Summary

The climate crisis has prompted the global search for sustainable solutions, including energy conservation and renewable energy generation. This article examines the importance of energy-efficient street lighting in Sri Lanka, focusing on current conditions and problems, as well as opportunities to improve efficiency with modern technologies.

Introduction

Amid the challenges arose by the climate crisis, the world is looking towards the methods of reducing the carbon footprint in every aspect. Therefore, world is turning for more sustainable energy solutions to meet the demand. In that sense renewable energy sources play a crucial role. However, it has become a challenge to fulfill the increasing energy demand of the world totally based on the renewable energy sources at this moment, because the technology development for harnessing the energy from alternative sources is not growing at the same rate. That is where the energy conservation comes into play. So, when we are considering the energy conservation, it has different aspects. It may be domestic, industrial, and institutional energy conservation or it can be even sustainable street lighting. In this article I am focusing on the energy conservation of street lighting.

Street Lighting in Sri Lanka

Municipal and town councils, among other local government bodies, bear the responsibility for energy expenses, maintenance, and investments related to street lighting. On the other hand, street lighting maintenance on specific roadways is the duty of the Road Development Authority.
By referencing to a study conducted by Asian Development Bank (ADB) in 2012, the following factors can be listed regarding the current conditions of the street lighting systems in Sri Lanka.
Equipment conditions:

• Poor quality of street lighting equipment.
• Use of incandescent lamps with very poor efficacy.
• A high portion of lamps are fitted in very poor quality luminaires with a very low coefficient of utilization.
• Inconsistency in types of lamps, luminaire, overhang arms,and height of luminaires.
• Very low lamp life and very high lumen depreciation factor.
• For manually controlled streetlamps it is often used indoor-quality control equipment, which expose to rain even causing life hazards while itself resulting in an energy wastage.

Controlling methods:

• In city areas most of the streetlights are controlled individually by daylight sensors. However, in rural areas they are equipped with manually controlled switches.
• Manually controlled lights operated by either local government staff or volunteers, are usually turned on early and turned off later than necessary, causing an energy wastage.

Maintenance Practices:

• Lack of periodical maintenance (cleaning and tuning), which is essential for the proper operation of photo sensors, has caused lights keeping on unnecessarily for longer.

Cost of street lighting:

In Sri Lanka public street lighting is offered as a quota based free energy for each distribution licensee.
“In 2016, a total of 143 GWh (about 1.2% of total sales) was granted as free energy, and its cost of supply of SLRs 2,954 million would be distributed across all customers. The burden on the cost of supply is 1.3%, or SLRs 0.25 per kWh sold.” - “Sri Lanka Energy Sector Assessment, Strategy and Road Map:,” 40.

Figure: Different conditions of the existing streetlamps

Modern technologies in energy efficient street lighting

At generation point: One aspect of energy conservation in street lighting is the using of alternative energy sources to electrify the streetlamps. By this method it isolates the streetlighting systems from the national grid. This can be achieved by solar or wind energy.

Solar energy - Solar lighting is more common nowadays in street lighting. In this method, the energy generated through PV panels during the daytime are stored in batteries, and at the night luminaires will be lighted by using this energy.
The main challenges here are the energy storage and the unavailability of solar power at night.

• Technologies for energy storage: Lead acid batteries, Lithium batteries, and Super capacitors

Wind energy – Here the energy harvested via small-scale wind turbines is used for street lighting applications. These are emerging technologies and academic research are ongoing on this. The technology is being developed using both horizontal and vertical axis small-scale wind turbines.
The main advantage here is the energy can be generated at night also.

At consumer point: As well as at the energy generation point, we can use the technology to improve the energy conservation at consumer point by implementing IoT based smart street lighting systems including technologies like IR sensors, IR cameras etc.

Opportunities

In my point of view, I would like to describe some opportunities in street lighting here. By considering the above factors we can implement public private partnership (PPP) models for street lighting projects, to enforce proper lighting of all the necessary streets and energy efficiency. For an example, we can go for a PPP model where private sector build and maintain the street lighting system and government will pay the tariff for the private operator. Furthermore, these street lighting projects can be launched with aesthetic aspect to attract the tourism industry, and there can be created some recreational areas like skating parks and outdoor gathering areas. These can create money making opportunities for membership based sports clubs, and musical shows, and restaurants. From this, private partners in the street lighting project can cover their maintenance cost through renting or leasing these facilities for the other private investors.

Photo by AlexanderLondoño on Unsplash

Conclusion

When we are stepping towards net zero targets, energy conservation also has become important. Since street lighting has a significant potential of energy conservation, in the global context, modern street lighting systems are being developed to ensure energy efficiency. As we discussed before in this article, public street lighting in Sri Lanka needs more sustainable improvements to save energy. So as a final thought, with public-private partnership, the government authorities could overcome the challenges in existing systems and implement modern technologies.

Feel free to share your ideas and feedback in the comment section.