Midlothian and East Renfrewshire Joint Schools Eastwood

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1 Midlothian and East Renfrewshire Joint Schools Eastwood Stage C Renewable Energy Feasibility Study Doc No: Issue: Rev: A Date: 22 November 2010 Issue Status Rev Status Prepared by Reviewed by Date A Draft Issued for Comment FH DR 22/11/10 Renewable Energy Feasibility Study November 2010

2 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November Introduction The following report is a high level feasibility report undertaken to investigate the most suitable and viable Low Zero Carbon (LZC) technologies for the Midlothian and East Renfrewshire schools. It is important to note that the client s brief states a requirement to achieve an Energy Performance Certificate (EPC) B+ rated building without the requirement for incorporating renewable energy systems. Although this is considered a challenging task, it is also important to highlight the difference between a renewable technology and a LZC technology. A renewable technology is considered to be a technology which generates energy from a renewable source, therefore gas fuelled CHP units and ventilation earth-tubes are not considered a renewable technology. However both these technologies are considered to be a LZC technology. The footprint of the proposed school is circa m 2. DCSF benchmarking data is detailed in the document entitled DCSF Energy and Water benchmarks for Maintained Schools in England ( ). The upper quartile figures have been selected as the baseline figures for determining carbon savings and ultimately the viability of the technology on the schools. Energy Breakdown (kwh/m2/annum) Carbon Emissions (kgco 2 /m 2 /annum) Electricity Gas Electricity Gas This report has been produced to investigate the various different LZC technologies which can be used on Midlothian and East Renfrewshire schools. The report does not make recommendations, only highlights feasible and viable solutions. The report is based upon high level design information and is intended to inform the design team s strategic approach. Where specific information is not known, guidance has been sought from best practise guidance, manufacturer consultation and experienced assumptions, all of which are noted throughout. The technologies considered are; Wind Ventilation Earth tubes Photovoltaic Cells Combined Heat and Power (CHP) Biomass Solar thermal hot water

3 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November This study attempts to covers areas such as; Energy generated from LZC energy source per year Payback typical costs of technology have been obtained from manufacturers where possible Feasibility of exporting heat/electricity from the system Life cycle cost / lifecycle impact of the potential specification in terms of carbon emissions - all carbon savings are comparable to the current proposals of a dual fuel boiler. Any available grants this is of particular interest with the recent confirmation that government Feed-in Tariffs are to be introduced in April 2010 with Renewable Heat Incentives to follow in Feed-in Tariffs (FITs) are financial support measures introduced by the government to increase the uptake of small-scale renewable generation (<5MWe) and help deliver the UK s 2020 renewable energy targets. The mechanism provides renewable generators with a 20 year guaranteed per unit support payments (p/kwh) for electricity generation. FITs will replace the current renewables obligation (RO) for systems <5MWe, designed at covering residential and small business installations. Systems with a capacity in excess of 5Mwe will still be assessed under the renewables obligation. The 5Mwe limit is set as the maximum under the energy act this final cut of point may be lower than 5Mwe. Feed-in tariffs are effectively long-term contracts where electricity companies promise to buy renewable energy generated and fed into the grid at a certain price for long-term periods, perhaps as much as 25 years. FITs are designed to offer greater incentive to emerging technologies to encourage their development and uptake. The rate of FITs for each technology type has been set by assessing the hurdle rate of various investor groups. This is basically the return per kwh generated at which investors will enter the market. All carbon reduction figures throughout this report (kgco2/m2), savings ( ) and payback periods (years) are comparable to the base case which is considered to be gas boiler providing the benchmark heating load and grid electricity supplying the electrical load.

4 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November Wind Energy A wind turbine on the site would generate carbon free, cost free electricity to the hospital. Advantages: Generate Free energy Provides an interesting landscape feature and may serve as an educational tool Electricity may be exported back into the grid (depending on size of installation) Eligible for Feed-in tariffs Issues to be considered; Planning conditions and how it fits in within local community. Site is sloped and therefore might be considered an ideal location. However the site is close to residential areas and planning permission would most probably be difficult to achieve. Noise and flicker issues ideally should be located in a remote corner of the site or as far away from residential areas as possible. This will need to be considered within the site noise assessment. Wind speeds for the site have been obtained from the BERR wind-speed database and are specific for the site based on its post code; approximately 5.8m/s at 25 meters above ground, 6.3m/s at 45 meters above ground. Most wind turbines start generating electricity at wind speeds around 5 m/s. It is strongly recommended that a wind speed monitoring exercise be undertaken on the particular site to determine if a wind turbine is viable. One option has been considered: 1. Wes 80 kw wind turbine - electricity would be exported back to the grid during the night. In this case, the school may benefit further with a fixed rate for electricity export (typically around 5p/kWh). However, there may be large electrical implications with providing capability to export to the grid. Assumptions: Revenue from Feed-in Tariff = 0.23 / kwh The output of the turbine has been determined from the manufactures data

5 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November WIND TURBINE Assumptions: Wind turbine type and model 80 kw Wes Wind Turbine Expected energy output 160, kwh/annum Cost of technology 220, Annual maintenance costs year Whole life costs 230, Available grants Feed-in-tariffs Year /kw Year /kw Year /kw Year /kw Life span 20 years Calculations: Benefit from grants Year 1 38, Year 2 38, Year 3 38, Year 4 - Year , TOTAL benefit from grants 771, TOTAL savings on electricity 384, Total benefits from wind turbines 1,155, Total costs of wind turbines 230, Energy savings 160, kwh/annum Equivalent CO2 savings 82, kgco2/annum Total CO2 savings 1,657, kgco2 Capital savings per year 19, /annum Payback Period 3.84 years Whole life costs /kgco2 saved % Renewable energy compared to base case 8.81%

6 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November Photovoltaic Cells Photovoltaic cells use light to generate electricity. There are a number of PV panel technologies, including polycrystalline, mono-crystalline and thin-film. Solar PV cells can be arranged in panels on a buildings roof or walls, and can often directly feed electricity into the building. With the latest PV technologies, cells can be also be integrated into the roof tiles themselves. Groups of solar PV cells can be added together to provide increasing levels of power. They can range from small, kilowatt sized solar panels for use in domestic households, to larger arrays, which function as separate solar plant feeding power directly into the electricity grid. PV heating systems are generally more expensive than solar heating, but they do have the advantages that there are no moving parts so simpler and more reliable to maintain and waterproof PV panels can be incorporated into a roof as part of the structure replacing tiles. The amount of available free area on the roof will ultimately determine their viability for the school. Advantages; Low maintenance costs. High reliability. Low visual impact if the appropriate location can be found. No planning permission is required (unless incorporated into a façade) Issues to be considered; Expensive technology with relatively low efficiencies and low carbon savings Additional roof support may be required to hold the weight of the panels

7 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November Assumptions: Revenue from Feed in Tariff = / kwh Solar Irradiation in UK = 1000 kwh/m 2 Solar shading factor =1 (ie. No over shading) Coverage required = 8m 2 / kwpeak costing approximately 4000 / m 2 SOLAR PHOTOVOLTAICS Assumptions: Area covered has been selected to meet the target carbon reduction Area covered by PV cells 200 m2 Cost of technology 500 /m2 Total cost of technology 100, Annual maintenance costs /annum Available grants Feed-in tariffs Year /kwh Year /kwh Year /kwh Year /kwh Life span 25 years Calculations: Benefit from grants Year 1 7, TOTAL benefit from grants 184, TOTAL savings on electricity 63, Total benefits from solar PV panels 247, Total costs of solar PV panels 100, Energy savings 21,250 kwh/annum Equivalent CO2 savings 11,008 kgco2/annum Total CO2 savings 275, kgco2 Capital savings per year 2, /annum Payback period years Whole life cost /kgco2 saved % Renewable energy compared to base case 1.18%

8 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November Combined Heat and Power (CHP) Combined Heat and Power (CHP) is the simultaneous generation of usable heat and power (usually electricity) in a single process. Electricity is generated using an engine or a turbine, and heat is recovered from the exhaust gases and cooling systems. CHP operates in parallel with the incoming mains, and its carbon emissions are much lower than for conventional electricity generating plant whose dump heat cannot be put to good use. The CHP unit generates electricity efficiently compared to grid supplied electricity as there are no transmission losses that are associated with electricity generated on site. Almost any fuel can be used for CHP plant, natural gas and fuel oil being the most common. Biofuels and biomass can be used, but there are currently few examples of this in the UK. There are also significant differences in the equipment required for biomass CHP systems. Advantages; Highly efficient. Generates thermal and electrical energy simultaneously Can export electricity back in the grid and get significant financial reward Issues to be considered; Macro scale CHP is not eligible for Feed-in Tariffs at the present time. However this may change in the near future. Assumptions; CHP efficiency = 90% Thermal efficiency = 55% Electrical efficiency = 35%

9 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November CHP: Outputs Output (kw) Energy Output (kwh) hours Electrical Thermal Electrical Thermal CHP unit running at 100% capacity for CHP unit running at 50% capacity for GIFA m2 Gas Conversion factor kgco2/kwh Electricity generated Conversion Factor kgco2/kwh CHP: Inputs fuel Input (taken from manufacturer's data) 335 kw 943 full load 335 kw 1007 half load kw total Gas required for the year kwh Gas Conversion factor kgco2/kwh Total carbon emissions from Gas kgco2/annum 7 kgco2/m2 Total kwh KgCO2/annum KgCO2/m2/annum Total carbon displaced 8.79 Total Carbon emissions offset from using CHP 1.46 kgco2/m2 Typical cost of electricty ( /kwh) 0.09 Typcial cost of gas ( /kwh) 0.04 Savings in electricity costs ( ) Savings in gas costs ( ) 8659 Total savings ( ) Total Capital cost ( ) Payback 200,000 (installed) 8.8 years

10 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November Solar Thermal Hot Water Energy from the sun has been harnessed for thousands of years, and peak solar radiation in the UK is around 1 kw/m2. Solar thermal systems can generate much more heat for space heating and hot water than passive solar alone. Solar collectors, at the heart of most solar thermal systems, absorb the sun's energy and provide heat for hot water, heating and other applications. The panels use incident solar radiation to heat a water glycol mix running through the panels. This heat is then transferred into a hot water cylinder. Due to the efficiency gains it is recommended that evacuated tube panels are selected over flat plate collectors. Ideally the collectors should be mounted on a south-facing roof, although south-east/south-west will also function successfully, at an elevation of between 10 and 60. Advantages; Carbon free source of hot water Very high temperatures can be reached, typically 90deg therefore a solar thermal system could provide 100% of the hot water demands during the summer months. Issues to be considered; Availability is confined to daylight hours and primarily summer months. the relative locations of the solar collectors and the hot water storage (the closer together they are the shorter the pipe-runs) The ease of establishing safe working access on the roof area where the collectors are to be mounted Additional roof support may be required to hold the weight of the panels Assumptions: Renewable Heat Incentive = 0.17 / kwh Solar collectors provide 100% of the heating demand for 3.5 months of the year only. Solar evacuated tubes have a conversional efficiency of 65% with a unit output of 500kWh/m2. Solar Irradiation in the UK is approximately 1000kWh/m2. 150kWh/m2 of evacuated tube

11 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November SOLAR HOT WATER Assumptions: 6 Classes a day 1 Dining Area and Kitchen 30 Occupants 100 Occupants 6 l of hot water/min 8 l of hot water/min 1080 litres of hot water/day 800 litres of hot water/ day 1880 Total litres of hot water per day 5 collectors assumed Evacuated tubes Area of solar panels 100 m2 25no. x 4m2 each Cost of technology /m2 Annual maintenance cost /annum Available grants RHI Incentive per annum 0.18 /kwh Life span 20 years Calculations TOTAL benefits from the grants 54, TOTAL savings on natural gas 12, Total benefits from solar hot water panels 66, Total cost of solar hot water panels 87, Energy savings 15, kwh/annum Equivalent CO2 savings 3, kgco2 per annum Capital savings per year /annum Payback period 6.07 years Whole life costs 0.53 /kgco2 saved % Renewable energy compared to base case 0.83%

12 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November Biomass Energy from biomass is produced by burning organic matter. Biomass products such as trees, crops or animal dung are harvested and processed to create bio-energy. Biomass is carbon based so when used as fuel it also generates carbon emissions. However, the carbon that is released during combustion is equivalent to the amount that was absorbed during growth, and so the technology is considered as carbon-neutral (the fuel generally requires treatment and transport, with associated carbon emissions). Unlike fossil fuels, biomass can be replaced relatively quickly. The two main types of biomass fuel considered are wood chip and wood pellet. Both have developed supply chains and provide renewable heat energy at reasonable costs. Wood chip supplies in the UK tend to be from local woodland management or council tree management sources rather than through a typical commercial supply process. Other sources of wood chips exist, but are not fully developed, such as waste wood recovery and energy crops. Wood pellets are a more processed wood fuel, whereby wood waste such as sawdust has been highly compressed into pellets. There is a slight extra carbon penalty that results from this processing, and pellets cost more than chips. However, the improved energy density, fuel density (fewer deliveries), size consistency and combustion efficiency outweighs this higher processing cost. Biomass has a carbon intensity of 1/8th that of natural gas. A biomass boiler may be provided to supply low carbon heat to the proposed hospital. A quick search has been undertaken and the site appears to be located in close proximity to a supply of wood-pellet and woodchip. If biomass was to be considered further for the scheme, it is advisable that local suppliers are contacted so to confirm stores size, future supplies and deliveries. Advantages Heating with biomass is now more sophisticated, automated, requires relatively lowmaintenance, and uses a renewable fuel which has a minimal carbon footprint, being part of the active carbon cycle. When sustainably-sourced, biomass has one of the lowest carbon emission factors of the available heating fuels. Issues to be considered; Access for fuel delivery and future supplies Large energy centre required Very tall chimney and may be unsightly plant Local air pollutions (NOx) Future supplies Cost of boiler is significantly higher than conventional gas boiler Requires regular maintenance

13 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November Assumptions: Biomass sized to meet 95% of the heating demand (taken from carbon calculator guidance) Biomass boiler is 85% efficient. BIOMASS BOILER Assumptions: Biomass boiler type and model Hoval 500 kw Boiler size 500 kw Energy output from Biomass MWhr Remainder should be made up from gas boiler MWhr Total energy output 1,399,632 kwh/annum Input required from biomass MWhr carbon emissions (kgco2) kgco2 Input required from gas MWhr carbon emissions (kgco2) kgco2 Total Carbon emissions (kgco2/m2) 4.10 kgco2/m2 Total carbon emissions (kgco2/m2) if same heat demand met by gas kgco2/m2 Cost of technology 300, Cost of fuel ( / biomass - woodpellets)) 61, Cost of fuel ( / biomass - woodchip)) 35, Cost of fuel ( / gas) 3, Total cost ( to meet heat demand) 39, Total cost of gas only to meet demand 55, Available grants RHI Incentive per annum 0.07 /kwh Life span 15 years Savings/ year 90,976 /annum Base case assumptions: Gas boiler efficiency 90.00% Calculations: Biomass boiler efficiency 85.00% Annual fuel consumption (wood chips) 39,089.07

14 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November Annual fuel consumption (wood pellets) 64, Annual CO2 emissions (wood chips) 39,107 kgco2/annum CO2 emissions saved 281,253 kgco2/annum Total CO2 emissions saved in 15hrs 4, tonnes of CO2 Payback period (wood chips) 5.10 years Payback period (wood pellet) 8.24 years Capital savings 24, per annum Total gas cost savings 365, Total biomass systems plus fuel costs (wood chip) 886, Total biomass system plus fuel costs (wood pellets) 1,261, Whole life cost 0.07 Energy savings 73% /kgco2 saved

15 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November Ventilation Earth tubes Earth tubes are simple, practically maintenance free, concrete, ground to air heat exchangers that are officially classed as a renewable technology by the Carbon Trust. As ground temperatures at 1m below the surface are constant and approximately equal to mean annual air temperature, the earth surrounding the earth tube will be warmer than ambient air temperature in winter and cooler than ambient air temperature in summer months. Fresh air supply is passed through the buried tube before reaching ventilation plant. Heat is taken from or rejected to the surrounding earth and supply air is pre-heated or cooled accordingly. Considerable energy savings in heating fresh air supply can be realised and the earth tubes also provide a source of free cooling to assist with thermal comfort during warmer months. Earth-tubes provide pre-heat of ventilation air in the winter and pre-cooling of ventilation air in the summer. During the winter, fresh air is brought into the building via earth tubes providing temperature gain from the earth. Taking into account the high efficiency heat recovery modules incorporated within the air handling units, the free heating of the ventilation air from the ground reduces the fresh air boiler heat input requirements by 60%. As the ground energy is replaced by solar gains this 60% reduction is generated via a renewable energy source. Advantages: Free heating in winter. Free Cooling in Summer. Can negate need for mechanical cooling. Reduced running costs. Low maintenance. Teaching aid. Issues to be considered; Spatial requirements Trenches required for the concrete tubes Relatively expensive

16 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November EARTH TUBES: Assumptions: Heating air flow rate 30 m3/s Cooling air flow rate 5 m3/s Temperature gradient achieved 6 C Air density 1.21 kg/m3 Air Cp KJ/kgK Cost of the technology 250, Available grants N/A Life span of technology 25 years Calculations: Heating savings 240, kwh/annum Equivalent CO2 savings 49, kgco2/annum Cooling savings 21, kwh/annum Equivalent CO2 savings 11, kgco2/annum Capital savings per year 12, /annum Payback period years Whole life cost 0.88 /kgco2 saved Energy savings over base case 14.46% approximate Heating degree hours hours approximate Cooling degree hours hours

17 Midlothian and East Refrewshire Schools Renewable Energy Feasibility Study November Summary of Results

18 Eastwood - Low and Zero Carbon Feasibility Study Stage C Low and Zero Carbon Study LZC Technology Micro-wind Photovoltaics Solar Hot Water Ground Source Heat Pump Earth Tube Biomass Boiler gas fuelled CHP Technology Description Overview Solar PV panels capture Solar water collectors could be the solar energy and integrated on the roof of the the Studies and databases transform it into electrical new school developlment and to indicate that the prevailing energy. The roof of the provide hot water for the sports wind is from the southwest. The site is enclosed school could be utilised and dining facilities. High quality to conceal the solar units can efficiently absorb by residential dwellings and panels if required. New energy from the diffuse radiation therefore a wind turbine is economical benefits may (cloudy conditions) as well as unlikely to be viable. prove the technology from direct sunrays (in bright feasible. days). Ground Source Heat Pumps could be considered for the school. The two options to be considered are Earth tubes make use of the horizontal trenches and vertical more constant temperatures at boreholes. Either case, detailed certain ground depths to studies will be necessary in order provide a degree of heating in to ensure the ground properties winter and cooling in summer. are appropriate for this type of The technology does not technology. Delays on the project involve any moving parts programme and interference on (minimum maintenance the existing school activities may requirements). apply due to uncertainty on the ground conditions. Biomass is a carbon-neutral neutral technology, as the amount of CO2 absorbed during photosynthesis of the vegetation balances much of the amount emitted when the biomass is subsequently converted into energy. The main aspect to consider is the volume of the fuel storage facility and the delivery access. Combined Heat and Power (CHP) is the simultaneous generation of usable heat and power (usually electricity) in a single process. Electricity is generated using an engine or a turbine, and heat is recovered from the exhaust gases and cooling systems. Land Use A wind turbine should be located approximately 120m away from any residences and 40m away PV panels would be from the nearest school mounted on support building. There is no frames oriented towards legislative requirement to the south to maximise provide a safety zone solar energy collection. around the base of the turbine, but the provision of protective fencing is recommended. Solar hot water panels are generally located at roof level on support frames, south-oriented to maximise solar heat absorption. The loops can be installed either vertically in bore holes (typically 50 to 100 metres deep), or horizontally in trenches at a depth of 2 meters. Either method is dependent upon local geology conditions. 4 no. x 40m concrete earth tubes would have to be buried at least 2m underground to utilise the benefit of the soil which remains at a temperature of approximately 12ºC throughout the year. It requires available land and good ground conditions - soils rich in clay offer the best conditions due to their insulation properties. Available space would be required for fuel storage and access for deliveries. Space requirements would vary depending on the frequency of delivery requested, fuel chosen (pellets or chips), and biomass boiler capacity. There are no significant land or spatial issues above those already associated with a standard gas boiler. LZC Technology Micro-wind Photovoltaics Solar Hot Water Ground Source Heat Pump Earth Tube Biomass Boiler gas fuelled CHP

19 Eastwood - Low and Zero Carbon Feasibility Study Stage C Noise Wind turbines potentially have two types of noise sources. One is produced by gearbox and generator and the other is due to the interaction of the air flow with the blades. With this in A PV system is mind, the distances completely silent in between the wind turbine operation. and the surrounding dwellings including classrooms have been kept to a maximum in order to prevent noise nuisance on the surrounding dwellings. Solar collector is silent in operation. Noise levels of ground source heat pump installations are generally low. Earth Tube is silent in operation. The operation of biomass boilers and associated activities should not be noisy if design of the site and delivery schedules have been carefully considered. The operation of CHP and associated activities should not be noisy. Other Limitations Shadow flickering effect is caused by the intermittent interruption of direct sunlight by the turbine blades. A flicker study may be required for planning application. Photovoltaics may be an expensive technology, but the potential intoduction of feed in tariffs could make them very competitive It requires constant hot water demand through summer holiday period to avoid panels overheating and wastage of heat energy. Subject to ground conditions. Even though a ground investigation report has been carried out, a more comprehensive study will have to be carried out. High initial costs may also be a limitation. Only suitable where mechanical supply ventilation is utilised. The biomass boiler shall be located with convenient transport access to suppliers of biomass, and with sufficient space for storage. The design and operation of fuel handling / storage can require as much consideration as the biomass plant itself. Only really viable when there is a need for the waste heat. In this case, the adjacent pool should be able to make use of the waste heat produced. Educational Impact - Visual / Pedagogical Very Good Very Good as long as roof is visible or PV technology is integrated within the building's cladding. Very Good as long as roof is visible. Good - can be demonstrated through providing a description of the technology, live data on energy generated and subsequent CO2 emissions prevented. Good - if air intakes can be integrated in a clear, visible way. Good - can be demonstrated through providing a description of the technology, live data on energy generated and subsequent CO2 emissions prevented. Good - can be demonstrated through providing a description of the technology, live data on energy generated and subsequent CO2 emissions prevented. Grants Feed-in tariffs (click here for Feed-in tariffs (click here for Renewable Heat Incentives (click here Renewable Heat Incentives (click here Renewable Heat Incentives (click Renewable Heat Incentives (click here for further Renewable Heat Incentives (click here for further further information) further information) for further information) for further information) here for further information) information) information) Whole life cost ( ) / kgco2 saved N/A Capital cost 220k - 250k 50k 85k N/A 250k 100k - 150k 100k - 150k Payback period (years) N/A years % LZC energy compared to base case Not considered Viable for the Scheme Unlikely - due to planning requirements and client's brief states a requirement to achieve an EPC B+ rated building without the incorporating renewable energy systems. Unlikely - due to cost implications and client's No - due to location and available No - due to cost implications and brief states a day time sun, and and client's available space, and client's brief requirement to achieve brief states a requirement to states a requirement to achieve an EPC B+ rated achieve an EPC B+ rated an EPC B+ rated building without building without the building without the incorporating the incorporating renewable incorporating renewable renewable energy systems. energy systems. energy systems. Yes No - due to maintenance issues and frequency of deliveries required, and client's brief states a requirement to achieve an EPC B+ rated building without the incorporating renewable energy systems. Yes