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 Resources Institute (TERI)
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.
The Energy and Resources Institute (TERI) implemented the project in collaboration with the Pune municipal corporation (PMC). The project comprised a number of different activities, starting with the collection of data about the existing city street lighting systems in Pune. The combined team of TERI and PMC surveyed various streets and different stretches of road were identified as project sites. In the next step, the optimal lighting schemes were chosen. Using computer simulation tools, the schemes were designed to meet the lighting requirements as per Indian standards. The next stage was to organise a manufacturer's meeting at PMC. Manufacturers of lighting fixtures were invited and briefed about the project and information about the most efficient fixtures and controls was shared. After deciding which technology should be used, the necessary equipment was procured and installed.
The 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.
Financial Issues and Management
The existing city lighting load in Pune is approximately 20 kW per km of road. With the sustainable city lighting system it would be reduced to 7kW per km. This would save approximately €3,200 per km per year. Retrofitting would cost about €10,500 per km so the payback period would be about 3.3 years. This proves that retrofitting street lightning systems is an attractive option for PMC and other local development authorities.
During this pilot project TERI acted as the technical expert and project manager, with PMC as the primary stakeholder and agency responsible for the implementation. For future projects the toughest challenge will be to bring the various stakeholders together in such a way that they take on joint ownership of the project.
Public 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.
Enhanced 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.
The installation of the energy efficient street lighting system has been successfully completed on different sample road stretches in the city of Pune. It has demonstrated that there is an energy saving potential of about 30% for city street lighting in India.
In total, 500 inefficient fixtures were replaced with more efficient fixtures and fitted with more efficient lamps. These fixtures have multi-tab ballasts so that after midnight, when traffic reduces on Indian roads, the fixtures can be dimmed. After the retrofit, the lighting levels were better - both in normal and dimmed modes.
In order to share the lessons learned from the completed demonstration project in Pune, a Handbook on Street Lighting has been published. The handbook explains in details every stage of the project, illustrates technological solutions, highlights energy and cost saving potentials and recommends a financial model. The handbook offers guidance in the design and implementation of energy efficient street lighting systems in India.
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.