35

thola: VOLUME 16. 2013/14

Figure 1: Estimated bird mortality rates for various wind farms in the United States (National Wind Coordinating Collaborative 2010).

ethekwini’s fi rst wind-energy

project, entitled the ‘Ethekwini

Wind Repowering Project’ was

initiated in 2010 during the lead

up to the COP17 climate-change meeting

hosted by the City. It stems from

collaboration between the Bremen Overseas

Research and Development Association and

the Municipality. Bremen is one of

eThekwini’s ‘twin cities’. The project involves

the transportation of two 150 kW wind

turbines from Bremen to eThekwini and their

installation somewhere in the metropolitan

area. The project has proved to be complex

and fi nding a suitable site in eThekwini has

been challenging. This article highlights

some issues around the impacts of wind

energy on birds and bats, a subject which

many in the Municipality knew little about

prior to the project.

The wind-energy industry has expanded

signifi cantly over the last decade. This

growth looks set to continue as the cost of

wind-energy decreases and the need for

more energy while reducing greenhouse gas

emissions increases. It is forecast that wind-

energy costs will drop substantially in the

future and that wind will become a more

cost-effective solution than traditional coal-

fi red power generation. In the face of

climate change and the associated need to

reduce greenhouse gas emissions, eThekwini

needs to assess the local viability of wind

energy, gain expertise in wind-project

development, and understand the

environmental and technological impacts

and how to mitigate these.

The wind-repowering project received

extensive media focus in the lead up to

COP 17. Much of this attention was due to

the proposed location, the Bluff Military

Base, being near a colony of Egyptian slit-

faced bats. This is not a threatened species

but the colony at the Bluff is the largest in

South Africa. The base is also an important

foraging area for the large-eared free-tailed

bat, which is a more vulnerable species.

Primarily due to pressure from wildlife

groups, the Municipality decided not to use

Bluff as a site for these turbines.

BIRDS AND WIND ENERGyConcern around birds colliding with the

blades of wind turbines has existed since the

1970’s but until the late 1990’s the topic

received little scientifi c attention. The

signifi cance of such bird fatalities was fi rst

pinpointed through experiences from the

Altamont Pass Wind Resource Area, one of

the fi rst regions in the United States to be

Craig Richards of the City’s Energy Office considers the impact of wind energy on birds and bats.

AGAINST THE WIND

Wind Repowering Project

Buff

alo

Mnt

, TN

(‘00

-’03

)

Blue

Sky

Gre

en F

ield

, WI

Lean

ing

Juni

per,

OR

Buff

alo

Ridg

e, M

N (P

h III

; ‘99

)

Map

le R

idge

, NY

(‘06

)

Diab

lo W

inds

, CA

Buff

alo

Ridg

e, M

N (P

h I;

‘96)

Buff

alo

Ridg

e, M

N (P

h II;

‘99)

Stat

elin

e, O

R/W

A (‘

02)

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le R

idge

, NY

(‘07

)

Foot

e Cr

eek

Rim

, WY

(Ph

I; ‘9

9)

Klon

dike

II, O

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Buff

alo

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e, M

N (P

h I;

‘98)

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th G

ap, M

T

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, WV

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03)

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iss,

NY

Nine

Can

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WA

Com

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Hill

s, O

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Horn

, WA

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alo

Ridg

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Ph II

; ‘97

)

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alo

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Ph II

; ‘98

)

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, WY

(Ph

I; ‘0

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, WI

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, WY

(Ph

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, WV

(‘08

)

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s Hi

ll, M

E (‘

08)

Mar

s Hi

ll, M

E (‘

07)

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swor

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High

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ds, C

A (‘

04)

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se, W

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(‘06

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, Alb

(‘0

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, CA

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, OR

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, OR

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of Io

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Wind Energy Facility

14

12

10

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4

2

0

The wind-energy industry has expanded

signifi cantly over the last decade. This

the proposed location, the Bluff Military

Base, being near a colony of Egyptian slit-

of the City’s Energy Office considers the impact of wind energy on birds and bats.

AGAINST THE WIND

5498_Thola_Vol16_FA.indd 35 2014/06/23 6:03 PM

developed for wind-energy on a commercial

scale. Altamont Pass drew attention because

of the number of endangered bird species

involved and the high concentration of wind

turbines (Altamont Pass Avian Monitoring

Team 2008).

Subsequently, numerous studies have

been carried out to assess bird fatalities

caused by wind turbines (e.g. see Figure 1)

and while much is still unknown, our

understanding of the interactions between

wind turbines and birds is improving. Most

studies have indicated that fatality rates are

generally low and that location is a crucial

factor in avoiding bird fatalities.

In assessing wind-energy impacts on

birds it is important to put such fatalities

into context. Figure 2 gives an indication of

bird fatalities due to other human activities.

Such comparisons are often used by wind-

energy backers to oppose the arguments of

conservationists. This can be misleading,

however, as it does not reflect the different

types of birds impacted by each activity,

e.g. factors such as oiling, fishing by-catch,

electrocution and wind turbines can kill

substantial numbers of large, rare and

formally threatened bird species, whereas

casualties through window collisions and

feral cats are typically restricted to smaller,

abundant passerines.

In a similar fashion, bird fatalities from

other traditional energy sources are rarely

compared and fatalities due to wind energy

are often presented without comparing

them with coal or nuclear facilities.

Benjamin Sovacool (2009) attempted to

do this (see Figure 3) and concluded that

fossil fuels represent a threat 17 times

greater to birds than wind energy. This

author makes three very telling conclusions

in his paper:

1. “Firstly, far more detailed, rigorous, and

sophisticated analysis is called for that

takes into account the complexities of the

wind, fossil-fuelled, and nuclear energy

fuel cycles.”

2. “Second, while the avian deaths

attributed to fossil-fuel, wind, and

nuclear power plants do vary, they also

imply that there is no form of electricity

supply completely benign to birds. The

best strategy for preserving avian wildlife,

therefore, would be to encourage the

more efficient use of energy before any

type of new power plant or wind farm

is constructed.”

3. “Third, and perhaps more important, for it

applies to many types of assessment

beyond the electricity sector, is the lesson

that the most visible impacts from a given

technology are not always the most

egregious. Wind turbines seem to present

a significant threat to birds because all of

their negative externalities are

concentrated in one place, while those

from conventional and nuclear fuel cycles

are spread across space and time. Avian

mortality and wind energy has

consequently received far more attention

and research than the avian deaths

associated with coal, oil, natural gas, and

36 Wind Repowering Project

thola: VOLUME 16. 2013/14

Figure 2: Estimated annual bird fatalities in millions of birds in North America stemming from various anthropogenic sources (Barnard 2013).

hunting

fishing by-catch

oil waste pits

oils spills

pesticides

electrocution

cars

wind turbines

high tension wires

communications towers

feral cats

windows

0 100 200 300 400 500 600 700 800 900 1000 Wind Energy Nuclear Power Fossil Fuels

Tota

l Avi

an M

orta

lity

/ Mill

ions

per

Yea

r

Avia

n De

aths

/ Gi

gaw

att-

hour

16

14

12

10

8

6

4

2

0

6

5

4

3

2

1

0

Figure 3: Estimated annual avian mortalities due to wind, nuclear and fossil fuels in the United States (Sovacool 2009).

5498_Thola_Vol16_FA.indd 36 2014/06/23 6:03 PM

nuclear power systems, even though this

study suggests that wind energy may be

the least harmful to birds.”

Although it can be argued that wind may be

less harmful to birds overall because the

impacts of wind energy are highly localised, if

a wind facility is poorly located, say in the

vicinity of populations of a threatened or

endemic species, e.g. Cape and Bearded

vultures, it could represent a significant threat

to avian biodiversity (Subramanian 2012).

BATS AND WIND ENERGyWhile the issue of birds has been around for

some time, the problem relevant to bats is

newer and even more poorly understood. In

fact, it is not even certain what causes bat

fatalities associated with wind farms and in

many ways the wind industry has highlighted

how little we know about these animals,

particularly in South Africa.

The prevailing current theory as to why

bats are particularly vulnerable to wind-

turbine fatalities is related to the low-

pressure zone behind a rotating turbine

blade which causes the bat’s lungs to

expand rapidly – a phenomenon known a

barotrauma – causing internal bleeding

which can be fatal. The alternative theory,

supported by the most recent research, is

simply that direct turbine strikes are primarily

responsible for most bat deaths.

Bat turbine fatalities are strongly related to

the bat species involved – it seems that some

bats are far more vulnerable than others. Of

fatalities recorded in North America, 11 of

the 45 species inhabiting this continent were

involved. In the United States, more than

75% of all collisions involved foliage-roosting

eastern red bats, hoary bats and the tree-

cavity-dwelling silver-haired bats. The

available information seems to indicate that

migrant bat species in particular seem to be

most vulnerable to wind-turbine fatalities.

IMPACT ON BAT AND BIRD SPECIES IN KZNBecause impacts appear to be very specific to

species, findings from one study cannot

simply be extrapolated to another, particularly

when these projects are in different regions.

This means that many of the findings from

international studies may not be applicable to

South Africa. Taking this further, findings from

the western and southern Cape, where most

of the wind-energy development in South

Africa is currently occurring, cannot be applied

willy-nilly to the eastern regions of the

country. This means that when attention

begins to shift to areas like KwaZulu-Natal,

the lack of information available on bird and

bat impacts on species specific to this province

may become a major barrier to the effective

roll-out of wind energy.

While small, the Ethekwini Wind Repowering

Project aims to gather sound scientific data

on the impacts of birds and bats in a local

context. This will be achieved by recording the

pre-existing conditions on the site selected

through a pre-construction monitoring

program and measuring the impacts thereafter

through a similar post-construction program. In

addition to this, the experience gained by the

Municipality regarding wind-energy

development and related environmental issues

should improve policy development, legislation

and spatial planning, which will benefit project

developers and conservationists alike.

37

thola: VOLUME 16. 2013/14

References:

Altamont Pass Avian Monitoring Team. 2008. Altamont Pass Wind Resource Area Bird Fatality Study. July. (ICF J&S 61119.06.) Portland, OR. Prepared for Altamont County Community Development Agency.

Barnard. M. 2013 “How significant is bird and bat mortality due to wind turbines?” Available online: http://barnardonwind.com/2013/02/15/how-significant-is-bird-and-bat-mortality-due-to-wind-turbines/.

National Wind Coordinating Collaborative. 2010. Wind turbine interactions with birds, bats and their habitats.” Available online: http://nationalwind.org/wp-content/uploads/assets/publications/Birds_and_Bats_Fact_Sheet_.pdf.

Sovacool, B.K. 2009. Contextualising avian mortality: a preliminary appraisal of bird and bat fatalities from wind, fossil-fuel, and nuclear electricity. Energy Policy 37: 2241-2248.

Subramanian, M. 2012. The trouble with turbines: an ill wind. Nature 486: 310-311. [Available online: http://www.nature.com/news/the-trouble-with-turbines-an-ill-wind-1.10849.

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5498_Thola_Vol16_FA.indd 37 2014/06/23 6:03 PM