Highland community embraces Hamish Hydro

The Applecross peninsula is located on the west coast of Scotland with the Isles of Raasay and Skye immediately to the west and Torridon and Strathcarron on the mainland to the East. Traditional crofting (rearing cattle and sheep on shared land) and fishing, which were once at the heart of the local economy, are in decline. Like many such communities across Scotland it can be a struggle to keep young people in the area, and over 40% of the population is now over the age of 60. In total the peninsula is home to a couple of hundred people spread through a number of crofting townships; only accessible by two single-track roads. However the peninsula is very popular with visitors year-round and is particularly busy in summer, with tourism providing an important source of income for the local community.

Applecross Community Company was formed in 2008 to take over the local filling station which was threatened with permanent closure. Locals involved in the formation of the company were always determined that it would have a wider remit, with the overall aim to promote sustainable development. Within two months of incorporation a representative of the newly formed Community Energy Scotland addressed a public meeting on the potential of renewable energy as an income generator for communities, and it was decided to investigate the potential of hydro and biomass in Applecross.

In 2009 the company commissioned Highland Eco-Design to undertake an assessment of the hydroelectric potential of the burns on the peninsula. Over 3MW of potential capacity was identified across eight sites. However, a follow-up grid connection feasibility study indicated that there would be a multi-million pound cost to reinforce the distribution network in order to be able to export this capacity. Without reinforcement the local network is only capable of exporting 90kW.

The central location of the Allt Breugach stream (located above Shore Street and close to a number of high energy use local businesses), combined with the electricity export constraints, guided the final location of the community hydro scheme. The site is not without difficulties however.

A new access track had to be driven through moorland to the intake location and the turbine house had to be excavated to a depth of 5m and built up on a concrete and hard-core plinth to mitigate the risk of subsidence due to the local geology. The name "Allt Breugach" means "deceptive stream" in Gaelic and reflects the fact that the entire watercourse disappears down a cave system about 200m below the intake location and re-emerges 200m upstream of the turbine house. The caves are accessed occasionally by potholing clubs and so special consideration had to be given to their safety in the event of an emergency shut-down of the turbine.
Before finance was sought and construction begun, planning permission had to be secured from the local planning authority and a Controlled Activities Licence had to be sought from SEPA to abstract and return the water in the watercourse.

Hydropower is generally welcomed by the public in Scotland and many express an opinion that small hydro schemes are more acceptable than wind farms to provide green energy. As a result, as long as the environmental impact is acceptable, there is little opposition to development and gaining planning permission is straightforward.

The Scottish Government issued a statement in 2010 stating that hydro schemes with an installed capacity of less than 100kW would be welcome where they can be shown to have "no adverse impact on the water environment" - something that is very difficult to achieve if the statement is taken literally. From this directive SEPA developed a rigid set of criteria for assessing the acceptability of small hydro schemes; promoting development in small, steep catchments rather than larger, lower gradient watercourses. In parallel to this Scottish Natural Heritage has rolled out a set of guidance directing development away from many small, steep west-coast catchments due to concerns about rare Bryophytes. Even with some of the most restrictive water regulations in Europe there are many viable small hydro sites in Scotland and, luckily, the Applecross Community Hydro Scheme is one of them.

Project finance

The project has been financed through a community share issue. Since Apple Juice (Applecross) Ltd is a community benefit society, the dividend payable from the scheme is capped and any earnings above this are cycled back into the community. The relatively low projected rate of return was offset by tax-incentives for investors, the UK government has now terminated these incentives for community and renewable energy developments.

The share issue went spectacularly well with the full £803,700 being raised in just under six weeks - a reflection of the dedication and effort that the community put into promoting it. However, the process of initiating the share issue took far longer than expected and the project would have failed if the community had not been able to secure bridging finance from other backers in order to begin construction before the share-issue was launched.

Construction began in August 2015 and was complete by the end of December that year. From March 2014 to date, the UK government has cut the Feed-In Tariff (a per-kWh generation tariff payable to small renewable energy installations in the UK) for micro hydro by 64%. The support available for micro hydro installations in the UK is now lower than it was in April 2009. If the Applecross scheme had not been commissioned by 21 December then it would have had its Feed-in Tariff payments cut and the community would have lost approximately £500,000 of revenue over the lifetime of the scheme.

Thanks to the dedication of the construction team and the timely connection installation by the local distribution network operator, the project commissioned with a full 36 hours to spare and is fully operational.

Run-of-river

The system utilises a static head of 172m and diverts up to 73 l/sec of water through a Canyon Pelton turbine. The turbine drives a 90kW asynchronous induction motor based generator with a Sustainable Control Systems control and power-factor correction unit. The system synchronises with the distribution network using a deflector plate and a custom spear valve controller ensures a very slow shut down of the water supply to prevent rapid inundation of the cave system. The system is expected to have a high capacity factor of around 55%; this is because the turbine has been under-sized due to network constraints. The intake, pipework and turbine house have been designed to permit the retrofitting of a second turbine to bring the total power up to 180kW (with permission to abstract more water) if the local electricity networks is upgraded or energy transport technologies such as small-scale hydrogen storage mature in the next 20 years.

It is a run-of river system. There is no storage reservoir although some small lochs above the intake provide a little rainfall attenuation. The intake uses a tilted wedge-wire screen with a 1mm gap between the wires to exclude most debris, gravel and sand from the system. The stream does not carry a high sediment load during spates so there is no settling chamber at the intake, only a stilling chamber to allow air to escape before the flow enters the pipeline.

The pipeline is primarily high density polyethylene pipe with a section of ductile iron towards the turbine house as the pressure reaches 17 Bar. The final section of pipeline passes through the same unstable ground as the turbine house so a restrained joint ductile iron pipe system was used to prevent catastrophic failure in the event of movement of the soil.

The generator is connected to a single-phase 11,000V distribution spur using a split-phase 11kV to 460V, centre-tapped transformer - this gives a nominal voltage of 230V in each of the two phases with a phase rotation of 180 degrees between them. This is a relatively common connection configuration for systems less than 92kW capacity in Scotland as it allows generators to be connected to a single-phase local distribution network and avoids the often prohibitive cost of upgrading the line to three-phase.

Initially the power will be primarily exported to the grid but the intention has always been to use as much locally as possible. As the import capacity of the grid connection is limited to around 90kW, it is not practical to power the local houses directly without selling the power on to the national market and buying it back 500m down the road at three times the price. Currently there are a few businesses that could benefit from augmenting their heating systems to reduce the fossil fuels they burn on-site and there is some potential to roll this out to private households too. In the long-term there are some interesting ideas floating around conversations in the Applecross Inn ranging from a community laundrette and an electric vehicle charging station to a microbrewery.

Supportive community

The local community were incredibly supportive throughout the build, especially once the reasons behind it had been conveyed; the project is an opportunity to earn a long term income for the community which can be used to address some of the many challenges the area faces. The ten pupils of Applecross Primary School visited the scheme during construction and raised £300 to buy a share in it in less than a month. The children have named the turbine Hamish Hydro.

The passion and determination of the communities of the Applecross peninsula to buck the trend leaves no doubt that the next phase in their journey will be as exciting and engaging as their hydro adventure.

Jamie Wallace is the Director of Highland Eco-Design Ltd. He can be contacted at jamie@highlandeco.com