Wind Report 2 Mike

8/8/2019 Wind Report 2 Mike

http://slidepdf.com/reader/full/wind-report-2-mike 1/27



Outline

ATA wind project origin and objectives

Resource assessment sites

Measurement equipmentWhat is a wind resource assessment and why is it

undertaken?

Key measurement results

A simple model for direct turbine energy yield

Turbulence findings

Key findings of this project



Project origins

ATA 2007 desktop study The Viability of Domestic Wind Turbines for Urban Melbourne

Micro Wind Turbine (MWT) technology focused.The main findings of this report included:

Recommendations to gather representative wind data fromurban locations as a prelude to any MWT installation.

The requirement for verification of turbine power curves withfield testing.



Urban Wind Resource

Assessment Objectives Produce a portrait of wind characteristics at a variety of

urban sites around Melbourne’s CBD based on at least 3

months of wind speed and direction data from each site.• Coastal areas

• Typical built-up urban areas

• Hilly areas

Investigate differences in wind behavior at likely MWT

mounting locations:

• Pitched and flat roofs (building mounted turbines)

• Open yard areas (pole mounted turbines)



Urban Wind Resource

Assessment Objectives The essential role of a wind resource assessment is to

allow for quantification of available wind energy

Measure levels of wind turbulence at these sites.

Correlate ATA data from sites with BOM station data.

All wind resource assessments are wholly specific to thesite where measurements are gathered



Measurement Sites Ten Measurement sites in total:

• Five sites with a roof mounted anemometer and a 10m pole

mounted anemometer in an open yard area.

• Three pitched roofed dwellings.• Two flat roofed dwellings.

• Four of the remaining sites hosted a single anemometer.

• Two flat roofed dwellings.

• One open coastal area.

• One open suburban yard area.

• The single remaining site was a prominent high rise CBD building

that hosted a single ultrasonic anemometer at a height of approx10m above the roof surface.



Measurement Sites

http://maps.google.com.au/)



Edithvale



Anemometers and Masts



ATA Anemometer at

Manningham



Measurement equipment and

duration Min 3 months of 2-D anemometer data from all sites

except the CBD site, consisting of 10 minuteaverages of wind direction and horizontal wind

speed.

An additional minimum of 2 weeks of high speed

(10hz) averaged ultrasonic anemometer data from

most sites. High speed data is necessary for examining rapid changes in wind flow character



Anemometers

APRS World Cup Anemometer

& data logger Gill Windmaster Ultrasonic

Anemometer



Why should we gather

this data? We want to model energy availability.

Pwind =½.ρ.A.v

3

[Pwind]= W=Js-1

• ρ = Air density(kgm-3) (also a function of

temperature, relative humidity and pressure)

• A = Area perpendicular to flow (m2)• v = Flow velocity (ms-1)

We are interested in power density [ Wm-2] available

for turbines to harness. Velocity is the mostimportant variable in determining available wind

power.



Theoretical Wind Power Density

•How do we get to energy estimates from power?



Power, energy and probability

Power has units of energy per second.

Integrate power with respect to time gives us an estimate of

available energy. If we observe wind conditions for long enough we can build a

model of the likelihood of different wind speeds.

If we understand how velocity changes with time at a site, we

can understand how energy availability changes with time at

the site.

How do we model wind probability?



The Weibull Distribution

• We can fit a statistical distribution to our observations.



What makes a suitable

MWT site? Energy production.

Low turbulence levels.

Sites suited for grid connected MWT installation aregenerally considered in the wind industry to require an

average horizontal wind speed of 5 ms-1.

Apart from deriving estimates of wind speed probability

at all sites, what did ATA’s Study reveal?



Summary of Results



Confused?

All this probability and statistics can be hard to grasp.

How about combining the Weibull curves with turbine

power curves (which relate available power to wind

speed) and estimating energy yield? Then we can just

compare single numbers from site to site….

For some context we can compare this to how a

common 1kW rooftop PV system would perform.

This is not intended as a model of actual end user energy yield.



A simple model for direct

turbine energy yield

PV Array modelled using ANU PV performance simulator:

http://solar.anu.edu.au/EduResources/applets/PVPanel/_PVpanel.php



Conclusions so far

• Only the Williamstown and CBD site can be considered

as potential MWT sites if turbines were to be installed at

the measurement heights.

• The remaining sites are likely to operate at low capacity

factors and suffer extended or indefinite financial and

energy payback periods.

• Most typical urban sites around Melbourne are likely to

fall into this category- there simply is not sufficient

available energy density for MWT installation to beattractive. They are highly unlikely to be able to compete

with PV arrays as an embedded generation technology.



Turbulence

Wind turbulence can be described as chaotic, highly

variable and unpredictable air movement.

It is typically characterised by Turbulence Intensity, adimensionless quantity which expresses the relative

change in wind conditions in a time interval.

High levels of turbulence reduce the ability of a turbine to

harness energy from a wind flow, reduce infrastructure

life spans and increase maintenance requirements.

High levels of Turbulence Intensity are undesirable for

turbine installation sites especially when they occur at

high wind speeds.



Turbulence Intensity vs. Wind Speed



Turbulence and Turbine

Performance

There are no established standards for the formulation of

MWT power curves to incorporate TI.

We know that turbulence reduces effectiveness of turbines, but without standardisation we cannot say by

how much.



Comment on Project Objectives Only open areas situated on the coast and high rise

buildings appear promising for MWT installation.

Most sites in built up urban areas appear to be situated

within the turbulent urban boundary layer of wind flow,significantly reducing the quality of the wind resource.

No clear differences in wind energy abundance were

observed at pitched and flat roofs and open areas inyards.

Vertical velocity components were not found to be

significant at all sites. BOM data suggests study covers a windy period.

These findings match those of similar studies performed

elsewhere.



Conclusions

Successfully deploying turbines at sites like the CBD

site, with high levels of turbulence and only modest

available wind energy represent the true challenge of urban wind technology.

The Williamstown site lies on the boundary of the urban

realm and represents wind conditions more akin to those

found at commercial-scale wind farms rather than other

built up domestic sites.

A wind resource assessment is a vital prelude to

installation of a MWT in an urban area.

The wind resource is and will always be site specific.

There is no substitute for gathering real data from a site

of interest.



Most gracious thanks to all site owners,ATA members and ATA employees

who helped out with this project.

Wind Report 2 Mike

Documents

Transcript of Wind Report 2 Mike