To demonstrate the energy saving potential which exists in city street lighting system by retrofitting a part of existing street lighting system
The Energy and Research Institute, India (TERI), introduced energy efficient city street lighting systems in Pune, Western India. The main objectives of this project was to demonstrate the energy saving potential of city street lighting systems by retrofitting about 500 existing lighting poles in the city of Pune with more efficient components. Lessons learned were divulged through workshops addressing key stakeholders and decision makers from different municipalities. The gathered experience were documented in handbooks with technical and financial guidance for replication.
Technology, Operations and MaintenanceThe existing systems in Pune generally use 70W, 150W and 250W high-pressure sodium lamps (HPSV) that are fitted into inefficient luminaries without automatic daylight controls. One of the most important factors of the new design was that energy consumption would be kept to a minimum. From the perspective of energy efficiency, the optimal combination of efficient luminaries would have been an arrangement of carefully selected overhang, mounting height and tilt angle luminaries. These would have to be arranged in such a way that poles are installed at the maximum spacing distances, so reducing the connected or operating load without compromising the lighting design requirements. However, as the project was a retrofit as opposed to a new installation, it would have been unrealistic to change the pole height and pole spacing as PMC would have had to uproot all the poles, disconnect all the wiring and feeder pillars and then install new poles and lay new electric wiring through new or existing feeder pillars. So PMC clearly stated that they wanted to improve the energy efficiency of the city lighting system but without changing the existing poles. Because of this, high- pressure sodium vapour lamps were selected to optimise the lighting system. In the retrofit, 250W HPSV lamps with 33,000 lumen were used to replace the existing 250W fixtures and 150W HPSV lamps, which give 17,500 lumen output, were used to replace the existing 150W fixtures. The newly installed HPSV lamps are much more efficient compared to the existing HPSV lamps. All installed fixtures were also fitted with multi-tab ballasts, enabling a fixture fitted with 250W lamps to operate both at 250W and 150W. Lighting controls with daylight sensors were also installed, meaning that the lights can be automatically controlled according to seasonal variations.
Environmental IssuesPublic lighting accounts for only 1% of India's total electricity consumption. However, according to available data, electricity consumption for public lighting systems is increasing at a rate of 10% (compared to an overall increase in India's electricity consumption of 7%). The actual consumption for public lighting in India is 7,753 GWh. With an estimated energy saving potential of 30% through efficiency improvements 2,326 GWh of electricity could be saved. This means that CO2 emissions could be reduced by as much as 1.9 million t annually. In Pune the saving potential in the public lighting sector is estimated to be 27.7 million kg CO2/year.
Social IssuesEnhanced street lighting improves the traffic safety. Further the savings from the improved public lighting systems could be used by the municipality for other purposes for example in the health or education sector.
Results & Impact
ReplicabilityThe potential for replication in India is very good, as currently nearly all public lighting systems are very inefficient. The main constraints for replication are local authorities' lack of technical expertise and their lack of finance. To overcome the financial constraints, TERI has evolved different financing strategies, which could help replicate energy-efficient city street lighting solutions. The proposed strategies include energy service companies, financial institutions and the local development authority, because the key for long-term viability and replicability is to involve all stakeholders. During the project TERI also developed an optimised lighting design for Indian carriageway widths taking into account Indian standards. This could be very helpful to local authorities and other organisations that want to establish efficient street lighting schemes in India.
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