Tarbela extension project Least-cost energy source

Pakistan has invited Austria for extending technical co-operation and investment as joint venture partner for development of various mega hydropower projects planned to be constructed shortly, which include multi-purpose Diamer Bhasha Dam and Tarbela Fourth Extension of 960 MW capacity.
For the purpose, a ministerial-level Pakistan delegation visited Vienna during last month with focus on seeking technical and financial assistance from the Austrian sources, aiming at further strengthening the existing cordial bilateral relations. The visit is termed successful insofar as achieving its objectives are concerned.
The Austrian government has shown willingness to contribute the projects funding, whereas global key players in hydropower business, like Andritz Hydro, Siemens-Voith and Alstom, have confirmed interest in participating in tenders for on-going and forthcoming projects. The world-reputed Austrian manufacturers of hydropower generation machinery, with history dating back to almost a century, have agreed, in principle, to transfer, progressively, cutting-edge hydropower technology to Pakistan's engineering industry with a view to creating local capability.
Currently, Wapda is actively engaged in the planning and development of a number of hydropower projects to meet growing demand of electricity and to improve share of hydropower in total energy mix, resulting in affordable cost of electricity in coming years. Hydropower is known the world over as reliable, renewable and least-cost energy resource.
Tarbela Fourth Extension project, an important constituent of the overall hydropower development plan, is declared to be undertaken on fast track. In September last, Wapda had appointed international consultants to carry out a detailed feasibility study to manage implementation of the project in such a manner so as not to affect irrigation releases, power generation at existing units, and sedimentation management.
These consulting services, costing $5.5 million are being financed by the World Bank under its $38 million programme of Water Sector Capacity Building and Advisory Services Project. The consultants, a joint venture of Mott MacDonald of the UK and Tractebel Engineering (formerly Coyne et Bellier of France), are preparing detailed engineering and design, PC-1 document and tender documents.
Mott MacDonald as lead partner have recently completed feasibility study of the largest 7,100-MW Bunji hydropower project, whereas Coyne et Bellier had worked in the past at Tarbela project on a short assignment. Consultancy services are scheduled for completion by September 2011. The project will then be launched for construction on ICB basis. The completion period is estimated four years and commercial power generation at the proposed units is scheduled to commence by 2016.
It is planned to install two generating units, each of 480-MW capacity, on the existing tunnel No 4. As main dam, intake and tunnel already exists, the civil works will be limited only to the construction of powerhouse, modification of intake structure, penstock between the outlet of tunnel and new powerhouse and extension of 500-kV switchyard. The project cost will, therefore, be much lower as compared to a greenfield project. The World Bank has indicated willingness to finance civil works. Supply and installation of hydro-mechanical and electrical equipment entails turbines, generators, transformers and allied accessories, for which financing sources are being explored.
Multipurpose Tarbela Dam, termed as the world's largest earth and rock-fill dam, is 148 meter high and 2,743 meter long, having gross storage capacity of 14,333 million cubic meters. The dam, completed in 1976, was designed to store water from the Indus River for irrigation, flood control and power generation. Its construction has been a challenge in global dam design and construction, given the complex geological conditions of the site. With a total installed capacity of generating 3,478 MW, Tarbela Powerhouse supplies about 20% of total electricity to the system. There are 5 tunnels for irrigation supply releases and power generation. Three tunnels are used for power generation, whereas the remaining two tunnels are used exclusively for irrigation releases. Tunnel no. 4 is proposed to be utilised for the extension project for which a pre-feasibility report is available since long.
Indeed, timely completion of Tarbela Fourth Extension project would result in extending power generation facilities at Tarbela, adding substantial power to the grid, thus strengthening the national economy. But the government has to take special measures for effective monitoring of its construction and completion on schedule, as Wapda's track record of ongoing hydropower projects, such as mega Neelum-Jhelum as well as medium-sized Khan Khawar, Allai Khawar and Duber Khawar, is far from satisfactory.
(The writer is Vice President of the Institution of Engineers, Pakistan)