Hydropower. Main advantages and disadvantages of hydropower systems. close to watercourses. watercourses and water levels

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1 Hydropower Energy Production in the Park: Water power in the past has been a widely used source of energy in the Dales, both directly to power machinery using water wheels and indirectly to power turbines to generate electricity. Any part of a watercourse which includes a significant fall in level can be used to produce hydroelectricity. This fall is used to create a head by pressurising part of the water flow by diverting it through a pipe or narrow channel down to a turbine and back to the watercourse. Main advantages and disadvantages of hydropower systems Consistency of electricity production Limited visual impact Very low maintenance requirements Very suitable for community ownership, as promoted by the Government Requires significant engineering works in and close to watercourses Can cause noise problems Can have adverse effects on the ecology of watercourses and water levels High initial expense for larger schemes A scheme may be described as high head, in which a relatively small quantity of water (flow) is piped down a steep gradient (head), or low head, in which a large quantity of water is piped down a gentle or short gradient. A typical high head hydro-scheme involves water being taken from a river or stream and diverting it through an intake at a weir along a pressurised pipe, or penstock, which can be buried or lain on the surface. The water then runs through a turbine which is enclosed in a building called a powerhouse that also houses a generator and control equipment. The water is then allowed to flow back to the river down a tail race. This is the type of scheme which is most likely to be appropriate for those sites in the National Park where water power has not previously been exploited. Very small-scale high head schemes can be well within the scope of land managers with an average level of engineering ability to develop themselves, yet can still produce a worthwhile electricity output. Most of the best potential sites for low head schemes that require artificial watercourses (canals or leats) are old watermills, most of which have become redundant or been converted to other uses. Where the mill building remains but is unused, there is often potential to reuse the artificial watercourse - either to take the water directly through a modern turbine housed within it, or to turn a refurbished or new water wheel, which itself might power a generator. If this is impractical, another alternative is a barrage scheme. A turbine is constructed either as part of the weir, or immediately adjacent to it, involving no new watercourse construction or pipework. Alternatively, where the artificial watercourse remains, but the building it serves is no longer available, the artificial watercourse could be used for some of its length before diverting the water through a suitably situated turbine. Types of turbines There are at least six principal types of conventional turbine in well established use in this country. They are all variable in size that will suit particular site considerations. In addition, there have been a number of recent schemes, including some within and close to the Park, using a different type of turbine based on the Archimedean screw. Park Authority, June 2011 pages 18-24

2 Energy Production in the Park: This type of turbine suits low head schemes, either within the watercourse or very close to it, and either where leat construction would be difficult or where fish protection is particularly important and would be difficult with a conventional system. Small-scale hydropower is the renewable technology most favoured by the National Park Authority. This is because of the widespread availability of suitable water courses and the fact that the landscape impacts tend to be restricted to the immediate vicinity of the plant. However, even with this relatively compatible technology, there is always some degree of associated landscape impact, which has to be considered and weighed against the benefits of energy production and emissions reductions. Sometimes changes to the natural appearance and character of an area, and to its other qualities, can be potentially so severe as to be a determining factor in a planning assessment. Some places, such as close to major waterfalls or where public access is well established, may be just too sensitive to be interfered with at all. PLANNING CONTROLS: micro-hydropower developments There are no current (2011) permitted development rights covering micro-hydro developments except for the change of use of existing agricultural buildings to accommodate generating equipment. Therefore, the construction of weirs, channels, screens, leats and powerhouses, and the excavation of penstock routes, will all need to be the subject of planning applications (although usually one application will suffice for all elements of a proposed system). It is possible that where there are existing elements of a former scheme, or where the turbine and powerhouse are particularly small in scale, the works could be considered to be de-minimis, and not need planning permission, although advise will still need to be sought from the National Park Authority. Any hydro-electricity development could potentially require an Environmental Impact Assessment (EIA) therefore, it is important that the relevant regulations are followed. These offer potential applicants the opportunity to obtain a screening opinion from the National Park Authority to determine whether the application needs to be accompanied by an Environmental Statement. If it does, the regulations also give the applicants the right to obtain a scoping opinion from the National Park Authority to tell them what the Environmental Statement needs to cover. EIA requirements can be difficult to understand and are best discussed with planning officers as early in the planning process as possible. In all cases it is important to contact Planning at the National Park Authority before works to install any structures or equipment relating to micro-hydropower development are undertaken. In addition to the need for planning permission, it is almost certain that detailed consents or licences will also be required from the Environment Agency. The Agency has responsibility for most matters relating to water courses, including abstraction, obstruction, impoundment and effects on wildlife. It is essential that they are contacted before any planning application is submitted. It is possible to use hydropower just to directly power an existing building or buildings. However, in most cases it may be a much more viable proposition to feed the electricity produced into the public network for direct financial return. The National Park Authority will not seek to limit the scale of hydropower developments on the grounds that they would exceed the energy requirements of the developer. The National Park Authority positively encourages maximising the energy producing potential of hydro sites wherever this is possible without radically increasing any adverse impact. This approach is reflected in the terms and conditions of the National Park Authority s Small-Scale Hydropower Feasibility Fund which is available to encourage hydropower development. It was established following the completion, in 2009, of Park Authority, June 2011 pages 18-24

3 Energy Production in the Park: a major research project looking into the practicalities of developing hydropower throughout the Park. Eligibility for funding is mainly limited to landowners, businesses and community groups who can demonstrate that their project is of value to their communities and the businesses within the National Park. It is not usually available to private householders unless wider public benefits would ensue. Anyone contemplating a small-scale hydroelectric scheme is strongly advised, as a first step, to consult the British Hydropower Association. The next step is to seek independent professional advice on whether an initial site assessment suggests that there is sufficient potential to warrant expenditure in conducting a full feasibility study to assess the type of scheme most suitable to the site, and likely viability. Planning and design considerations Generally the challenges of assimilating hydro technology are ones for which solutions are much more readily available than for those encountered with other technologies: i. The appearance of all of the elements of construction within and adjacent to the watercourse, including dams, weirs, fish screens, fences, buildings and access tracks. The design of the scheme should marry operational factors with those of landscape impact. Special attention should be given to ways of assimilating a new development to the character of the setting - for example, in locations where concrete or blockwork would be alien, but where it is essential to include these materials for basic constructional purpose, stone facing needs to be considered and assessed as part of the initial viability exercise. Existing buildings should be used to house machinery wherever possible. New buildings should be designed to fit in with the appearance and character of existing buildings in the locality, and located as close as possible to them. Metal structures should be kept to a minimum and painted in appropriate colours. Signs should be as few and as discreet as possible. Schemes should include landscaping proposals to help assimilation. Breached walls should be rebuilt and not replaced with fences. New access tracks, if needed, should be constructed of materials which will allow partial revegetation. ii. Disturbance to natural features of the landscape, including the river beds and banks, and ponding behind weirs. The choice of site for any construction within the river should be sensitive to its particular characteristics and patterns of public access - for example, places used for recreational activities should be avoided if possible, both to maintain the resource they provide and to minimise the need to make special provisions for public safety, which is likely to add to visual intrusion. iii. Visual and ecological impact of loss of water from stretches of watercourse between inlet and outlet. The Environment Agency controls the quantity of water which can be abstracted from most watercourses, and takes into account the need to maintain certain flow levels to protect both their ecology and their value to other users. The extent to which this may be an issue needs to be given early consideration and the scheme tailored to meet likely constraints at the outset. Park Authority, June 2011 pages 18-24

4 Energy Production in the Park: iv. Visual impact of leat construction. The construction of leats (engineered artificial watercourses) usually of bar concrete construction, can add considerable visual impact. However, with care and appropriate site restoration, new watercourses can enhance the landscape rather than detract from it. Adherence to a formally agreed and detailed method statement is an important requirement. v. Visual impact of pipeline burial. In a high head scheme the route of the pipeline between inlet and powerhouse is an important element capable, if handled insensitively, of greatly increasing the visual profile of the scheme. Pipes do not have to be laid in straight lines or to descend continuously throughout their length - they can be laid to closely follow the variations in ground detail. With careful planning and liaison with National Park Authority staff, routes can usually be found which avoid important landscape features and make best use of existing contours. Attention to detail at this stage, and commitment to a detailed method statement for subsequent restoration, should usually make it possible to produce a result which is visually acceptable. There may be occasional situations where a pipeline would be more easily laid on the surface than buried - for example, through woodland. This is likely to be unacceptable, apart from in exceptional circumstances and when exposure to public view is minimal. vi. Impact on the watercourse as a habitat for fish and other aquatic creatures. The Environment Agency is responsible for ensuring that developments within watercourses do not detract from their habitat value. Although this is an extremely important constraint to be aware of, it is usually one which can be overcome through mitigation measures, including restrictions on the time of year when initial development can take place, and the incorporation of features such as fish ladders and screens. Early consultation with the Environment Agency is always very strongly recommended. The need to protect fish can be an important consideration when deciding upon the type of generator to be used in view of the alleged fish friendliness of Archimedean screws, and the cost and other problems associated with providing screens for conventional generators. vii. Impact on ecological value of other land affected by the development. If the location of the weir, leat, pipeline, powerhouse or tail race affects land known to support plant communities or habitats of special value, this could, in exceptional circumstances be problematic. However, it is much more likely that mitigation measures can be agreed. Early consultation with the National Park Authority s ecologists is therefore strongly recommended. viii. Loss of trees. Trees are important both as landscape features and as habitats for legally protected species, including some species of bats. Their presence and retention can also make assimilation of a development much easier. There must be as little tree loss as possible and if any is proposed it has to be justified as being unavoidable. An assessment of the potential use of the trees by bats will be required this may result in the need for a full bat survey. ix. Noise impact on residential properties and on public amenity generally. This needs to be addressed through the detailed design of the powerhouse and the positioning of the turbine within it. Although the noise that some larger generators cause can be extremely loud when experienced close at hand, it is relatively easily reduced to an acceptably low level by containment within a suitably designed building (especially where there is background noise from the watercourse itself). The National Park Authority will consult the environmental health Park Authority, June 2011 pages 18-24

5 Energy Production in the Park: department of the relevant district council and will act on their advice. Early consultation between a developer and the relevant environmental health department is strongly recommended. x. Archaeological issues. Most hydropower schemes will involve some ground excavation. It is always important that the National Park Authority s archaeologists are consulted as early as possible. Usually, mitigation measures will overcome potential problems, but there may be cases where the site s archaeological value, especially if it is within a scheduled monument, present problems which are insurmountable unless the scheme is re-located. A high head scheme at General and Coniston in the Lake District National Park. A building containing both a powerhouse and a bunkhouse there has been no complaints about noise from people using the bunkhouse. A small high head scheme at a farm near Malham in the Yorkshire Dales National Park. The small stone shed containing the generator and other equipment for the hydro scheme. Park. The underground route of the penstock can been seen in front of the trees, travelling down the hill. Bainbridge Hydro, a low Park. The Archimedean Screw turbine. Bainbridge Hydro, a low Park. The leat just after construction was finished Park. The water course above the weir. Park. The weir with a short length of exposed penstock. Park Authority, June 2011 pages 18-24