Environmental impact assessment of two different streetlight technologies R. Lukman1* and D. Krajnc2 1

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Nigrad d.d., Utility Company, R&D Department, Zagrebška 30, 2000 Maribor, Slovenia University of Maribor, Faculty of Chemistry and Chemical Engineering, Smetanova 17, 2000 Maribor, Slovenia *Corresponding author: E-mail: [email protected], Tel +386 2 45 00 391

Abstract Public lighting in Slovenia is energy intensive. Analyses from 2006 and 2007 show that energy consumption per capita for public lighting in Slovenia was 84 kWh, whilst the European average was 50 kWh. Maribor municipality has one of the highest energy consumptions for public lighting in Slovenia (120 kWh per capita). In 2009, Maribor municipality started a pilot project on replacing existing streetlights with light emitting diode (LED) technology, manufactured in Slovenia. This study evaluates the environmental impacts of this public lighting service from the aspects of two different technologies (LED and high pressure sodium (HPS)) lights, during all phases of their life-cycle (production, operation, end-of-life). The LCA (life-cycle assessment) methodology used in this research was based on the ISO 14040 and 14044 series. This study was performed using the LCA software GaBi 4 Professional® and Ecoinvent database. The results from this study will support local decision-makers when seeking a balance between the environmental, financial, and social requirements of public lighting services. Keywords: Life cycle assessment, streetlight technologies, LED (light emitting diode), high pressure sodium lamps (HPS).

1. INTRODUCTION A major challenge for the global society in the 21st century is how to mitigate and adapt to the climate change, whilst still ensuring clean and secure energy supply, and implementing end-use technologies to meet the needs of current and future generations [1,2]. The main sources of manmade GHG emissions are the burning of fossil fuels for electricity generation, transport, industry, and households. In the EU, energy consumption generates nearly 80 % of the GHG emissions [2]. In 2008, the European Union (EU) decided to reduce its greenhouse gas emissions by 20 % from the 1990 level by 2020. In December 2008, the European Council confirmed “the European Union's commitment to increase the 20 % reduction to 30 % within the framework of an ambitious and comprehensive global agreement, which still remains EU policy today” [3]. Almost 20 % of electricity consumption worldwide is used-up by lighting applications, which corresponds to 2651 TWh/year [4]. The electricity consumed for municipal street lighting in European cities annually accounts for up to 38 % of all electricity used [5]. Thus, energy-efficient lighting represents a hot topic during discussions on climate change, sustainable energy policy, and energy efficiency [6]. Many cities across the world, such as Bogota, Chicago, Hong Kong, London, New York, Paris, Sao Paulo, Amsterdam, Stockholm and others, have decided to reduce their carbon footprints. Most of them have carried out new retrofit programmes by replacing their streetlight technologies with new Proceedings of the 3rd International CEMEPE & SECOTOX Conference Skiathos, June 19-24, 2011, ISBN 978-960-6865-43-5

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ones [7]. Those local authorities generally responsible for purchasing street-lighting systems, spend between 14 and 16 % of EU GDP on public procurement each year, by opting for energy-efficient lighting [8]. Currently, light-emitting diode (LED) street lamp is the most modern technology on the market. The LED technology is popular for its high energy-efficiency, maintainability, and flexibility [9]. Public lighting in Slovenia is very energy-intensive. Analyses from 2006 and 2007 show that energy consumption per capita for public lighting in Slovenia was 84 kWh, whilst the European average was 50 kWh [10]. Maribor municipality has one of the highest electricity consumption for public lighting, which is 120 kWh / per capita [11]. In 2009 several cities and municipalities in Slovenia decided to replace their current streetlight technologies with the LED. The most common technologies used for the lighting of roadways and streets are mercury vapour fixtures (HgV), highpressure sodium lamps (HPS), compact fluorescent lamps, and reflectors. This research presents the case study of the pilot project for changing the technology of public lighting in the Maribor municipality. It is based on life-cycle assessment methods, revealing the differences between the environmental impacts of these two technologies, LED and HPS, lamps. This study focuses on the manufacturing, operations, and end-of-life for both technologies, and evaluating them according to their environmental impacts. 2. METHODOLOGY Life Cycle Assessment (LCA) is a tool for identifying and quantifying potential environmental burdens. It has become more systematic and robust over the past three decades [12]. LCA can help quantify the materials and energy used, as well as the emissions and wastes produced during the life cycle of public lighting. LCA enables an estimation of those cumulative environmental impacts resulting from all stages of the product's life-cycle, often including some impacts not considered in more traditional analyses (e.g., raw material extraction, material transportation, ultimate product disposal, etc.) [13]. The LCA methodology for environmental impacts assessment used in this research is based on the ISO 14040 and 14044 series [14]. This study was performed using the LCA software GaBi 4 Professional® [15], and Ecoinvent database [16]. 2.1 Objectives of the study, the functional unit and system boundaries The objectives of this study was to evaluate the life-cycle environmental impacts of the public lighting service process for two different technologies (LED lights, and high-pressure sodium lights), including their comparison from the environmental perspective, during all the phases mentioned above (production, operation, and end-of-life). This was in order to help local decisionmakers to find a balance between environmental and financial requirements. The systems under consideration were two streets within the Maribor municipality, Slovenia. In one street, 14 LED lights were installed to replace 14 mercury lamps dating back to 1970 in comparison with 14 already situated high- pressure sodium lights. The functional unit is to provide an annual lighting (4015 hours) for a 500 m long street within the urban area. 2.2 Data used The primary data were obtained from the following sources: x The electricity consumption for the LED and HPS lamps was obtained by direct measurements from field research, including energy-flows for start-up phase, generated by a ballast, but no specific infrastructure required to operate the lighting devices was considered during the study.

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x

The information about the LED lamps (production technology, suppliers, mass balance) was obtained from Grah-Automotive – a Slovenian company producing LED lamps. Information about the HPS came from the producers' webpage.

Further more data needed for the LCA study, such as the composition of materials within the lamps housings, and their internal area, transportation paths during the production, operational, and endof-life phases, were obtained by direct measurements or via the internet. The secondary data for the LCA were sourced from the Ecoinvent database. Energy usage for the production processes have been obtained from the literature. Transportation paths were calculated using a Michelin Route Planner.

3. RESULTS AND DISCUSSION The environmental impacts were calculated following the CML 2001 as at December 2007.

Figure 1. Overall environmental impacts of the two technologies for public lighting.

Fig. 1 shows the overall environmental impacts of the two streetlight technologies (LED and HPS) covering their three life-cycle phases (production, operation, end-of-life). It can be observed that the LED technology has during its whole life-cycle, smaller environmental impacts within all the categories, when compared to the HPS technology. The more significant impacts from both technologies (LED and HPS) are global warming and human toxicity potentials, followed by acidification and terrestric ecotoxicology potentials. Normalization was carried out in order to define the relative significances of these potential impacts and to create datasets with common units, Fig. 2. A Western European normalization database was used.

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Figure 2. Normalized overall environmental impacts (Western Europe) from the streetlight technologies. The normalized results shown in Fig. 2 indicate that the more significant impacts from both technologies (LED and HPS) during their life-cycles are acidification potential (AP) and global warming potential (GWP), followed by photochemical ozone creation potential (POCP). The normalization results also indicate that HPS technology has a higher environmental impact for all the categories, in comparison with LED.

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Figure 3. Relative contribution during different life-cycle phases in regard to the total environmental impacts of both technologies. The life-cycle phase within the system, contributing most to the total environmental impacts is the operational one (see Fig. 3) for both technologies, and accounts for more than 90 % of all environmental impacts. The production and end-of-life phases make smaller contributions to the environmental impacts.

Figure 4. Relative contributions of different life cycle phases for the three technologies, regarding global warming potential. 987

Fig. 4 shows the relative contributions during the life cycle phases of both technologies investigated, in relation to the global warming potential. The results indicate that HPS makes a larger contribution to the GWP than LED technology, during all the life-cycle phases. The biggest difference between these two technologies is in the operational phase, where HPS contributes around 4 times more to the GWP than LED technology. Such a result is linked to the fact that LED lights consume less energy than HPS. During the end-of-life phase, the HPS and LED technologies are comparable regarding GWP potential.

4. CONCLUSIONS This study provided an LCA analysis of two street-light technologies in regard to their environmental impacts. The results show that the overall environmental impacts are higher by the HPS technology when compared to the LED. The phase, which contributes most to overall environmental impacts by both technologies, is the operational one. LED technology is at the forefront when reducing global warming potential. It consumes less energy during the same lighting process and has consequently a lower impact on the climate change. This LCA study is also of practical value for the Maribor municipality, because it presents an objective evaluation enabling a simple comparison of two technologies in order to decrease environmental impacts and costs. Maribor and other Slovenian municipalities do have smaller, pilot projects of introducing LED streetlights technology. However, LED technology requires higher initial investment costs and the payback time is longer, therefore, most of the projects realized are European Funded.

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