East Kintyre Renewable Energy Group Ltd

A Technical and Economic Scoping Study of Potential Hydro Sites Based on Forest and Land Scotland land within the EKCC Boundary Rob Lee EKREG Ltd 5/12/2019

SUMMARY Five sites on Forestry and Land Scotland (FLS) land within EKCC boundaries were identified as possible community interest hydro sites and registered with FLS. Simple model estimation, using tie-points from actual depth and flow data of Lephincorrach Burn and Carradale Water at Dippen were used to estimate the possible hydro capacity at each site and the likely annual energy output: Narachan confluence = 250-400kW capacity, 1000-1500MWh per annum Alt Deucheran = 100-150kW capacity, 400-600MWh per annum Guesdale = 100-150kW capacity, 400-600MWh per annum Alt Buidhe = ~50kW capacity, 150-250MWh per annum Torr Mor = 4kW capacity, 20-25MWh per annum A simple economic costing model for the different sites indicates that in general, without a new ‘Feed In Tariff’ (such as the Small Export Guarantee), these sites are going to be hard to make economic. However, if interest-free loans or grants were available, the larger Narachan site could be economic under a subsidy-free system. Similarly, if a Private Wire Network could be installed {whereby the electricity produced by the hydro is ‘sold’ electronically to local residents at a price advantageous to both the hydro and the residents (i.e. between that of the National Grid baseload contract price offered to producers and typical consumer prices offered by suppliers}, then Narachan might be economic if funded via a Community Benefit Society (which could access the required capital at a low rate (e.g. 3%) rather than commercial bank loan rates. This report does not replace the need for a proper hydrological flow assessment, should the economic or technological conditions change, but should be read as an initial, zero cost to the community scoping of the potential of the sites.

INTRODUCTION In late October 2019, Forest & Land Scotland (FLS) opened a call for registering of interest by Communities of possible renewable energy schemes on FLS land and assets, with a deadline of Nov 6th for submissions. Given that this was only the third such call in over a decade and after receiving assurances from FLS that there were no subsequent deadlines to be met, East Kintyre Renewable Energy Group decided to register a number of possible hydro sites with FLS on behalf of East Kintyre. The hydro sites were chosen by a map-based comparison of streams and rivers on FLS land within EKCC boundaries that had similar sized or larger rain catchment areas than Lephincorrach burn. The comparison with Lephincorrach burn was made since this burn has an operational 99kW hydro running from it. The sites chosen were Guesdale (Figure 1), Torr Mor reservoir (Figure 2), Alt Deucheran and Alt Buidhe (Figure 3) and the Narachan confluence (Figure 4). Given the lack of Feed In Tariff, it was recognised by EKREG that these hydros may not be economically viable, however due to the short timescale to the submission deadline, no further analysis was undertaken before submission. This report summarises the subsequent work done to assess both; i) the likely capacity of a hydro on each the waters and ii) electricity price required to make such a hydro economic. Figure 1 – Map view of Guesdale and possible hydro pipe run

Figure 2 – Map view of Torr Mor hydro and possible pipe run

Figure 3 – Map View of Alt Deucheran and Buidhe and possible pipe runs

Figure 4 - Map View of Narachan confluence and possible pipe run

EXPERIMENTAL METHODS Background Data After moderate rains on the 10th and 11th of November (26.0mm & 33.5mm respectively), Carradale Water level peaked at ~1.3m at 6am on November 12th. After that peak it dropped consistently until at noon on Nov 13th it had levelled out at 0.486m. Given the depth was within normal range for Carradale Water and stable, it was decided to undertake comparison measurements on the different burns that afternoon. Subsequent data from the SEPA level gauge at Dippen on Carradale water, confirmed that within the accuracy of the gauge, the depth remained constant over the afternoon (See Figure 5 – taken from SEPA Water Level at Carradale webpage, https://apps.sepa.org.uk/waterlevels/). Figure 5 – Carradale Water depth

The Torrisdale estate hydro (99kW) on Lephincorrach burn is one set of tie-points for the estimation of the likely output of the 5 identified possible hydro systems (the other being Carradale Water). The Torrisdale hydro output is reported at www.ref.org and a summary of the monthly output from ref.org is given in Table 1. Table 1 – the monthly reported energy output of the Torrisdale Hydro

Overall, the mean annual output is 394MWh, which with a mean annual energy load factor of 0.454, where:

2015 2016 2017 2018 2019January 60 40 56 46February 42 40 34 32March 31 36 27 45April 31 16 18 7May 11 8 16 9June 6 35 5July 33 28 8August 25 38 39September 26 40 40.8October 19 8 55 42.2November 58 36 46 39December 63 39 47 50

Energy produced (MWh)

Energy Load factor = [annual energy output (MWh)]/[365x24xinstalled capacity (MW)] (1)

Prior to installing the Torrisdale hydro, a scoping report was commissioned (Torrisdale Hydropower Development MNV/NMH001/1474, courtesy of Mr Niall Macalister Hall). This report measured the height of the burn at Lephincorrach over the course of a year, correlated it to flow and then cross-correlated it with the SEPA data on Carradale Water to ensure accuracy before utilising the flow distribution data to estimate a likely output. The ‘pair-wise’ matching of mean daily flow at Lephincorrach with Carradale Water gave a high degree of correlation and this flow distribution is the one used in the analysis in this report (see Table 2). The predicted power from a flow of water through a turbine is given by: Predicted Power (W) = g x nett head (m) x mass flow (kg/s) x turbine-drive-generator efficiency (2) Where g = 9.81 m/s2, nett head = head x constant, t-d-g efficiency is also a constant (between 0.7-0.9) Where the head constant and t-d-g efficiency constant are not known eq. 2 can be rewritten to become the following: Predicted power = g x head (m) x mass flow (kg/s) x system efficiency (3) The Torrisdale scoping report gives the head as 120m, the flow as 132 kg/s and the system efficiency (SE) as 0.62 for a predicted hydro power of 102kW. This is odd as a predicted power of 102kW requires an SE of 0.66. Using a SE of 0.66 and the actual installed power (99kW) gives a rated mass flow of 128 kg/s for the actual installed hydro. A system efficiency of 0.66 is used through-out the remainder of the scoping work. Simple Model and Tie-Point Development Pelton and Turgo design hydros typically have a high constant efficiency as the flow decreases, until the mass flow through the system is around 15% of the rated flow, at which point the efficiency drops with flow in a non-linear manner. For the sake of simplicity, the calculations reported here assume a fixed efficiency until the flow reaches 20% at which point the power is assumed to drop to zero. Using this assumption of how the power varies with flow, along with an assumption that SEPA requires a minimum flow equal to the flow observed at 90% exceedance, allows the flow through the Torrisdale hydro (based off the match pair flow distribution) and the subsequent energy produced to be modelled and calculated (see Table 2). This simple model predicts a total energy produced of 405MWh which is within 3% of the actual mean annual energy produced of 394MWh, indicating that the simplifications used are reasonable assumptions. Table 3 shows the flow exceedance distribution and mean flow data for Lephincorrach (match pair) and Carradale Water (SEPA, measured 1995-2018). Unfortunately the SEPA data is missing many of the intermediate exceedance values. However, by assuming that the two sets of flows are correlated (to the local rainfall) a plot of the Lephincorrach flow against the Carradale Water flow allows a power curve fit to be found that correlates between the 2 burns (see Figure 6).

Table 2 – flows and estimated annual energy produced at Lephincorrach hydro

Table 3 – flow data for Lephincorrach and Carradale Water

The power curve correlation between the 2 flows of water allows a fitted flow exceedance distribution for Carradale Water to be calculated from the more complete Lephincorrach distribution (see final column in Table 3) which includes the missing intermediate flows. Figure 6 – Plot of flow data for Lephincorrach and Carradale Water

% exceedance

hrs exccedance

per year

match pair flow (t/s)

where tonne = 1000kg

useable flow (t/s) % load

energy produced

kWhtotal annual energy kWh

total annual energy MWh

5 438 1.092 1.082 1 43362 43362 4310 438 0.791 0.781 1 43362 86724 8720 876 0.371 0.361 1 86724 173448 17330 876 0.196 0.186 1.00 86724 260172 26040 876 0.133 0.123 0.96 83336 343508 34450 876 0.074 0.064 0.50 43362 386870 38760 876 0.037 0.027 0.21 18293 405164 40570 876 0.021 0.011 0.09 080 876 0.015 0.005 0.04 090 876 0.01 0 0.00 095 438 0.005 0 0.00 0

% exceedance

Lephincorrach match pair flow (t/s)

Carradale Water

(SEPA) flow (t/s)

Carradale Water

fitted flow (t/s)

5 1.092 9.545 8.98010 0.791 6.413 7.12120 0.371 4.13130 0.196 2.61040 0.133 1.97550 0.074 1.186 1.29560 0.037 0.78770 0.021 0.601 0.52480 0.015 0.41190 0.01 0.30795 0.005 0.173 0.186

mean flow 0.167 2.492

y = 8.4293x0.7193

R² = 0.9954

0.1

1

10

0.001 0.01 0.1 1 10

Carr

adal

e w

ater

flow

(ton

ne/s

)

Lephincorrach flow (tonne/s)

exceedance & mean flow data

Nov 13 nominal flow

Nov 13 actual flow

Power (exceedance & mean flow data)

Measurements and Tie-points The width of each burn was measured with a Nikon range finder (+/- 1m) or with a tape measure. The depth of each burn was measured by walking through the water at right angles to flow and measuring the depth with a gauging stick (+/- 5cm) every metre. Surface flow velocity was obtained by measuring the time taken for a 16cm3 block of pine wood to travel 7m (duplicate measurements). All data was averaged to give the following cross-sectional areas and surface flows: Lephincorrach = 1.6m x 0.25m with surface flow of 1m/s Carradale water = 9m x 0.475m with surface flow of 1m/s Narachan confluence = 7m x 0.35m with surface flow of 1m/s Alt Deucheran = 2m x 0.3m with surface flow of 1m/s Torr Mor = 0.8m x 0.12m with surface flow of 0.33m/s Alt Buidhe – much smaller than Alt Deucheran so not measured. Guesdale – not measured, assumed to be similar (from map catchment area) to Lephincorrach. The measurements of the burns cross-sectional area and surface flow velocity shows that for all, bar the Torr Mor flow, the surface velocity was an identical 1m/s. Whilst it is recognised that the actual velocity across the height of the burn’s water column will vary non-linearly from 1m/s at the surface to 0m/s at the burn’s base, for the sake of simplicity it is assumed that the nominal mean velocity is equal to the surface flow. Using this assumption and calculating the resulting nominal flow (cross-sectional area x surface velocity), the nominal flows are 0.4 t/s & 4.275 t/s for Lephincorrach and Carradale Water respectively. Figure 6 shows that this assumption is a reasonable simplification – the orange data point for these nominal flows falls on the fit of the flow exceedance data. On the afternoon of Nov 13th, the Lephincorrach hydro was producing 88kW (Mr N. Macalister Hall). This allows a flow to be inferred – 123kg/s (0.123t/s). This value is calculated from the pro-rata calculated full-power flow i.e 128 x 88/99 + a SEPA minimum flow of 0.01 t/s. Using this inferred flow for Lephincorrach gives a fitted flow of 1.87 t/s for Carradale Water (shown in Figure 6 by the blue open circle). Finally the reservoir at Torr Mor was measured. It is 20m wide, 60m long and 3.2m deep. Assuming a rectangular shape, this would give 3840m3 volume. However if the reservoir is assumed to have a sloping shelf then the maximum volume is 1920m3. On the assumption that SEPA would only allow 50% take-off, then the maximum useable volume would be 1000m3 or 1000 tonnes or 1,000,000 kg. Pro-rata inferred flows Using the cross-sectional area and surface flow of Nov 13th gives the following nominal flows: Alt Deucheran - 0.6 t/s Narachan - 2.45 t/s Torr Mor - 0.03 t/s.

Thus in comparison with the nominal flow of Lephincorrach (0.4 t/s), the pro-rata factor for Alt Deucheran is 1.5, Narachan is 6.13 and Torr Mor is 0.08. Similarly the pro-rata factor for Narachan is 0.57 when compared with the Carradale Water nominal flow (4.275 t/s). Based off the Lephincorrach match pair and the Carradale Water fitted flows, these pro-rata factors were used to calculate the flow distribution exceedances for the three burns and shown in Table 4. Table 4 – pro-rata flow distribution for the burns

Hydro Power Capacity and Annual Energy Production The flow distributions given in Table 4 allow an estimate of the possible power capacity and annual energy production to be calculated. Assuming that (like the Lephincorrach calculation shown in Table 2) that the 60% useable flow exceedance is 20% of the maximum turbine flow and that the 90% exceedance flow is the SEPA minimum flow, the flow for the possible turbine can be obtained (e.g. Narachan based off Carradale water – 90% flow is 0.18 t/s, giving a useable flow of 0.45-0.18 = 0.27 t/s – assuming this is 20% of the rated flow, then the rated flow is 1.35 t/s). Once the flow has been obtained, then from equation 3, the turbine size for that the flow and head can be calculated – these are shown in Table 5 along with an ‘install’ turbine power for the economic costings. Since highland spate burns are notorious for varied flows, a second (lower, conservative) ‘install’ turbine capacity was assumed for Alt Deucheran – basically rating it as the same size as Lephincorrach burn and hydro (100kW). Table 5 – Calculated turbine power and install turbine power

% exceedance

Narachan pro-rata flow (t/s)

based off Carradale

Water

Narachan pro-rata flow (t/s)

based off Lephincorrach

Alt Deucheran pro-rata flow

(t/s) based off Lephincorrach

Torr Mor pro-rata flow (t/s)

based off Lephincorrach

Lephincorrach match pair flow (t/s)

Carradale Water

fitted flow (t/s)

5 5.15 6.69 1.64 0.086 1.092 8.98010 4.08 4.84 1.19 0.063 0.791 7.12120 2.37 2.27 0.56 0.029 0.371 4.13130 1.50 1.20 0.29 0.016 0.196 2.61040 1.13 0.81 0.20 0.011 0.133 1.97550 0.74 0.45 0.11 0.006 0.074 1.29560 0.45 0.23 0.06 0.003 0.037 0.78770 0.30 0.13 0.03 0.002 0.021 0.52480 0.24 0.09 0.02 0.001 0.015 0.41190 0.18 0.06 0.02 0.001 0.01 0.30795 0.11 0.03 0.01 0.000 0.005 0.186

Narachan pro-rata flow based off Carradale

Water

Narachan pro-rata flow based off

Lephincorrach

Alt Deucheran pro-rata flow

based off Lephincorrach

Alt Deucheran pro-rata flow

based off Lephincorrach

Torr Mor pro-rata flow (t/s)

based off Lephincorrach

head 45 45 100 120 50flow kg/s 1350 850 200 200 11System Efficiency 0.66 0.66 0.66 0.66 0.66turbine power kW 393 248 129 155 4Install turbine kW 400 250 100 150 4

RESULTS Using the same methodology as used in the data shown in Table 2, the predicted total annual energy (MWh) and load factor for each of the ‘install’ turbine-burn configurations shown in Table 5 was calculated (see Table 6). For Torr Mor, a 1,000,000kg draw-down of water from the reservoir at 11 kg/s would last circa. 25 hours. Three years of daily rainfall data at Creag Lodge, Torrisdale indicates that on average the area gets 70 occasions/annum where the daily rainfall is >10mm allowing fast refilling of the reservoir. Based on this, it is predicted that there are a further 7000kWh (4 x 70 x 25 kWh) of electricity production from reservoir flow per annum giving a total load factor of 0.656. Table 6 – predicted annual energy production, load factor and cost to install

Based on a ‘typical’ house using 10MWh of electricity a year, it is worth noting that a combination of Narachan and Alt Deucheran hydros might be able to supply enough electricity for the Grogport/Carradale/Torrisdale/Saddell communities. The predicted power capacity results of the measurements and flow calculations can be summarised thus: Narachan confluence = 250-400kW likely to be closer to 400kW (based off Carradale Water) Alt Deucheran = 100-150kW Guesdale = 100-150kW (due to similarity to Lephincorrach and Alt Deucheran) Alt Buidhe = ~50kW Torr Mor = 4kW Figure 7 shows the cost to build different sizes of hydro as supplied by Renewablesfirst (https://www.renewablesfirst.co.uk/hydropower/hydropower-learning-centre/how-much-do-hydropower-systems-cost-to-build/). Based off this curve, approximate cost to install were calculated for the configurations given in Table 5 and are shown in Table 6. The exception is Torr Mor, where the size of the predicted hydro (4kW) is so small it puts it into the pico-hydro class. The market leader for this size of hydro is PowerSpout, BabyHydro‘s costing for a DIY install of 3x Powerspout turbines is £10,000 (https://babyhydro.co.uk/wp-content/uploads/2018/09/2017-12-18-PICO-Hydropower-DIY-Briefing-V1.4.pdf) – note though that this would entail the community doing a fair amount of work themselves. Using the installed costs and annual energy production given in Table 6, the price of electricity required to service the loan debt was calculated at different loan rates (see Table 7). Note that this is the minimum electricity price required and does not take into account

Narachan based off Carradale

Water

Narachan based off

Lephincorrach

Alt Deucheran based off

Lephincorrach

Alt Deucheran based off

Lephincorrach

Torr Mor based off

LephincorrachLephincorrach actual hydro

head (m) 45 45 100 120 50 120flow kg/s 1350 850 200 200 11 128Install turbine kW 400 250 100 150 4 99total annual energy MWh 1510 995 400 605 16+7 393load factor 0.431 0.454 0.454 0.461 0.459/0.656 0.454Install cost k£ 1325 950 500 725 6

any operating costs (e.g. land rent, insurance, business rates, maintenance and repair) or profit that the community would be required to generate. Figure 7 – cost to build for different sizes of hydro

Currently the mean electricity baseload contract rate is circa 4.7p/kWh, therefore a substantial new Feed In Tariff equivalent would be needed in order to make even the larger hydro at the Narachan confluence attractive. However if a new Feed In Tariff equivalent (such as the proposed Small Export Guarantee (up to 5MW)) was enacted, then it could be worthwhile looking for CARES enablement grant support to pay for an actual flow measurement (over 1 year) of the Narachan confluence and a scoping study possible size and output of a hydro on this stretch of the Carradale Water. Table 7 – loan cost and electricity price required to service debt for the different hydros

If interest free loans or grants were available, then the larger scale Narachan might just be possible under current zero subsidy systems (20 year loan but note that hydros often have a 40 year lifespan). If the community considered building and running a hydro using a Community Benefit Society (loan equivalents of the 1.03 rate), then a Narachan scale hydro might be economic if a means to sell the electricity directly to the local users (say at 9p/kWh) was available. Such a system is known as a virtual private wire and has been trialled by SP Energy

annual repayment for Y yearsloan rate 10 20 23,000 400,000 600,000 1,000,000 1,500,000 23,000 400,000 600,000 1,000,000 1,500,000

£ 10 years 10 years 10 years 10 years 10 years 20 years 20 years 20 years 20 years 20 years

10,000 1.00 1,000 500 4.3 2.2500,000 1.00 50,000 25,000 12.5 6.3725,000 1.00 72,500 36,250 12.1 6.0950,000 1.00 95,000 47,500 9.5 4.8

1,325,000 1.00 132,500 66,250 8.8 4.410,000 1.03 1,344 903 5.8 3.9

500,000 1.03 67,196 45,153 16.8 11.3725,000 1.03 97,434 65,472 16.2 10.9950,000 1.03 127,672 85,790 12.8 8.6

1,325,000 1.03 178,069 119,655 11.9 8.010,000 1.05 1,629 1,327 7.1 5.8

500,000 1.05 81,445 66,332 20.4 16.6725,000 1.05 118,095 96,182 19.7 16.0950,000 1.05 154,745 126,032 15.5 12.6

1,325,000 1.05 215,829 175,781 14.4 11.7

electricity price p/kWh required to service loan at X kWh/yr over Y years

Networks (part of ScottishPower) in Wales with a similar hydro scheme (Virtual Private Wire Report CES, 20/02/2017).