Shadow Flicker Issues and their Handling for Wind Farm Approval in Germany

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2 Shadow Flicker Issues and their Handling for Wind Farm Approval in Germany Wind Power and human health June 23rd 2016, Warsaw Oliver Thomas, BBB Umwelttechnik GmbH 2

3 Company History, Founders and Company Sites 1996: Foundation of BBB Umwelttechnik as project developer 2004: Technical consulting services for utilities, investors, project developers and banks Gerhard Binotsch Klaus Bergmann Joachim Binotsch 3

4 Range of Consulting Services / European References for Noise and shadow Impact Studies Technical Due Diligence Construction Supervision Wind Measurements Contracting and Procurement Service Yield Assessments Expert Reports Feasibility Study Project Management Detailed Planning 4

5 Directory 1. General background 1.1 Definition of shadow flicker 2. Impact and immission limits 2.1 Legal Framework 2.2 Impacts of shadow flicker 2.3 Immission limits in Germany 3. Assessment of shadow flicker immission 3.1 Prediction methods of shadow flicker 4. Operational impacts, technical solutions and monitoring 4.1 Operational impacts 4.2 Technical solution (shadow module) 4.3 Monitoring 5

6 Directory 1. General background 1.1 Definition of shadow flicker 2. Impact and immission limits 2.1 Legal Framework 2.2 Impacts of shadow flicker 2.3 Immission limits in Germany 3. Assessment of shadow flicker immission 3.1 Prediction methods of shadow flicker 4. Operational impacts, technical solutions and monitoring 4.1 Operational impacts 4.2 Technical solution (shadow module) 4.3 Monitoring 6

7 1. General background 1.1 Definition of shadow flicker The rotation of a WTG rotor might cause a periodic shadowing in neighboring residential areas These shadow flickers are affected by different effects: - Location of the WTG (x, y, z) - Hub height / rotor diameter of the WTG - Location of the place of immission (x, y, z) - Topography and Obstacles - Location of the sun (azimuth / elevation angel) - Duration of a day (sunrise to sunset) - Intensity of solar radiation (clouds) - Wind direction - Wind speed Source: Fichtner (modified) 7

8 Directory 1. General background 1.1 Definition of shadow flicker 2. Impact and immission limits 2.1 Legal Framework 2.2 Impacts of shadow flicker 2.3 Immission limits in Germany 3. Assessment of shadow flicker immission 3.1 Prediction methods of shadow flicker 4. Operational impacts, technical solutions and monitoring 4.1 Operational impacts 4.2 Technical solution (shadow module) 4.3 Monitoring 8

9 2. Impact and immission limits 2.1 Legal Framework Legal Basis: Federal immission Control Act - Prevention of harmful effects on the environment caused by air pollution, noise, vibration and similar phenomena Definitions: Harmful effects on the environment as used herein shall mean any immissions which, because of their nature, extent or duration, are likely to cause hazards, significant disadvantages or significant nuisances to the general public or the neighborhood. Immissions as used herein shall mean any air pollution, noise, vibration, light, heat, radiation and similar effects on the environment which affect human beings, animals and plants, soil, water, the atmosphere as well as cultural objects and other material goods. Detailed references from the Federal / State Working Group for Pollution Control (LAI) are used on an authority level for the specification of requirements. 9

10 2. Impact and immission limits 2.2 Impacts of shadow flicker Shadow flicker is to be considered an immission according to the definition in the law From shadow flicker no direct public health risks arises (other than from noise) Shadow flicker is considered annoying by local residents Determination of materiality thresholds and respective limit values not by law but in technical guidelines Protected property: human being, not animals Source: BWE 10

11 2. Impact and immission limits 2.3 Immission limits in Germany Relevant limit values are based on principals of materiality and have their origin in an investigation of Kiel University. Astronomically maximum shading (worst-case): WTG are continuously operating Sun is shining sufficiently Rotor is in a position perpendicular to the immission point Limit value of astronomically maximum shading: max. 30 hours/year max. 30 minutes/day (for not more than 3 days a year) Limit value of actual shading: max. 8 hours/year max. 30 minutes/day 11

12 2. Impact and immission limits 2.3 Immission limits in Germany Limit values apply for each individual immission point Limit values strictly apply for residential use For working use, including schools, etc. an individual case study must be performed Bad example (Source: betterplan.squarespace.com) Relevant immission points are buildings (with affected windows), but also adjacent areas like e.g. terraces, balconies. No protection provided for stables etc. The limit values are to be observed with respect to total exposure (previous load + additional load = total load) accumulating from all relevant WTG Shadowing only occurs when the elevation angle of the sun is 3 (due to obstacles and light diffusion in the atmosphere) and at least 20% of the sun is covered by the blades (smaller differences in brightness will not cause shadowing). 12

13 Directory 1. General background 1.1 Definition of shadow flicker 2. Impact and immission limits 2.1 Legal Framework 2.2 Impacts of shadow flicker 2.3 Immission limits in Germany 3. Assessment of shadow flicker immission 3.1 Prediction methods of shadow flicker 4. Operational impacts, technical solutions and monitoring 4.1 Operational impacts 4.2 Technical solution (shadow module) 4.3 Monitoring 13

14 3. Assessment of shadow flicker immission 3.1 Prediction methods of shadow flicker During the approval procedure shadow casting impacts have to be calculated. The following points have to be clarified: - Are there residential buildings affected by the planned WTG s shadow immission? - Are those buildings affected by other turbine shadows? - Which is the accumulated maximum shading duration? - Is it possible that the prescribed exposure limits can be exceeded? Prognoses are carried out by means of specialized software solutions (e.g. WindPro) Prognoses have to refer to the astronomically maximum possible duration of shading (the factual shading depends on stochastic parameters e.g. sunshine probability and wind direction probability) 14

15 3. Assessment of shadow flicker immission 3.1 Prediction methods of shadow flicker Basic procedure: - Project set-up (existing/planned WTG, elevation model) - Test calculation for the production of a map with a shading isoline - Identification of affected buildings / setting of receptors - Calculation of astronomically maximum shading duration at all receptors (previous load + additional load = total load) - Compliance verification regarding application of exposure limit values and possibility of exceedance Next to the listing of the expected shading duration at each immission point, it is also possible to produce maps showing isolines or calendars indicating the relevant dates and times. By means of stochastic parameters the actual/probable shading duration can be estimated. 15

16 3. Assessment of shadow flicker immission 16

17 3. Assessment of shadow flicker immission 17

18 Directory 1. General background 1.1 Definition of shadow flicker 2. Impact and immission limits 2.1 Legal Framework 2.2 Impacts of shadow flicker 2.3 Immission limits in Germany 3. Assessment of shadow flicker immission 3.1 Prediction methods of shadow flicker 4. Operational impacts, technical solutions and monitoring 4.1 Operational impacts 4.2 Technical solution (shadow module) 4.3 Monitoring 18

19 4. Operational impacts, technical solutions and monitoring 4.1 Operational impacts If the rotor is not spinning or the sun is not shining no shadow flicker is possible. If at one immission point the limit value is exceeded, the shadow casting WTG(s) has to be shut down. Shutting down turbines leads to yield losses. The resulting losses are strongly depending on the individual project (accumulated hours of exceedance). Normally the losses can be neglected (in the per mill range). The implementation of the shut-down function of wind turbines is technically realized by means of shadow modules IP Shadow duration Shutdown Previous load Additional load Total load Additional load A 10:15 19:45 30:00 00:00 B 00:00 22:48 22:48 00:00 C 00:00 32:15 32:15 02:15 D 29:15 04:35 33:50 03:50 E 45:48 00:00 45:48 00:00 F 31:25 14:54 46:19 14:54 G 00:10 30:00 30:10 00:10 H 04:54 04:47 09:41 00:00 Total (Worst Case) 21:09 Loss (Worst Case) 0,24% 19

20 4. Operational impacts, technical solutions and monitoring 4.2 Technical solution (shadow module) Modern shadow modules independently calculate the shadow casting at each programmed immission point cumulating it over the entire year. If an exceedance of limit values is threatened, the respective WTG is shut down as long as necessary. 1 Shadow module can simultaneously monitor all turbines of a wind farm. Shadow module (Source: Northtec) The exact shape of affected buildings can be programmed in the shadow module (though they are represented as a dot in the prognosis). Normally a light sensor is used to verify the intensity of solar radiation (if it is strong enough I > 120 W/m² to produce shadows). If such a sensor is used, the yearly limit is set to 8 h/year. Light sensor (Source: Northtec) 20

21 4. Operational impacts, technical solutions and monitoring 4.3 Monitoring Project-specific clauses referring to the shadow casting issue are normally part of the approval. The operator has to follow the approval s side conditions - the authorities control their compliance. Normally all data regarding sunshine duration and shut-down times are stored by the turbine. If requested it has to be transferred to the authorities. Additional regulations demand for a regular cleaning of the light sensors. Regarding the proper programming of the shadow module, protocols have to be prepared (observing all immission points according to the side conditions of the approval). 21

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