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Methodology for the assessment of the impact of existing high voltage lines in urban areas
Energy Policy 38 (2010) 6036–6044
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Methodology for the assessment of the impact of existing high voltage lines in urban areas Andreas Sumper a,c,, Oriol Boix-Aragone s b, Roberto Villafa´fila-Robles a, Joan Bergas-Jane´ b, Rodrigo Ramı´rez-Pisco a a
´ Tecnologica Centre d’Innovacio en Convertidors Esta tics i Accionaments (CITCEA-UPC), Departament d’Enginyeria Ele ctrica, Universitat Polite cnica de Catalunya, EU d’Enginyeria Te cnica Industrial de Barcelona, Comte d’Urgell, 187; 08036 Barcelona, Spain b ´ Tecnologica Centre d’Innovacio en Convertidors Estatics i Accionaments (CITCEA-UPC), Departament d’Enginyeria Ele ctrica, Universitat Polite cnica de Catalunya, ETS d’Enginyeria Industrial de Barcelona, Av. Diagonal, 647, Pl. 2. 08028 Barcelona, Spain c Catalonia Institute for Energy Research (IREC), Spain
a r t i c l e in f o
a b s t r a c t
Article history: Received 2 March 2010 Accepted 24 May 2010 Available online 9 June 2010
This paper presents a methodology for the assessment of the impact of existing high voltage lines in urban areas. This methodology is based on the numeric evaluation of several impacts which are combined with weight factors. The novelty is that it opens up the possibility of citizen participation, basically in the way in which impacts and weighting factors are determined. The proposed methodology has been applied first in the municipality of Rubı´, a mid-sized town near Barcelona, and later on in several municipalities in the Catalonia region in Spain. The results were used to prioritise mitigation action in the Catalonia Energy Plan. & 2010 Elsevier Ltd. All rights reserved.
Keywords: High voltage lines Environmental impact Social impact
1. Introduction Electricity is essential for our modern societies (Blok, 2005), and obviously it has to be transmitted from remote power stations to consumers. Electricity transmission is generally performed by high voltage overhead lines, and in a few cases, by high voltage cables (in urban areas). These installations are connected to substations where high voltage is transformed to medium and low voltage which is distributed to the end consumers. All of these infrastructures are necessary for the transmission and distribution of electrical energy; and in the past, their planning was made by the state or local governments, all in accordance with utility services. Nowadays, citizens and municipalities are interested in participating in the various stages of infrastructure planning. However, due to the expansion of urban development, power lines, which were once located on the periphery of cities, have now been integrated into urban areas. That leads to the fact that citizens living near these installations, become increasingly concerned about them and therefore want to participate in planning the actions which have an impact upon them.
Corresponding author at: Universitat Polite cnica de Catalunya. EU d’Enginyeria Te cnica Industrial de Barcelona, Comte d’Urgell, 187; 08036 Barcelona, Spain. Tel.: + 34 934016727; fax: + 34 934017433. E-mail addresses: [email protected], [email protected] (A. Sumper), [email protected] (O. Boix-Aragone s).
0301-4215/$ - see front matter & 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.enpol.2010.05.059
As society has become more concerned about its environment, it wants to more actively participate in the decision process (Lee, 2007; Bakken and Holen, 2004; Roussopoulos, 2005). In general, the active participation of citizens in issues involving infrastructures consists of three different groups: the first is the group of elected representatives, a few legitimate decision makers; the second group, the proactive citizens who are creative and critical but who represent a small part of the population; and, lastly, citizens from all social backgrounds representing various opinions. All of these groups suffer from a lack of information required in order to be able to argue about infrastructures. Due to the expansion of the group (from the elected representatives to all citizens), objective information may be rare and distorted. This can lead to social conflict, because it seems that all decisions are made by citizen representatives on their own and without consideration of the public opinion. Therefore, stakeholders should be involved in the preparation of project proposals (conflict prevention) and conflict solving. Some possible participation criteria are listed below (Retzl, 2010; Mohanty and Tandon, 2006; Roussopoulos, 2005):
Projects should be developed on a wide base and participation. Participation of citizens should be applied at any similar situation of conflict.
Participation should work on fixed and binding rules. All citizens should receive the same information. Vested or minority interests should be eliminated.
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Detailed information should be understandable and manage
able for any citizen. Any citizen should be aware that information is available and accessible.
In all those listed points, it is necessary to provide the citizens with objective, precise and understandable information. Once a conflict is caused, it can be solved by means of mediation techniques. Their objectives are to involve the conflicting parties and to find a common, self-provided ‘win win’ solution. Mediation techniques require a neutral mediator, applying the following principles (Mohanty and Tandon, 2006; Roussopoulos, 2005):
The mediator has to be neutral, providing all required information without personal opinion.
The conflicting parties should voluntarily participate and without external pressure.
Any conflicting party should be constructive and autonomously work on the solutions.
Any information required to work on the solution should be provided.
The mediator has to maintain confidentiality towards the conflicting parties. The potential for local conflicts, like conflicts in municipalities, is often underestimated because people have high requirements and are very loyal to their local area. Universities have a mandate to collect and organise internal expertise in ways that enjoy public confidence, and are able to be neutral and objective. Thus, universities can serve as excellent mediators in projects that involve multiple and conflicting objectives. Providing objective information to all involved parties is a complex task, especially in electrical infrastructure projects. Most of the citizens, administration and representatives are unable to interpret complex technical information which is even hard to be understood by electrical engineers. For this reason, it is understood that a lack of information exists. In this scenario, universities are able to provide:
Preparation of information in an understandable way. Additional information and didactic annexes in order to
explain significance and importance of operation of high voltage lines and cables. Interpretation of technical issues and assessment for parties without a technical background. Information and didactic sessions for interested citizens. Correct interpretation of challenges of high voltage planning (Morrow and Brown, 2007).
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difficulty of new energy infrastructures in the US. Cole et al. (2005), Duffy and Craven (1993), Bardouille and Koubsky (2000) introduce social concerns about energy and network planning. Social syndromes for public opinion like the ‘Not In My Backyard’ (NIMBY) (Horst, 2007), ‘Build Absolutely Nothing Anywhere Near Anything’ (BANANA) (Vajjhala and Fischbeck, 2007), and ‘Not In My Term of Office’ (NIMTO) for politics are known. Marshall and Baxter (2002) shows that, due to careful routing, the degree of visual intrusion can be reduced. Say et al. (2007) presents an environmental impact assessment tool for decision makers, in order to take into account the possible effects of a proposed project on the environment for power plants. Hadrian et al. (1988) present an approach to automated mapping of the visual impacts in utility corridors for transmission lines. Cloquell-Ballester et al. (2006) proposes a methodology of impact quantification by establishing the appropriateness of the instruments (indicators) used, so that their level of objectivity is the highest possible one. This method was applied to the aesthetic impact assessment of solar power plants (Torres-Sibille et al., 2009a) and the aesthetic impact of wind farms (Torres-Sibille et al., 2009b). The contribution of this paper is a simple methodology that allows a broad participation of those involved. This enables a social dialogue between the interested entities who broadly approved of the process and the decisions assisted by the study. This methodology has been successfully applied in several municipalities near Barcelona, Spain. To the best of our knowledge, the presented methodology has not been applied before, in order to evaluate the impact of high voltage lines. The method presented in Cloquell-Ballester et al. (2006), which is used for impact quantification of the visual impact of generation installations (Torres-Sibille et al., 2009a, b), requires a complex method and computing tools. This paper is structured as follows: Section 2 introduces the impact of overhead power lines on their environment. Section 3 presents a methodology of evaluation of the impact of high voltage lines. In Section 4, an example of the methodology in a municipality is given, Section 5 describes the use of the methodology for energy planning in Catalonia, Spain; and Section 6 presents the conclusions of this work.
2. Impact of overhead power lines Impacts are divided into two types: environmental and visual (which includes architectural). In addition, these can be looked at from a technical and social point of view. The environmental aspect deals with lifecycle impacts, impacts on vegetation and wildlife and electromagnetic impacts. The visual and architectural aspects relate to visibility and architectural issues caused by overhead lines. 2.1. Environmental impact
The use of universities as mediators can also represent disadvantages, for example the difficulty in obtaining results in a limited time and the need to publish afterwards (no long-term confidentiality). The evaluation of the impact of transmission system planning has not been exhaustively reported in literature. Woldemariam and Simpson (2008) and Furby et al. (1988) presents a public outreach process involving stakeholders in the identification and selection of the transmission line route. Design criteria were established in order to meet project objectives with the lowest possible environmental impact in a cost-effective way (Tummala and Burchett, 1999). In Trogneux et al. (1996), a method, used in E´le´ctricite´ de France which takes into account the impact of a project on the environment, by considering environmental risks, is presented. Vajjhala and Fischbeck (2007) reports the siting
2.1.1. Life cycle impact Overhead lines have, as have all infrastructures, an impact on the environment during their lifecycle. Overhead lines basically have three elements: pylons, isolators and phase conductors. Pylons are usually made of the following materials (Gonen, 2007):
wood, concrete, steel tube, lattice steel, and concrete filled steel tube.
In all cases, masts are fixed into the ground by concrete basements. The most common poles are lattice steel pylons, due
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to their uncomplicated transportation and easy positioning. Isolators are generally made of ceramic materials, nowadays, polymer and silicon are more often used. Phase conductors are normally composed of aluminium conductors, reinforced by steel. Constructing overhead lines causes impacts on the environment due to the production of the materials mentioned, their transport, and the positioning of the pylons. In the last case, an impact is caused by the concrete base, which delivers stability to the pylon, and the necessity for the removal of vegetation below the overhead line phase conductors in order to prevent flashovers from the lines and fires. During their lifecycle, overhead lines are maintained by corrective or preventive maintenance, by the substitution of spare parts. At the end of a lifecycle, overhead lines are easily removed and the environment can recover to its former state without difficulty. At the end of a transmission line lifecycle, the line is often upgraded to a new and higher voltage level rather than returned to its former state. Usually, overhead lines have very long lifecycles, 50 years (Raineri, 2010) or more are common. 2.1.2. Impact on vegetation and wildlife Overhead lines in rural areas intrude into the environment and have impacts on the adjacent areas of the line corridor. Vegetation: Impacts are caused by the construction of overhead lines due to the disruption of the soil and construction accesses (rural roads) to remote areas (in order to prepare the soil for the pylons with heavy machinery); and the transport of the pylons, insulators and phase conductors. The overhead line is designed to provide conductor clearance above vegetation, which can be managed either by clearing the vegetation or by having taller towers, both affecting the visual impact in different ways. Tree trimming should be carried out within periods of three to five years. An overhead line with covered conductors represents an option, reducing need for vegetation clearance. Wildlife: When overhead lines are located in rural areas, animals can come into contact with pylons and bare phase conductors. Contact with bare phase conductors may cause electrocution of the animal. Furthermore, depending on their location, overhead lines can lead to collisions of birds with lines, especially if the lines are located in the vicinity of established bird flight patterns (Sovacool, 2009). Birds often collide with overhead ground wires (small-diameter conductors at the top of the line), because these prove almost invisible, compared to phase conductors of a larger diameter (Bevanger, 1994). 2.1.3. Electromagnetic impact As overhead lines transport electrical energy in low frequency (50 or 60 Hz), electrical and magnetic fields are generated. In the low frequency spectrum, both fields are decoupled; the electrical field is generally related to the voltage level of the line, and the magnetic field is related to the line current (Sarma Maruvada et al., 1998a, b; Joseph et al., 2009). Both fields decrease with the distance to the phase conductors, an example of field distribution is shown in Fig. 1(a) and (b). Established limits from the WHO (2010) for the electrical field are 5 kV/m and 100 mT. Until now, it has neither been proven nor disproven that electromagnetism causes harm to people’s health. 2.2. Visual impact Overhead lines are visible from a long distance, because the higher the voltage, the higher the pylons have to be in order to respect insulation coordination. Visual impact is subjective from person to person, but in general, it depends on the landscape,
position and the angle of the observer and the contrast (Koglin and Gross, 1988). 2.2.1. Architectural impact In urban areas, impact is not only confined to visual impact. Overhead lines also cause an architectural impact, because they represent an urbanistic structure which, due to its intrinsic properties, changes its architectural environment. Architectural impacts are listed below.
Overhead lines constitute barriers between urban areas or limit urban expansion.
Visual impact on schools, parks and other urban installations is perceived as being higher.
Overhead lines can expose individuals to dangerous situations due to broken phase conductors or fallen pylons.
Traffic or work accidents can occur by accidental contact.
2.2.2. Other impacts On the one hand, overhead lines decrease the risk of individuals on the ground near the line from being struck by lightning. On the other hand, they represent an increase in the risk from broken phase conductors or falling pylons in adverse weather (wind and ice) (Gonen, 2007). Accidental contact with overhead lines during work near overhead lines can cause severe accidents. Construction industry has significantly greater proportions of occupational fatalities resulting from contact with overhead power lines than expected (Janicak, 1997).
3. Methodology of evaluation of the impact of existing high voltage lines The principal problems in the evaluation of the impact of existing high voltage lines are: firstly, different impacts appear simultaneously; and secondly, impact measurement is strongly affected by the evaluators’ subjective opinion. Therefore, it is difficult for even impartial and objective evaluators to get full acceptance of a large number of citizens. In order to obtain an objective and inclusive evaluation of the impact, a methodology of the evaluation of the impact of existing high voltage lines has been designed. Fig. 2 depicts the steps of this methodology and the participation required. 3.1. Delimitation of the studied area and determination of overhead lines In Step 1, the expert, municipality and citizen movements should carefully define the area of study. In many cases, urban areas are well defined, but some residential zones can be affected from overhead lines from outside the urban area. In these cases, a consensus from all parties should be obtained. Also, it should be agreed upon which line type (high or medium voltage) should be included into the study. In Step 2, the expert and the utility service should determine the main characteristics and the exact route (GPS data, geographical information system, etc.) of the overhead lines causing the impact. 3.2. Definition of impacts and weights In the next three steps, the methodology is fitted to the requirements of analysis in the studied area. During these steps, a
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Fig. 1. Electric and magnetic field at 1 m from the ground of a 400 kV overhead line (22 m conductor distance from the ground, 1000 A). X axis in (m). Figures obtained by a simulation programme developed by the authors. (a) Electric field in kV/m and (b) magnetic field in mT.
maximum of participation and consensus is required in order to obtain full support for the study. In Step 3, the impact types to be studied are defined. Once the type of impact to be analysed has been defined, the measurable criteria should be established in order to evaluate impacts (Step 4). If objective criteria are not possible, a subjective evaluation methodology should be established by comparing it with other situations. It is recommended to translate these criteria into a numeric scale. The numeric scale is defined in such a way as to take into account the contribution of all interested groups (including the citizens) to assure a broad acceptance of the methodology. Therefore, the used methodology should be easy to understand and the used scale should be approved by all participants. In addition, statistic data can be used to classify impacts, e.g. for the pedestrian and car traffic impact.
The translation of impacts (for example: no impact; light impact; medium impact; heavy impact) to numeric values can be made on different scales: linear scale (e.g. 1; 2; 3; 4, respectively) or non-linear scale. In order to deal with the concerns of citizens’ movements about the choice of a scale, linear, power of two and power of three scales were analysed. All stakeholders agreed that few heavy impacts may be considered with a higher score than many low impacts. Table 1 shows different theoretical situations regarding the combination of low, medium and high impacts. An initial situation with three medium impacts (base case) was taken and then, the result was compared with other combinations in order to look at the compensation level of compensation between heavy and light impacts.
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Methodology
Participation required
Step 1: Delimination ot the area of the study
Expert; Municipality; Citizen movements
Step 2: Determination of the overhead lines to study
Table 2 Application of the linear scale on the impacts from Table 1.
Base case Extreme case Combination 1 Combination 2 Combination 3 Combination 4
Expert; Utility
Imp 1
Imp 2
Imp 3
Sum
3 3 2 2 1 1
3 3 3 2 2 1
3 4 4 4 4 4
3.0 3.3 3.0 2.7 2.3 2.0
All three impacts are weighted equally.
Step 3: Determination of the number of impact types (In)
Expert; Municipality; Citizen movements
Step 4: Determination of the scale of impact types
Expert; Municipality; Citizen movements
Step 5: Determination of the scale of weights
Expert; Municipality; Citizen movements
Expert
Step 7: Analysis and conclusions of the study
Expert
Imp 2
Imp 3
Sum
4 4 2 2 1 1
4 4 4 2 2 1
4 8 8 8 8 8
4.0 5.3 4.6 4.0 3.6 3.3
All three impacts are weighted equally.
Base case Extreme case Combination 1 Combination 2 Combination 3 Combination 4
Imp 1
Imp 2
Imp 3
Sum
9 9 3 3 1 1
9 9 9 3 3 1
9 27 27 27 27 27
9.0 15.0 13.0 11.0 10.3 9.7
All three impacts are weighted equally.
Expert; Municipality; Utility
Fig. 2. Methodology of evaluation of the impact of high voltage lines.
Table 1 Test impact situations.
Base case Extreme case Combination 1 Combination 2 Combination 3 Combination 4
Base case Extreme case Combination 1 Combination 2 Combination 3 Combination 4
Imp 1
Table 4 Application of the power of three scale on the impacts from Table 1.
Step 6: Impact determination
Step 8: Proposals for impact mitigation
Table 3 Application of the power of two scale on the impacts from Table 1.
Imp 1
Imp 2
Imp 3
Medium Medium Low Low Null Null
Medium Medium Medium Low Medium Null
Medium High High High High High
The results of the application of the linear scale (1 for no impact, 2 for light impact, 3 for medium impact and 4 for heavy impact) can be seen in Table 2. In this case, only one light impact can compensate one heavy impact. Two light impacts and one heavy impact result in a lower overall impact than the base case. The results of the application of the power of two scale (1 for no impact, 2 for light impact, 4 for medium impact and 8 for heavy impact) are depicted in Table 3. In this case, two light impacts can compensate one heavy impact. Finally, with the power of three scale (1 for no impact, 3 for light impact, 9 for medium impact and 27 for heavy impact) the
results are depicted in Table 4. In this case, two non-impact situations cannot compensate one heavy impact. Fig. 3 summarizes the results of the analysed impacts with different scales. It can be seen that the base case changes its relative position regarding other impact scenarios as a function of the scale applied. The power two relationship (e.g. 1; 2; 4; 8, respectively) and the power three relationship (e.g. 1; 3; 9; 27, respectively) have the advantage that a few heavy impacts will automatically have more weight in the overall impact than many light impacts. Once numeric values have been assigned to the level of impact, a global impact ratio can be calculated by defining weights for each impact type (Step 5). This is the most difficult part because every person has their own criteria for assigning weights to impact types. For this reason, a decision matrix is used to obtain a simple and effective method. A table with the weight of the number of impact types is drawn, and on the horizontal (columns) and vertical (rows) borders, each type of impact is written. If the impact of the column is more important than the impact of the row, then 3 is written into the cell; if the column impact is less important than the row, then 1 is written and if they are equal, 2 is written into the cell. This process is repeated for all cells and the sum of the rows is calculated. The upper elements above the diagonal elements of the matrix obviously show inverted values of the elements below the diagonal matrix. This fact can be used to check that the table is correctly filled. The division of the sum of the rows by the overall sum equals the weight of every impact. The stated method is a modified application of the costeffectiveness analysis (CEA) and the cost-utility analysis (CUA), which are well-known applications in health technology
A. Sumper et al. / Energy Policy 38 (2010) 6036–6044
linear
16 14 12 10 8 6 4 2 0
power 2
power 3
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Table 6 Impact evaluation for a hypothetic situation.
Imp Imp Imp Imp Sum
1 2 3 4
Numeric impact value
Impact weight in per unit
Result
0 2 1 3
0.250 0.281 0.156 0.313
0 0.562 0.156 0.939 1.657
Fig. 3. Result of the application of different scales of impact.
Table 5 Example of an impact weighting table.
Imp Imp Imp Imp
1 2 3 4
Imp 1
Imp 2
Imp 3
Imp 4
Sum
%
2 3 1 2
1 2 1 3
3 3 2 3
2 1 1 2
8 9 5 10
25.0 28.1 15.6 31.3
assessments (Johannesson, 1995). The advantage of this methodology is the transparency and the possibility to easily prove the applied criteria (Ryder et al., 2009). Nevertheless, this method may contain a certain potential for inconsistency when dealing with a large number of impacts (large matrix). More complex methods, like the Analytic Hierarchy Process (AHP), which is an extended application of CUA, provide a more accurate result, because this method compares each impact pairwise. Its disadvantage is that it needs more complex mathematical operations and it is more time consuming (Vaidya and Kumar, 2006). For this reason, it was decided to use the simpler modified CEA in this study. Table 5 shows an example for four impact types. This method is simple and can be immediately carried out by interested parties. For example, a commission with government participants, interested citizens, engineers and representatives from the utility can themselves evaluate impact weights, and a mean value can be taken for the global evaluation. Nevertheless, other more sophisticated methods to obtain the weights can be used, with the drawback that with increasing sophistication, the participation of non-experts could be more difficult. 3.3. Impact determination and analysis Once the impact types, the impact scale and the weights have been established, the result of the impact analysis can be calculated for every impact situation by applying those to the impact numeric scale (Step 6). The overall impact (Isum) is calculated from individual impacts (In) and the weights for each impacts (Wn) by Isum ¼
m X
In Wn
ð1Þ
n¼1
where m is the number of individual impacts to consider. Table 6 shows an example for one hypothetic situation. The sum of the impact evaluation is a numeric value which is proportional to the previous impact scale; in this example no impact¼0; light impact¼1; medium impact¼2; heavy impact¼3. In the example, the overall impact is between light and medium impact. In this stage, electric and magnetic field measurement can be performed in order to check the compliance with legal limits.
Fig. 4. General map of the Rubı´ municipality with high voltage installations. Colour code of the overhead lines: red 400 kV, green 220 kV, blue 110 kV and yellow 66 kV. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
The results of the study should be analysed and conclusions drawn (Step 7); and finally, together with the utility and the municipality, mitigation actions defined (Step 8). Mitigation can mainly be classified into two actions: Firstly, the change of the overhead line route outside of the urban area and, secondly, the conversion of the overhead line into an underground cable. The first option is mostly preferred by the utilities due to lower costs and there are no significant changes of the operation condition of the line (Kiessling et al., 2003). The drawback of this solution is that there must be sufficient space for the overhead line routing outside of the urban area. In very dense population areas, the option for alternative overhead line routings can be very limited. The second option is preferred by the citizen movements due to its low visual impact, but is not very well accepted by the utilities in the very high voltage range, due to
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technical limitations of this solution regarding operation and maintenance (Peschke and Olshausen, 1999) (Fig. 4).
4. Example of application The presented methodology was applied to several municipalities in the Barcelona region. In this paper, a municipality near Barcelona called Rubı´ is analysed. In Rubı´, 70,000 people live in an area of 32 km2, two bulk substations with a combined 1500 MVA transformation capability are located in its territory. The number of high voltage lines is listed below. Fig. 5 shows the general situation.
4 400 kV, all one circuit, 9 220 kV, all two circuits, 3 110 kV, two of four circuits, one of two circuits, and 2 60 kV, all two circuits.
As well as a high density of voltage lines, a main highway crosses the municipality. All this is paired with a high population density which is increasing. This means that urban space is expanding and is approaching existing high voltage installations. In order to coordinate the planning actions, the municipality has engaged the university to elaborate the methodology depicted in Fig. 2 in order to study the impact of high voltage lines. After designing the methodology, steps 1 and 2 were executed. 4.1. Impact types, impact weightings and methodology used The objective of the study was to measure the different impact situations in the same way over all the urban area of the municipality and rank them to prioritise mitigation actions. In order to obtain support from all the participants (utility, municipality government, citizens movement, etc.), several meetings were carried out to agree on the impact types to be analysed and the weights to be used (steps 3 and 4 of the methodology). In this case, the impact types used were:
Circulation of vehicles (I1). Pylons could form an obstacle or streets have to be redirected due to the pylons.
Table 7 Numeric values for impacts. Impact
Numeric value
High Middle Low None
27 9 3 1
Table 8 Weighting factors for each impact. Weight
Impact type
Value
W1 W2 W3 W4 W5 W6
Circulation of vehicles Passage of pedestrians Proximity to installations of public interest Proximity to residences Proximity to municipality installations Landscape impact
0.195 0.195 0.240 0.195 0.065 0.110
Proximity to municipality installations (street lights, etc.) (I5).
Maintenance operation of municipality installation could cause accidents. Landscape impact (I6).
To assign a numeric value to impacts, a power three relationship was chosen. Table 7 shows the relationship between subjective impacts and the assigned numeric value. The landscape impact (I6) is a combination of three factors: visibility of the line (V), fragility of the landscape (F) and the intrinsic quality of the area (IQ). The overall landscape integration is calculated by pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi I6 ¼ 3 V F IQ ð2Þ For example, a line can have a certain visibility; the landscape of the area can help to decrease or increase the impact (fragility). Nevertheless, the quality of the analysed area (industrial, commercial, residential, etc.) should be taken into account. Following (1), the overall impact (Isum) is calculated from individual impacts (In) and the weights for each impact (Wn) by
Passage of pedestrians (I2). Pylons are often placed on
pedestrian walks, that could be an obstacle for the circulation of the pedestrians. Proximity to schools, hospitals and other installations of public interest (I3). Proximity to residences (I4).
Isum ¼
6 X
In Wn
ð3Þ
n¼1
where the weighting factors for each impact are determined by consensus and are given in Table 8 (step 5). 4.2. Determination of the impact in the Rubı´ municipality
Fig. 5. Voltage line r2 in an avenue of the Rubı´ municipality.
Eleven situations of the impact of high voltage lines (equal or above 66 kV) were detected in the municipality area. These situations are sets of physically adjacent areas, which have the same impacts over their physical extension. E.g., an overhead line along a street can be treated as a single situation even if this line has some 100s of metres of extension. Some situations may imply more than one overhead line. Figs. 5 and 6 show an example for the impact (r2) of a 220 kV line in a residential area. The evaluation of the impact of all eleven impact situations is depicted in Table 9 (steps 6 and 7). Due to confidentiality, the names of the streets and voltage lines are not given. The results of the impact evaluation vary between 1.22 and 15.95. In this case, it can be seen that three situations have an impact value over 10, eight situations are between 5 and 10, and three situations are below 5.
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situation, all impacts over a single overhead line were analysed as a whole, in order to propose mitigation measures. The proposed measures were discussed with the utility and a cost estimation of those measures was realized. 4.3. Stakeholder participation
Fig. 6. Photograph of the 220 kV voltage line r2.
Table 9 Impact values for the high voltage lines (equal or greater than 66 kV) for the Rubı´ municipality. Line
r1 r2 r3 r4 r5 r6 r7 r8 r9 r10 r11
Impact I1
I2
I3
I4
I5
I6
Isum
1 1 1 1 1 27 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1
1 1 1 27 27 1 27 1 1 1 1
9 27 1 27 1 27 27 1 27 27 27
27 27 1 27 1 27 27 1 1 1 27
6.24 6.24 3 9 9 6.24 18.72 3 9 6.24 9
4.826 8.336 1.220 14.880 8.120 13.406 15.949 1.220 6.950 6.646 8.640
Table 10 Mitigation action proposed for the studied high voltage lines (equal or greater than 66 kV) for the Rubı´ municipality. Line
Mitigation action proposed
r1 r2 r3 r4 r5 r6 r7 r8 r9 r10 r11
Alternative overhead line route Alternative overhead line route No mitigation action proposed Alternative overhead line route Alternative overhead line route Alternative overhead line route Underground cable No mitigation action proposed Alternative overhead line route Alternative overhead line route Alternative overhead line route
During the study, several stakeholders were very interested in participating in the study, especially people who live near the lines. People who were not familiar with electric engineering were interested to understand technical constraints of the planning and operation of high voltage lines. Therefore, it is necessary to dedicate time to explain these technical aspects in order to prevent misunderstandings. The municipality and the utility fully supported the project and delivered necessary information for this study. Nevertheless, confidential agreements were necessary in order to receive sensitive information. The results of this study were very well accepted by the municipalities, because they were useful for planning issues in the community. The utilities showed a reserved attitude at the beginning of the study, but as they were invited to discuss possible mitigation actions, they were collaborative.
5. Application of the methodology for energy planning in Catalonia As already stated, the urban expansion of the Catalonian municipalities has led to the high voltage lines located in the surroundings being urbanised in the last 30 years. In October 2002, the Catalonian Parliament adopted a legislative initiative (Act (1522/VI, 2002)) to request the Catalonian Government to negotiate with utilities, municipalities and the Spanish state to adopt mitigation measures for the affected areas within a period of 10 years. In order to comply with the Act of Parliament, the Catalonian Government ordered the realisation of studies in order to detect the territorial and environmental impact of existing high voltage lines with a nominal voltage higher than 36 kV in urban areas. These studies were performed in 29 municipalities using the methodology presented in Section 3. The results of the studies were used to perform the planning of the electrical infrastructure in the energy plan of Catalonia 2006–2015 (Generalitat, 2006).
outside the municipality area outside the municipality area outside the municipality area outside the municipality area outside the municipality area
outside the municipality area outside the municipality area outside the municipality area
Electromagnetic field aspects were taken into account because several citizens were very interested in this subject. Electric and magnetic field measurement was performed in all impact situations. After the measurements, the results were extrapolated to full load (at time of the measurement, the lines had partial load) and compared with the legal limits. All studied cases were below these limits. This classification was used to prioritise the mitigation actions with the utility (step 8). The proposed mitigation actions in the studied case are listed in Table 10. As the analysis gives an impact value for each
6. Conclusions This paper presents a methodology to evaluate the numeric impact of existing high voltage lines from several impact measures, using weights. The results presented in this paper show that this methodology enables the ranking of different impact situations on a common scale. The strength of this methodology is not the absolute objectivity of the overall impact value, but the participation of different entities (utility, citizen movements, governments, etc.) in the application of the methodology. This increases the social acceptance of the utility planning activities and allows the ranking of impacts in order to prioritise mitigation activities. The methodology has successfully been used in 29 municipalities the Catalonia region in Spain.
Acknowledgement The authors would like to thank the Rubı´ municipality for the support of this project.
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Mohanty, R., Tandon, R., 2006. Participatory Citizenship: Identity, Exclusion, Inclusion. Sage Publications, Thousands Oaks, New Delhi, California. Morrow, D.J., Brown, R.E., 2007. Future vision—the challenge of effective transmission planning. IEEE Power and Energy Magazine 5 (5), 36–45. Peschke, E., Olshausen, R.v., 1999. Cable Systems for High and Extra-high Voltage: Development, Manufacture, Testing, Installation and Operation of Cables and their Accessories. Publicis MCD Verlag, Erlangen, Munich. Raineri, R., 2010. Asset life and pricing the use of electricity transmission infrastructure in chile. Energy Policy 38 (1), 30–41. ¨ die Retzl, I., 2010. Der Umgang mit Konflikten im lokalen Bereich. Grundregeln fur praktische Arbeit. [On-line] URL: /http://www.institut-retzl.at/gemeindeS. URL: /http://www.institut-retzl.at/gemeinde/pdf/Umgang_mit_Konflikten. pdfS. Roussopoulos, D., 2005. The Participatory Democracy: Prospects for Democratizing Democracy. Black Rose Books Montreal, New York, London. Ryder, H.F., McDonough, C.M., Tosteson, A.N., Lurie, J.D., 2009. Decision analysis and cost-effectiveness analysis. Seminars in Spine Surgery 21, 216–222. Sarma Maruvada, P., Turgeon, A., Goulet, D.L., Cardinal, C., 1998a. An experimental study of residential magnetic fields in the vicinity of transmission lines. IEEE Transactions on Power Delivery 13 (4), 1328–1334. Sarma Maruvada, P., Turgeon, A., Goulet, D.L., Cardinal, C.U., 1998b. A statistical model to evaluate the influence of proximity to transmission lines on residential magnetic fields. IEEE Transactions on Power Delivery 13 (4), 1322–1327. ¨ Say, N.P., Yucel, M., Yilmazer, M., 2007. A computer-based system for environmental impact assessment (EIA) applications to energy power stations in Turkey: C - edinfo. Energy Policy 385 (12), 6395–6401. Sovacool, B.K., 2009. Contextualizing avian mortality: a preliminary appraisal of bird and bat fatalities from wind, fossil-fuel, and nuclear electricity. Energy Policy 37 (6), 2241–2248. Torres-Sibille, A.d.C., Cloquell-Ballester, V.-A., Cloquell-Ballester, V.-A., ArtachoRamirez, M.A., 2009a. Aesthetic impact assessment of solar power plants: an objective and a subjective approach. Renewable and Sustainable Energy Reviews 13, 986–999. Torres-Sibille, A.d.C., Cloquell-Ballester, V.-A., Cloquell-Ballester, V.-A., Darton, R., 2009b. Development and validation of a multicriteria indicator for the assessment of objective aesthetic impact of wind farms. Renewable and Sustainable Energy Reviews 13, 40–66. Trogneux, F., Doquet, M., Mallet, P., 1996. Taking environmental constraints into account in the planning of the extra high voltage transmission network; EDF’s approach. IEEE Transactions on Power Delivery 11 (4), 1901–1906. Tummala, V.M.R., Burchett, J.F., 1999. Applying a risk management process (RMP) to manage cost risk for an EHV transmission line project. International Journal of Project Management 17 (4), 223–235. Vaidya, O.S., Kumar, S., 2006. Analytic hierarchy process: an overview of applications. European Journal of Operational Research 169, 1–29. Vajjhala, S.P., Fischbeck, P.S., 2007. Quantifying siting difficulty: a case study of us transmission line siting. Energy Policy 35 (1), 650–671. WHO, 2010. What are electromagnetic fields? [Online] URL: /http://www.who. int/peh-emf/en/S. Woldemariam, J., Simpson, K.D., 2008. Sunrise powerlink project: meeting reliability, renewable energy, and economic goals in Southern California. In: Proceedings of the T& Transmission and Distribution Conference and Exposition IEEE/PES, pp. 1–8.
Contents lists available at ScienceDirect
Energy Policy journal homepage: www.elsevier.com/locate/enpol
Methodology for the assessment of the impact of existing high voltage lines in urban areas Andreas Sumper a,c,, Oriol Boix-Aragone s b, Roberto Villafa´fila-Robles a, Joan Bergas-Jane´ b, Rodrigo Ramı´rez-Pisco a a
´ Tecnologica Centre d’Innovacio en Convertidors Esta tics i Accionaments (CITCEA-UPC), Departament d’Enginyeria Ele ctrica, Universitat Polite cnica de Catalunya, EU d’Enginyeria Te cnica Industrial de Barcelona, Comte d’Urgell, 187; 08036 Barcelona, Spain b ´ Tecnologica Centre d’Innovacio en Convertidors Estatics i Accionaments (CITCEA-UPC), Departament d’Enginyeria Ele ctrica, Universitat Polite cnica de Catalunya, ETS d’Enginyeria Industrial de Barcelona, Av. Diagonal, 647, Pl. 2. 08028 Barcelona, Spain c Catalonia Institute for Energy Research (IREC), Spain
a r t i c l e in f o
a b s t r a c t
Article history: Received 2 March 2010 Accepted 24 May 2010 Available online 9 June 2010
This paper presents a methodology for the assessment of the impact of existing high voltage lines in urban areas. This methodology is based on the numeric evaluation of several impacts which are combined with weight factors. The novelty is that it opens up the possibility of citizen participation, basically in the way in which impacts and weighting factors are determined. The proposed methodology has been applied first in the municipality of Rubı´, a mid-sized town near Barcelona, and later on in several municipalities in the Catalonia region in Spain. The results were used to prioritise mitigation action in the Catalonia Energy Plan. & 2010 Elsevier Ltd. All rights reserved.
Keywords: High voltage lines Environmental impact Social impact
1. Introduction Electricity is essential for our modern societies (Blok, 2005), and obviously it has to be transmitted from remote power stations to consumers. Electricity transmission is generally performed by high voltage overhead lines, and in a few cases, by high voltage cables (in urban areas). These installations are connected to substations where high voltage is transformed to medium and low voltage which is distributed to the end consumers. All of these infrastructures are necessary for the transmission and distribution of electrical energy; and in the past, their planning was made by the state or local governments, all in accordance with utility services. Nowadays, citizens and municipalities are interested in participating in the various stages of infrastructure planning. However, due to the expansion of urban development, power lines, which were once located on the periphery of cities, have now been integrated into urban areas. That leads to the fact that citizens living near these installations, become increasingly concerned about them and therefore want to participate in planning the actions which have an impact upon them.
Corresponding author at: Universitat Polite cnica de Catalunya. EU d’Enginyeria Te cnica Industrial de Barcelona, Comte d’Urgell, 187; 08036 Barcelona, Spain. Tel.: + 34 934016727; fax: + 34 934017433. E-mail addresses: [email protected], [email protected] (A. Sumper), [email protected] (O. Boix-Aragone s).
0301-4215/$ - see front matter & 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.enpol.2010.05.059
As society has become more concerned about its environment, it wants to more actively participate in the decision process (Lee, 2007; Bakken and Holen, 2004; Roussopoulos, 2005). In general, the active participation of citizens in issues involving infrastructures consists of three different groups: the first is the group of elected representatives, a few legitimate decision makers; the second group, the proactive citizens who are creative and critical but who represent a small part of the population; and, lastly, citizens from all social backgrounds representing various opinions. All of these groups suffer from a lack of information required in order to be able to argue about infrastructures. Due to the expansion of the group (from the elected representatives to all citizens), objective information may be rare and distorted. This can lead to social conflict, because it seems that all decisions are made by citizen representatives on their own and without consideration of the public opinion. Therefore, stakeholders should be involved in the preparation of project proposals (conflict prevention) and conflict solving. Some possible participation criteria are listed below (Retzl, 2010; Mohanty and Tandon, 2006; Roussopoulos, 2005):
Projects should be developed on a wide base and participation. Participation of citizens should be applied at any similar situation of conflict.
Participation should work on fixed and binding rules. All citizens should receive the same information. Vested or minority interests should be eliminated.
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Detailed information should be understandable and manage
able for any citizen. Any citizen should be aware that information is available and accessible.
In all those listed points, it is necessary to provide the citizens with objective, precise and understandable information. Once a conflict is caused, it can be solved by means of mediation techniques. Their objectives are to involve the conflicting parties and to find a common, self-provided ‘win win’ solution. Mediation techniques require a neutral mediator, applying the following principles (Mohanty and Tandon, 2006; Roussopoulos, 2005):
The mediator has to be neutral, providing all required information without personal opinion.
The conflicting parties should voluntarily participate and without external pressure.
Any conflicting party should be constructive and autonomously work on the solutions.
Any information required to work on the solution should be provided.
The mediator has to maintain confidentiality towards the conflicting parties. The potential for local conflicts, like conflicts in municipalities, is often underestimated because people have high requirements and are very loyal to their local area. Universities have a mandate to collect and organise internal expertise in ways that enjoy public confidence, and are able to be neutral and objective. Thus, universities can serve as excellent mediators in projects that involve multiple and conflicting objectives. Providing objective information to all involved parties is a complex task, especially in electrical infrastructure projects. Most of the citizens, administration and representatives are unable to interpret complex technical information which is even hard to be understood by electrical engineers. For this reason, it is understood that a lack of information exists. In this scenario, universities are able to provide:
Preparation of information in an understandable way. Additional information and didactic annexes in order to
explain significance and importance of operation of high voltage lines and cables. Interpretation of technical issues and assessment for parties without a technical background. Information and didactic sessions for interested citizens. Correct interpretation of challenges of high voltage planning (Morrow and Brown, 2007).
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difficulty of new energy infrastructures in the US. Cole et al. (2005), Duffy and Craven (1993), Bardouille and Koubsky (2000) introduce social concerns about energy and network planning. Social syndromes for public opinion like the ‘Not In My Backyard’ (NIMBY) (Horst, 2007), ‘Build Absolutely Nothing Anywhere Near Anything’ (BANANA) (Vajjhala and Fischbeck, 2007), and ‘Not In My Term of Office’ (NIMTO) for politics are known. Marshall and Baxter (2002) shows that, due to careful routing, the degree of visual intrusion can be reduced. Say et al. (2007) presents an environmental impact assessment tool for decision makers, in order to take into account the possible effects of a proposed project on the environment for power plants. Hadrian et al. (1988) present an approach to automated mapping of the visual impacts in utility corridors for transmission lines. Cloquell-Ballester et al. (2006) proposes a methodology of impact quantification by establishing the appropriateness of the instruments (indicators) used, so that their level of objectivity is the highest possible one. This method was applied to the aesthetic impact assessment of solar power plants (Torres-Sibille et al., 2009a) and the aesthetic impact of wind farms (Torres-Sibille et al., 2009b). The contribution of this paper is a simple methodology that allows a broad participation of those involved. This enables a social dialogue between the interested entities who broadly approved of the process and the decisions assisted by the study. This methodology has been successfully applied in several municipalities near Barcelona, Spain. To the best of our knowledge, the presented methodology has not been applied before, in order to evaluate the impact of high voltage lines. The method presented in Cloquell-Ballester et al. (2006), which is used for impact quantification of the visual impact of generation installations (Torres-Sibille et al., 2009a, b), requires a complex method and computing tools. This paper is structured as follows: Section 2 introduces the impact of overhead power lines on their environment. Section 3 presents a methodology of evaluation of the impact of high voltage lines. In Section 4, an example of the methodology in a municipality is given, Section 5 describes the use of the methodology for energy planning in Catalonia, Spain; and Section 6 presents the conclusions of this work.
2. Impact of overhead power lines Impacts are divided into two types: environmental and visual (which includes architectural). In addition, these can be looked at from a technical and social point of view. The environmental aspect deals with lifecycle impacts, impacts on vegetation and wildlife and electromagnetic impacts. The visual and architectural aspects relate to visibility and architectural issues caused by overhead lines. 2.1. Environmental impact
The use of universities as mediators can also represent disadvantages, for example the difficulty in obtaining results in a limited time and the need to publish afterwards (no long-term confidentiality). The evaluation of the impact of transmission system planning has not been exhaustively reported in literature. Woldemariam and Simpson (2008) and Furby et al. (1988) presents a public outreach process involving stakeholders in the identification and selection of the transmission line route. Design criteria were established in order to meet project objectives with the lowest possible environmental impact in a cost-effective way (Tummala and Burchett, 1999). In Trogneux et al. (1996), a method, used in E´le´ctricite´ de France which takes into account the impact of a project on the environment, by considering environmental risks, is presented. Vajjhala and Fischbeck (2007) reports the siting
2.1.1. Life cycle impact Overhead lines have, as have all infrastructures, an impact on the environment during their lifecycle. Overhead lines basically have three elements: pylons, isolators and phase conductors. Pylons are usually made of the following materials (Gonen, 2007):
wood, concrete, steel tube, lattice steel, and concrete filled steel tube.
In all cases, masts are fixed into the ground by concrete basements. The most common poles are lattice steel pylons, due
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to their uncomplicated transportation and easy positioning. Isolators are generally made of ceramic materials, nowadays, polymer and silicon are more often used. Phase conductors are normally composed of aluminium conductors, reinforced by steel. Constructing overhead lines causes impacts on the environment due to the production of the materials mentioned, their transport, and the positioning of the pylons. In the last case, an impact is caused by the concrete base, which delivers stability to the pylon, and the necessity for the removal of vegetation below the overhead line phase conductors in order to prevent flashovers from the lines and fires. During their lifecycle, overhead lines are maintained by corrective or preventive maintenance, by the substitution of spare parts. At the end of a lifecycle, overhead lines are easily removed and the environment can recover to its former state without difficulty. At the end of a transmission line lifecycle, the line is often upgraded to a new and higher voltage level rather than returned to its former state. Usually, overhead lines have very long lifecycles, 50 years (Raineri, 2010) or more are common. 2.1.2. Impact on vegetation and wildlife Overhead lines in rural areas intrude into the environment and have impacts on the adjacent areas of the line corridor. Vegetation: Impacts are caused by the construction of overhead lines due to the disruption of the soil and construction accesses (rural roads) to remote areas (in order to prepare the soil for the pylons with heavy machinery); and the transport of the pylons, insulators and phase conductors. The overhead line is designed to provide conductor clearance above vegetation, which can be managed either by clearing the vegetation or by having taller towers, both affecting the visual impact in different ways. Tree trimming should be carried out within periods of three to five years. An overhead line with covered conductors represents an option, reducing need for vegetation clearance. Wildlife: When overhead lines are located in rural areas, animals can come into contact with pylons and bare phase conductors. Contact with bare phase conductors may cause electrocution of the animal. Furthermore, depending on their location, overhead lines can lead to collisions of birds with lines, especially if the lines are located in the vicinity of established bird flight patterns (Sovacool, 2009). Birds often collide with overhead ground wires (small-diameter conductors at the top of the line), because these prove almost invisible, compared to phase conductors of a larger diameter (Bevanger, 1994). 2.1.3. Electromagnetic impact As overhead lines transport electrical energy in low frequency (50 or 60 Hz), electrical and magnetic fields are generated. In the low frequency spectrum, both fields are decoupled; the electrical field is generally related to the voltage level of the line, and the magnetic field is related to the line current (Sarma Maruvada et al., 1998a, b; Joseph et al., 2009). Both fields decrease with the distance to the phase conductors, an example of field distribution is shown in Fig. 1(a) and (b). Established limits from the WHO (2010) for the electrical field are 5 kV/m and 100 mT. Until now, it has neither been proven nor disproven that electromagnetism causes harm to people’s health. 2.2. Visual impact Overhead lines are visible from a long distance, because the higher the voltage, the higher the pylons have to be in order to respect insulation coordination. Visual impact is subjective from person to person, but in general, it depends on the landscape,
position and the angle of the observer and the contrast (Koglin and Gross, 1988). 2.2.1. Architectural impact In urban areas, impact is not only confined to visual impact. Overhead lines also cause an architectural impact, because they represent an urbanistic structure which, due to its intrinsic properties, changes its architectural environment. Architectural impacts are listed below.
Overhead lines constitute barriers between urban areas or limit urban expansion.
Visual impact on schools, parks and other urban installations is perceived as being higher.
Overhead lines can expose individuals to dangerous situations due to broken phase conductors or fallen pylons.
Traffic or work accidents can occur by accidental contact.
2.2.2. Other impacts On the one hand, overhead lines decrease the risk of individuals on the ground near the line from being struck by lightning. On the other hand, they represent an increase in the risk from broken phase conductors or falling pylons in adverse weather (wind and ice) (Gonen, 2007). Accidental contact with overhead lines during work near overhead lines can cause severe accidents. Construction industry has significantly greater proportions of occupational fatalities resulting from contact with overhead power lines than expected (Janicak, 1997).
3. Methodology of evaluation of the impact of existing high voltage lines The principal problems in the evaluation of the impact of existing high voltage lines are: firstly, different impacts appear simultaneously; and secondly, impact measurement is strongly affected by the evaluators’ subjective opinion. Therefore, it is difficult for even impartial and objective evaluators to get full acceptance of a large number of citizens. In order to obtain an objective and inclusive evaluation of the impact, a methodology of the evaluation of the impact of existing high voltage lines has been designed. Fig. 2 depicts the steps of this methodology and the participation required. 3.1. Delimitation of the studied area and determination of overhead lines In Step 1, the expert, municipality and citizen movements should carefully define the area of study. In many cases, urban areas are well defined, but some residential zones can be affected from overhead lines from outside the urban area. In these cases, a consensus from all parties should be obtained. Also, it should be agreed upon which line type (high or medium voltage) should be included into the study. In Step 2, the expert and the utility service should determine the main characteristics and the exact route (GPS data, geographical information system, etc.) of the overhead lines causing the impact. 3.2. Definition of impacts and weights In the next three steps, the methodology is fitted to the requirements of analysis in the studied area. During these steps, a
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Fig. 1. Electric and magnetic field at 1 m from the ground of a 400 kV overhead line (22 m conductor distance from the ground, 1000 A). X axis in (m). Figures obtained by a simulation programme developed by the authors. (a) Electric field in kV/m and (b) magnetic field in mT.
maximum of participation and consensus is required in order to obtain full support for the study. In Step 3, the impact types to be studied are defined. Once the type of impact to be analysed has been defined, the measurable criteria should be established in order to evaluate impacts (Step 4). If objective criteria are not possible, a subjective evaluation methodology should be established by comparing it with other situations. It is recommended to translate these criteria into a numeric scale. The numeric scale is defined in such a way as to take into account the contribution of all interested groups (including the citizens) to assure a broad acceptance of the methodology. Therefore, the used methodology should be easy to understand and the used scale should be approved by all participants. In addition, statistic data can be used to classify impacts, e.g. for the pedestrian and car traffic impact.
The translation of impacts (for example: no impact; light impact; medium impact; heavy impact) to numeric values can be made on different scales: linear scale (e.g. 1; 2; 3; 4, respectively) or non-linear scale. In order to deal with the concerns of citizens’ movements about the choice of a scale, linear, power of two and power of three scales were analysed. All stakeholders agreed that few heavy impacts may be considered with a higher score than many low impacts. Table 1 shows different theoretical situations regarding the combination of low, medium and high impacts. An initial situation with three medium impacts (base case) was taken and then, the result was compared with other combinations in order to look at the compensation level of compensation between heavy and light impacts.
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Methodology
Participation required
Step 1: Delimination ot the area of the study
Expert; Municipality; Citizen movements
Step 2: Determination of the overhead lines to study
Table 2 Application of the linear scale on the impacts from Table 1.
Base case Extreme case Combination 1 Combination 2 Combination 3 Combination 4
Expert; Utility
Imp 1
Imp 2
Imp 3
Sum
3 3 2 2 1 1
3 3 3 2 2 1
3 4 4 4 4 4
3.0 3.3 3.0 2.7 2.3 2.0
All three impacts are weighted equally.
Step 3: Determination of the number of impact types (In)
Expert; Municipality; Citizen movements
Step 4: Determination of the scale of impact types
Expert; Municipality; Citizen movements
Step 5: Determination of the scale of weights
Expert; Municipality; Citizen movements
Expert
Step 7: Analysis and conclusions of the study
Expert
Imp 2
Imp 3
Sum
4 4 2 2 1 1
4 4 4 2 2 1
4 8 8 8 8 8
4.0 5.3 4.6 4.0 3.6 3.3
All three impacts are weighted equally.
Base case Extreme case Combination 1 Combination 2 Combination 3 Combination 4
Imp 1
Imp 2
Imp 3
Sum
9 9 3 3 1 1
9 9 9 3 3 1
9 27 27 27 27 27
9.0 15.0 13.0 11.0 10.3 9.7
All three impacts are weighted equally.
Expert; Municipality; Utility
Fig. 2. Methodology of evaluation of the impact of high voltage lines.
Table 1 Test impact situations.
Base case Extreme case Combination 1 Combination 2 Combination 3 Combination 4
Base case Extreme case Combination 1 Combination 2 Combination 3 Combination 4
Imp 1
Table 4 Application of the power of three scale on the impacts from Table 1.
Step 6: Impact determination
Step 8: Proposals for impact mitigation
Table 3 Application of the power of two scale on the impacts from Table 1.
Imp 1
Imp 2
Imp 3
Medium Medium Low Low Null Null
Medium Medium Medium Low Medium Null
Medium High High High High High
The results of the application of the linear scale (1 for no impact, 2 for light impact, 3 for medium impact and 4 for heavy impact) can be seen in Table 2. In this case, only one light impact can compensate one heavy impact. Two light impacts and one heavy impact result in a lower overall impact than the base case. The results of the application of the power of two scale (1 for no impact, 2 for light impact, 4 for medium impact and 8 for heavy impact) are depicted in Table 3. In this case, two light impacts can compensate one heavy impact. Finally, with the power of three scale (1 for no impact, 3 for light impact, 9 for medium impact and 27 for heavy impact) the
results are depicted in Table 4. In this case, two non-impact situations cannot compensate one heavy impact. Fig. 3 summarizes the results of the analysed impacts with different scales. It can be seen that the base case changes its relative position regarding other impact scenarios as a function of the scale applied. The power two relationship (e.g. 1; 2; 4; 8, respectively) and the power three relationship (e.g. 1; 3; 9; 27, respectively) have the advantage that a few heavy impacts will automatically have more weight in the overall impact than many light impacts. Once numeric values have been assigned to the level of impact, a global impact ratio can be calculated by defining weights for each impact type (Step 5). This is the most difficult part because every person has their own criteria for assigning weights to impact types. For this reason, a decision matrix is used to obtain a simple and effective method. A table with the weight of the number of impact types is drawn, and on the horizontal (columns) and vertical (rows) borders, each type of impact is written. If the impact of the column is more important than the impact of the row, then 3 is written into the cell; if the column impact is less important than the row, then 1 is written and if they are equal, 2 is written into the cell. This process is repeated for all cells and the sum of the rows is calculated. The upper elements above the diagonal elements of the matrix obviously show inverted values of the elements below the diagonal matrix. This fact can be used to check that the table is correctly filled. The division of the sum of the rows by the overall sum equals the weight of every impact. The stated method is a modified application of the costeffectiveness analysis (CEA) and the cost-utility analysis (CUA), which are well-known applications in health technology
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linear
16 14 12 10 8 6 4 2 0
power 2
power 3
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Table 6 Impact evaluation for a hypothetic situation.
Imp Imp Imp Imp Sum
1 2 3 4
Numeric impact value
Impact weight in per unit
Result
0 2 1 3
0.250 0.281 0.156 0.313
0 0.562 0.156 0.939 1.657
Fig. 3. Result of the application of different scales of impact.
Table 5 Example of an impact weighting table.
Imp Imp Imp Imp
1 2 3 4
Imp 1
Imp 2
Imp 3
Imp 4
Sum
%
2 3 1 2
1 2 1 3
3 3 2 3
2 1 1 2
8 9 5 10
25.0 28.1 15.6 31.3
assessments (Johannesson, 1995). The advantage of this methodology is the transparency and the possibility to easily prove the applied criteria (Ryder et al., 2009). Nevertheless, this method may contain a certain potential for inconsistency when dealing with a large number of impacts (large matrix). More complex methods, like the Analytic Hierarchy Process (AHP), which is an extended application of CUA, provide a more accurate result, because this method compares each impact pairwise. Its disadvantage is that it needs more complex mathematical operations and it is more time consuming (Vaidya and Kumar, 2006). For this reason, it was decided to use the simpler modified CEA in this study. Table 5 shows an example for four impact types. This method is simple and can be immediately carried out by interested parties. For example, a commission with government participants, interested citizens, engineers and representatives from the utility can themselves evaluate impact weights, and a mean value can be taken for the global evaluation. Nevertheless, other more sophisticated methods to obtain the weights can be used, with the drawback that with increasing sophistication, the participation of non-experts could be more difficult. 3.3. Impact determination and analysis Once the impact types, the impact scale and the weights have been established, the result of the impact analysis can be calculated for every impact situation by applying those to the impact numeric scale (Step 6). The overall impact (Isum) is calculated from individual impacts (In) and the weights for each impacts (Wn) by Isum ¼
m X
In Wn
ð1Þ
n¼1
where m is the number of individual impacts to consider. Table 6 shows an example for one hypothetic situation. The sum of the impact evaluation is a numeric value which is proportional to the previous impact scale; in this example no impact¼0; light impact¼1; medium impact¼2; heavy impact¼3. In the example, the overall impact is between light and medium impact. In this stage, electric and magnetic field measurement can be performed in order to check the compliance with legal limits.
Fig. 4. General map of the Rubı´ municipality with high voltage installations. Colour code of the overhead lines: red 400 kV, green 220 kV, blue 110 kV and yellow 66 kV. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
The results of the study should be analysed and conclusions drawn (Step 7); and finally, together with the utility and the municipality, mitigation actions defined (Step 8). Mitigation can mainly be classified into two actions: Firstly, the change of the overhead line route outside of the urban area and, secondly, the conversion of the overhead line into an underground cable. The first option is mostly preferred by the utilities due to lower costs and there are no significant changes of the operation condition of the line (Kiessling et al., 2003). The drawback of this solution is that there must be sufficient space for the overhead line routing outside of the urban area. In very dense population areas, the option for alternative overhead line routings can be very limited. The second option is preferred by the citizen movements due to its low visual impact, but is not very well accepted by the utilities in the very high voltage range, due to
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technical limitations of this solution regarding operation and maintenance (Peschke and Olshausen, 1999) (Fig. 4).
4. Example of application The presented methodology was applied to several municipalities in the Barcelona region. In this paper, a municipality near Barcelona called Rubı´ is analysed. In Rubı´, 70,000 people live in an area of 32 km2, two bulk substations with a combined 1500 MVA transformation capability are located in its territory. The number of high voltage lines is listed below. Fig. 5 shows the general situation.
4 400 kV, all one circuit, 9 220 kV, all two circuits, 3 110 kV, two of four circuits, one of two circuits, and 2 60 kV, all two circuits.
As well as a high density of voltage lines, a main highway crosses the municipality. All this is paired with a high population density which is increasing. This means that urban space is expanding and is approaching existing high voltage installations. In order to coordinate the planning actions, the municipality has engaged the university to elaborate the methodology depicted in Fig. 2 in order to study the impact of high voltage lines. After designing the methodology, steps 1 and 2 were executed. 4.1. Impact types, impact weightings and methodology used The objective of the study was to measure the different impact situations in the same way over all the urban area of the municipality and rank them to prioritise mitigation actions. In order to obtain support from all the participants (utility, municipality government, citizens movement, etc.), several meetings were carried out to agree on the impact types to be analysed and the weights to be used (steps 3 and 4 of the methodology). In this case, the impact types used were:
Circulation of vehicles (I1). Pylons could form an obstacle or streets have to be redirected due to the pylons.
Table 7 Numeric values for impacts. Impact
Numeric value
High Middle Low None
27 9 3 1
Table 8 Weighting factors for each impact. Weight
Impact type
Value
W1 W2 W3 W4 W5 W6
Circulation of vehicles Passage of pedestrians Proximity to installations of public interest Proximity to residences Proximity to municipality installations Landscape impact
0.195 0.195 0.240 0.195 0.065 0.110
Proximity to municipality installations (street lights, etc.) (I5).
Maintenance operation of municipality installation could cause accidents. Landscape impact (I6).
To assign a numeric value to impacts, a power three relationship was chosen. Table 7 shows the relationship between subjective impacts and the assigned numeric value. The landscape impact (I6) is a combination of three factors: visibility of the line (V), fragility of the landscape (F) and the intrinsic quality of the area (IQ). The overall landscape integration is calculated by pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi I6 ¼ 3 V F IQ ð2Þ For example, a line can have a certain visibility; the landscape of the area can help to decrease or increase the impact (fragility). Nevertheless, the quality of the analysed area (industrial, commercial, residential, etc.) should be taken into account. Following (1), the overall impact (Isum) is calculated from individual impacts (In) and the weights for each impact (Wn) by
Passage of pedestrians (I2). Pylons are often placed on
pedestrian walks, that could be an obstacle for the circulation of the pedestrians. Proximity to schools, hospitals and other installations of public interest (I3). Proximity to residences (I4).
Isum ¼
6 X
In Wn
ð3Þ
n¼1
where the weighting factors for each impact are determined by consensus and are given in Table 8 (step 5). 4.2. Determination of the impact in the Rubı´ municipality
Fig. 5. Voltage line r2 in an avenue of the Rubı´ municipality.
Eleven situations of the impact of high voltage lines (equal or above 66 kV) were detected in the municipality area. These situations are sets of physically adjacent areas, which have the same impacts over their physical extension. E.g., an overhead line along a street can be treated as a single situation even if this line has some 100s of metres of extension. Some situations may imply more than one overhead line. Figs. 5 and 6 show an example for the impact (r2) of a 220 kV line in a residential area. The evaluation of the impact of all eleven impact situations is depicted in Table 9 (steps 6 and 7). Due to confidentiality, the names of the streets and voltage lines are not given. The results of the impact evaluation vary between 1.22 and 15.95. In this case, it can be seen that three situations have an impact value over 10, eight situations are between 5 and 10, and three situations are below 5.
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situation, all impacts over a single overhead line were analysed as a whole, in order to propose mitigation measures. The proposed measures were discussed with the utility and a cost estimation of those measures was realized. 4.3. Stakeholder participation
Fig. 6. Photograph of the 220 kV voltage line r2.
Table 9 Impact values for the high voltage lines (equal or greater than 66 kV) for the Rubı´ municipality. Line
r1 r2 r3 r4 r5 r6 r7 r8 r9 r10 r11
Impact I1
I2
I3
I4
I5
I6
Isum
1 1 1 1 1 27 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1
1 1 1 27 27 1 27 1 1 1 1
9 27 1 27 1 27 27 1 27 27 27
27 27 1 27 1 27 27 1 1 1 27
6.24 6.24 3 9 9 6.24 18.72 3 9 6.24 9
4.826 8.336 1.220 14.880 8.120 13.406 15.949 1.220 6.950 6.646 8.640
Table 10 Mitigation action proposed for the studied high voltage lines (equal or greater than 66 kV) for the Rubı´ municipality. Line
Mitigation action proposed
r1 r2 r3 r4 r5 r6 r7 r8 r9 r10 r11
Alternative overhead line route Alternative overhead line route No mitigation action proposed Alternative overhead line route Alternative overhead line route Alternative overhead line route Underground cable No mitigation action proposed Alternative overhead line route Alternative overhead line route Alternative overhead line route
During the study, several stakeholders were very interested in participating in the study, especially people who live near the lines. People who were not familiar with electric engineering were interested to understand technical constraints of the planning and operation of high voltage lines. Therefore, it is necessary to dedicate time to explain these technical aspects in order to prevent misunderstandings. The municipality and the utility fully supported the project and delivered necessary information for this study. Nevertheless, confidential agreements were necessary in order to receive sensitive information. The results of this study were very well accepted by the municipalities, because they were useful for planning issues in the community. The utilities showed a reserved attitude at the beginning of the study, but as they were invited to discuss possible mitigation actions, they were collaborative.
5. Application of the methodology for energy planning in Catalonia As already stated, the urban expansion of the Catalonian municipalities has led to the high voltage lines located in the surroundings being urbanised in the last 30 years. In October 2002, the Catalonian Parliament adopted a legislative initiative (Act (1522/VI, 2002)) to request the Catalonian Government to negotiate with utilities, municipalities and the Spanish state to adopt mitigation measures for the affected areas within a period of 10 years. In order to comply with the Act of Parliament, the Catalonian Government ordered the realisation of studies in order to detect the territorial and environmental impact of existing high voltage lines with a nominal voltage higher than 36 kV in urban areas. These studies were performed in 29 municipalities using the methodology presented in Section 3. The results of the studies were used to perform the planning of the electrical infrastructure in the energy plan of Catalonia 2006–2015 (Generalitat, 2006).
outside the municipality area outside the municipality area outside the municipality area outside the municipality area outside the municipality area
outside the municipality area outside the municipality area outside the municipality area
Electromagnetic field aspects were taken into account because several citizens were very interested in this subject. Electric and magnetic field measurement was performed in all impact situations. After the measurements, the results were extrapolated to full load (at time of the measurement, the lines had partial load) and compared with the legal limits. All studied cases were below these limits. This classification was used to prioritise the mitigation actions with the utility (step 8). The proposed mitigation actions in the studied case are listed in Table 10. As the analysis gives an impact value for each
6. Conclusions This paper presents a methodology to evaluate the numeric impact of existing high voltage lines from several impact measures, using weights. The results presented in this paper show that this methodology enables the ranking of different impact situations on a common scale. The strength of this methodology is not the absolute objectivity of the overall impact value, but the participation of different entities (utility, citizen movements, governments, etc.) in the application of the methodology. This increases the social acceptance of the utility planning activities and allows the ranking of impacts in order to prioritise mitigation activities. The methodology has successfully been used in 29 municipalities the Catalonia region in Spain.
Acknowledgement The authors would like to thank the Rubı´ municipality for the support of this project.
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