the relatively high upfront cost and a lack of cost reduction potential is likely to limit future growth without support”  The simple truth is that when the delivered cost to consumers is calculated hydropower is a very competitive generation option for the widely spread population of users which exists in rural Wales and other parts of UK.

The reality is that the capital cost per KWHr for hydropower is lower than the capital cost per KWHr of Wind turbines, when the different potential load factors are taken into account, as shown below:

Wind turbines

Total investment (as per IRENA)   =  $1,600 per KW

Expected load factor            =   27%

Expected annual production      =   2,365 KWhrs

Capital cost per KWHr          =    $1,600/2,365    =  67c per KWHr



Total Investment (as per IRENA)    =   $4,000 per KW

Potential load factor            =   90%

Expected annual production      =   7,900 KWhrs

Capital cost per KWHr          =    $4,000/7,900    =  50c per KWHr


Recommendation  It is recommended that both UK and Welsh governments ensure that sufficient engineering/economic expertise is applied to renewable energy policies to enable robust and valid conclusions to be drawn for the future direction of renewable energy  in Wales.



Wales probably has two  major opportunities on which further research is justified, these are:

  1. Distributed Generation


Wales is very well placed to become a leading region in the development of ‘Distributed Generation’ In this system local generators supply power to local users (either domestic or industrial), so avoiding the very high operating and environmental costs of the central generation system which presently prevails in UK.


  1. Pumped Storage in existing dams


Wales has a major opportunity to utilise its existing dams to store and recover electrical energy.  Such storage and recovery would:

However, the issue needs to be taken seriously and professional research is required to decide whether it is worth pursuing or not.

Q4  What opportunities are there for renewable generators in Wales of greater interconnection with other electricity markets?

My full answer is as follows:

The major constraint preventing renewable generators in Wales from connecting to the grid is the high cost of grid connection.  One of the  ways that this could be overcome is to use of existing dams for pumped storage in Mid Wales The potential economic benefits of this are as follows:

  1. Peak power supply

The cost of the additional grid connections may become economically viable when pumped storage is used for ‘peak lopping’  on the grid. The value per KW Hr for peak power is so much higher than for baseload power.

               2.Active management of existing line capacity.

Hydropower can be switched on or off very quickly to meet external conditions. One of the external conditions is the load on the transmission network resulting from other generation sources.  This characteristic allows for Active Management of the transmission capacity in existing networks. The key question is whether this would free up sufficient line capacity to influence the capital cost of transmission.


3.    Transmission cost of sporadic intermittent flow vs steady flow. The following chart shows the typical relationship between a sporadic flow of power (from say a wind turbine) and a constant flow of the same amount of energy from  recovered hydropower.  The key question to be assessed is whether there is a worthwile saving by transmitting a steady flow vs a sporadic flow of energy.

Recommendation   I believe that investigation of each of the above issues warrants a full feasibility study by a competent agency or organisation.


Q5   How can the UK Government facilitate Welsh contributions to COP26?

The renewables  situation in Wales is marked by:

  1. A fragmented approach

Responsibility for renewables in Mid Wales seems to be divided between


  1. An excess of political rhetoric.

Various ‘strategic reports’ have been produced including the following examples

Strategic priorities for the Mid Wales region a report by AECOM.:

                        Strategic Economic Plan & Growth Deal Roadmap, by Growing Mid Wales.May 2020


However, despite there being a number of strategic reports there seem to be very few actual investment proposals.


The UK government can facilitate Welsh contributions by ensuring that there is sufficient engineering and financial expertise being applied to bring forward viable projects in renewables in Wales.



February 2021