Water spillage from reservoirs: Is CEB to blame?

Let us examine the facts

By Chris Ratnayake

‘The pen is mightier than the sword’ is an old adage. However, it has gained new currency in today’s world where mass communication, in the form of press and other media, greatly influences public opinion. Consequently, this valuable tool can become lethal in the hands of some who lack professional competence to understand what they write about, are unable to comprehend the relevant issues or analyse relevant data of a complex technical problem. Such an issue has arisen with respect to the water spillage that occurred last month in our hydroelectric reservoirs.

I refer to three articles in The Island recently by Dr. Vidhura Ralapanawe, G. A. D. Sirimal, and Ifham Nizam, alleging mismanagement and even corruption simply because water was spilling, and thermal plants were operating simultaneously. No additional data or analysis was presented. As a professional engineer, with 23 years of experience at the Ceylon Electricity Board (CEB), focusing on power system planning, and some 30 years’ experience as a Senior Power Engineer at the World Bank, reviewing power sector operations in about 17 developing countries, I could well see the fallacy of these accusations. However, I soon realised that the general public appears to accept the validity of these accusations at face value. Public officials are fair game, any article alleging inefficiency or dishonesty is readily believed without any examination of the merits of these articles. I therefore decided to research the relevant facts and submit the findings in the hope of correcting the grave misinformation propagated.

Facts

Any professionally competent article, addressing the subject, to determine whether there was any inefficiency or miscarriage of duty should have considered the following:

1. Responsibility for water level management:

The articles place the sole blame for spillage on the CEB’s system control centre (SCC) engineers. They seem to be unaware that water level management of the main reservoirs (namely the Mahaweli complex) is the responsibility of the Water Management Secretariat (WMS), not the CEB. WMS has representation from the CEB, Water Board, Irrigation, Mahaweli, and more. The release policy, every week from every reservoir, is issued by the WMS and the CEB cannot store or release water through a unilateral decision. So, the accusation on the CEB is misplaced!

2. Drawdown curves:

These are optimum water level charts, developed based on years of past experience and specialised computer programmes designed to optimise the often-competing demands of agriculture and power, which guide system operators in the management of reservoir water levels. To determine any possible mismanagement, one has to prove that, for sustained periods, the drawdown did not correspond to these curves, subject, of course, to the current rainfall expectations and plant capacities available for dispatch. This is a complex exercise that the writers of these articles appear to be ignorant of.

3. Optimal dam design envisages some spilling:

Occasional spillage in a few years is no indication of mismanagement. Reservoirs are designed and constructed to optimise the competing demands of costs and benefits. In fact, if water never spills, it is a sure indication of bad design and excessive investment on taller dams, inundating larger areas of land than necessary! The articles never examined whether such spillage was a regular occurrence or a one-off after many years.

4. Reservoir heights deviated from optimum:

It may be noted that in some instances the reservoir heights were reduced due to complaints of inundation of affectees, making spillage unavoidable. Clear examples are Kukule (2002) and Upper Kotmale (2012), pruned down to mere ‘ponds’ and not storage reservoirs owing to public protests. Expert hydrologists and the CEB engineers said, at that time, that if Kukule was allowed to be built as a full capacity reservoir, frequent flooding of Kalawana and Baduraliya, sometimes with severe loss of life, would have been avoided. Raising the Kotmale dam for greater storage has been suspended due to protests. We can’t have it both ways: Avoid spillage but refuse to allow the required dam height!

5. Difference between operational ponds and storage reservoirs:

Cascading hydropower systems have both storage reservoirs and operational ponds. The latter are built to enable a power plant to operate with some water storage for a short time period and function by the discharges from upstream plants, secondary inflows in the locality or releases from the main storage reservoirs. The levels of these small capacity reservoirs are not readily controllable and often spillage cannot be avoided.

6. Historical performance:

To do justice to the issue, I obtained historical data of reservoir performance from 2011 to 2020 which the CEB publishes with respect to each reservoir, and computed the extent of spillage as a percentage of annual inflows. It is observed that the spillage that has occurred is extremely minimal and as expected. The results of the 10-year study are as follows:

Laxapana complex:

0.044% in 2013, 0.029% in 2014, 0.002% in 2015, 2.741% in 2018, 0.327% in 2019. All other years zero spill.

Mahaweli complex: Spilling occurred only in 2016: 0.663% and 2018: 5.807%

Samanalawewa: Spilling occurred only in 2019: 3.333%

7. Maximum hydro capability vs system demand:

The mere fact that private thermal power plants operate during spillage, the sole basis of these articles, is absolutely no indication of mismanagement. Our maximum hydroelectricity capability is 1450 MW vs a peak power demand of about 2700 MW. The balance must necessarily come from other sources, mainly thermal power. Consequently, thermal power may be used even when spillage is occurring.

8. Contractual issues with respect to private (thermal) power:

The private power contracts are made with capacity charges payable, irrespective of output, when they are contracted (periods of 10 or 20 years are typical). Once contracted, the capacity charge must be paid, whether it is ordered to operate or not. Private power plants with active agreements and the CEB power plants are scheduled or ‘committed’, generally on the basis of monthly or weekly dispatch plans. The principal in scheduling is to achieve the lowest operating cost of the generating system as a whole, subject to meeting (i) water release schedules (ii) reliability of the transmission network, (iii) purchasing all electricity from renewable energy, whatever the price. Once ordered to operate, additional (variable) charges payable to private oil power plants are based on actual energy discharged and these are determined on the basis of agreed plant efficiencies (specified in the contracts) and CPC-announced current fuel prices. Hence situations may arise where it may even be more profitable to dispatch private power in preference to CEB’s own plants, as the efficiencies of some private thermal plants may be superior to the CEB’s own plants.

9. Contractual issues with respect to private renewable energy:

Since 1996, lucrative contracts were provided to private renewable energy on must-take contracts. Consequently, many situations may arise when private renewable energy power plants, including rooftop solar power, are dispatched and paid for while water is overflowing at the reservoirs. None of the renewable energy plants have any long-term storage capacities and must be discharged when available. The average rates for renewable energy plants for 2020 were: Rs 15.47 (mini-hydro), 16.79 (wind), 22.36 (solar), 22.39 (biomass), and 36.20 (Waste to energy) while the variable cost of the CEB’s own plants vary from Rs 6.78 for coal and 17.26 for diesel plants (Ref: ‘dispatch and fuel cost data’ published by the CEB). During the whole of October-November, one generator at Norochcholai was shut down due to very good rainfall. Financially, the implication is to stop producing at Rs 6.78 from coal (2021 prices are a bit higher) and purchase from private mini-hydros and other such sources at Rs 15.47 or more. So, the CEB reports losses; private mini-hydros report profits! While this may be acceptable due to environmental considerations, the financial impacts may be noted.

10. Exigency situations: The sudden rains last November in Sri Lanka was quite unprecedented.

Many areas, not adversely affected under normal circumstances, were flooded or subject to landslides. Tens of thousands were affected and many lost their lives. We know that such catastrophic weather patterns have occurred recently and are still happening in many countries around the world as a result of global warming. In all such instances the usual operating patterns have been disrupted. Even these considerations have escaped the imagination of the writers of these articles.

Have any of the above issues been analysed in these articles? The answer is a clear ‘no’ and clearly displays the absurdity of the accusations.

Responsible journalism

In the international press we often see articles written by journalists on highly technical subjects. This is acceptable to create a platform for healthy public opinion. However, such reputed journalists carry out extensive research and consult experts as well as the hands-on operators or practitioners. These are usually cited in the articles and give credibility to their contents. However, this is unfortunately not the case in Sri Lanka. Many journalists rush to print sensational stories without even bothering to corroborate basic information, as the above analysis clearly shows. None of the key pertinent facts have been checked or verified. To add insult to injury they also impute fraud and corruption! They also add catchy journalistic innuendos, leading the public completely astray. One article refers to ‘opening a pandora box’, an innuendo that lets the reader imagine massive corruption occurring within the CEB. Instead of imagining a ‘pandora’s box’ he should have studied the generation and water inflow/releases published in the CEB website and done the required analysis. Is this responsible journalism?

I may also add that it is not only such journalists who lose their way handling a complex engineering problem. Sometime ago The Island carried an article by an experienced engineer, who specialises in another field, unrelated to electrical engineering, who recommended pumped storage plants using water released for agriculture in the Mahaweli complex. In reality, this is an impossibility as (a) all pumped storage plants need to collect the water discharged in a storage pond immediately at the outlet and (b) water released for agriculture is widely spread out and can never be collected and pumped back to the head pond. This example further illustrates that complex engineering problems are best left to subject specialists and any laymen’s attempt to address such issues would require understanding and analysis of data and extensive consultation with experts, not simply a reflex action to what appears on the surface.

To right the grave misinformation propagated, I have placed the pertinent facts related to the issue for public scrutiny. It is left for the reader to judge: Is there any evidence that the CEB acted inefficiently or fraudulently, or are the accusations due to the lack of understanding in the subject, not attempting any analysis of the wealth of information available publicly in the CEB’s website, and the need for sensationalism?