Micro hydro

Before the arrival of reliable mains electricity in the Brecon Beacons, many landowners relied on private micro hydro schemes to generate electricity.
Now, with rising energy prices and the incentive of Feed-In Tariff payments, micro hydro is once again a viable option, and a key part of our strategy to make Llangattock a carbon negative community.

Why micro hydro?

There are three very good reasons for choosing micro hydro:
1. Good annual rainfall and plenty of steep hillside streams make micro hydro the natural choice for generating sustainable renewable energy in the Brecon Beacons.

2. Micro hydro is small scale, so it has a very low visual and environmental impact.

3. Micro hydro uses tried-and-tested technology, proven over many years.

Where we are at

Initial feasibility work begins using funding provided through the British Gas Green Streets Competition. Five potential streams identified.

Summer 2011
LGV wins the British Gas Green Streets competition, securing £100,000 to develop community micro hydro.

Summer 2011 – Autumn 2013
Further feasibility work whittles the five streams down to three. Of these, one is taken forward privately by the landowner. The remaining two schemes for phase 1 – Cwm Gu and Llwmws – go into development through our trading arm, LGV Ventures, in partnership with the landowners.

Autumn 2013
Llangattock Green Valleys Micro Hydro (1) Co-operative Ltd successfully raises the full £270,000 needed to fund the development and construction costs of the two schemes, with construction on track to start in summer 2014.

Spring 2014
Llangattock Green Valleys Micro Hydro (2) Co-operative Ltd launches, with a share offer target of £690,000 to build a further four schemes. Micro Hydro (1) schemes receive planning permission from Brecon Beacons National Park Authority.

Spring 2014 onwards
Development work continues on other streams, which are set to become the subject of future share offers.

June 2014

MH-1’s first AGM is held. LGV welcomes two new directors, Mike Proctor and Miriam Griffiths to the Board.

August 2014

MH-2 share offer scheme closes to investors.


November 2014

Construction starts at our first MH-1 scheme Cwm Gu, on the Glanusk Estate and the penstock pipe is delivered to site. We now have full permission and licensing for our first MH-2 scheme Nant yr Hafod, above the Clydach Gorge. Planning permission is granted with some conditions for the Gargwy Fach scheme.

January 2015

The turbine house base is complete and the penstock pipe for the lower half of the Cwm Gu scheme is joined together, dragged into position and trenched.

Full planning permission and licensing is granted for LGV’s MH-2 schemes, Gargwy Fach and Nant y Gadair.

Planning permission is refused for Blaen Dyar.


March 2015

Cwm Gu’s turbine house structure is now complete.


April 2015

The intake at Cwm Gu is now complete.


May 2015

Cwm Gu trenching work for the penstock pipe in the upper section is complete, the turbine is installed and the output electricity pole with transformer is in position.


June 2015

Electrics and meter are installed and the environmental improvements are complete at Cwm Gu. The construction of our Nant yr Hafod scheme is now well underway. The main excavation and rock cut back has been completed, all the pipework is on site and has been partly joined and concreting work has started. The turbine house slab was cast last week and the structure itself will be erected next month.

The official commissioning date for LGV MH-1’s Cwm Gu, is 23rd June 2015.


July 2015

The Gargwy Fach scheme is shelved due to a landowner withholding consent for the erection of a pole to export the electricity.

The planning application decision for the amended Blaen Dyar scheme is now expected on 31st July, and LGV has the necessary drainage consent.

Talks begin with the landowner of Abernant, near Builth Wells, regarding the feasibility of hydro.


August 2015

Revised application for Blaen Dyar receives planning permission.

The intake and turbine house are almost complete and all the penstock pipe is in place at Nant yr Hafod, and the DNO service cable is in place from the grid pole into the turbine house.


March 2016

A Partnership Agreement has been drawn up and signed to concrete our relationship with Welcome To Our Woods, our partners for the proposed Cwm Saebren (MH-2) hydro scheme.


August 2016

MH-1 receives its first FITs payment.

Nant yr Hafod is granted full FIT accreditation.


September 2016

LGV MH-1 and MH-2 are now supporting active micro hydro schemes at Cwm Gu and Nant yr Hafod and will develop a further three schemes during 2016/2017. Preliminary FIT accreditation for Abernant granted and the full accreditation application process has been started. Access arrangements and planning permission for Cwm Saebren has been secured from landowner, NRW.


October 2016

The landowner lease is being drawn up for the Cwm Saebren scheme, in liaison with NRW.


November 2016

LGV has signed the contracts and paid deposits to TGVH and the DNO for the Abernant scheme. Construction is scheduled to start in the summer of 2017.


December 2016

Our construction company TGVH is continuing to gauge the water flow at the intake of Cwm Gu, in preparation for applying to NRW for an adjustment to the HoF notch height, so that we can take more water from this stream.

LGV signs a wide ranging partnership agreement with Welcome to Our Woods (WtOW).


January 2017

We received confirmation from OFGEM this month of preliminary FIT registration for Cwm Saerbren.


February 2017

TGVH now has sufficient flow data for Cwm Gu and has commissioned a hydrology company to write a report to support an application to NRW to raise the HoF notch.

The lease for Cwm Saebren has been completed and we will start building the scheme later this year.

LGV welcomes Leona Jones and Penny Hallas as HYDRO artists in residence.


March 2017

We had a couple of weeks of persistent rain at the beginning of the month and the power output at Cwm Gu reached close to maximum levels for the first time since February 2016.

Construction work at Blaen Dyar begins. For more news on the construction of Blaen Dyar, please sign up to our newsletter and visit our dedicated pages: Construction News and Artists in Residence.

A legal partnership is formed with Welcome to Our Woods (WtOW) to proceed with micro hydro at Cwm Saebren, Treherbert – planning permission is granted and leases are signed.

Construction orders for both the planned MH-2 micro hydro schemes, Cwm Saebren and Abernant, have been signed and deposits paid. Construction of both schemes should start within the next 6 months.


April 2017

There was less than half the average UK rainfall this month.

TGVHydro received the hydrology report for Cwm Gu which indicates that the water flow through the turbine house could be increased. They are running some in-house models to support the findings of the report prior to submitting the revised HoF notch application to NRW.

Penstock pipe and other materials are delivered to the Blaen Dyar construction site and a fallen tree removed.

Hydro Artists in Residence, Penny Hallas and Leona Jones, start the initial research phase of their work by following the installation work at Blaen Dyar site to gather material related to hydro technology and the landscape in which it is situated.


May 2017

A lot of comment appears in the media about the winter of 2016/17 being the driest on record for over 20 years. May is also dry.

Discussions take place between TGVHydro and NRW prior to an application submission to adjust the size of the HoF notch.


June 2017

Co-op hydro AGMs are held on Monday 5th June at The Old Rectory Hotel, Llangattock.

Voting is unanimous from both co-ops for the part purchase of Blaen Dyar by MH-2 from MH-1 and the transfer process starts. Money from MH-2 will be used to cover MH-1’s expenditure on Blaen Dyar up until the point of transfer.

There have been some short periods of rain, but the forecast is dry for June.

TGVHydro submits the HoF notch adjustment application to NRW.

NRW requests that further flow gauging is carried out at Cwm Gu to support the application.

Penstock at Blaen Dyar has been fully joined and dragged in to position, the impoundment and intake area nears completion, the turbine house is built and the main electrical work completed.


July 2017

There have been some short periods of rain but it’s been mainly warm and dry so there has been very little generation at Nant yr Hafod (MH-2) and none at Cwm Gu (MH-1) this month.

As a result flow gauging has not started at Cwm Gu.

The low water levels have also revealed a small hole at the intake of Cwm Gu – TGVHydro has been asked to repair this as soon as possible.

Construction of the Blaen Dyar scheme (MH-2) is nearing completion.

The regional electricity operator, Western Power, has carried out their major works and LGV is now waiting for EoN to change the meter from single to split phase and reposition it in the new kiosk. The turbine house is almost complete and a date will soon be set for final testing.

LGV is in discussions with Western Power about the two remaining MH-2 schemes, Abernant and Cwm Saerbren, which will be built before the end of the year.


August 2017

There have been some periods of rain and both Nant yr Hafod (MH-2) and Cwm Gu (MH-1) generated some small amounts of electricity towards the end of last month.

TGVHydro have repaired the hole at Cwm Gu’s intake and they are continuing to flow gauge at the Hands-off flow notch, to provide additional data to support the NRW application. They are also flow gauging at Nant yr Hafod as part of a wider project to collect data to support a change in the way HoF notch sizes are calculated.

Last week LGV completed and commissioned Blaen Dyar (MH-2). In the first couple of days there was just enough water to start the turbines turning before the water level dropped again.

Work has started at Abernant (MH-2) and is progressing well. The penstock pipe has been delivered and joined and work has begun on the intake. The scheme’s size had initially been restricted because there was no spare export capacity in the local electricity Grid, however, LGV has been informed by Western Power that a wind farm in mid-Wales has failed to obtain planning permission and so the Grid capacity allocated to that scheme has been released. As a result, the restriction has been fully lifted and all electricity generated by the Abernant scheme will now go to the Grid.

Preparation work has been started at Cwm Saerbren (MH-2) – the 700 metres of 280mm penstock pipe will be delivered in the next couple of weeks and will then be joined and dragged into position. Work will also begin on the concrete intake structure.


September 2017

Flow gauging at Cwm Gu (MH-1) has been completed.  Comparison data from a local donor gauging station is needed before the hydrologists can complete their report. Frustratingly, there was no generation at Cwm Gu this month, with the water level consistently rising to near the top of the intake weir but not triggering the scheme to start generating.

There has been a small amount of generation at Nant yr Hafod and also at the new MH-2 Blaen Dyar scheme. The snagging and other issues at this site are all completed and the official hand-over takes place with some instruction from TGVHydro.

Construction of the Abernant scheme (MH-2) is ahead of schedule and commissioning maybe possible within the next two weeks. As usual, there have been some challenging issues to overcome but the various contractors and authorities have worked well together and this scheme should be handed over to LGV MH-2 next month.

Progress has also been good at Cwm Saerbren (MH-2). The penstock has been delivered and its location marked out, the concrete intake structure has been built and a contract has been signed to construct the reinforced concrete turbine house. This scheme is also on track to be commissioned before the end of the year.

Artists in Residence, Penny Hallas and Leona Jones’ research phase nears completion.

The LGV-MH2 Board agrees to help fund the next phase of this arts project, which is to develop an audio-visual installation for display in a local arts venue in April 2018. In partnership with LGV, the artists apply for match funding from a grant-funding body to support the public presentation.


October 2017

Total generation at Cwm Gu (MH-1) at the end of October stands at approximately 94,000 kWhs.


November 2017

The hydro schemes have been generating close to capacity for some days this month. Water has been running off the basin that feeds the Cwm Gu scheme (MH-1) and its turbines have been busy. The comparative flow data from NRW to support the HoF notch application for Cwm Gu has been received and the hydrologists are producing their report.

In mid-October the Nant yr Hafod scheme (MH-2) was in flood to such an extent that the intake screen could hardly be seen. Similarly, Blaen Dyar (MH-2) had a lot of flow and was generating well. The final data and files for Blaen Dyar have been submitted to OFGEM for the conversion of LGV’s initial FITs application to full permission – once this is granted, LGV can start receiving FITs payments.

The third MH-2 scheme, Abernant, is commissioned and is generating well.

LGV and the Artists in Residence receive investment from A&B Cymru’s CultureStep Investment Programme to strengthen and develop their creative partnership.


December 2017

All the operational hydro schemes have been generating electricity.

Total generation at Cwm Gu (MH-1) at the end of December was approximately 113,000 kWhs.

LGV receives the hydrologist’s report regarding the flow at Cwm Gu and instructs TGVHYDRO to submit the report along with a licence variation form to NRW, to request a reduction in the size of the HoF notch.

NRW has indicated that they are likely to keep the abstraction regime at a 90/10% split, which is positive news. If the proposals are accepted, the changes should lead to an overall increase in flow through the Cwm Gu scheme and greater generation potential.

Nant yr Hafod (MH-2) continues to generate steadily and at the end of last month the total generation was close to 74,700 kWhs. It is clear that the marshy peatland surrounding this scheme has caused a build-up of brown deposits on the inside of the penstock pipe and also in the turbine. To combat this LGV purchases some hydro ‘pigs’, which are made of polyurethane and will be used to clean the inside of the penstock pipe.

The generation total at Blaen Dyar (MH-2) at the end of its first full month of operation stood at 2,700 kWhs.

Local volunteers agree to help monitor and maintain Blaen Dyar and Abernant.

Some teething problems are experienced at the Abernant hydro scheme which involves LGV, TGVHYDRO and the manufacturers attending site to assess the cause of the problems, which are now fixed.

The construction of Cwm Saerbren, (final MH-2 scheme), is progressing well and the sinking penstock pipe is stabilised. Western Power informs LGV that that the outstanding S37 consent for them to be able to carry out their electric works has been granted. They have already visited site to assess the project and they expect to start work during the first week of this month.

Artists in Residence, Penny Hallas and Leona Jones’ calendar of events for April 2018 comes together.


January 2018

There have been several good rainy spells this month and all the hydro schemes have been generating some decent amounts of electricity.

Total generation at Cwm Gu (MH-1) at the end of January stands at approximately 125,500 kWhs. There have been a couple of minor technical problems with this scheme which are now resolved. NRW’s consent for the changes to the HoF notch are received – work will be carried out by TGVHydro when the weather is more suitable.

The generation total at Blaen Dyar (MH-2) at the end of December stands at 11,000 kWhs. This scheme developed a fault with the spear valve/actuator unit before Christmas and so the turbine manufacturer visited the site and fitted a new actuator under the warranty.

The total electricity generated by Nant yr Hafod (MH-2) at the end of last year was around 80,000 kWhs. The pigs are delivered for cleaning inside the penstock pipe which will be carried out later in the year.

LGV’s newest scheme at Abernant (MH-2) had generated almost 17,000 kWhs by the end of 2017, which is encouraging news despite some technical problems and slight damage to the turbine house roof caused by a large fallen tree, brought down by the recent gales.

The final hydro scheme, Cwm Saerbren (MH-2), is nearing completion. The turbine house is almost complete, much of the electrics are done and the meter is fitted. The next task is to finish inside the turbine house and to commission the scheme, with the hand-over to LGV MH-2 and partner group Welcome to Our Woods scheduled for 13th February.

Artists in Residence, in conjunction with LGV, submit the arts project for consideration to A&B Cymru Awards 2018 under three categories: Arts, Business and the Community; Arts and Small Business; Arts, Business and the Environment.


February 2018

There is a fair amount of rain, snow and freezing temperatures locally, which tests monitoring equipment and means our volunteers can’t get to some of our schemes for a week, but overall it is another decent month of electricity generation.

Total generation (approx.) in kWhs at the end of February:

Cwm Gu:                      132,225

Nant yr Hafod:             89,674

Blaen Dyar:                  25,324

Abernant:                     31,630

Cwm Saerbren:            3,000

The final MH-2 hydro scheme, Cwm Saerbren in Treherbert in the Welsh Valleys, is commissioned and generating electricity. This is the largest and most costly scheme, developed in partnership with a local community group Welcome to Our Woods.

A community celebration day is planned for later in the month and members of both community organisations will attend. The scheme has already attracted a visit from Wales Assembly Member for Environment Hannah Blythyn, who made a business rates announcement from near the Cwm Saerbren turbine house and featured on BBC Wales News.

The manufacturer of a faulty spear valve at Cwm Gu services and replaces it and it is generating at full power again.

The generation total at Blaen Dyar (MH-2) at the end of January stands at 20,700 kWhs and at Nant yr Hafod around 87,000 kWhs.

Abernant’s (MH-2) RCD is regularly tripping and TGVHydro’s electrician will replace this. The total generation at end of January stands at 24,700 kWhs.

Two of our new schemes have not reached the predicted peak power since commissioning at the end of last year, despite plenty of flow through the schemes. LGV is in discussions with TGVHydro about the reasons for this and possible solutions and they are considering whether boring new nozzles in the spear valves will solve the problem.


March 2018

The persistent recent rain is good for hydro generation, with all 5 schemes performing reliably and productively this month.

Total generation in kWhs at the end of March are approximately:

Cwm Gu:                      148,880

Nant yr Hafod:             94,750

Blaen Dyar:                  33,290

Abernant:                     39,660

Cwm Saerbren:            14,300

A major regional power failure in the Clydach Gorge area halted operation of both Blaen Dyar and Nant yr Hafod this month, affecting generation to some extent and knocking out the video monitoring system.

OFGEM agrees the FITs conversion for Cwm Saerbren and LGV applies to get the scheme registered for FITs payments with their electricity company Ecotricity. At the scheme, LGV’s partners Welcome to our Woods get to grips with monitoring and recording data from the scheme. There is still some snagging work to be carried out but the ground is too wet for some of the remaining jobs to be completed.


April 2018

April is another very wet month in Wales and the five hydro schemes generate decent amounts of electricity. Total generation (approx.) in kWhs at the end of April:

Cwm Gu:                      163,230

Nant yr Hafod:             101,630

Blaen Dyar:                  42,890

Abernant:                     49,220

Cwm Saerbren:            28,470

NRW approves the HoF notch adjustment application at Cwm Gu and issues a new abstraction licence. The changes should result in slightly more water flowing through the system and higher electricity generation. The work includes creation of new fish passes which will need to be carried out after 15th May. Discussions with NRW and TGVH regarding the scope and details of the project are taking place.


May 2018

Warmth and sunshine is balanced by less rain and a significant slowing of the hydro schemes since the end of April, with some schemes stopping completely for the first time for many weeks.

Total generation (approx.) in kWhs at the end of May for our schemes was approximately:

Cwm Gu:                      163,537

Nant yr Hafod:             102,061

Blaen Dyar:                  44,092

Abernant:                     50,644

Cwm Saerbren:            31,422

At Cwm Gu, a site meeting is held with the Fish Officer from NRW and TGVHydro employees to agree and plan for the necessary changes at the intake involving. reduction in the size of the hands-off flow notch and creation of new fish passes below the intake wall. It is not thought that salmon would swim this far upstream but there is a chance that small brown trout may live here. The proposed minor changes now need to be agreed and signed off by NRW and, disappointingly, this could take until the end of the summer. However, the work should be carried out before the heavier Autumn rains come again (no works within the watercourse can take place between 15th October and 15th May, so careful management of these works is critical).


June 2018

A very dry month.

LGV applies to Welsh Government for 100% relief from business rates for Cwm Gu, as a community-owned hydro scheme – all MH-2 schemes will also benefit from this decision.

LGV receives a pre-app response letter from NRW concerning the new fish easement at the Cwm Gu intake, indicating that they are happy with the revised design.

LGV submits an application for a minor variation with this design which is accepted and LGV gives the required 4 weeks’ notice that they plan to carry out the work week commencing 6th August.

The boards of LGV MH-1 and LGV MH-2 seek advice and are in discussions concerning a possible merger between the two Co-operatives. The directors of both boards think a merger will be in the long-term interests of the Societies and is likely to result in considerable savings in terms of ongoing costs and management time. It is likely that a formal vote on a merger proposal will be put to Members of the two Societies in October this year. If passed, the merger will take place at the end of 2018.


August 2018

There is no generation for two months because of the dry weather.


September 2018

Most of the hydro schemes have generated no electricity since mid-May, so income in the third quarter is likely to be very low. All the hydro schemes are modeled with the assumption that they will not generate electricity for some periods each year but this dry summer period is unusually long.

Total generation (approx.) in kWhs at the end of September:

Cwm Gu:                      166,780

Nant yr Hafod:             103,570

Blaen Dyar:                  45,900

Abernant:                     52,010

Cwm Saerbren:            46,470


October 2018

The heaviest rains fall for 30 years locally.

Total generation in kWhs of our five hydro schemes at the end of October was:

Cwm Gu: 168,820

Nant yr Hafod: 105,720

Blaen Dyar: 48,980

Abernant: 56,280

Cwm Saerbren: 53,210

November 2018

Following Special General Meetings for both hydro Co-ops on 15th October and another ‘confirmation SGM’ on 12th November for LGV-MH1, Members of both societies voted unanimously in favour of the motion to merge the two societies. This is predicted to lower the ongoing running costs, lessen the burden on volunteer directors and Members involved in the governance and daily management of the Societies, unify the development activities of the two organisations and spread the risks for all Members between a larger portfolio of hydro schemes. Therefore the Board will seek approval for the merger from the Financial Conduct Authority and we are hopeful that the merger will take place at the end of 2018.

Total generation to date in kWhs at the end of November was:

Cwm Gu: 180,770

Nant yr Hafod: 110,020

Blaen Dyar: 55,770

Abernant: 62,720

Cwm Saerbren: 64,740

December 2018

Our five hydro schemes have benefitted from some fairly typical Welsh Autumn weather with several periods of persistent rain. The schemes have been relatively fault-free and have all generated decent amounts of electricity.

We are still awaiting a final response from the Financial Conduct Authority on the proposed merger of our two hydro Co-operatives but they have indicated they will sanction the merger. Therefore we have been working hard to ensure the merger is able to take place at the end of this month, which is also the financial year end for both Co-ops. The Boards wish to thank Members for their support and backing of the merger proposal and the directors look forward to a slightly reduced workload next year, with just one Society to manage and now that all five hydro schemes are operational.

January 2019

The directors of both our micro hydro Co-operatives are pleased to announce that last month the FCA approved of the merger of the two organisations by transfer of engagements and so this became effective at the end of 2018, which coincided with the financial year end for both Co-ops. Therefore the assets and engagements of LGV-MH1 have been transferred to LGV-MH2 and we will be working to finalise the merger over the next couple of months. We will use the trading name ‘Llangattock Green Valleys Micro-hydro Co-op Ltd.’ for the merged organisation.

A prolonged period of rain in December meant that all five hydro schemes generated some good amounts of electricity. The month of December and the October-December quarter were our highest combined generation periods to date, although this is the first rainy season when all five schemes have been operating. Generation was as follows:

Generation last quarter (kWhs) Generation to date (kWhs):

Cwm Gu:                      32,290                         199,070

Nant yr Hafod:             14,690                         118,250

Blaen Dyar:                  19,220                         65,120

Abernant:                     21,230                         73,240

Cwm Saerbren:             31,860                         78,330

Unfortunately the first half of January has been quite dry but at least we haven’t had a Beast from the East, as last year.






Our micro hydro partners

LGV and LGV Ventures are working in partnership with three other organisations:
• Sharenergy (sharenergy.coop) – a Shrewsbury-based co-operative that specialises in helping community groups set up renewable energy co-operatives. Sharenergy has provided development support for the Co-operative, is managing the administration of the Share Offer and will provide ongoing Member administration once Shares are issued.
• TGV Hydro (tgvhydro.co.uk) – a Brecon-Beacons based micro hydro supplier. The company has pioneered and championed the emerging micro hydro market in Wales and has built and run numerous similar schemes in the Brecon Beacons and other parts of Wales.
• Welcome to Our Woods (Facebook) – a community in the Upper Rhondda Fawr, South Wales Valleys, created to make local woodland more useful & relevant to the community and region. WTOW LTD is a not for profit social venture. The company has been created by the Cwm Saebren steering group to develop micro hydro projects.