ASHENDEN WIND TURBINE TRIAL: PHASE I RESULTS

PROJECT TEAM

London Borough of Southwark: Tony Moseley, Sustainable Development and Infrastructure Manager; Client; data dissemination.

Brian Dunlop Associates and Gas Dynamics Ltd: Planning application; technical co-ordination; instrumentation selection; commissioning; data acquisition software; quality assurance and data processing.

London South Bank University: Prof. Tony Day, Dr. Steve Dance and students. Acoustic and vibration monitoring; analysis and reporting; wind and energy monitoring research programme.

KCCC Ltd: Site survey; design and construction of footings and mounting frame; installation of anemometer mast.

Photon Ltd: Lead installer – construction programme; site manager; turbine assembly; erection and electrical installation

CONTENTS

Introduction

Background

Trial objectives

Target site description

Target site yield predictions

Installation

Results

Yield

Anemometry

Power Curve

Yield reconciliation

Annual yield estimate

Carbon abatement costs

Noise and vibration results

Discharging of planning conditions

INTRODUCTION

The purpose of this pilot wind turbine installation is to assess the viability of deploying small scale roof top turbines across the Elephant and Castle core development area with a view to generating a significant proportion of the Mayor's 10% renewable energy requirement.

CORE DEVELOPMENT AREA SHOWING LOCATION OF ASHENDEN

Phase I of the Ashenden wind turbine trial commenced in June 2007. A Proven 6kW horizontal axis wind turbine (HAWT) was installed on the roof of Ashenden House, an 11 storey residential block within the Heygate estate. This initial phase is now complete.

The performance of the turbine, based on 12 months of monitoring, is assessed in the presentation that follows.NOTE: Phase 2 of the trial commenced in June 2008. The Proven HAWT has been moved to a new location further along the building and a second turbine, the Quiet Revolution QR5 (a vertical axis turbine), installed in its place.

Gas Dynamics Ltd and London South Bank University will continue to monitor the performance of both turbines. The results of Phase 2 will be posted on the Elephant and Castle website at a later date.

New Kent Road

Walw

orth Road

Heygate Street

George Road

Newin

gton

But

ts

TURBINE TRIAL OBJECTIVES

Monitor site specific energy yield

Compare with current prediction methods and manufacturer’s data

Use measured data to refine prediction of energy yield from desk-top studies

Identify impacts of constraints e.g. size, weight, maintenance requirements etc

Obtain acoustic data: pre- and post-installation

Gauge community reaction to deployment of wind turbines on buildings e.g. visual impact

Compare performance of turbine technologies and responses from local community

Dissemination of site specific advice to planners and design teams

TIMELINEPlanning

Planning permission was granted in December 2006. The following files can be downloaded from the website:

• Planning application supporting documentation

• Conditions attached to planning consent

Roofworks

Carried out during March/ April 2007. Construction of concrete footings/ making good roof membrane. Design and fabrication of steel mounting frames.

Turbine Trial

The trial is being conducted in two phases.

Phase 1 (June 2007 – June 2008): COMPLETED

Install the Proven WT6000 turbine above a vacant flat. Monitor wind speed, turbine power, noise and vibration. Analyse data, discharge planning conditions and release preliminary results. A series of photographs documenting the full construction/ turbine erection sequence can be downloaded from the website.

Phase 2 (commenced June 2008)

Relocate the Proven turbine above an occupied flat to make way for the installation of the Quiet Revolution QR5 6kW turbine. Ongoing monitoring of wind speed, power output from both turbines, noise and vibration emanating from the QR5 turbine. Analyse data and release final results.

It is anticipated that at the end of this period the turbines will be demounted and relocated to London South Bank University for ongoing study.

TEST SITE DESCRIPTION

Turbine(s) mounted on a 9m mast on top of an 11 storey tower block.

3-axis ultrasonic anemometer mounted at hub height ~10m from the turbine.

3-axis ultrasonic anemometer

Proven 6kW HAWT

TURBINE DESCRIPTION – PHASE 1

Proven WT 6000 rated at 6kW with a wind speed of 12 m/s 1

Cut-in wind speed of 2.5 m/s 1

Rotor diameter = 5.5m

0 2 4 6 8 10 12 14 16 18 200

1000

2000

3000

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6000

7000

Wind speed (m/s)

Pow

er, W

1 Power curve and data extracted from Catalogue of European Urban Wind Turbine Manufacturers

MOUNTING FRAME

CONSTRUCTION SEQUENCE

1 2 3 4

5 6 7 8 9

10 11

12 13

14

15 16 17

18

19

INSTALLATION COSTS

Roof works(exclusive of VAT) Common

Crane Hire (one visits) £2,150.00

Handrail £8,593.46

Plinths £6,766.48

Sarnafil roofing £6,771.11

Lightning protection £998.89

Walkway £1057.50

Total £26,337.44

Turbine Installation(exclusive of VAT) Common Proven QR5

Turbine, mast, inverter, controller & delivery £19,003.91 £31,925.00

Steel mounting frames (2 nr) £10.826.36

Crane Hire (two visits) £6,336.00

Installation & commissioning £8,500.00

Meeting, site organization, health and safety £995.00

Electrical items £4,433.25

Total £20,264.25 £19,003.91 £31,925.00

TARGET SITE YIELD PREDICTION – WIND ROSE TRANSPOSITION

Essentially a technique for extrapolating wind resource data from one site to another, by correcting for differing terrain and altitude.

1. Using known data at a reference site (Heathrow)

2. Wind speed data is transposed to target site (Elephant & Castle)

YIELD PREDICTIONS – REFERENCE SITE DATA FOR HEATHROW

5%

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20%0

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0 < V (knots) < 4

4 < V (knots) < 8

8 < V (knots) < 12

12 < V (knots) < 16

16 < V (knots)

Average wind speed = 3.96m/s

A = 4.46m/s, k = 1.9

1 2 3 4 5 6 7 8 9 10 1112 1314 15 1617 18 1920 212223 24 250.00

0.02

0.04

0.06

0.08

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0.12

Wind speed (knots)

Prob

abilit

yWind speed distribution modelled using a 2 parameter Weibull function in the form:

Where A is the scale factor and k is the shape parameter

Wind speed distribution based on data supplied by the Met Office for Heathrow for the period Dec 97 to Nov 07

f(u) = k uk-1

A Aexp - u

A

k

ESTIMATED WIND SPEED AND ENERGY YIELD PROFILES FROM DESKTOP STUDY

Upper and lower estimates of wind speed (left plot) and yield (right plot) for the target site.

Estimated average wind speed 4.15 – 4.35 m/s, giving an estimated annual yield figure of between 8,000 and 8,900 kWh.

Wind speed distribution based on data supplied by the Met Office for Heathrow for the period Dec 97 to Nov 07

2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.010

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Wind speed (m/s)

Hei

ght (

m)

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Yield (MWh)

INSTRUMENTATION

Anemometer: 3-axis Gill ultrasonic sensor logging continuously at 1 Hz on a PC.

Multicube multifunction current transformer (CT) meter: Instantaneous power readings logging continuously at 1 Hz on a PC.

Sunny-boy controller: Gross yield readings at ~15 min intervals, downloaded to a PC.

Data analysis performed using SCILAB

Rectifier

Inverter

Sunny-boy controller

CT Meter

Data Acquisition PC

Anemometer comms interface

RESULTS – TURBINE YIELD

Turbine Yield kWh (blue curve) and cumulative capacity factor CF (red curve) for data between June 2007 and June 2008.

The recorded annual yield from 07th June 2007 was 4,200kWh.

7/Jun 27/Jul 15/Sep 4/Nov 24/Dec 12/Feb 2/Apr 22/May 11/Jul0

50010001500200025003000350040004500

time

Yiel

d (k

Wh)

7/Jun 27/Jul 15/Sep 4/Nov 24/Dec 12/Feb 2/Apr 22/May 11/Jul4.55.05.56.06.57.07.58.08.59.0

time

CF

(%)

5%

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25%0

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0 < V (knots) < 4

4 < V (knots) < 8

8 < V (knots) < 12

12 < V (knots) < 16

16 < V (knots)

RESULTS - ANEMOMETRY

Wind rose and wind speed distribution evaluated from all data collected between June 2007 to May 2008 inclusive. Distribution based on hourly averages.

Average wind speed of 3.82 m/s, significantly less than the desktop estimate of 4.15 –4.45m/s. Shape parameter k of 2.24 also much higher than the reference site (Heathrow).

Vmean = 7.4knots

A = 8.4knots, k = 2.24

0 2 4 6 8 10 12 14 16 180.00

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Wind speed, knots

Pro

babi

lity

RESULTS - ANEMOMETRY

Wind rose comparison between the target site at Ashenden(left) and Heathrow (right).

Note: monthly wind roses for the test site are available to download from the website

Ashenden House Heathrow Short Term

AnnualData

Jul 07

Aug 07

5%

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0 < V (knots) < 4

4 < V (knots) < 8

8 < V (knots) < 12

12 < V (knots) < 16

16 < V (knots)

5%10%15%20%25%30%35%40%0

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0 < V (knots) < 4

4 < V (knots) < 88 < V (knots) < 12

12 < V (knots) < 1616 < V (knots)

5%

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25%0

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0 < V (knots) < 44 < V (knots) < 88 < V (knots) < 12

12 < V (knots) < 1616 < V (knots)

5%

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20%0

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150180

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0 < V (knots) < 4

4 < V (knots) < 8

8 < V (knots) < 12

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16 < V (knots)

5%

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25%0

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4 < V (knots) < 8

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16 < V (knots)

5%

10%

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030

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0 < V (knots) < 4

4 < V (knots) < 8

8 < V (knots) < 12

12 < V (knots) < 16

16 < V (knots)

RESULTS – POWER CURVES

0 2 4 6 8 10 120.0

0.1

0.2

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Wind speed (m/s)

Pow

er C

oeffi

cien

t

One minute average data

Black dots denote raw data;

Green curve denotes published power curve;

Red curve denotes mean power in 0.5m/s intervals

Average power coefficient curve

Black curve denotes published power curve;

Red dots denote one hour average in 0.5m/s intervals (limited data points above 8 m/s);

Blue dots denotes one minute average in 0.5m/s intervals;

Green curve represents power curve used to reconstruct yield.

RESULTS – YIELD RECONCILIATION

Annual yield calculation using annual Weibullparameters (A = 8.4 knots, k= 2.24) and the measured average power curve.

Yield using Weibull distribution = 4,051kWh, compared with actual reading from inverters of 4,200kWh

• First plot shows the wind speed distribution in 0.25m/s intervals;

• Second plot shows the published power curve (red) and measured average power curve (blue);

• Third plot shows the yield in each wind speed interval using the published and measured power curve;

• Fourth plot shows the cumulative yield as a function of wind speed using the measured power curve – note that by 8m/s the turbine has generated 90% of the total yield.

Note also that the yield found using the published power curve is around 36% higher than the yield calculated using the measured average power curve.

0 2 4 6 8 10 12 140.000.010.020.030.040.050.06

V (m/s)

dPro

b

0 2 4 6 8 10 12 1401234567

V (m/s)

P (k

W)

0 2 4 6 8 10 12 140

50100150200250300350

V (m/s)

E (k

Wh)

0 2 4 6 8 10 12 140102030405060708090

100110

V (m/s)

Cum

ulat

ive

yiel

d %

RESULTS – ANNUAL YIELD ESTIMATION BASED ON 12 MONTHS DATA

Can we predict the annual yield at the target site in a 'mean' year? i.e. is the wind speed distribution at the target site representative of an average year?

Begin by comparing short-term wind data (from June 2007 to May 2008) with the long-term distribution at the reference site (Heathrow). Plots below (from left to right) show; annual wind speed distribution at Ashenden House; annual wind speed distribution at Heathrow; long-term average distribution at Heathrow. Note that the scale factor for the Heathrow short term data is considerably higher than the long term average.

If the same trend was applied to the Ashenden dataset, the average wind speed would be 3.44m/s, resulting in a mean yield of around 2,800 to 3,050 kWh (cf 4,200kWh in the year to June 2008).

Ashenden House Heathrow Short Term Heathrow Long Term

Vmean = 7.4knots

A = 8.4knots, k = 2.24

0 2 4 6 8 10 12 14 16 180.00

0.02

0.04

0.06

0.08

0.10

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0.18

Wind speed, knots

Prob

abilit

y

Vmean = 8.7knots

A = 9.72knots, k = 1.95

0 2 4 6 8 10 12 14 16 180.00

0.02

0.04

0.06

0.08

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Wind speed (knots)

Prob

abilit

y

Vmean = 7.7knots

A = 8.67knots, k = 1.9

0 2 4 6 8 10 12 14 16 180.00

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Wind speed (knots)

Prob

abilit

y

0 2 4 6 8 10 12 14 16 18 200.0

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0.6

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1.0

1.2

1.4

%Carbon abatement vs Discounted Abatement cost

AEC

Cos

t (£/

kgC

O2)

CARBON ABATEMENT COSTComparison of cost per kg of carbon abated for three renewable energy technologies based on detailed consideration of the available resource and the physical constraints of the Elephant and Castle development:

• roof mounted pv (limited to roof areas receiving 800 – 1000 kWh/m2) MAGENTA LINE;

• 6kW wind turbines (spaced at 5 times diameter apart) RED LINE

• centrally located biomass boilers (i.e. operating as peak load boilers and part of a shared infrastructure feeding an area-wide district heating network) BLACK LINE

Limited by heat demand

Limited by number of fuel deliveries during peak month (10 lorry loads)

Limited by available space in energy centre

KYOCERA KC120-1 120w panels on Solion “Sunmount”(data supplied by LSBU)

BLUE SHADED AREA INDICATES UPPER AND LOWER LIMITS FROM RENEWABLES TOOLKIT

6kW Proven roof mounted turbine (extrapolated from measured data)

NOISE AND VIBRATION STUDYBackground noise study

The plot below shows the 15 minute equivalent noise levels at six sites on and around the target building.

Major source of noise at Ashenden House is the A2. The location is in central London and as such even in the middle of the night there are significant levels of noise.

AB

C Roof topD By the road sideE Garages behind target buildingF 85m behind target building

11th floor bedroom of flat 22311th floor balcony opposite flat 223

NOISE AND VIBRATION STUDY

Turbine noise levels

5minute equivalent noise levels presented as a function of wind speed over a three-day period from 23rd - 25th July 2007.

There appears to be no correlation with wind speed, although further data is required to establish noise levels at higher wind speeds.

NOISE AND VIBRATION STUDY

Vibration Study

Plots show vibration levels for various wind speeds recorded on the turbine frame (bottom plot) and a wall in flat 223, located immediately below the turbine (top plot).

The coloured lines represent the human body's ability to work efficiently under various vibration periods.

In both cases the vibration levels are below the threshold tolerance for continuous working (24hrs).

PHASE I CONCLUSIONS

• Yield well below expectations based on desk top studies using transposed wind data from Heathrow and manufacturer's power curve

• Sources of this discrepancy are 1) the manufacturers power curve which indicated higher power outputs at any given wind speed in particular in the 3m/s to 8m/s range and 2) lower mean wind speed coupled with a tighter distribution around the mean (higher shape factor than Heathrow data)

• No measurable impact on noise levels both externally and within the flat due to operation of the wind turbine

• Vibration levels within the flat are well below the comfort criteria for 24hr working

• Residents supportive of the project. No adverse reaction from occupants or members of the public to date

• Proceed with Phase II