Survey of Potential Hydropower Sites in the Wear and Tyne Catchments

Transcription

1 Small hydro from idea to operation Survey of Potential Hydropower Sites in the Wear and Tyne Catchments Nick Forrest and Gordon Black August 2010 babyhydro Ltd, Gateside Farm, Kilncadzow, Carluke, ML8 4QN Registered in Scotland no: SC VAT registration no:

2 Executive Summary In March 2010 babyhydro was contracted by RENEW to quantify the remaining hydro potential in the Wear and Tyne rainfall catchments. Hydrobot, remote hydro modelling software owned and developed by babyhydro, was applied to the Wear and Tyne catchments. Sites with hydro potential were analysed using multiple iterations to optimise design, taking all costs and revenues into account. These were analysed using an 8% per annum discount on future cashflows, and financially viable schemes were defined as those yielding a positive Net Present Value within 20 years. In total, 167 financially viable schemes were identified, representing an installed capacity of 11.76MW. These were then screened by scrutinising the proposed layout on a map, and the schemes found to be technically feasible numbered 89, with a total installed capacity of 5.47MW. A sample of 12 schemes was selected for further examination, and site visits were carried out. Two more schemes were added during the site visits. For each site, measurements were taken and observations made about favourable features and barriers. This allowed a revised financial analysis of each site where a hydro scheme still appeared viable. Of the 14 site evaluations, 9 suggest the sites warrant further investigation. The survey has demonstrated that the Wear and Tyne catchments, while not being hydro hotspots, have a considerable number of attractive sites for development by landowners or communities. 1

3 Acknowledgements We would like to express our thanks to the following organisations, for their cooperation and contributions to this report: Durham City Council Environment Agency Forestry Commission Natural England NEDL Northumberland National Park RENEW 2

4 Table of Contents Executive Summary... 1 Acknowledgements... 2 Table of Contents Introduction Background babyhydro, Hydrobot and SISTech Introduction to Hydropower Phase 1: Hydrobot Modelling Methodology Data sources How Hydrobot works Technical screening Shortlisting Results Longlist Shortlist Phase 2: Site Evaluation Methodology Site 2: Featherstone Castle Site 4: Chirdon Burn Site 7: Plashetts Burn Site 11A: Blaeberry Burn, Whitfield Estate Site 11B: Blueback Weir, Whitfield Estate Site 13: Glendue Burn, Knarlsdale Estate Site 20: Durham North Site 21: Durham South Site 22: Sunderland Bridge Site 25: Shittlehope Bridge Site 26: Eastgate Bridge Site 28: Craigside Caravan Park Site 29: Stanhope Burn Caravan Park Site 30: Swinhope Burn Summary of Site Evaluations Analysis and Discussion General Features Quality of Inputs and Results Elevation data and the Detailed River Network The Environment Agency s Barriers dataset Technical screening Site Evaluations Conclusions and Recommendations Appendix 1: Longlist of Sites Identified by Hydrobot

5 1 Introduction This report describes a survey of the Wear and Tyne catchments in 2010 to identify the remaining sites with potential for a financially viable small hydroelectric scheme. The report covers the rationale and methodology for the study, as well as the results at two levels: a high-level, region-wide survey, and more detailed Site Evaluations on an agreed shortlist. Following analysis of these results, the report concludes with various options for disseminating the information about viable sites, and assisting with their development where appropriate. 1.1 Background The survey was commissioned in March 2010 by RENEW, based in the Centre For Process Innovation in Wilton, Redcar. RENEW was established in 2008 with Regional Development Agency funding, to maximise the economic opportunities being created by the emerging environmental industries specifically renewable energy and environmental sectors. RENEW s remit is to identify business opportunities, initiate projects and support both the development and growth of regional businesses and inward investors. RENEW required that the survey should review the realistic and practical opportunities for hydro electric power within the Tyne and Wear catchments, making recommendations on which sites showed most promise. For a shortlist of five projects within each valley, Site Evaluations would be carried out, producing a detailed physical and financial analysis also known as a pre-feasibility study. These will pave the way for the investigation of other viable sites. It is intended that this report be distributed to landowners, developers and communities in the study area. The goal is to raise awareness of the region s hydroelectric potential, and to facilitate the development of projects through to installation. 1.2 babyhydro, Hydrobot and SISTech The contract to undertake this survey was awarded to babyhydro Ltd, established in 2008 to take micro-hydro projects from initial concept through to generation of renewable electricity. babyhydro supports landowners and developers through every stage of creating electricity from running water. babyhydro owns and has exclusive use of Hydrobot remote hydro surveying software. Hydrobot is a geographical and hydrological computer model developed in 2006 to remotely predict financially viable hydroelectric schemes across large areas. The model has been used twice to survey the whole of Scotland for the Scottish Government. SISTech (the Scottish Institute for Sustainable Technology) is a research consultancy experienced in sustainable development, including carbon and environmental assessment and working with extensive GIS datasets. In this survey, SISTech provided support in obtaining field data, contact with landowners and additional GIS analysis. 1.3 Introduction to Hydropower As this report refers in detail to why one particular hydro scheme might be better than another, a brief description of hydropower is necessary. A hydro scheme 4

6 comprises a system for extracting energy from water as it moves, normally dropping from one elevation to another. The uppermost part of a hydro scheme is therefore the intake, and a weir is typically used to ensure the water remains deep enough to cover the intake. In some cases, such as above a small waterfall, a natural pool will suffice but it is uncommon to find a site that does not require an impoundment structure. Water that is restricted in a sloping pipe (or penstock) will build up a head of pressure at the bottom, which can be used to drive a turbine wheel (or runner). In flatter areas where there is less pressure build-up or no penstock at all, much larger flows are required to compensate for the reduced head, and so larger turbines are used. In addition to flow and head, a destination or load for the power is needed. In this study, the load is the national grid. As connection and the cost of lines are significant parts of most schemes, distance from the grid may be the deciding factor of whether a scheme is viable. Furthermore, the grid operator must take into account the capacity of the local grid before allowing a scheme to connect. Not all water within a river can be used for generation a proportion called the reserve flow must be left within the river for ecological reasons. Unless there is a storage dam, the usable flow will fluctuate throughout the year, and the system s efficiency will vary as a result. Different turbines have different responses to variations in flow, and this must be taken into account when predicting the available energy. Finally, for any hydro scheme there are usually a number of layouts and sizes that could be used. Finding the best solution is a matter of experience and costing out the various options. As Hydrobot carries out multiple iterations to evaluate a large number of layouts for each site, it mimics the approach of an engineer in the flesh, so is ideally suited to this survey. The methodologies and results are grouped into two sections to reflect the two phases of the survey: the desk-based survey of both valleys using Hydrobot, followed by physical site visits. Analysis and Discussion is presented as one section, followed by Conclusions and Recommendations. 5

7 2 Phase 1: Hydrobot Modelling This section of the report explains how the desk-based survey of the whole of the Wear and Tyne catchments was undertaken, producing the list of remaining financially viable hydro sites. Data sources are described, as well as the basic approach of the Hydrobot software. Subsequent treatment of the results is also explained, followed by the results themselves: a longlist of all financially and technically viable sites; and a shortlist of sites for more detailed examination. 2.1 Methodology Data sources Ordnance Survey provided elevation and contour datasets, as well as building and settlement locations that were used to identify potential grid connections at low voltage and 11kV. In addition, roads, railways and existing lakes were identified using Ordnance Survey data. The 20kV and 30kV distribution networks were mapped using information from NEDL. Flow duration curves for gauging stations across the region from the National River Flow Archive were obtained from the Centre for Ecology and Hydrology. The Environment Agency provided information on gauged weirs, but also data on barriers identified in their recent report Opportunity and Environmental Sensitivity Mapping for Hydropower in England and Wales 1 Electronic mapping of environmentally sensitive areas were obtained from Natural England, with advice on the relative sensitivity and necessary mitigations coming from both Natural England and the Environment Agency. Existing hydro schemes were plotted using information from the British Hydropower Association and prior knowledge. Land ownership was established from a variety of sources including the Forestry Commission, Durham County Council, the Land Registry and local knowledge. Other information such as costs, energy production and impacts of environmental sensitivities or other barriers, were previously incorporated into Hydrobot and are described in the Scottish Hydropower Resource Study How Hydrobot works In analysing a river basin, Hydrobot operates as follows: 1. River courses and the flow duration curve at each point on every watercourse are modelled across the river basin. 2. Watercourses affected by existing hydro schemes or other licensed abstractions are removed from subsequent calculations. 3. Likely river reaches for high-head turbines are selected, and turbines are initially positioned at the foot of such reaches. Nearest gridconnections are located at as many voltage levels as exist within that river basin. 1 Environment Agency, Mapping Hydropower Opportunities and Sensitivities in England and Wales, February Nick Forrest Associates Ltd et al, Scottish Hydropower Resource Study, August

8 4. A range of penstock lengths from 20m to 1500m are simulated. For each length, turbine and other elements are sized appropriately using industry standards. 5. Each configuration is evaluated using cost formulae for each element, and the lifetime energy and revenue are calculated based on the flow duration curve. This leads to selection of the best solution. 6. Steps 4 and 5 are repeated with each turbine 20m upstream, then 20m again, until no better solution is found for that site. 7. Nearby schemes are tested to see whether they would be better joined into one large scheme or kept as separate ones. 8. Weirs registered under the Controlled Activities Regulations are tested for low-head hydro potential, similar to high-head but without the penstock. Input parameters can be varied to suit current economic conditions and policy changes. Such parameters were not the main focus of this study so were maintained at the following levels: Recovery period: schemes were deemed viable if they broke even within 20 years, including interest, taxes, etc. A typical hydro scheme should keep generating for well over 30 years, with a turbine overhaul at some stage after 20 years. Business rates: 9/kW per year. Railway crossing ransom charge: 33% of NPV payable to rail company for penstocks crossing under a railway (based on case history in Scotland). Environmental constraints: environmental designations were split into three levels of severity, relating to the level of protection they entail. Special Areas of Conservation and Special Protection Areas will generally require thorough investigation beforehand, and the cost of the additional environmental surveys can be roughly estimated from the scheme size. SSSIs, Nature Reserves and National Parks will entail some extra surveying, and therefore costs, but not as much. Schemes on salmon migratory routes will not only require an additional survey but also mitigation measures, in particular a fish ladder whose cost can be related to the total height of the ladder and the flow. Grid constraints: as this report is taking the long-term view of hydro growth, it may be assumed that planned upgrades to the transmission and distribution grid will relieve the principal current bottlenecks in grid connection approvals. Therefore the only grid constraints taken into account are typical ratings of the lines and existing transformers to which schemes are connecting. Costs for upgrades to the network were found to be comparable to those in Scotland, and are included in the model. Table 1 below outlines the Feed-in Tariff levels implemented in the Hydrobot model. These have been transcribed directly from the UK government s response to its Summer 2009 consultation 3. The tariff comprises an amount paid per unit generated whether used onsite or not (the Feed-In Tariff element) and a 3 DECC (2010). Feed-In Tariffs: Government s Response to the Summer 2009 Consultation. 7

9 guaranteed minimum price for each unit exported to the grid (the export revenue). Table 1. Feed-In Tariff levels announced by UK Government. Installed Capacity Feed-in Tariff Export Revenue (p/kwh) (p/kwh) 15 kw kw 100 kw kw 2 MW MW 5 MW Total Revenue assuming 100% export (p/kwh) Finally the threshold for financial viability was set as positive Net Present Value after 20 years, discounting cashflows at 8% per annum. This is equivalent to an 8% Internal Rate of Return over 20 years. This discount rate would previously have been too high for many domestic-scale schemes, but with the Feed-In Tariffs, good domestic schemes will still be financially viable Technical screening Hydrobot optimises each scheme according to the topographic, flow and other data available as described above, taking into account various barriers and problems. However, there are some factors that can inhibit a hydro scheme but may not show up in the input data. These include but are not restricted to: Gorges which do not have any flatter points along their banks, thus making it too difficult to run a pipe along the contour; Roads, or groups of roads, which would be too expensive to cross compared to the potential value of the resulting hydro scheme; Houses, schools or other non-industrial buildings blocking the pipe route; Disagreement between the Environment Agency s Detailed River Network and Ordnance Survey s elevation data, giving the impression of sudden drops in the river where none exist; Errors in the Environment Agency s barriers dataset, suggesting there is a weir or waterfall where none exists. Some of these can be detected fairly easily. Others require experience of hydro development to assess the technical feasibility of a site by careful reference to maps on a variety of scales. For this reason, a technical screening was conducted on all financially viable projects identified. In some cases a small adjustment to Hydrobot s suggested layout is required, and such notes were included in the results. Rejected solutions were grouped into three categories: gorges, false positives, and other barriers, should anyone wish in the future to establish why their site of interest might have been rejected. It should be noted that a range of solutions normally exists for any engineering problem, so there is an element of subjectivity in the technical screening. A different hydro engineer could arrive at a different conclusion for a site based, for example, on local knowledge or new technology Shortlisting It was agreed that the Site Evaluations should be carried out on sites with a reasonable chance of successful development, so that they would be worthwhile 8

10 examples to future developers. To this end, the longlist of solutions remaining after technical screening were ranked by the cost of energy, calculated as: Cost of energy ( /MWh) = Capital cost ( ) / Annual energy (MWh) Twelve sites from the two river basins were selected with a low cost of energy, and with a mixture of high-head (hillsides) and low-head sites (weirs or other barriers). This was to allow for up to two sites being deemed unsuitable upon arrival, leaving ten Site Evaluations. For these twelve sites, land ownership was established by various methods: The Forestry Commission provided data showing areas they manage The Land Registry Northumberland National Park Durham County Council Contacting local hotels, pubs, campsites etc. Where possible, landowners were contacted and permission was obtained to access their land in order to carry out the Site Evaluations. 2.2 Results This section describes the results from Hydrobot s region-wide survey of the Wear and Tyne Catchments. Following the National River Flow Archive s naming convention, the Tyne river basin is referred to as c23, and the Wear is c24. Applying the model to both catchments 1,502 sites were examined. Of these, 167 showed a positive Net Present Value within 20 years, discounting future cashflows at 8% per annum, and so were deemed financially viable. They represent a total installed power of 11.76MW. The split between catchments can be seen in Table 2. Table 2. Results of Hydrobot s region-wide survey for Tyne (c23) and Wear catchments (c24). Results show total number of sites examined; viable projects with a positive NPV after 20 years; projects longlisted after technical screening; and a breakdown of the longlist by installed power of scheme, in the size categories devised for the FITs tariff levels. River basin Number of sites examined Financially viable projects Financially viable power (kw) Technically viable projects Technically viable power (kw) Count 0kW to 15kW Count 15kW to 100kW Count 100kW to 2MW c23 1, , , c , , Total 1, , , Longlist Technical screening removed almost half of the projects, leaving 65 in c23 and 24 in c24 a total of 89 projects in the longlist. Their total installed power is then 9

11 5.47MW. The majority of schemes for both river basins are in the range 15kW to 100kW. The full list of financially and technically viable projects can be found in Appendix Shortlist The shortlisted sites are listed in Table 3, with some headline figures for each. The third digit of the turbine number indicates which projects are high-head (a pipe or penstock running down a hillside to a turbine) and which are low-head (a weir, waterfall or other short drop that presents a barrier to fish passage): 0 indicates high-head while 1 indicates low-head. Table 3. Shortlisted sites selected for Site Evaluations. There are five schemes in the Tyne catchment (c23) and seven in the Wear catchment (c24). Only one scheme in c23 was low-head (i.e. a weir or waterfall), and four of the seven in c24 were low-head. The table lists the installed capacity or design power; flow and head; capital cost and annual net revenue (including FITs, net of operating costs); the discounted Net Present Value; and the simple payback (not including inflation or loan interest). River basin Installed power (kw) Design flow (m3/s) Net revenue ( /Yr) NPV discounted 8% ( ) Simple payback (years) Turbine number Head (m) Capital cost ( ) c ,767 74, ,822 6 c ,317 97,800 90,902 9 c ,459 69, ,753 5 c ,011 53, ,104 6 c ,878 63, ,610 6 c ,164 62,829 84,700 8 c ,709 76, ,257 7 c ,271 98, ,228 8 c ,933 57,986 95,379 8 c ,538, , ,794 6 c ,353 62,022 93,583 8 c , , ,

12 3 Phase 2: Site Evaluation This section contains a description of the site visits carried out for each of the shortlisted sites, with a summary of the key findings for each. These Site Evaluations include an assessment of the potential for practical and commercially viable development. 3.1 Methodology The sites from which the shortlist was drawn had been renumbered using shorter numbers for convenience, as shown in Table 4. Two extra sites were added during the course of the Site Evaluations: 11B (which had not been identified by Hydrobot ) and 21. Table 4. Numbering of sites visited during the Site Evaluations. Hydrobot s initial prediction of the potential power is also given. Site Number Turbine Number Initial Power (kw) A B The locations of the various sites are shown in Figure 1. 11

13 A & B Figure 1. Map of site locations visited for Site Evaluations. Crown copyright License number The process by which a potential scheme was evaluated through a site visit had a core structure which was modified in response to circumstances on the day, physical access routes and the topography of the area. The core structure was as follows: 1. Examine Hydrobot information and from the map assess the location of the key features (turbine house, abstraction point and most probable route of penstock) and create plan for the site visit incorporating access, restrictions and potential risks. 2. Meet on site with the landowner or their representative for general orientation and recommendations on access routes and restrictions, for example neighbours. 3. Examine the Hydrobot identified location of the turbine house and explore upstream and downstream on both banks to generate a set of options considering the aspects of security from flooding, tailrace, visual impact and engineering access. 4. Determine the most likely incoming route for the penstock. 5. Walk the route of the most probable penstock line establishing nature of the terrain (steepness and rock versus soil) and engineering access. 12

14 6. Examine the Hydrobot identified location of the abstraction point plus other options upstream and downstream, along with the location implied by the optimum route of penstock. The key features for assessment are; secure location for the weir, impact of water back-up and potential risk of bank flooding, physical structure of the abstraction point given the nature of the river bed, banks, local terrain and engineering access. 7. Determine the options available for initial run of the penstock to enable the route to be separated from the river course as early as possible to maximise route flexibility. 8. Revisit the location(s) of the turbine house and determine the options available for interconnection with the Electrical Distribution Network. Throughout the process environmental aspects and implications were noted, and photographs taken to record all of the key features. For each site visited, general information about the site is provided below, along with more technical observations and headline figures. 13

15 3.2 Site 2: Featherstone Castle Observations: The site comprises a weir with an existing fish pool. This scheme would have to be developed in close collaboration with the EA due to the nature of the works that would be required on either bank, or on the weir itself, coupled with the fact that there is a Flow Gauging Station incorporated. It is recommended that the ownership be identified (most likely The Environment Agency, or possibly Featherstone Castle) and an exploratory conversation held. Location: Singe-phase power line Figure 2. Map of Site 2. Red dot marks position of turbine. Single-phase overhead power line shown at farm and running across the park (orange). Crown copyright License number

16 Scheme Layout: Steep slope OPTION B Fish-pass Pool OPTION A OPTION C Dry Flow Gauging Station Flow Bank flat & 2.5m above river level Bank flat & 3m above river level Figure 3. Illustration of scheme layout for Site 2. Three options for positioning the turbine are illustrated, and explained below. Scheme Options: There are three physical layout options all of which have significant negative aspects. Option A: This would require a channel to be cut around the Flow Gauging Station to a depth of approximately 4m, a concrete pipe to be inserted, and then the ground backfilled. A critical issue at construction stage would be maintaining the structural integrity of the buttress and the FGS. The turbine employed could be either an Archimedes screw or a Kaplan. The key issue would be gaining sufficient elevation to keep the generator above the flood level. Equipment access is excellent. This is the preferred option. Option B: Similar to the above but on the left bank. Access for construction machinery would be very difficult no access track, soft ground, and a steep slope to fields at the top. Option C: A Kaplan turbine could be placed on the weir itself and the solid bedrock just below it. The turbine would be placed vertically to enable the generator and control instrumentation to be raised above the flood level. This 15

17 scheme option is likely to be considered by the EA to cause a restriction on river flow. Again, engineering access would be very difficult. Figure 4. Featherstone Castle weir looking upstream. Fish pass pool in foreground. Flow and Power Analysis: The design flow (Q des ) modelled by Hydrobot was 10.25m 3 /s. Given the structure of the fishpass the available flow is likely to be less than this. There is a 25mm difference in the heights of the two sections of weir, with the dry being 28m wide and the wet being 14m wide. This results in a substantial body of water flowing down the fishpass. Visual inspection suggests that this is significantly in excess of Q95, the normal reserve flow. The gross head was observed as 1.3m. Assuming a reserve flow of Q80 (2m 3 /s), the output power would be as reported below in Key Numbers. Electrical Distribution Network Interconnection: There is a single phase supply to the farmhouse shown on the map, and a single phase supply running across the park, again, shown on the map. Environmental Observations: Based on initial discussions, the EA is not opposed in principle to works on weirs, providing the developer demonstrates the continuity of their measurements at the FGS. The scheme should not affect flow measurements significantly, and EA has expressed support for low-head schemes. 16

18 Figure 5. Featherstone Castle weir looking downstream. Gauging station visible to far right. Conclusion: Site valid. Key Numbers: Site Name Head (m) Installed power (kw) Initial cost Annual cost Annual gross revenue Simple payback (years) 20 year simple profit 2 - Featherstone Castle ,054 4,597 75, ,017,308 17

19 3.3 Site 4: Chirdon Burn Observations: The site is on Forestry Commission land. Hydrobot had identified the optimum scheme as having a head of 28m but inspection revealed the practical head to be 13m based on Jerry s Linn waterfall. The land upstream of this was almost level right up to Hydrobot s preferred abstraction point. Scheme Layout: Figure 6. Map of Site 4. Red line indicates penstock route; red dot indicates turbine site. Crown copyright License number

20 Abstraction Point: The selected abstraction point is immediately above Jerry s Linn on top of a solid rock base. There is a risk however that a one metre high weir could cause significant backing up of the water causing it to overspill onto the surrounding flat land. Figure 7. Upstream view of Jerry s Linn showing the flat land above it, and the nature of the difficult terrain/rockface on the left bank where the penstock would run. Figure 8. Site of the abstraction point immediately above the waterfall - river flowing from left to right. 19

21 Route of Penstock: The penstock would have to be routed around the rockface on the southern bank. This is not quite vertical and with a drop of some 5m, but it is fragmented and is likely to be an expensive engineering challenge. Turbine & Generator: The turbine house would be located just outside of the field close to the burn. A second option would be to locate it a little further downstream at the footbridge and thus gain a few extra metres of head at the expense of 300m or so of additional penstock run. Electrical Distribution Network Interconnection: The nearest point of interconnection to overhead single phase is some 2km distant at Bower near the end of the public roadway. The majority of the transmission line could be routed over open fields but some would have to go through the forest. Engineering Access: Access to all points is good trees in the surrounding area have recently been harvested. Environmental Observations: Jerry s Linn presents an impassable barrier to migratory fish. Conclusion: Engineering challenges too great for this head and size of scheme. Not valid. 20

22 3.4 Site 7: Plashetts Burn Observations: The site is on Forestry Commission land, and would be a high-head scheme running from near Wainhope to a point approximately 1km downstream. Hydrobot s identified intake and turbine locations were found to be optimal. Scheme Layout: 3-phase overhead line Figure 9. Map of Site 7. Crown copyright License number Abstraction Point: The abstraction point is confirmed as being just downstream from the field. The ground is fairly flat and peaty, therefore soft, making access possibly difficult for the last few metres, though there are several possibilities for the location of the weir. The forest track provides excellent access on the approach. Route of Penstock: It appears to be possible to transport the water by means of low pressure pipe above the 260m contour all the way around the escarpment to a point close to the forest rack just below the digit 2 of the turbine number. Here it would enter a forebay before being run down the steep bank to the turbine house. Some of the route of the low pressure pipe would be through a young plantation, therefore passable. 21

23 Turbine & Generator: The turbine house would be located on a flat but raise area of ground adjacent to the burn. Figure 10. Photo taken from the site of the turbine house looking up the probable access and penstock routes. Electrical Distribution Network Interconnection: There is a 3-Phase overhead power line some 700m from the turbine house site. Engineering Access: Access to the turbine house would require 100m of new track to be created running from the forest track in a north-westerly direction down the steep bank at an angle difficult, but achievable. Potential Enhancement: A modification to the scheme would be to locate the turbine house adjacent to the track bridge downstream. This would result in an additional 20m of head but would require the penstock to be extended. The revised location would make for easier access for construction of the turbine house, and the routing of the penstock would be down a gentler gradient. The turbine house would also be closer to the power lines. Conclusion: Site valid. 22

24 Key Numbers: Site Name Head (m) Installed power (kw) Initial cost Annual cost Annual gross revenue Simple payback (years) 20 year simple profit 7 - Plashetts Burn ,151 4,941 72, , Plashetts Burn - extended ,919 4,332 90, ,354,784 23

25 3.5 Site 11A: Blaeberry Burn, Whitfield Estate Observations: The Blaeburry Burn scheme would be high-head, but is in a slight gorge. This scheme is very unlikely to be viable due to almost every aspect presenting a difficulty. Scheme Layout: Figure 11. Map of Site 11A. Crown copyright License number Abstraction Point: The forest shown on the map is in fact extremely dense and impassable. Additionally, from inspection on the hillside, the river is in a slight gorge. A potential abstraction point was identified slightly downstream of that indicated on the map. This would result in the head being reduced by approximately 20m. Route of Penstock: The penstock would be routed on the northern bank (photo below) but would be required to cross two tributaries. 24

26 Figure 12. Route of penstock for Site 11A. Turbine & Generator: A flat and flood secure zone was identified for the turbine house. A new access track would be required coming in from the hill fields to the west. Figure 13. Turbine house location for Site 11A. Electrical Distribution Network Interconnection: Connection to single phase O/H supply could be made at either Park Head Farm or Mainsrigg both at about 500m. 25

27 Conclusion: The site is valid with a modified layout. Key Numbers: Site Name Head (m) Installed power (kw) Initial cost Annual cost Annual gross revenue Simple payback (years) 20 year simple profit 11A - Blaeberry Burn ,135 3,558 26, ,744 26

28 3.6 Site 11B: Blueback Weir, Whitfield Estate Observations: This is a practical scheme based on a derelict weir located by the EA, but whose height was underestimated at 1m, where it is actually 3.5m. Location: The weir is shown in the exact centre of the map. Figure 14. Map of Site 11B. Crown copyright License number

29 Scheme Layout: Direction of flow Proposed inlet channel Existing sluice Wall 10m Old workings and site of village hydro Turbine House Archimedes screw Original water power channel R o a d Figure 15. Layout at Site 11B. 28

30 Photos: Figure 16. Blueback weir looking across to old wheelhouse. Figure 17. Existing Village Hall micro-hydro scheme intake. Abstraction Point: The abstraction would be made on the left bank where the land is only 1.5m above the surface of the water. Turbine & Generator: An Archimedes screw or Kaplan turbine could be employed. 29

31 Figure 18. Site of Archimedes screw looking down to the river below the weir Electrical Distribution Network Interconnection: There is a single phase O/H powerline some 200m to the west across an open field. Engineering Access: There is an access track leading from the public road right down to the water some 100m upstream. This leads to a ford which has been used for riverbed managements (shifting stones in evidence). Environmental Observations: The weir appears sound and almost watertight. Some repairs will be required. Conclusion: Scheme valid. Key Numbers: Site Name Head (m) Installed power (kw) Initial cost Annual cost Annual gross revenue Simple payback (years) 20 year simple profit 11B - Blueback Weir ,195 2,752 38, ,140 30

32 3.7 Site 13: Glendue Burn, Knarlsdale Estate Observations: This high-head scheme is required to cross under the A689 a layout that is unlikely to be viable due to the limited space within the bridge infrastructure. The landowner was not identified, and therefore permission to survey the site not achieved. Furthermore, there is evidence of historic abstraction to the north, which might affect the viability of a hydro scheme here. Scheme Layout: Figure 19. Map of Site 13. Crown copyright License number Abstraction Point: The abstraction point was not identified, but from the hillside the burn appeared to be in a very narrow gorge which was partially obscured by trees. 31

33 Figure 20. Looking up the glen towards the proposed location of the abstraction point. Figure 21. River flowing towards the bridge. Route of Penstock: The penstock would be required to cross under the road. The construction of a dedicated pipe route would be expensive since the works would have to be carried out by Northumberland Council Transport Department. The alternative 32

34 would be to secure the penstock to the side wall of the existing river channel under the road. This is likely to be considered by Northumberland Council Transport Department as unacceptable as it would cause a reduction in the space available for floodwater which is already observably restricted. The dimensions of the culvert are 1.25m by 1.25m. This is likely to be exacerbated by the recent planting of new deciduous trees in the glen. Figure 22. Looking upstream from the culvert clear evidence of moving rocks. Turbine & Generator: The site identified by Hydrobot for the turbine house is in a densely forested area. Close inspection was not possible. Conclusion: Engineering challenges too great for this size of scheme. Not valid. 33

35 3.8 Site 20: Durham North Observations: This scheme is misplaced on the jpeg. The weir is shown on the map adjacent to the Castle, but in fact extends further downstream. The weir stretches some 57m across the river and arcs some 196 along the course of the river. With a gross head of 2.5m and a Qdes of 14.7 the power potential is 257kW. An excellent site exists for the location of the turbine with no intervention required on the weir. Scheme Location: Extent of the weir Turbine Figure 23. Map of Site 20. Crown copyright License number Description of the Weir: The main weir consists of an arc spanning some 57m across the river and running 237m downstream to reach a system of sluice gates on the east bank. There is a fish pass on the west bank of the main weir. Below the main weir there are three lower weirs, each with a fish pass. The available gross head from the main weir to the level below the sluice gate (but still above the lower weir) was visually estimated at 2.5m. The lowest weir could provide an additional head of 0.5m. 34

36 Figure 24. Durham weir looking downstream from right to left. Top fish ladder visible just beyond ducks. Turbine location in upper left of photo where white water visible beyond bridge. Turbine Location: There is an ideal site for the turbine and generator etc at the existing sluice gate workings. The workings show evidence of recent partial refurbishment making them sound and presenting a 1m wide by 1m deep sluice gate. It is proposed that a turbine (Archimedes screw or Kaplan) be installed using the sluice gate as an inlet and discharging on to the gravel bed below. This would avoid any engineering works having to be carried out on the weir itself, plus avoiding any impact on the existing fish-passes other than flow reduction, which would be managed. This would result in a small scheme with reduced power output and costs. For the full potential to be achieved significant restructuring of the sluice workings would be required. 35

37 East bank Wall River Flow Pebble shore Secondary sluice gate Public Road Primary sluice gate Turbine Walkway Existing Trash Screen Lower water level Weir Upper Water level Figure 25. Illustration of sluice gate area and proposed hydropower infrastructure not to scale. 36

38 Ice rink Lower weir Pebble shore Target sluice gate Figure 26. Turbine site between lowest extremity of upper weir (on right of photo), and lower weir downstream. Figure 27. Target sluice gate. 37

39 Electrical Distribution Network Interconnection: It is anticipated that there will be a 3-phase supply to the redundant icerink/bowling centre 100m downstream on the east bank. Engineering Access: Access is excellent. Subject to permissions the removal of a wooden fence and a tree is all that would be required. Heavy equipment could be craned over the wall separating the site from the public road. Environmental Observations: The key environmental issue is the maintenance of sufficient water flow through the fish-passes There is the option to extend the scheme further down the east bank and discharge below the bottom weir. This would provide an additional 0.5m head and take the output power to 308kW, but would require significant engineering and the development of a supply channel along the bank. Key Numbers: Site Name Head (m) Installed power (kw) Initial cost Annual cost Annual gross revenue Simple payback (years) 20 year simple profit 20 - Durham ,299 9, , ,548,585 38

40 3.9 Site 21: Durham South Observations: This weir is situated slightly south of Site 20, though the EA dataset indicated that it was slightly further south. The weir is shown on the map adjacent to the Cathedral. However, the original mill buildings are still in place on either bank with sluices and channels still carrying water. There might have been an opportunity for the development of two small schemes to be placed within the existing historical infrastructure. While the EA dataset suggested the head was considerably more, the gross head is only around 0.4m. The theoretical power potential is 33kW, but in practice this head is not sufficient for a practical hydro scheme. Scheme Location Weir Figure 28. Map of Site 21. Crown copyright License number

41 Photos: Figure 29: Durham weir from the west bank looking towards the mill museum and the Cathedral above. Figure 30. View from downstream showing tailrace. Conclusion: 40

42 While there is infrastructure from historical use of the weir for driving mill equipment, the head is too low to be practical for electricity generation. Not viable. 41

43 3.10 Site 22: Sunderland Bridge Observations: This site was indicated by the EA dataset and the height of the weir was estimated by Hydrobot to be over 3m. However, this is an error due to the presence of two wide bridges. There is a weir of some 300mm under the older bridge and integral to its foundations. There is a line of large stones across the river at the site of the original bridge (evidenced by the pier on the north bank) but these are not dressed and therefore are not part of the original bridge nor an earlier weir. The estimated head across these stones is 750mm. There was no visual evidence of other weirs upstream or downstream. Location: Figure 31. Map of Site 22. Crown copyright License number

44 Photographs: Figure 32. Bridge and weir looking upstream. Figure 33. Zone of stones producing 750mm level difference. It would be a major engineering task to create a new weir and given the presence of the original bridge (archaeological interest), the old bridge in the photograph and the risk of flooding, it is inconceivable that planning permission would be granted for a scheme that would be producing only 50kW. Conclusion: Insufficient head and archaeological obstacles. Not viable. 43

45 3.11 Site 25: Shittlehope Bridge Observations: The site was identified by the Environment Agency as being on the River Wear close to the road bridge downstream from Stanhope. However, during inspection the reported 3.2 metre weir was discovered to be not on the main river course but on a tributary on the north bank a few metres downstream from the bridge. Location: Figure 34: Map of Site 25 showing the predicted location of the weir of interest as a red dot. The actual location was on the tributary to the north. Crown copyright License number

46 Photographs: Figure 35: Photo of the bridge looking upstream Figure 36: Weir discovered on the minor tributary Conclusion: Actual location of weir has very small flow. Not viable. 45

47 3.12 Site 26: Eastgate Bridge Observations: The potential scheme is on the River Wear downstream from Eastgate and adjacent to the road bridge. The weir would require extensive reconstruction. Location: Figure 37: Map showing the location of the scheme marked by the red dot on the main river. Crown copyright License number Scheme Layout: 46

48 Archimedes screw Bridge stonework Intake Road Bridge Fish-pass River flow Figure 38: Layout of the weir and the site of the potential turbine. Photos: Figure 39: Photo taken looking upstream showing the fishpass in the centre of the weir. 47

49 Figure 40. Erosion on weir face. Figure 41: Proposed turbine location is in centre of photograph Electrical Distribution Network Interconnection: There is a 3-phase overhead powerline some 50m to the south. Conclusion: While there is a practical location for a turbine the scheme is unlikely to be viable due to the low head (1.3m) providing 36kW, and the poor condition of the weir (which would require extensive reconstruction). However, it is still possible if upgrades to the weir were planned anyway. As the weir is unsafe in its present condition, an upgrade would seem likely. 48

50 Key Numbers: Site Name Head (m) Installed power (kw) Initial cost Annual cost Annual gross revenue Simple payback (years) 20 year simple profit 26 - Eastgate Bridge ,289 2,622 29, ,117 49

51 3.13 Site 28: Craigside Caravan Park Observations: The site lies on the Rookhope Burn to the north of Eastgate. The penstock would be routed through Craigside Caravan Park to the turbine house which would be located close to the Warden s office. The penstock immediately below the abstraction point may be required to be surface mounted on the exposed rockface. Location: 3-Phase O/H powerline Figure 42: Map showing location of the potential scheme on the Rookhope Burn. Crown copyright License number Abstraction Point: The abstraction point was as identified by Hydrobot. The far bank and the floor of the river are solid rock. The level of the weir would have to be set carefully to minimise the back-up and risk of overspill onto the near bank. 50

52 Figure 43: Abstraction point, water flowing from left to right. Route of Penstock: The initial routing of the penstock is difficult and will need to circumvent some exposed rock forming a cliff face of some 50m. Thereafter it can be laid under the footpath all the way down to the caravan site, then either through the caravan site or around it. Figure 44: Samples of the footpath under which the penstock would be run. Turbine & Generator: The turbine house would ideally be placed alongside the footbridge shown on the map and just below the caravan park office. Access would be along the route of the existing narrow footpath some widening would be required. However, this would result in the Eastgate Flow Gauging Station being in the depleted zone. If this was unacceptable to EA then it would be possible to place the turbine house above the FGS with a loss of some 6m of head. 51

53 Electrical Distribution Network Interconnection: The route of the local 3-phase supply is shown on the map. The powerlines terminate at the church closest to the footbridge some 150m from the turbine house. Figure 45: Transformer adjacent to the church. Engineering Access: Access to the abstraction point would be through fields. The penstock would have to be laid using a mini-digger operating along the footpath, which will require to be widened. Environmental Observations: The Eastgate Flow Gauging Station lies between the desired sites for the abstraction point and the turbine house. This could be a significant impediment; an opinion has been requested of the Environment Agency. The falls present an impassable barrier to migratory fish, as does the weir associated with the Flow Gauging Station. 52

54 Figure 46: Eastgate Flow Gauging Station. Key Numbers: Site Name Head (m) Installed power (kw) Initial cost Annual cost Annual gross revenue Simple payback (years) 20 year simple profit 28 - Craigside Caravan Pa ,624 10, , ,808 53

55 3.14 Site 29: Stanhope Burn Caravan Park Observations: The site lies on a tributary of the River Wear to the north of Stanhope, and adjacent to Stanhope Burn Caravan Park. After a difficult initial penstock section the route would be through a deciduous wooded area on the bank opposite to the caravan park. Scheme Location: Figure 47: Map showing the location of the scheme. Crown copyright License number Abstraction Point: The abstraction is at the location identified by Hydrobot, where both banks and the floor of the river are solid rock, which is advantageous for weir construction. However, the construction of the weir would cause the river to back-up and overflow the existing ford unless the height could be restricted. The alternative would be to move the weir 50m upstream. 54

56 Figure 48: Location of weir looking downstream. Route of Penstock: The penstock would have to be mounted on the cliff face for the first 50m or so then again on a second section downstream to keep it above the flood zone. The remained could be buried in the deciduous wood. A second option would be to place the scheme on the east bank and run it through the caravan park. Figure 49: Penstock may have to be mounted on cliff face. 55

57 Figure 50: Route through wood. Turbine & Generator: The turbine house would be placed in a field at Cats Pool, 4m above the level of the river and 30m from a 3-phase O/H powerline. Access would be through the field. An alternative would to be to place it 50m upstream just inside the end of the deciduous wood to obscure it from sight from the caravan park.. Conclusion: Site valid. Key Numbers: Site Name Head (m) Installed power (kw) Initial cost Annual cost Annual gross revenue Simple payback (years) 20 year simple profit 29 - Stanhope Burn CP ,030 7,523 64, ,418 56

58 3.15 Site 30: Swinhope Burn Observations: The site is on the Swinhope Burn south of Westgate. Scheme Location: Figure 51: Map showing the location of the scheme. Crown copyright License number

59 Abstraction Point: The weir would be located as identified by Hydrobot just below the confluence of the three tributaries, and the water would be routed down the east bank. However, there may be a requirement to move the abstraction point upstream to enable the route of the penstock to take a path above the top of the gorge at the southern most point of the forest shown on the map. Figure 52: Location of the weir. Route of Low Pressure Pipe and Penstock: The penstock route will be required to traverse the scree shown on the right of the photo below with some significant erosion protection being put in place. It would then be routed with the intention of remaining above the trees (and top of the gorge) in the distance (southern most corner of the forest shown on the map). 58

60 Figure 53: Burn from the abstraction point looking downstream. The penstock would then be routed in a straight line down the side of the forest to the point where the farm track enters the forest close to the Hydrobot identified site of the turbine. Figure 54: Sample of the route of the penstock. Turbine & Generator: There are three options for the location of the turbine house; the final choice would be dependent on the firmness of the ground and engineering access. 59

61 These locations are all within 50m of each other and are on the north side of the farm track shown entering the forest. The current preferred option would be to place it adjacent to the track for ease of access and avoidance of apparent soft ground, however this sacrifices some 10m of head. Figure 55: Preferred turbine house location. Figure 56: Route of incoming penstock to site of turbine house note the O/H powerline. Electrical Distribution Network Interconnection: There is a single phase O/H powerline some 30m up the hill from the turbine house. 60

62 Engineering Access: Physical access to all locations is fairly good mainly though farm access tracks except in the area below the turbine house where the tailrace would have to be placed. Environmental Observations: A fish-pass was constructed many years ago to enable migratory fish to avoid the waterfalls and move to spawning beds upstream. It was reported that the breeding of fish is still being managed or possibly just monitored. This may be a significant obstacle that may have to be negotiated through a reduction in the level of abstraction during times of migration. Figure 57: Fish-pass just above the site of the discharge point from the turbine house. Conclusion: Site valid. Key Numbers: Site Name Head (m) Installed power (kw) Initial cost Annual cost Annual gross revenue Simple payback (years) 20 year simple profit 30 - Swinhope Burn ,508 5,669 81, ,030,250 61