From the edges of the rainforests to the heart of Colombo, with a 98% electrification rate, Sri Lanka has nearly accomplished its goal of providing electricity to every household in the nation. Although impressive, challenges still exist for the CEB (Ceylon Electricity Board) in achieving its main objective in fulfilling ‘local energy demand’.
The local energy demand can be classified as the total demand for electricity throughout the island at any given time. Demand for electricity routinely peaks between 6pm-10pm to around 2700MW (Mega Watts), while at night, after 10pm it is as low as 1200MW, less than half of the peak demand. Storing energy on the grid is not possible yet, so the grid must strategically utilize Sri Lanka’s power plants to match the island’s demand for power at any given time under several constraints. These include managing a unique set of restrictions in utilizing each power plant and minimizing the grids total generation and transmission costs. This is a complex challenge that is made further difficult when increasing the capacity of Renewable sources. This article looks specifically at the benefits and challenges of Sri Lanka’s renewable energy plants in the context of its current energy crisis.
A breakdown of the installed “Other Renewable Energy” Power plants and capacities in Sri Lanka (P2)
Sri Lanka’s Energy Crisis
Sri Lanka has added no new power plants to the grid in the last 4 years. The total generation capacity of Sri Lanka’s power plants is about 4087MW. Although well above peak demand, the different challenges in scheduling and using each power plant make meeting the total energy demand at any given time extremely difficult. Demand is growing, and the CEB predicts adding 150MW to the grid annually is required to keep up with this growth.
The CEB’s long term power generation plan 2018-2037, submitted in 2017 and approved in 2018 by the PUCSL (Public Utilities Commission of Sri Lanka), maps out how to keep up with the growth in energy demand on the island until 2037. It includes a road map for the implementation of recommended power plants and a breakdown of the best-suited mix of energy generation types. Worryingly has not been put into practice. The generation mix includes several types of renewable energy sources, classified ‘ORE (Other Renewable Energy)’. These include mini-hydro, wind power, solar, and biomass from waste and from wood. The currently installed capacities of these are shown above. In this article, we will look at the technology behind and state of; mini-hydro, solar, and wind energy plants. However, before that it is important to note that the technologies of conventional plants such as coal power plants have also evolved worldwide to meet improving green standards and therefore a truly sustainable generation plan for the island needs to include such power stations.
Mini Hydro Turbines are small hydro power plants, with a lower environmental impact. (P3)
The energy of moving water in a river can be captured by channeling a portion of a stream through a mini hydroelectric system. At the highest available point in a stream, water is routed into a turbine, which rotates a shaft and spins a generator to produce electricity. This mechanism is the transformation of the kinetic energy of flowing water into electrical energy. The water then moves through the system and returns to the stream at a lower point.
The power (W) a system can generate depends on two things; the height the water drops from in “m” (meters) and flow of the water in “m3/s” (cubic meters per second).
Power (W) = height (m) x flow (m3/s)/10
In Sri Lanka mini-hydro started in 1996, and presently it is the largest contributor of the ORE ‘other renewable energy’ sources with an installed capacity of 406.11MW. However actual production depends on the seasonal condition of its waterways and such plants yield around 36% of its full capacity on average per year.
It is important to have comprehensive regulations and a well-designed system to avoid causing environmental damage. And the common challenges stem from a lack of understanding and government policy regarding the proper and safe implementation of these mini-hydro projects. In addition to this obtaining the necessary approvals, and the facility to connect the plant to the grid is often difficult.
Wind power has a high potential in Sri Lanka (P4)
From sailboats to windmills, humans have harnessed the wind’s energy for millennia to propel boats, grind grain, pump water and aid the growth of civilization. Today’s wind turbines are the modern equivalent of a windmill; converting the wind’s kinetic energy into clean, renewable, electric energy.
Most wind turbines consist of three blades mounted to a steel tower with a height of 100 feet or more to catch faster winds found at higher altitudes. The blades are structured like airplane wings. As wind blows on them low pressure forms on one side while high pressure forms on the other and each blade moves toward the region of low pressure in a process called ‘lift’. The lift is stronger than the winds force against the blade, known as the drag, which spins the turbine’s blades like a propeller. A series of gears increase the rotor’s rotation from around 18 revolutions per minute to roughly 1800 revolutions per minute, allowing the turbine’s generator to produce Alternative Current (AC) that can be fed to the grid. Onshore turbines generate up to 3MW while offshore can generate up to 9.5MW
Sri Lanka’s operational generation capacity through wind has reached around 130MW but a massive 100MW wind farm will be added the grid next year. Access Engineering is the primary contractor for this 100MW wind farm which is owned by the CEB.
As wind blows day and night, as well as when the island has a peak energy demand wind farms can play a bigger role alleviating our generation burdens on the Island. It is important however to address on site environmental concerns, such as bird flight paths, as well as generation and transmission constraints for truly sustainable solution.
Small residential solar systems have added 180MW of Renewable Energy to the grid (P5)
Photovoltaic (PV) panels allow photons, particles of light, to dislodge electrons from Silicon atoms embedded in these panels which generate a DC (Direct current). These panels are connected to an inverter to convert this DC into AC (Alternate Current) – usable in the home, and suitable for exporting to the grid.
In Sri Lanka, the CEB offers Net metered connections that allow households or businesses to generate and export electricity from rooftop solar panels during the day to offset their electricity consumption during the night. A total of 180MW in capacity of domestic rooftop solar panels has been installed, mainly through net metering programs such as the ‘Soorya Bala Sangramaya’; which aims to achieve an installed residential rooftop capacity of 200MW by 2020.
In addition to this Sri Lanka has 8 large projects directly connected to the grid totalling 51MW in capacity. Progress on tenders called from the private sector to purchase electricity through competitive bidding has been halted however and no new plants have been approved.
The large land area required for solar (3-5 acres for 1 MW) and environmental factors such as a high intermittency due to clouds and dust are some of the challenges large scale solar farms need to overcome. These issues will need to be addressed as solar grows in importance, even though it is presently a minor contributor to the grid.
A more refined approach needs to be taken to assess the needs of the grid to ensure national energy security (P6)
The many challenges of ensuring uninterrupted power to all Sri Lankans in the years to come does not seem insurmountable but requires strategic planning, and the coordinated use of multiple types of power generation. The primary advantage of renewable sources of energy; that they harness energy readily available in the environment is mainly limited by the fact that they can’t be controlled and planned for like other power generation sources including thermal power generation. For a look at the approved long-term generation plan by the CEB that has not been followed please click here.
Wise planning must involve both increasing the input of renewable energy sources while implementing greener technologies to conventional power sources such as coal plants to reduce their environmental impact while taking advantage of the benefits they bring. Stay tuned for our next article on how coal power plants around the world are becoming cleaner.