Urban wind, urban legend?

Transcription

1 Urban wind, urban legend? Mark Runacres Vrije Universiteit Brussel Collaborators: T. De Troyer, Q. Deltenre, J. Vermeir Oct 2017

2 Overview Introduc)on Economic viability Case study Comparison of urban wind and solar PV Impact, in par)cular vibra)ons Conclusions 2

3 Wind energy has great potential Wind has the poten)al to provide % of European electricity 3

4 Wind power is diffuse, cities are compact Wind energy has low power produc)on per land area: ~ 1-3 W/m 2 can be higher for offshore, but 6 W/m 2 is excep)onal Ci)es have high power use per land area: W/m 2 (150 W/m 2 for Mumbai) Urban wind energy will not provide a large frac)on of the energy needs of any major city 4

5 Renewable energy will need to be everywhere There is no such thing as centralised genera)on of renewable energy En)rely non-fossil, non-nuclear electricity produc)on of electricity means living around power plants 5

6 Why bother? Bringing power produc)on closer can create awareness and goodwill There is unused space in ci)es: roosops above all If there is wind (= big if), this space may be used for wind turbines Wind turbines can be easily combined with other roosop users 6

7 Central question of this contribution Can wind energy produce local electricity in an urban area in a economically viable manner safely with limited impact on surroundings? Feasibility depends on viability and impact 7

8 Feasibility of a small or medium wind turbine (SMWT) project Economic viability: measured with a metric such as levelised cost of energy (LCOE) payback period internal rate of return (IRR) secondary benefits (e.g. greening of company image) have tangible monetary value Impact: safety, shadow flicker, noise, vibra)ons, biodiversity, air traffic 8

9 Urban wind viability Turbine choice Resource assessment Turbine microsi)ng Installa)on 9

10 Viability: quality varies 10

11 Viability: knowing the market is crucial VUB data base of small wind turbines Turbines < 100 kw > 750 turbines Most extensive survey to date HAWT VAWT Other concepts 11

12 Viability: challenge of small wind turbines Low-cost low budget for resource assessment, micro-si)ng and feasibility Generally complex environment 12

13 Wind potential in Brussels: global wind conditions Wind maps based on terrain informa)on and meteo data Figure!1:!Roughness!map!(left)!and!wind!speed!at!10!m!above!mean!building!height!(right)!for!the!Brussels! Region.! 13

14 Measurement campaigns on 6 sites (and on-going) Case study: The Hotel building height 94 m over 1 yr of measurements average wind speed: 5.8 m/s This is comparable to the wind at the Belgian coast (at normal hub height) 14

15 What would a wind turbine on The Hotel produce? The Hotel: Yearly produc)on for a 10 kw rated turbine: kwh/yr for a 3 kw rated turbine: 8170 kwh/yr (Based on independently measured power curves) Dynamic payback )me SME: 7 yr for 3 kw rated (10-12 yr without support) 15

16 Other Brussels locations: results Other high-rises (Manhakan-tower): comparable results Lower buildings (40 m): condi)ons much less favourable Unclear: poten)al for medium-sized turbines in semi-open terrain 12 m above ground (typical hub height < 15 m): mean wind speed 3.7 m/s comparable to Schoondijke (Zeeland) 16

17 Comparison of wind and PV: AEP AEP [kwh] PV WT 8 m/s 7 m/s 6 m/s 5 m/s 2 4 m/s m 2 of roof surface 17

18 Comparison of wind and PV: LCOE PV WT 4 m/s 0.4 LCOE [EUR/kWh] m/s m/s 7 m/s 8 m/s m 2 of roof surface 18

19 Technical feasibility and impact Turbine should not affect structural health of building Impact on occupants and surrounding should be negligible Impact on air traffic should be negligible Impact on biodiversity should be negligible Portland, Oregon (2009) 19

20 Impact: characterisation of vibrations Vibra)on measurements on small wind turbine (ground mounted) Three turbines, different loca)ons The vibra)on data of these turbines are then combined with wind measurements on roosops and with building models 20

21 Impact: characterisation of vibrations Acceleration PSD (m/s 2 ) m/s 3 5 m/s 5 7 m/s 7 9 m/s Vibra)on spectrum only weakly dependent on wind speed Some increased damping at higher wind speeds (aero damping, fore-as in par)cular) Frequency (Hz) 21

22 Impact: characterisation of vibrations What about different turbines? Dominant modes are from the mast, which has roughly standard dimensions and usually similar s)ffness (steel) so dominant frequencies vary likle over different types of HAWT So vibra)ons are quite generic (independent of wind speed and turbine type) 22

23 Impact: structural impact of vibrations Vibra)on measurements combined with building model Structural impact negligible if wind turbine is mounted on the suppor)ng structure of the building Local reinforcements may be necessary when turbine mounted away from suppor)ng column Damping methods will mainly address possible acous)c issues, rather than structural (vibra)ons above ~ 50 Hz). Dallas, Texas (2011) 23

24 Impact: conclusions Structural effect of vibra)ons: very limited Shadow: within Belgian guidelines Visual impact Noise: direct: inaudible through vibra)ons: inves)ga)on ongoing Biodiversity: likle impact 24

25 Conclusions If done right, urban wind energy can be economically viable, with limited impact Urban wind won t save the world In terms of AEP, urban wind can compete with solar PV, essen)ally on cramped windy roosops In terms of LCOE, urban wind cannot compete 25