by Asoka Abeygunawardana
The power crisis has become a hot topic these days. The experts and politicians are accusing each other for the crisis situation. As certain issues are highly technical, it is necessary to analyze the data carefully in the proper context to understand the real situation.
At present the annual electricity requirement in Sri Lanka is about 11,000 GWh and the installed power plant capacity is about 2700 MW. This installed capacity consists of 1200 MW of hydro power and 1500 MW of thermal power. The thermal power plants generate electricity by firing coal, Heavy Fuel Oil (HFO) and diesel. The cheapest option for power generation is hydropower as it has no fuel cost involved. The most expensive option is diesel and the costs of HFO and coal are in between these two.
The total electricity requirement in the country is about 33 GWh/day at present. The power requirement varies during the day and the day time (from 6.30 am – 6.30 pm) demand is about 1200-1400 MW. The demand increases and reaches a peak of about 2000 MW during the night from 6.30 pm -9.30 pm. Again it drops to about 800 MW during the night bay which is from 9.30 pm -6.30 am. The utility provider has the responsibility of providing uninterrupted power supply to this varying daily demand.
The CEB needs to prioritize and operate the power plants owned by both the CEB and IPPs (Independent Power Producers) to minimize the cost of generation while ensuring uninterrupted power supply to the consumers. During the rainy seasons the hydro power plants are utilized to the optimum to minimize the cost of generation. If those plants are not utilized adequately during the rainy season then ponds and reservoirs spill and water is released without generating power. On the other hand during the dry season the hydro power is used for peaking purposes only to minimize operating expensive diesel power plants. Some of the hydro power plants are used during the day time as spinning reserves to absorb the load fluctuations and hence to stabilize the system. As the peak load is about 2000 MW at present it is not possible to meet the peak demand purely using thermal power plants as the installed thermal power plant capacity is only 1500 MW. The balance should be supplied from hydropower.
In early 1990’s Hydro power contributed to generate over 90 per cent of the annual electricity requirement, however due to increase in demand the situation has changed drastically. Hydro power contribution is now reduced to 40-50 per cent. The 2011 estimated hydro power supply is, about 4100 GWh. At present if the total consumption is to be satisfied using hydro power, then hydropower will be adequate only for 133 days. On the other hand the hydro power alone cannot meet the peak demand as the peak is higher than the installed hydro capacity.
Currently 90 per cent of power is generated from thermal power plants and the residual 10 per cent is generated from hydropower. The capacity of the coal power plant is 300 MW and it is at present generating about 6 GWh/day. This is about 20 per cent of the daily electricity need. The HFO contributes to generate about 16 GWh/day (50 per cent of total) with a capacity of about 700 MW and the Diesel contribution is about 7 GWh/day (20 per cent of the total) having a capacity of about 300 MW. The balance 4 GWh/day (10per cent of the total) is generated from hydropower plants. As hydro power is seasonal, the present effective hydropower plant capacity is only about 500 MW. During this period of the year hydro power generation mainly comes from Laxapana Complex (about 3 GWh) as it gets benefitted from the South West monsoon. Kukule generates about 0.5 GWh and the Mahaweli reservoirs collectively generate only 0.5 GWh.
The year 2011 recorded the decade’s lowest South West monsoon rain fall to the catchment areas of hydro power reservoirs. The water inflow to the hydro power reservoirs during the period from May to September was only 865 GWh; the lowest of the decade. (See graph 1)
It is also noteworthy that the electricity demand in Sri Lanka was rising at a rate of 7 per cent per annum during the last two decades. In 2000 the annual electricity demand was only 6700 GWh and by 2010 it had increased to 10,700 GWh. This year it is expected to increase up to 11,200 GWh (see graph 2). The hydro power plant capacity has not changed significantly as almost all the large hydro power potential is already tapped. In this context it is not possible to adopt the same old tactics to manage the system.
Taking into consideration the average amount of rains experienced during the month of June there is a decline of 70 per cent in rainfall this year. Generally for a 30 year average Castlereagh receives 631 mm of rains, but this time it was limited to 230 mm. Maussakale average is 530 mm however it received only 170 mm this year. This situation arose especially during the months of May and June. Moreover monsoon rainfall was experienced not in the higher elevation areas which feeds the ponds but in the low lying populated areas. Meteorologists have cited the changes in the wind pattern for this difference. As a result of low rainfalls during the South West monsoon the hydro power storage in the reservoirs reduced to about 300 GWh by the end of August. This is around 25 per cent of the total reservoir capacity. This water level is the lowest recorded during the last decade.
Some argue that this situation occurred due to mismanagement of water in the reservoirs. Their argument is based on the fact that the 2010 North East monsoon and the rain-fall in the first quarter of 2011was higher than the average. It is true that the rainfall during that period was high however it is also true that the storage level at the beginning of May was higher than the previous years (see graph 3). It is not recommended to maintain the water level at an unnecessarily higher level at the beginning of May as there is a possibility that the ponds and reservoirs may spill when the flash rains occur at the beginning of the South West monsoon. It is clear that the CEB has kept the water at appropriate levels at the start of May and hence it is not a matter of mismanagement.
The officials were expecting heavy rainfalls as usual at the beginning of the South West monsoon and kept the water levels at the start of May at a reasonably higher level when compared with last 2 years (see graph 3). Soon the CEB officials realized that the expected heavy showers are unlikely and decided to use the water sparingly.
The water in the reservoirs is used for multi-purposes: water supply, irrigation and power. The decisions regarding releasing the water in the reservoirs are taken by the CEB, irrigation, Mahaweli Authority and Water Secretariat officials collectively. The priority is always given to irrigation as that affects the Mahaweli farmers and food production in Sri Lanka. Issuing of water for cultivation in the Yala season was essential. Even with the reduction in rainfall, with the influx of farmers seeking to cultivate their land after the war, adequate amounts of water had to be released to meet their agricultural requirements.
The situation worsened with the inability to generate the anticipated power output from the Puttalam “Lakwijaya” coal power station and the Kerawalapitiya combined cycle power plant. While the Lakwijaya power plant was scheduled to commence operation at the beginning of this year, it was expected to add 720 GWh of power to the National Grid during the first 6 months of this year, but due to the delay in commencement and the technical faults experienced it was only able to add 265 GWh of energy to the National Grid.
Furthermore due to fuel supply related issues which arose at the Kerawalapitiya combined cycle Power plant, of the 670 GWh power generation expected from this power plant, only 275 GWh of energy was generated. The CEB is bound to purchase oil from the CPC. The recent delays of CPC on purchasing oil affected the operation of the Kerawalapitiya Power plant. The CPC tender for purchasing oil for Kerawalapitiya plant was cancelled on five occasions. As the situation worsened the CEB insisted the CPC to supply HFO immediately. The CPC accepted that it was their fault and hence they finally agreed to supply Diesel instead of low sulphur HFO, not at the diesel price but at the HFO price until HFO is supplied to the Kerawalapitiya power plant. The CPC is responsible for this situation and there is no way that they can put the blame on the others.
Recently there was another allegation made against the CEB officials regarding releasing water from the Rantambe pond without generating electricity. The news item highlighted that the water released in Rantambe is equivalent to 15 GWh of electricity. The system control officials of the CEB claim that this news item is factually incorrect and misleading. What actually occurred at Rantambe is that the CEB on a request made by the Mahaweli Authority has released water equivalent to 0.14 GWh through the bottom outlet when the water level of the pond is not capable of generating power. This water release was done to ascertain dam safety issues and to inspect the extensive repair works carried out to intake screen three years ago which could be inspected when the pond is emptied.
As the electricity demand in Sri Lanka is increasing at an annual growth rate of about seven per cent it is necessary to double the generation in every 10 years. It is necessary to add 200 MW of new power plants each year to meet this increasing demand. The governments that ruled the country before 2005 are responsible for the present crisis as it takes over 5-10 years to establish power plants in a systematic way. The UNP parliamentarians cannot put the blame on the present government for the power crisis we are experiencing today, as they failed to implement appropriate long term generation expansion plans while they were in power.
The challenges facing the present government are enormous. They have to manage the crisis situation carefully. Necessary short term measures should be taken to ensure uninterrupted power supply at the lowest possible cost. In the years to come: oil price hikes are a reality and it will have a huge impact on the oil fired power plants; Climate change is a reality and it will have a huge impact on both coal fired power and hydro power. Unlike previous governments the present government should take necessary steps to formulate and implement appropriate long term generation expansion plans to meet this increasing demand.