An important factor contributing to the widening electricity demand-supply gap has been the inordinate delay in either the commencement or completion of rehabilitation projects related to various medium and small hydropower plants planned by the Pakistan Water and Power Development Authority (WAPDA). These projects, if undertaken and completed timely, could directly address the prevalent energy crisis, also resulting in reducing the average generation cost of the energy mix.
Currently, WAPDA operates 21 hydropower stations — large, medium and small — with a cumulative installed capacity of 9,406MW, and generates more than 37,000GWh of net electrical energy annually. The large and medium hydropower plants are known as Tarbela, Ghazi Barotha, Mangla, Neelum-Jhelum, Warsak, Chashma, Duber Khwar, Allai Khwar, Golen Gol, Jinnah and Khan Khwar. Small hydropower stations connected to the national grid are Rasul, Dargai, Jabban, Satpara, Gomal Zam, Nandipur, Shadiwal, Chichoki, Kurram Garhi, and Renala.
Energy experts believe that the only solution to the energy security, reliability and affordability is the optimal utilisation of hydropower resources. To achieve the objective, it is projected that the share of hydropower generation needs to be restored to 70 percent in the total energy mix (which was maintained until the 1980s) from the current 24 percent share. The development of hydropower, of which Pakistan has huge identified potential, slowed down in the past decades due to a variety of factors. The most important of these were the long gestation periods and the large amount of funding required for developing medium and large hydropower projects.
In this backdrop, WAPDA had worked out, decades ago, a comprehensive plan of ensuring least-cost hydropower generation capacity to be achieved by optimising the existing operations and maintenance of hydropower stations through carrying out major renovation, upgrading and modernization, and to undertake capacity expansion, primarily with a view to attain designed installed capacity and to optimise water-flow availability. The plan, which was to be implemented on fast track, has not been undertaken effectively, resulting in long delays causing loss, as it is now, of at least 340MW capacity in WAPDA’s power generation system, which translates into depriving the national grid of millions of units of electricity on annual basis.
The on-going refurbishing and upgrading of Mangla Hydropower Station, being undertaken at a total project cost of over $483 million, has run into long delays. The project on completion will not only restore Mangla power station’s designed original power generation capacity of 1,000MW, it will also result in increasing the installed capacity of power station to 1,310MW, effectively utilising the improved energy potential attained on completed Mangla Dam Raising project that provides additional water storage of 2.88 million acre-feet (MAF), and availability of increase in water-head by 40 feet. Implementation of the project will ensure optimisation of reliable operations of all its ten generating units, each of 100MW capacity, constructed from 1967 through 1994.
Mangla power plant has been operating largely trouble-free but the quality and reliability of the original electro-mechanical equipment has deteriorated due to ageing, and efficiency reduced from the designed values and parameters of the respective equipment installed. Resultantly, the power plant’s total operating capability, which historically could go up to 1,100MW during peak water season, has de-rated to less than 980MW. Rehabilitation and upgrading will improve the reliability and availability of this power station for the next 30 years, besides providing safe, reliable and cost-effective energy generation.
The refurbishment project was scheduled to commence in early 2014, and implemented in different phases spanning over a period of ten years’ time, achieving full commissioning of power station sometime in 2024. This is not likely to be achieved, given the present status of progress. In the first phase, the works to be completed include main package for the supply, installation and refurbishment of Units 5 & 6 (turbine, generator, governor, excitation system etc) increasing generating capacity from existing 80MW to 135MW for Unit 5 and existing 100MW to 135MW for Unit 6. This critical milestone has not reached.
Scope of supply and services of other packages include refurbishment and upgrade of powerhouse crane, supply of 169MVA power transformers for eight units, supply, installation and refurbishment of powerhouse’s turbine inlet valves for all ten units, supply and installation of mechanical equipment and balance of plant and civil works, and procurement and installation of plant control and instrumentation system, switch-yard, and control automation and protection equipment. All these items of machinery and equipment have reached at site from different sources.
Under the second phase of the programme, refurbishment of Units 1-4 is to be undertaken, while refurbishment of Units 7 and 8 is planned under the third and final phase. Refurbishment of the remaining two units is not considered as these were commissioned in 1994. The different phases of project implementation covered refurbishment of various power generating units, with a view that minimum units are shut-down at one time, and thus, least power generation is lost during project implementation stage. Alas, the first phase of project remains much behind schedule, as the refurbishment of the first two units has not yet been done. This contract was awarded to a French company in August 2018. It was to achieve commercial operations of refurbished Units 5-6 by February 2019.
But the detailed design and engineering was delayed by two years and delivery of equipment over two years. Due to abysmal performance of contractor the pace of work at site remained very slow. Thus, completion date was revised a number of times. These units are now scheduled for commissioning this year. Consequently, implementation of second and third phases of the project for refurbishment of other units will be further delayed, resulting in huge loss of power generation. Units 5 and 6 of cumulative capacity of 200MW are shut down since 2017, whereas additional capacity of 310MW remains a dream yet to be realised. Another critical aspect of delay is non-operation of the corresponding irrigation tunnel as the two units are not in operation.
Another project facing long delays in implementation is the second rehabilitation project of the Warsak hydroelectric power station. The project was approved in July 2015 at a total cost of Rs23.36 billion. It was to be completed within seven years. Sadly, physical work on the project has not yet started. Contract for civil works was awarded only in April this year, whereas the contract for electromechanical works has not yet been announced. After the project’s completion, installed capacity of powerhouse will be restored to its original designed capacity of 243MW and enable it to generate 1,236GWh of energy. International financial institutions, including France’s AFD, the European Investment Bank and Germany’s KfW Development Bank are financing the project.
Constructed during 1952-1960, the Warsak Dam is the first medium/large multi-purpose hydropower project, having four turbo-generator units of 40MW each. Two additional units of 41.48MW capacity each were commissioned at Warsak during 1980-81, resulting in a 243MW cumulative installed capacity. During these years, the project has largely contributed towards improving socioeconomic conditions of the area through electrification and irrigation. While the Warsak power station has been operating largely trouble-free, it has been facing a number of problems since the early days. One of the major problems is the excessive quantity and abrasive nature of the silt carried by the river water. Operations of the turbo-generating units during the monsoon season with river water, which is laden with silt containing quartz, causes rapid erosion in the hydraulic equipment, which results in severe and chronic operations and maintenance problems.
Remedial measures like regular repairing and rebuilding the worn equipment and replacement of turbine components are therefore adapted. Still, the powerhouse remains vulnerable to frequent breakdowns due to its ageing and obsolescent machinery. Thus, its installed capacity of power station has been de-rated to 210MW, which has necessitated major rehabilitation. To ensure optimal and reliable functioning of the dam, the rehabilitation project aims to replace four generators, electrical components of four units, all transformers, and install a new Scada system and replace all six runners with erosion-resistant special coating, in addition to civil works. After rehabilitation and upgrading, all the turbo-generating units will be operable for another 30-40 years, well beyond the dam’s designed useful life.
WAPDA also plans to carry out major renovation, refurbishing, upgrading and modernisation of six of its small hydropower plants, aiming to harness optimal hydropower potential at the sites. This would also ensure reliable operations of power stations and restoring them to the original power generating capacity. Renala hydropower, the oldest power station in Pakistan, was commissioned in March 1925. After rehabilitation and refurbishment, there is a potential to enhance the power station’s capacity up to 4MW, utilising full available water discharge. On completion, the powerhouse will generate 25.6GWh annually, almost four times its existing power generation. Shadiwal hydropower station is currently generating 4MW, compared to its installed capacity of 13.5MW. Commissioned in January 1961, power station has the potential of increasing its total capacity to 27MW.
Dargai power station has four units of 5MW each, and was commissioned in December 1952. Likewise, the Kurram Garhi power station was constructed in 1958. Rasul powerhouse, with two units of 11MW each, was installed in July 1952. Nandipur hydropower (three units of 4.6MW each) was commissioned in March 1963. Similarly, Chichoki Hydel (three units of 4.4MW) has been operating since August 1959, and generating about 23GWh annually. Over the years, reliability of the existing electro-mechanical equipment of these powerhouses has deteriorated, and efficiency reduced from designed values and parameters of the installed equipment. However, refurbishment schemes for these old powerhouses are still at the stages of planning and feasibility, though financing for a few schemes have already been committed by international donor agencies.
TAILPIECE-- It is interesting to note that, utilising a total power generation capacity of 9,389MW, WAPDA provided a record 37,425GWh of energy to the national grid during fiscal year 2019-20, but with slightly increased capacity of 9,406MW in year 2020-21 ending June 30, total power generated was reduced to 37,147GWh. Of course, annual power generated at a hydropower station depends upon water reservoir level and irrigation needs.
The writer is retired chairman of the State Engineering Corporation