Perth & Kinross Council Small Scale Renewables Workshops Wind Turbines
Small-scale Renewable technologies Wind turbines Hydro turbines Solar photovoltaic panels Anaerobic digestion Biomass heaters/boilers Solar hot water panels Heat pumps
Renewable Energy Sources
Wind Resource Onshore
Wind Resource Offshore
Wind Turbine Design Evolved
Wind Turbine Design
Small Wind Turbines
Small Wind Turbines
Small Medium Scale Wind Turbines Endurance 50kW Enercon 330kW
Large Scale Wind Turbines
Wind Farm
Wind Turbine Design
Turbine Selection The output of a wind turbine can vary depending on a number of factors, all of which can be analysed during a site assessment. Some of these factors include: Surroundings Weather Location Wind speed Turbulence from buildings and trees Access for installation After an initial consultation, the site survey will ensure suitability for a wind turbine and will combine all of the relevant factors to provide an overview of what can be expected from the wind turbine.
Turbine Selection Wind turbines need consistent wind speeds annual average of around 5m/s indicates a potential site Output can vary greatly between identical turbines on different sites doubling the wind speed increases power generated by 8 times, so good siting is essential Any turbulence or drag caused by neighbouring buildings or trees will significantly reduce their effectiveness the ground itself causes drag so tower height is important Larger turbines tend to give the best return on investment due to scaling factors roof mounted turbines in urban areas are rarely effective
Turbine Selection Is my site windy enough? Wind speed varies with time, from calm days to occasional violent gusts. If the wind speed at a site is recorded over a year, it will be seen as a mean wind speed value. This is the annual mean wind speed and an indication the wind energy available. In the UK, the average wind speed could be as low as 4 m/s (9.0 mph) for an inland site to around 8 m/s (13 mph) or higher on the most exposed sites.
Useful rules of thumb on wind speed How Much Wind is Enough? Need average annual wind speed of at least 4 m/s Up to 4 m/s (about 15 km/h) No good 5 m/s (18 km/h) Acceptable 6 m/s (22 km/h) Moderate 7 m/s (25 km/h) Good 8 m/s (29 km/h) Excellent But Low turbulence!
Wind Speed The UK Government funded database (NOABL) gives an estimate of Annual Mean Wind Speeds in meters per second for each 1km square all over the British Isles at heights of 10m, 25m and 45m above ground level. http://www.bwea.com/noabl/index.html A very approximate method Actual wind speed also influenced by local topography and nearby obstructions such as trees, buildings etc. Allows indication only of the possible energy capture from the wind turbine.
Wind Speed NOABL - Numerical Objective Analysis of Boundary Layer observations for 1975-1984 for 56 stations NCIC - National Climate Information Centre 1971 to 2000 for approximately 220 sites less reliance on interpolation. NOABL tends to overestimate
Wind Speed
Wind Speed NCIC detail
Wind Speed Wind Speed The Carbon Trust Wind Yield Estimation Tool Users can input a postcode and details about the surrounding landscape & type of turbine to calculate the annual mean wind speed and the likely energy generation and carbon savings. Freely available on the Carbon Trust website at: www.carbontrust.co.uk/wind-estimator
Wind Speed A number of other companies have wind estimation tools which can be accessed from their own web sites
Wind Speed Measurement Anemometry - wind data collection. Measure the wind speed for a period of at least 3 years to get a truly accurate average In practice, extrapolation is used, calling on data from nearest Met Office weather station or a friendly neighbourhood wind farm operator Power Predictor
Site Selection location, location, location Higher ground produces better wind speeds/capacity factor Grid connection survey Locate near your building so you can maximise own usage Avoid putting near woodland turbulence Telecoms microwave links, RADAR clutter 80% of our wind comes from the South West
Planning & Environmental Impacts Effect of noise on the local buildings Effect of flicker from blades on local housing Effect on Aviation radar Electromagnetic interference Visual Intrusion Effect on local environmentally sensitive sites Effect on key species bats and birds
Guidance Guidance for the planning of wind turbine installations
Guidance
Site Selection Proximity to other residential dwellings (noise and flicker issues) Proximity to your own dwelling can be much closer. If located on North East side, prevailing wind keeps any noise away, but avoid wind turbulence turbine should be 20 times the house height away.
Site Selection Tower Height The higher the tower, the higher the average wind speed and the cleaner the air flow Normally a taller tower will generate sufficient extra energy to justify it's additional cost, especially if there are local obstacles to be avoided. Where there are obstructions near the turbine, a tall tower may place the turbine above the turbulence created by nearby trees or buildings.
Site Selection Other factors Planning may dictate the maximum height of tower you are able to install and some areas may stipulate a maximum tower height, say, 9m. Low towers must be sited well away from obstructions such as buildings and trees, or the energy generation may be significantly reduced.
Turbine Siting Trees and obstacles A stand of trees or a building in the direction of the prevailing wind will significantly impact the average wind available to a turbine. Trees to the South and West of a proposed location would mean that the amount of wind may be much lower than hoped for and the site might not be recommended for a small turbine, unless it is on ground much higher than the obstacle.
Site Selection Seasonal Variations There is normally more wind in winter than the in summer, so matching increased demand for heating and lighting in winter. The chart gives an indication of how the amount of wind energy varies during the year at an average UK site, with typically 60% of the wind energy coming in the 6 months from October - March.
Site Selection Wind Direction There is a dramatic difference between the amount of wind energy from the South West and the North East. Plymouth Leuchars
Site Selection Hills and Valleys Wind speeds up as it nears the top of a slope and slows down considerably as it descends into the valley. The exact impact of this effect is very dependant upon the exact local conditions. Avoid locating a wind turbine on the North East side of a hill.
Calculating the power output Using the power output equation - Output = CPoa A PA G Where: CPoa A PA G Annual Production Aerodynamic power coefficient (efficiency of the rotor to convert energy) Swept area of the blade Power density of the wind = 0.6125 x S³ where S is the wind speed in m/s Generator efficiency Example: For a turbine with a 1.75 diameter rotor at a wind speed of 10m/s with a power coefficient of 0.35 (generous!) and a generator efficiency of 90%: Output = 0.35 (3.1416 (1.75/2)2) (0.6125 10³) 0.9 = 464W Using the same equation but for a wind speed of 5m/s would give an output of 58W
Annual Production Indicative Manufacturers Production for Proven 15kW Turbine Average Wind Speed (m/s) Mega Watt Output 4 17.844 4.5 23.976 5 30.107 5.5 35.931 6 41.755 6.5 46.717 7 51.679 7.5 55.623 8 59.566 8.5 62.501 9 65.436 9.5 67.422 10 69.408 10.5 70.538 11 71.667
Annual Production Assessing manufacturers claims The turbine manufacturers rate their turbines as providing a certain output at a given wind speed. Some rating definitions are those wind speeds providing maximum output whilst others are less than maximum outputs at different wind speeds. There is no industry standard. The rating for a turbine is unlikely to be an indication of its actual energy production. Checking the claimed output rating against the likely efficiency We know from the above that the maximum practical efficiency is around 35%. Most turbines work at efficiencies of between 22% - 31% at 10m/s and between 17% - 26% at speeds of 12m/s. If we take the manufacturers output rating for a given wind speed and insert it into the above output equation and calculate the assumed efficiency, we can judge the manufacturer s claim.
Grid Connection Distribution Network Operator (DNO) is a company that: Owns, operates and maintains a public electricity distribution network Holds a Distribution Network Operator Licence There are seven DNOs in the UK.
Electrical Constraints Up to 3.7 kw per phase No problem Up to 50 kw in total Simplified connection procedure Permission required Over 50 kw per phase Permission required 3-phase supply required
Grid Connection Three types of connections to DNO: G83/1-1 Stage 1 G83/1-1 Stage 2 Single Generator <11Kw 3Phase or <3.66Kw 1phase Multiple Generators <11Kw 3Phase or <3.66Kw 1phase G59/2 Generators >11Kw 3 Phase
Grid Connection Electricity is fed directly into your fuse box or distribution board, providing power to your premises. Any surplus electricity produced is spilled to the grid and purchased by a licensed electricity provider, depending on local regulations.
Off Grid Connection Battery Charging Energy produced by the turbine is stored in batteries to provide power supply. Most beneficial in remote locations which are not connected to the grid, or which rely on a diesel/oil generator. Installing a turbine can reduce fuel consumption by up to 95% and payback for such sites can be immediate as alternative to expensive grid connection. Positive environmental impact when fossil fuel is not used for power generation. Battery charge regulator used to prevent overcharging of the battery: If a turbine system supplies more current than can be absorbed by the battery, the charging current is reduced by the charging regulator. Excess current transferred to a dump load, which can be utilised for heating air or water.
Microgeneration Certification Scheme Has your scheme installer got Microgeneration Certification Scheme approval? The Microgeneration Certification Scheme (MCS) is an independent scheme that certifies microgeneration products and installers in accordance with consistent standards. It is designed to evaluate microgeneration products and installers against strict criteria providing greater protection for consumers. MCS applies to installations (product and installer) in the 0-50kW range. Checking that the equipment and installation company you are using has MCS accreditation is essential, and best done at the very outset of any project.
Microgeneration Certification Scheme The MCS was designed to raise the level of quality starting with the plant and extending to the installers. The legal definition of Micro generation applied to products producing: <50kW of power generation or <45kW of renewable heat. MCS technologies include: Solar PV Wind power Solar collectors Biomass CHP & Heat pumps including: GSHP Ground Source & ASHP Air Source.
Microgeneration Certification Scheme MCS has now become a prerequisite for many schemes and also for government tender lists. For manufacturers the process is long winded and expensive. It involves factory procedure inspections and witness tests. For installers it involves inspections of compliance, stability and technical ability to design, install and follow up. e.g. A heat pump must achieve a specific CoP and it must have a full set of test results.
Microgeneration Certification Scheme Remember, clean energy cashbacks (Feed-in Tariffs) and renewable heat incentives are only available to those installations using MCS approved products and installation companies. All MCS registered suppliers and installers can be checked on the MCS web site: www.microgenerationcertification.org
Financial Assistance A business to claim 100% first-year capital allowances on their spending on qualifying plant and machinery. Information available on web site - www.eca.gov.uk Carbon Trust Interest Free Loans - Funding has been reduced and loan offering to be withdrawn from 28 March 2011 New loan scheme to be launched in April 2011 backed by the Carbon Trust who will assess cost, energy and carbon savings. East of Scotland Investment Fund (ESIF) loan scheme can provide finance for projects up to 50,000
Feed in tariff Background to Feed-In Tariffs (FITs)? To incentivise small scale (<5MW) low carbon electricity generation Scheme went live on 1 April 2010 Encourage deployment of additional low carbon electricity generation, particularly by organisations, businesses, communities and individuals who are not traditionally engaged in the energy market.
Feed in tariff How it works The scheme provides a fixed payment for the electricity you generate, called the generation tariff. It also pays for any unused electricity that you export to the grid, the export tariff Payments for: Hydro Wind Solar PV Anaerobic Digestion A further benefit is that you won t have to pay for electricity that you generate and use yourself.
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Feed in tariff Issued April 2010
Feed in tariff Update Feb 2011 Feed in Tariff Payment Rate Table with Retail Price Index adjustments Description Scale Tariff received between 01 April 2011 and 31 March 2012* (p/kwh) Tariff Lifetime (Years) Anaerobic digestion <500kW 12.1 20 Anaerobic digestion >500kW 9.4 20 Hydro <15kW 20.9 20 Hydro 15kW -100kW 18.7 20 Hydro 100kW-2MW 11.5 20 Hydro >2MW 4.7 20 Solar Photovoltaic - (new build) <4kW 37.8 25 Solar Photovoltaic - (retrofit) < 4kW 43.3 25 Solar Photovoltaic 4kW - 10kW 37.8 25 Solar Photovoltaic 10kW - 100kW 32.9 25 Solar Photovoltaic >100kW 30.7 25 Stand-alone system 30.7 25 Wind <1.5kW 36.2 20 Wind 1.5kW - 15kW 28 20 Wind 15kW - 100kW 25.3 20 Wind 100kW - 500kW 19.7 20 Wind 500kW - 1.5MW 9.9 20 Wind >1.5MW 4.7 20 EXPORT TARIFF 3.1 * Adjusted by the 2010 Retail Price Index of 4. 8% - 21 February 2011
Feed in tariff Aim to give return on capital of 5-8% in real terms Index linked to RPI UK Wide Guaranteed for 20 years (25 for PV) Aim is to generate 6TWh of electricity by 2020 (1.6% of UK generation) Review in 2012/13 then every 5 years
Feed in tariff Administered by Electricity Supplier Main Payment is Generation Tariff paid on every kwh generated Also paid when supplying surplus electricity into grid at a flat rate payment of 3p/kWh or Power Purchase Agreement (PPA) Offsetting Electricity Revenue is tax free when generating electricity for domestic purposes An owner may assign FiT payments to a third party (subject to controls to ensure risk of fraud and abuse is minimised) This should help where the FiT revenue is assigned to the Bank which will help debt financing
Feed in tariff Selling to the Grid Normal power station sells electricity Sell electricity for Export Tariff price Feed in tariff payment up to 500 kw Total payment to landowner 5p kwh 3pkWh plus 34.5 18.8p kwh 37.5p 21.8p kwh
Feed in tariff Related Issues? Degression affects PV (c. 9% p.a.) and smaller wind installations (c. 4.5% p.a.) from 1 April 2012 Max Capacity of 5MW Sites will be tightly defined Payment rate based on when the scheme starts generating Can receive FITs on different technologies on the same site
Feed in tariff No Feed in Tariff payments for reconditioned or second hand equipment Equipment & Installer must have MCS accreditation approval (up to 50kW) Do not use second hand equipment, often cannot get spare parts Important to select renewables and installers with good track record Avoid cheap imports! Check warranty period need 5 years
Feed in tariff Why would the Feed in Tariff Interest Me? You have the resource Land/Water/Wind/Solar Rates index linked and guaranteed income for 20 years (or 25) Great opportunity to develop diversified income stream for your business Offset electricity usage on property Reduce your carbon footprint Increase your profit!
Feed in tariff Impact of Spending Review? They will be refocused on the most cost-effective technologies saving 40m in 2014-15. Changes will be implemented at the first scheduled review of tariffs (in 2013) Changes won't be announced until 2012 The expectation is that industry costs will fall over time, reducing the need for the FiT
Case Study Small scale wind turbine on a farm where the farmer uses approximately 14,000 kwhs of electricity per annum in the business. After the assessment and quotation from the suppliers, a wind turbine on a 18 metre mast is installed for a total installed cost of 55,000 and an anticipated annual production of 28,000kwh. Annual economic benefit Generation 0.28p x 28,000 kwh (Generation) 7,840 Export (50%) 0.03.1p x 14,000 kwh 434 Reduced bills 0.10p x 14,000 kwh (Retail price x use) 1,400 Annual maintenance ( 800) Net annual income 8,874 Anticipated simple payback period 7 Years Annual Net return (pre tax and finance costs) 14%
Case Study A medium scale wind turbine on a farm where the farmer uses approximately 30,000 kwhs of electricity per annum in the business. After the assessment and quotation from the suppliers, he has selected a wind turbine on a 36 metre mast for a total installed cost of 830,000 and an anticipated annual production of 800,000kwh. Annual economic benefit : Generation 0.197p x 800,000 kwh (Generation) 157,600 Export 0.03.1p x 770,000 kwh 23,870 Reduced bills 0.10p x 30,000 kwh (Retail price x use) 3,000 Annual maintenance cost ( 10,000) Net annual income 174.470 Anticipated simple payback period 5 Years Annual Net return (pre tax and finance costs) 20%
Wind Turbine Comparison Turbine Size 15 kw 50kw 330kw Electricity Generated (KWH) 39,000 135,000 870,000 Capital Cost ( ) 65,000 250,000 850,000 Annual Gross Income ( ) 12,000 39,000 180,000 Cash Income after Costs ( ) 6,000 15,500 110,000
EST Trial - Best performing Site Location: Turbine: Profile: Wind speed: Annual generation: Payback period: Orkney Islands 6kW pole-mounted Rural, flat, open space 5.75m/s (average) 22,000kWh less than 10 yrs (before FITs) Source: Energy Saving Trust
EST Trial - Worst performing Site Location: Turbine: Profile: Wind speed: Essex Annual generation: 0kWh Payback period: 1kW building mounted Urban heavily developed 2.37m/s (average) never Source: Energy Saving Trust
Turbine Rating Figures Manufacturers of MCS approved machines must provide data measured under standard conditions and certified by an accredited lab: Power curve Power rating Figure measured at 11 m/s Annual Reference Energy Figure based on mean annual wind speed of 5 m/s Test conditions set by: British Wind Energy Association Small Wind Turbine Performance and Safety Standard (2008)
Industry Standards Industry standards are there to help consumers
Embedded carbon Mast steel Turbine equipment rotors, generator gearbox, drive shaft, cables Foundations Soil disposal Installation effort travel subsistence etc Maintenance works during life in use Life expected 10 to 50 years???
Assessing Alternative Projects Where do I start? What do I need to consider? How much do they cost? What is the likely return? Which is the best one for my circumstance? Prefeasibility study should narrow down options available Assess the likely returns over 20 years? How realistic are the assumptions I am given? Where are extra costs likely to appear?
Project Flowchart
Pre Feasibility Study What should you consider? A site survey, including detailed photographic survey and technical measurements Comparisons between different technologies Compare wind turbine outputs and alternative tower heights Energy generation estimates based on local wind data Examination of likely environmental issues Capital costs Financial returns An appraisal of the grid connection issues on site and to the substation An assessment of the likelihood of obtaining planning permission, including application costs and time scales.
Conclusion - Wind turbines Identify an exposed site, clear of nearby obstructions with access for the installation. Commission on independent onsite survey of the site to give advice and assessment of the location and likely benefits Contact an MCS-accredited installer for a quotation for the turbine Check the online UK wind speed database and other wind estimation tools. Consider installing a wind gauge for at least three months to check the wind speed you want an average of at least 5m/s. Check you can connect the turbine to your property and the grid. Remember: the higher you get, the better the wind - Consider raising turbine to improve energy output. Contact the local authority to check if there are any planning restrictions.