Does Transmission Technology Influence Acceptance of Overhead

Power Lines? An Empirical Study

Barbara S. Zaunbrecher

, Marco Stieneker

, Rik W. De Doncker

and Martina Ziefle

Human-Computer Interaction Center (HCIC), Chair for Communication Science, RWTH Aachen University,

Campus Boulevard 57, 52074 Aachen, Germany

Institute for Power Generation and Storage Systems (PGS), E.ON Energy Research Center, RWTH Aachen University,

Mathieustr. 10, 52074 Aachen, Germany

Keywords: Transmission Lines, DC Grid, AC Grid, Social Acceptance, Public Perception, Information.

Abstract: For the transmission of electricity across long distances, high voltage direct current (DC) transmission is

discussed in Germany as an alternative to the currently used alternating current (AC) as it is more efficient

for these distances. Changes in energy infrastructure are known to raise public awareness. However, little is

known whether differences in transmission technology are relevant for the public and if so, to what extent.

Two consecutive empirical studies were run in which acceptance towards transmission lines operated with

DC in contrast to AC was explored. AC and DC power lines were not evaluated differently, yielding overall

quite neutral ratings (Study 1) which might be due to a low information level in the public. A closer look

(Study 2) showed that giving information on technical and design parameters of the transmission lines used

for either AC or DC technology also did not change attitudes substantially. It is therefore concluded that

transmission technology alone did not influence acceptance of power lines for the investigated sample. In

addition, a need for more information on DC for high voltage transmission was identified. Further research

is required on the influence of different power line layout of AC and DC on acceptance.

1 INTRODUCTION

In Germany, the goal to have a quota of at least 80%

of renewable energies in electricity production until

2050 (German Renewable Energies Act (EEG),

2014) poses challenges to the current grid, not only

with respect to the grid structure itself but also to the

geography of transmission networks. The distributed

electricity production from renewable energies and

its far-off consumption requires a grid that is capable

of long-distance transmission.

Electrical transmission grids allow highly

efficient transporting of electrical energy over long

distances. But high-voltage alternating current

transmission (HVAC) suffers from losses due to

reactive-power demand (which requires reactive

VAR compensation or over-designing the

infrastructure) or skin effects, for example. These

losses can be compensated if transmission lines are

operated with high-voltage direct current (HVDC).

HVDC, however, has the disadvantage that power-

electronic converters are required to transform AC

into DC and then DC back into AC, which causes

investment costs and losses. Also, HVDC converter

stations are bigger than transformers and auxiliary

equipment may be required for HVAC transmission.

HVDC is nonetheless superior to HVAC for long

transmission lengths, especially for cable grids.

Because transmission lines operated with AC

technology have faced considerable public

opposition in the past (Cotton and Devine-Wright,

2013; Zaunbrecher et al., 2015), the question arises

if the integration of DC technology into the grid will

face the same opposition. From a technology

acceptance point of view, it is unclear which

outcome and argumentation line residents would

follow. Basically, different outcomes might be

assumed: One possibility is that changes towards DC

technology might achieve greater acceptance among

residents, as it is more efficient for long distance

transfer. Besides, electro-magnetic fields (EMF) do

not occur in DC transmission and, on top,

transmission lines operated with DC are more

compact (doubling the power as compared to AC

transmission, Clerici et al. (1991)) thus reducing the

visual impact on the landscape. This outcome would

Zaunbrecher, B., Stieneker, M., Doncker, R. and Zieﬂe, M.

Does Transmission Technology Inﬂuence Acceptance of Overhead Power Lines? An Empirical Study.

In Proceedings of the 5th International Conference on Smart Cities and Green ICT Systems (SMARTGREENS 2016), pages 189-200

ISBN: 978-989-758-184-7

189

reflect a quite mature understanding among

laypeople. The second outcome could relate to a

more negative attitude, referring to residents’

general aloofness to infrastructure changes in terms

of supergrids (Van Hertem and Ghandhari, 2010). In

this context it is pivotal to learn which features of

the infrastructure receive public attention. For

electricity grids it has been shown (Devine-Wright et

al., 2010) that elements belonging to a grid and

which are not visible are rarely associated with it, as

people rather rely on concrete objects such as fuses,

cables, etc. when describing their ideas of electricity

transmission. It is thus possible that for the

acceptance of transmission lines, from a layperson’s

point of view, transmission type does not play a

decisive role, because it refers to a rather abstract

concept and, furthermore, is hardly visible at all.

For a successful gird expansion, adequate

communication is vital (Apt and Fischhoff, 2006).

Hence, it is necessary to know what matters, what is

relevant to residents, and which information they

need to participate in the dialogue about grid

expansion. In this context, a basic question is if

information and knowledge play a mediating role for

acceptance. First of all, it is therefore essential to

come to an understanding how informed the general

public is about AC and DC transmission. Second, it

should be investigated whether a change of

transmission technology changes the attitude and

acceptance towards transmission lines. Third, the

question will be answered in how far information on

the two technologies influences preferences for one

or the other technology. For these purposes, two

empirical studies were conducted in which the role

of the transmission technology for the acceptance of

power lines (Study 1) and the relation between level

of information and other, attitudinal factors about

the technologies, and social acceptance (Study 2) is

investigated.

2 ELECTRICITY

TRANSMISSION

The high efficiency of transmission grids that

transport electrical energy over long distances is

important to ensure the economic operation of the

system. Thus, the operation voltage is increased to

reduce the current and hence the ohmic losses due to

resistance of the conductor. In conventional systems

operated with AC, transformers are used to step up

the voltage level for transmission. Afterwards,

overhead lines (OHL) or power cables are used for

energy transport. However, limitations are given due

to the reactive power demand of OHL and power

cables (“ABB review Special Report: 60 years of

HVDC,” 2014). Reactive power results from

alternating electromagnetic fields that occur if OHL

and power cables are operated with AC and

increases with transmission length. Hence, the

conductor (OHL or cable) does not only have to

carry the active current that contributes to the power

transfer but also the additional reactive current. This

reactive current also loads the conductor and causes

ohmic losses. Furthermore, the reactive current

reduces the active power-transfer capability of the

OHL and power cable (“ABB review Special

Report: 60 years of HVDC,” 2014; Song-Manguelle,

et al., 2013).

The maximum length of OHL and

especially of power cables to transport a certain

power is limited due to the reactive power demand

when the system is operated with AC. Since power

cables have a higher reactive power demand than

OHL, the maximum possible AC transmission

length is shorter.

However, the reactive power

demand of OHL and power cables can be reduced by

compensation measures. But these additional

components cause additional investment costs and

losses. If DC is used instead of AC, the maximum

transmission length is not limited since the reactive

power demand of OHL and power cables vanishes.

The omission of reactive power is a great

advantage of DC transmission systems. In this case,

the conductive material is not unnecessarily loaded

with reactive current. Furthermore, the utilization of

the conductor is improved since the skin effect,

causing an unequal current density in the cross-

section of the wire and leading to higher ohmic

losses, disappears with DC. Hence, ohmic losses are

reduced and the efficiency of the OHL and power

cable is improved in this case.

Today, HVDC

transmission systems (Flourentzou et al., 2009;

Bahrman and Johnson, 2007) are embedded in an

existing AC grid infrastructure. Therefore, power-

electronic converters have to be applied to convert

AC into DC and vice versa (Figure 1).

Since the power-electronic converters lead to

additional investment costs and power loss, HVDC

systems compete with HVAC systems with

increasing transmission length.

Figure 1: Schematic of a HVDC transmission system.

The transmission length where DC becomes superior

to AC depends on whether OHL or power cables are

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applied. Since the reactive power demand of power

cables is higher than of OHL, HVDC becomes more

economical for transmission lengths above 50 – 80

km (Glasdam et al., 2012; Lundberg, 2006), whereas

transmission systems based on OHL are more

efficient with AC for transmission lengths up to 500

– 800 km (Meah and Ula, 2007). However, due to

decreasing costs for power-electronic converters (De

Doncker, 2014), a further reduction of the break-

even is expected. Also, DC transmission differs from

AC in the infrastructure needed in two aspects:

On the one hand, the HVDC converter stations

that impact the characteristic landscape are larger

than transformers needed for AC. For example, a

1,200 MW converter station has a footprint of 120 x

150 m

and is 20 m high (“ABB review Special

Report: 60 years of HVDC,” 2014). On the other

hand, since transport capacities of DC transmission

systems are not wasted for reactive power, the size

of OHL and power cable routes can be reduced. It is

shown in Figure 2 that the space requirement of

HVDC OHL can be halved compared with HVAC.

If power cables are applied, pylons do not even

impact the scenery.

Figure 2: Space requirement of AC and DC overhead lines

(“ABB review Special Report: 60 years of HVDC,” 2014).

Figure 3: Exemplary trench width for power-cable

transmission (Hofmann, 2015).

Furthermore, due to the lower number of power

cables and higher power capability with DC, the

width of the trenches can be reduced as shown

exemplarily in Figure 3.

The characteristics discussed so far are relevant

for grid expansion and modification. The question

remains if they are also relevant from an acceptance

point of view, especially from the perspective of

laypeople, as they represent the majority of residents

and form public acceptance.

3 FACTORS INFLUENCING

ACCEPTANCE OF

TRANSMISSION LINES

From a social science point of view, energy

infrastructure poses challenges to existing

technology acceptance models like, for example,

TAM (Venkatesh and Bala, 2008) and UTAUT

(Venkatesh et al., 2003) for various reasons:

Infrastructure changes influence space and landscape

to a great extent, thus being subject to, e.g.,

influences of place attachment (Devine-Wright,

2013). They represent systems which are a lot more

abstract, thus more complex to grasp and to gain an

understanding of (Cohen et al., 2014; Kowalewski et

al., 2014). In addition, especially in the context of

renewable energies and connected grid expansion,

acceptance of the infrastructure is often impacted by

attitudes and personal norms (Huijts et al., 2012),

such as

risks and benefits, positive and negative

attitudes towards the technology, trust, but also the

assumed costs for infrastructure changes or

procedural and distributive fairness.

With the turn towards renewable energies, social

acceptance of the infrastructure needed to achieve

the ambitious goals has therefore become the focus

of a large strand of research. It has become clear that

without sufficient support by the public, it will be

very difficult to put the energy reconversion

(“Energiewende”) into practice (Wüstenhagen et al.,

2007). However, even though this might be essential

from a technical point of view, convincing the public

in terms of marketing issues might not be the most

successful way. Rather, understanding the nature of

solicitudes and the specificity of argumentation

patterns in line with a persons’ cognitive concept

about a technology is essential in order to develop

individually-tailored information or communication

strategies.

As has been pointed out, the extension or

modification of the grid plays a vital part in the

energy reconversion, and therefore, public attitudes

to transmission lines have come into focus in the

recent public and scientific discussion.

Does Transmission Technology Inﬂuence Acceptance of Overhead Power Lines? An Empirical Study

191

When a new transmission line is planned, in

some cases affected residents protested and formed

civil action groups. These actions delayed grid

expansion over many decades. Arguments by

opposing groups often state that transmission lines

might spoil the landscape (Atkinson, 2006).

A recent study (Zaunbrecher et al., 2015)

revealed that the relative location of the pylon and

the distance to people’s own home is of vital

importance for acceptance and the willingness to

tolerate electricity pylons near residents area of

living. Interestingly, health consequences are

evaluated much more important than the availability

of compensation payments, corroborating previous

findings (Jay, 2007) which shows that acceptance

cannot simply be “bought”. Consequences for nature

and health (Priestley and Evans, 1996), notably by

electromagnetic fields (EMF), is another argument

against transmission lines that is frequently cited by

residents (Cotton and Devine-Wright, 2013).

According to Claassen et al. (2016), what is most

important concerning this topic is a clear

communication about the current scientific

uncertainty about health risks caused by EMF, as

well as raising awareness about exposure to EMF

not only from transmission lines, but also from

sources in daily life, so as to counterbalance the

overestimation of EMF exposure from transmission

lines. Connected to the issue of EMF and visual

disamenities is the worry of a decrease of property

values of adjacent houses (Furby et al., 1988).

In Germany, most of the high-voltage

transmission lines are operated with AC. However,

DC is currently being discussed as an alternative due

to a higher effectiveness for long-distance transfer.

Because of the different characteristics, for example

the number of power lines, it is of interest if social

acceptance is influenced by a change of transmission

technology. Little is known so far about this issue,

which is also connected to the question if

information levels and knowledge about grid

technologies has an influence on acceptance. A

number of studies have addressed public knowledge

and knowledge of laypeople about transmission

lines.

Aas et al. (2014) investigated perceived

knowledge about electric power line systems and

their operators across three countries, and found

overall low familiarity. Besides, they found

(although low) significant correlations between

perceived familiarity and acceptance, calling for

further investigation of the relation between

knowledge, perceived familiarity and acceptance.

The fact that there is little knowledge in the general

public about the electricity network, its functionality

and responsible institutions was also underlined by a

further study in the UK, in which participants also

sought other types of networks (railway, mobile

communication) as references for comparison

(Devine-Wright and Devine-Wright, 2009).

While participation has been identified as a

means to create knowledge in the general public

(Ciupuliga and Cuppen, 2013), a lack of information

was found to be connected to negative feelings

concerning the opportunity of locals to influence

decision processes in the context of transmission line

siting (Cotton and Devine-Wright, 2011).

Although transmission lines and their social

acceptance have been researched in depth, and a

variety of influential factors have been identified,

ranging from design to social issues, technical

specifications and their influence on acceptance

have remained under-researched. The current study

aims to shed some light on the role of transmission

technology for acceptance of transmission lines by

means of two empirical studies.

4 QUESTIONS ADDRESSED AND

LOGIC OF EMPIRICAL

PROCEDURE

AC and DC technology have not been addressed in

contrast from a social science point of view in the

context of the grid in any of the studies conducted so

far. Investigating whether acceptance changes based

on the transmission technology used is a pressing

question for grid operators and electrical engineers

concerned with the expansion of the grid. In this

context, the social representation of electricity

network technologies (Devine-Wright and Devine-

Wright, 2009) comes into focus and the question if

mental models of residents do differ with respect to

the way electricity is transferred. It could very well

be that respondents are indifferent towards the

different technologies because of a lack of

knowledge or because they simply do not care and

focus more on infrastructure characteristics in terms

of overhead transmission vs. underground cable.

In order to understand if acceptance differences

can be expected, two empirical studies were

executed. In the first study, no further information

about AC and DC technologies was given, thus

capturing the unbiased evaluation and acceptance of

transmission lines operated with either of the two

technologies. In the second study, in contrast,

acceptance of AC and DC transmission was

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measured after information on both technologies

was given to the participants.

5 STUDY 1: ACCEPTANCE OF AC

VS. DC TRANSMISSION LINES

In study 1, the goal was to analyze how the

acceptance of a transmission line would change if

instead of AC, DC technology would be used. In this

first study, no prior information about the

technologies was given to the participants as to

investigate the acceptance of the two technologies

based on their current state of knowledge, without

being influenced by additional information. This

exploratory procedure allowed – beyond capturing

unbiased public view on AC and DC technologies -

to assess the current state of knowledge on both

technologies in the general public.

5.1 Methodology

In order to reach a broad range of participants, an

online questionnaire was designed and distributed

via social networks and online discussion forums.

The questionnaire contained three major parts. In the

first part, generic demographic information of the

participants was gathered (age, gender, area of

living, and highest educational degree).

The second part addressed the technical

expertise, including knowledge about electricity and

participants’ personal attitude towards technologies

(ATT) in general. Participants were asked to indicate

(on a six-point scale) from “expert” to “layperson”

how they would classify themselves in the fields of

electricity and technology in general. They also

answered five questions on attitude towards

technology (ATT) which were based on Karrer et al.

(2009) but formulated more generally, because they

were used in the context of technology infrastructure

rather than technical devices in this study.

• “I am interested in technology”

• “Using technology is easy for me”

• “I don’t trust technology in general”

• “I have fun using technology”

• “I avoid technology whenever possible”

For each participant, a mean score for ATT was

calculated for which negatively formulated items

were recoded (Cronbach’s alpha (CA) =0.85). High

scores thus indicated positive attitude towards

technology. While the first two parts of the study

were used to gain an understanding of the sample, in

the third part, the knowledge and acceptance of AC

and DC transmission lines was in the focus. The

perceived knowledge and information on AC and

DC technology as well as on grid expansion was

assessed using the following items:

• “I feel well informed about AC technology”

• “I feel well informed about DC technology”

• “I feel well informed about the grid expansion in

general”

• “I would like to know more about AC”

• “I would like to know more about DC”

Items were answered on a 6-point Likert scale (1=

do not agree at all, 6= fully agree).

Further eight items were given to measure

acceptance towards AC transmission lines, five of

which referred to characteristics of power lines

(CA=0.81) and three to attitude towards them

(CA=0.86), (cf. Figures 3 and 4). The same set of

items was repeated in a scenario in which DC

technology was used (CA characteristics=0.74, CA

attitudes=0.77). The items were selected to represent

the most prevailing arguments in the discussion on

pylon acceptance, such as health concerns (Jay,

2007; Claassen et al., 2012) and impact on landscape

(Navrud et al., 2008; Soini et al., 2011), as well as

items on potential for protest and general

acceptance. All questions were answered on a 6-

point Likert scale (1= do not agree at all, 6= fully

agree), unless indicated otherwise.

For analysis, the statistical software SPSS was

used. The confidence level was set at 5%. Not all

participants filled out the questionnaire completely,

thus pairwise exclusion of missing values was used

when necessary.

5.2 Sample

Overall, 109 participants fully completed the

questionnaire and were included in statistical

analyses (largely incomplete answers were

excluded).

Demographic information: 47% of the

participants were female, 53% male. The mean age

was 33.2 years (SD=15.6), age ranged from 18 to 81

years. 54% had completed university education,

further 28% had obtained a qualification for

university entrance. 45% lived in a city center, 23%

in the outskirts, and 32% in a village. 11.9% lived

near transmission lines. 12.8% of the participants

had a technically-oriented occupation, 34.5% a non-

technical occupation (51.5% could not be specified,

as respondents had answered generically, e.g.,

“student” or “self-employed,” 9.2% did not disclose

this information).

Technology expertise: On a scale of 1

Does Transmission Technology Inﬂuence Acceptance of Overhead Power Lines? An Empirical Study

193

(layperson) to 6 (expert), 59.6% classified

themselves as “electricity laypeople,” while only one

participant reported to be an “electricity expert.”

Five participants (4.6%) found they were “technical

experts”, compared to 32 (29.6%) who found they

were “technical laypeople”. Mean score for ATT

was 4.4 (SD=1.0, Max: 6). Over all, the sample

under study had a rather positive attitude towards

technologies, but was not too confident about their

expertise regarding electricity.

5.3 Results

First, results of the level of information and interest

in AC and DC technology are presented. Then, the

acceptance regarding the “AC transmission line” and

“DC transmission line” is compared.

Information and interest in AC und DC

Technology:

The subjective level of information was equally low

for both AC and DC transmission (both: M=2.4,

SD=1.4), which was also true for perceived level of

information on the expansion of the grid (M=2.4,

SD=1.3). Participants expressed their interest in

more information on the two technologies (both:

AC: M=4.0, SD=1.3).

Acceptance of AC vs. DC technology:

In a next step, from the eight items measuring

acceptance of AC and DC transmission lines, means

were calculated for the factors “attitude” and

“ascribed characteristics” for both AC and DC

technology (negatively worded items included in

reversed order). Results are displayed in Table 1. It

can be seen that attitudes and ascribed characteristics

were the very same in the AC and DC scenario.

Table 1: Means for attitude towards DC and AC

transmission lines and means for ascribed characteristics.

DC AC

Attitudes

M=4.0 (SD=1.1) M=4.0 (SD=1.2)

Characteristics

ascribed

M=3.7 (SD=0.9) M=3.7 (SD=1.0)

By comparing the agreement to the statements in AC

and DC settings (using paired samples t-tests), it was

examined whether the acceptance for transmission

lines operated with AC or DC technologies was

different. Outcomes are given in Figure 4 and 5.

Two things are noticeable: One is that AC and DC

technologies are not evaluated differently:

Transmission lines do not raise strong acceptance

concerns, but evoke a neutral if not indifferent

public opinion.

Figure 4: Ascribed characteristics to AC and DC

transmission lines.

Figure 5: Attitude towards AC and DC transmission lines.

The second point refers to the bias towards the

middle of the scale of participants’ answers here.

Most of the answers were oriented towards the

middle of the scale, with no clear opinion towards

the transmission lines operated with either of the two

technologies.

From these results, it is inferred that transmission

technology does not change attitudes towards or

perceptions of transmission lines. However, it still

remained unclear whether the indecisiveness was the

result of lack of knowledge or of indifference

towards the transmission mode.

Further analyses into attitudinal factors on

expertise and their relationship to attitude and

perception were conducted by using Spearman

correlations to gain insights into other possible

influential factors on acceptance. Table 2 shows the

Spearman correlations between attributes of

technical expertise and attitude towards and

acceptance of AC and DC transmission lines. It was

found that especially ATT correlated weakly but

significantly and consistently with all factors,

123456

I fear health problems caused

by this TL

(AC/DC) TL spoil the

landscape

I think new (AC/DC) TL are

useful

I reject new (AC/DC) TL

because of their visual impact

on the landscape

I think (AC/DC) TL are not

dangerous

do not fully

agree at all agree

AC DC

123456

I would protest against this

I would accept this TL

I am against new (AC/DC)

TL in general

do not fully

agree at all agree

AC DC

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194

suggesting an increase in acceptance of AC and DC

transmission lines with increasingly positive

attitudes towards technology.

Table 2: Correlations between attributes of technical

expertise and perception of AC and DC transmission lines

in study 1. *p≤ 0.05, **p≤ 0.01, ***p≤ 0.001.

attitude

charac.

ATT

0.35***

(n=109)

0.36***

(n=109)

0.36***

(n=109)

0.23*

(n=109)

Elec.

expert

0.28***

(n=108)

0.18

(n=108)

0.30***

(n=108)

0.07

(n=108)

Techn.

expert

0.28**

(n=108)

0.25**

(n=108)

0.32***

(n=108)

0.17

(n=108)

informed

0.22*

(n=109)

0.19

(n=109)

0.24*

(n=109)

0.09

(n=109)

informed

0.22*

(n=109)

0.18

(n=109)

0.24*

(n=109)

0.08

(n=109)

5.4 Summary

The results of study 1 indicated that incidentally

selected laypeople participants do not differ in their

attitude towards transmission lines operated with AC

or DC technology. As the overall level of

information and expertise on the topic had been

quite low in the sample, this could well be an effect

of a lack of information. Technical expertise and

participants’ attitudes towards technology on the

other hand, were positively related to acceptance and

perception. In order to gain further insights into the

role of the level of information and expertise for the

perception of AC and DC transmission, a second

study was conducted.

6 STUDY 2: ROLE OF

INFORMATION ON THE

ACCPETANCE OF AC VS. DC

TRANSMISSION LINES

In study 2, the objective was to examine if

participants differed in their acceptance of AC and

DC transmission lines when they are informed about

the technical characteristics of both technologies.

The study design therefore included a section with

detailed information on both technologies before

participants were asked the set of items about AC

and DC transmission lines. It was also taken care

that the second study was distributed more

frequently among technically oriented persons (by

education, occupation, etc.), to investigate further

the relationship between general technology

expertise and transmission technology perception.

6.1 Methodology

For reasons of comparison, the questionnaire used

was that of study 1, with some alterations regarding

the information given on the technologies. In

contrast to study 1, the second survey contained a

text with information about the two kinds of

electricity transmission. The text addressed

technical, financial, environmental, and health issues

and how the two technologies differed in those

respects and was written in a non-technical style:

Technology: So far, the transmission of energy using

alternating current (AC) was the only option,

because the technology did not offer the possibility

to increase the current of direct current (DC) to such

an extent that transmission was possible. Nowadays,

however, DC and AC converters can convert

electricity in a suitable form and feed it into the grid.

One of the advantages of DC HVL is the reduced

number of power lines (2 instead of 3), thus saving

material. Besides, transmission via DC is more

efficient from 600km onwards, as there are no losses

like in AC transmission.

Health: In contrast to AC, transmission lines

operated with DC do not create an electro-magnetic

field, only a magnetic field which is similar to that

of the earth. No medical studies have to date

confirmed that there are health risks to be expected

from fields induced by AC, but should this be an

issue in future, only lines operated with AC would

be subject to debate.

Costs: Transmission via AC is economically

efficient up to 600 km. From 600 km onwards, DC

is more economically efficient in transport, as the

energy losses are lower.

The validity and quality of the information was

checked by experts prior to the study. It was taken

care that both AC and DC were presented in an

objective manner. A pre-test with laypeople (n=8)

was performed to ensure comprehensibility of the

information

. After the information text in the

questionnaire, participants were again presented first

with the scenario with DC, then with AC

technology, and asked for their agreement to various

statements (items see Study 1).

Subjective level of information was not surveyed

out of methodological reasons, as this could be

distorted by the information text.

Does Transmission Technology Inﬂuence Acceptance of Overhead Power Lines? An Empirical Study

195

6.2 Sample

147 participants were recruited from various

sources, including social networks and online

discussion groups. 15 had ended the questionnaire

after the first few questions, therefore they were

excluded from analysis. Answers of 132 participants

were finally taken into account. Of those, 34.1%

were female, 65.9% male. The mean age was 33.2

years (SD=12.1). 47.7% held a university degree,

further 29.5% a qualification for university entrance.

53% lived in a city center, 26.5% in the outskirts of

a city, and 20.5% in a village. 18.9% reported to live

within view of a power line. 18.2% reported to be

“electricity laypeople,” while 9 (6.8%) reported to

be electricity experts. 27.3% estimated themselves to

be “technical experts” (compared to 3.0% technical

laypeople).

Compared to study 1, the sample included more

male participants and felt more technically

knowledgeable which was directly related

(ANOVAs with gender as independent variable:

electricity level of expertise: F(1,117)=45.77,p≤0.01,

technical level of expertise: F(1,117)= 57.92, p≤

0.01). 25% of the sample had a technical occupation,

15.2% a non-technical (55.3% could not be

categorized, 4.5% missing answers). The mean score

for ATT was M=5.2 (SD=0.8), thus markedly higher

than in study 1.

6.3 Results

First, overall scores on attitude and ascribed

characteristics were calculated (Table 3).

Table 3: Means for attitude towards DC and AC

transmission lines and means for ascribed characteristics.

DC AC

Attitude

M=4.5 (SD=1.0) M=4.4 (SD=1.1)

Characteristics

ascribed

M=4.2 (SD=0.9) M=4.0 (SD=0.9)

Paired samples t-tests were performed for the single

items to investigate possible differences between the

AC and the DC scenario (Figures 6 and 7).

On a descriptive level, compared to study 1,

answers showed more extreme values, i.e., were

more positive on the positive items and more

negative on the negative items, which overall

reflects a more welcoming attitude towards

transmission lines in this sample.

It was found that for three items, answers

differed significantly depending on whether they

were presented in an AC or DC scenario: Perceived

usefulness for DC was evaluated significantly higher

Figure 6: Ascribed characteristics to AC and DC

transmission lines.

Figure 7: Attitude towards AC and DC transmission lines.

than for AC (n=114, T=-2.92, p≤ 0.01, r

=0.07), DC

was perceived to spoil the landscape to a

significantly lesser extent than AC (n=115, T=2.07,

p≤ 0.05, r

=0.04), and participants were less scared

of health problems caused by DC than by AC

(n=116, T=2.81, p≤ 0.01, r2=0.06) though effect

sizes were small (J. Cohen, 1988).

In a next step, attributes of technical expertise

were again correlated with attitude and

characteristics ascribed to AC and DC to analyze if

the relationship between technical expertise and

perception, which was found in study 1, also holds

for study 2 (Table 4). After this, we analysed if

differences in perception of AC and DC occur

because of the information text which was given to

the participants or, rather, because of the level of

technical expertise. To this end, the sample was split

into an expert group and a laypeople group. Experts

were defined as participants who had an ATT score

of 6 and/or classified themselves as technology

experts (=6) and/or as electricity experts (=6). Using

this classification, 45 participants were categorized

as experts, 76 as laypeople (11 participants could not

be classified due to missing data).

123456

I fear health problems caused

by this TL

(AC/DC) TL spoil the

landscape

I think new (AC/DC) TL are

useful

I reject new (AC/DC) TL

because of their visual impact

on the landscape

I think (AC/DC) TL are not

dangerous

do not fully

agree at all agree

AC DC

123456

I would protest against this

I would accept this TL

I am against new (AC/DC)

TL in general

do not agree at all fully agree

AC DC

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196

Paired samples t-tests for both groups revealed

that for experts no significant differences between

the AC and the DC setting occurred. Laypeople, in

contrast, perceived possible health risks of DC

significantly lower than of AC transmission lines

(T(1,72)=2.22, p≤ 0.05, r

=0.05) and also found

them significantly more useful (T(1,71)=-2.70, p≤

0.01, r

=0.09). The split according to expertise thus

indicated that the differences in acceptance scores in

the overall sample are mainly due to the evaluation

of laypeople.

Table 4: Spearman correlations between attributes of

technical expertise and perception of AC and DC

transmission lines in study 2. *p≤ 0.05, **p≤ 0.01, ***p≤

0.001.

Attitude

Charac.

ATT

0.14

(n=116)

0.12

(n=125)

0.26***

(n=116)

0.23*

(n=125)

Elec.

Expert

0.25***

(n=116)

0.24***

(n=118)

0.26***

(n=116)

0.3***

(n=118)

Techn.

Expert

0.25***

(n=116)

0.24***

(n=118)

0.26***

(n=116)

0.3***

(n=118)

6.4 Summary

Study 2 validated the findings of study 1. For

experts, transmission technology did not influence

attitudes or ascribed characteristics towards

transmission lines. For laypeople, there was a small

difference in favour of DC for perceived health risks

and usefulness. Thus, in spite of the additional

information which was given to the participants, the

attitudes towards transmission lines did not reveal

fundamental differences but showed a quite solid

positive perception towards transmission lines

operated with AC or DC technology.

Correlation analyses revealed that expertise was in

fact a prominent variable. Participants with a high

technology and electricity expertise had more positive

perceptions and attitudes about transmission lines in

general (not differing between AC and DC). In

contrast, the general attitudes toward technology (ATT)

showed a lower prediction power compared to study 1.

7 DISCUSSION

In this paper, we introduce two empirical studies

concerned with the question if different transmission

technologies – AC and DC- are evaluated differently

with respect to public perception and acceptance.

The first study addressed a quite uninformed

incidental sample of participants of a wide age range

in order to capture an unbiased acceptance profile. In

the second study, technical information about health,

costs and effectiveness of both technologies was

presented prior to the acceptance evaluation. Also,

further insights about effects of expertise on

acceptance were given.

It was shown that participants did not differ

significantly in their opinion about AC and DC

transmission lines when relying only on their

knowledge about the two technologies at the time of

the survey (Study 1). In study 2, it was evident that

even when detailed information was given on the

two technologies, only small differences in

preference for the two technologies were detected

for the overall sample (for usefulness, effect on

landscape and perceived health risks).

Overall it was clearly revealed that transmission

technology in this context does not influence

perception and acceptance. In study 1, answers were

very balanced, indicating a rather indecisive attitude

towards the topic and in assessing characteristics.

This would support the hypothesis that the effects,

which had to be evaluated in the context of different

transmission technologies, were not easily accessible

for the majority of participants, because the framing

in the context of transmission technology might have

been too abstract (Devine-Wright et al., 2010). This

could also be an effect of the relatively small

number of participants who reported to live within

view of a transmission line; further research is thus

needed in actual case-study scenarios. The result that

no difference was found should therefore be treated

with caution, as it does not mean that this will be

true for every group.

It is noteworthy that those items for which

significant differences were detected in study 2 refer

to specific evidence given in the information text

and that they refer to characteristics of the

transmission line rather than people’s attitude

towards the transmission line (such as reject, accept,

protest, etc.). It is thus likely that the small but

significant effects are a direct result of the

information given in the info text. They might even

have biased participants towards DC, as DC was

more favourable concerning the factors presented in

the information text.

Because the sample still was quite small, it could

also be the case that the effects did not show yet and

a bigger sample could lead to clearer results here. It

would also be instructive in future studies to use

information texts which focus on different aspects to

find out if the new information is directly reflected

in the acceptance pattern, as this has shown to be the

Does Transmission Technology Inﬂuence Acceptance of Overhead Power Lines? An Empirical Study

197

case for information on risks (MacGregor et al.,

1994). Nevertheless, the effect sizes are quite small

(Cohen, 1988) and therefore their practical

importance is questionable. Further studies will be

necessary to test and replicate these findings.

The instruction text did not disclose

visualizations of different layouts of transmission

lines due to different transmission technologies (like

in Fig. 2 and 3), to avoid that participants focus on

the visuals only and instead take a range of

characteristics into account for their judgement. As

it was shown that the transmission technology alone

did not influence preference for power lines, further

research should concentrate on preferences for

power line design (thus indirectly reflecting

transmission technology). The topic of overhead vs.

underground power lines was already covered in

several studies (McNair et al., 2011; Menges and

Beyer, 2014; Navrud et al., 2008) as was that of

pylon design (Devine-Wright and Batel, 2013;

Atkinson et al., 2004), but the connection between

transmission technology and power line layout (e.g.,

DC overhead power lines and AC overhead power

lines) has not been studied from a social science

point of view. This could be very useful in order to

disclose underlying mental models between

technology infrastructure and their appearance in the

landscape. Methodologically, however, another

instrument than a traditional survey seems to be

appropriate. As the concurrent examination of

design factors and infrastructure variations (layout,

efficiency, exposure to EMF) as well as their

interdependence is of interest and possible trade-offs

between them, a conjoint study would yield

insightful evidence into acceptance relevant factors,

as applied in the context of, e.g., mobile phone base

stations (Arning et al., 2014) or camera surveillance

(Arning and Ziefle, 2015). It will then also be of

interest to discuss acceptable locations for converter

stations, which possibly are subject to similar

concerns as locations for pylons (Zaunbrecher et al.,

2015). The converter stations needed for DC

transmission also present a trade-off that needs to be

made between transmission lines with lower

landscape impact and a larger basal area of

additional components.

The studies conducted lead to the conclusion that

there is a substantial lack of knowledge, on the one

hand, but an interest in more information on grid

expansion as well as AC and DC transmission, on the

other hand. Furthermore, the studies support earlier

findings (Aas et al., 2014; Owens, 2000) that low

familiarity is related to low levels of acceptance. In our

case, it was not so much the perceived knowledge

about AC and DC transmission which correlated with

acceptance (study 1) but expertise and confidence in

the context of technology in general as well as

electricity. These results indicate that the relation of

knowledge and acceptance of transmission lines is a

complex one that does not only involve knowledge

directly related to the grid. Lienert et al., (2015), for

example, found in a study in Switzerland that it is not

only knowledge about the grid itself that is lacking, but

also the role of the grid in the context of the energy

transition. In their study, it was unclear to about half of

the participants that there was a connection between

grid expansion and the energy transition. Those who

were aware of the relation showed a significantly more

positive attitude towards HVL.

8 CONCLUSIONS

The success and acceptability of new transmission

lines, irrespective of AC or DC technology, will

largely depend on adequate information and

communication concepts which allow for early

participation (Jewell et al., 2009), for which it is

vital to identify relevant attributes and influencing

factors for acceptance. The studies presented add to

future information and communication concepts by

investigating the role of transmission technology for

the acceptance of power lines. Overall, the studies

had three major findings: First, transmission

technology does not have a major influence on

acceptance of transmission lines for the sample

under study, even if specific information on AC and

DC technology is given. Second, acceptance and

perception are, however, positively influenced by

general ATT and expertise. Third, there is a

substantial lack of information of the general public

on grid expansion and the future role and potential

of DC for electricity transmission.

Although the hypothesis held true that a change

from AC to DC did not substantially change

attitudes of participants towards transmission lines

in our sample, it could be well worth investigating

into this topic further, as DC offers some advantages

in aspects often debated in the context of power lines

(no EMF, more compact lines, possibility to use

underground cables).

ACKNOWLEDGEMENTS

Thanks to Orlando Berger and Martin Przybysz for

help with the collection of the data, Chantal Lidynia

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for language support and to four anonymous

reviewers for helpful comments on an earlier version

of this paper.

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