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Exploiting tidal energy potential

The National Power Policy 2013-18 lacks vision and a plan for the development of non-conventional, alternative and renewable energy, excluding hydropower.

Power generation based on solar, biomass, wind and tidal is an important area. These resources are capable of producing clean, environmentally friendly, and most importantly, affordable electricity on a large scale. Optimal exploitation of renewable energy resources has the potential to provide a solution to the prevalent power crisis.

Energy generation based on renewable resources already accounts for about one-fifth of the global power generation capacity. There is, therefore, a need to give policy directive to encourage these indigenous resources too, in line with neighbouring countries like India and China, where such resources are being rapidly harnessed economically.

India has a full-fledged Ministry of New and Renewable Energy, and the country has made tremendous progress in the field in the last few years. As of June 2013, India’s energy from new and renewable resources increased to 27,542MW; an over 12 per cent share in its total energy mix of 225,793MW. India now targets to have 55,000MW of cumulative installed capacity of power generation through renewable energy resources by 2017.

There are many other new energy resources that could benefit Pakistan, such as ocean energy, including marine current power, osmotic power (from salinity gradients), ocean thermal energy, oceanogenic power (from surface waves), wave energy, and tidal power.

Theoretically, global ocean energy resources are estimated to be over 32,000GW. Interestingly, the net potential of both wave and tidal power is greater than that of wind and solar, on a global perspective. The world’s largest tidal power station, of installed capacity of 260MW, is currently located at Sihwa Lake in South Korea. The power station was completed in 2011 at a cost of $250 million, and has the availability rate of 98 per cent.

The related technology, though emerging, is well-proven, as the first large-scale powerhouse, the Rance Tidal Power Plant of 240MW, was established in France in 1966. Since then, a number of tidal power stations have been constructed.

Tidal energy is another form of hydropower. The two above-mentioned power stations have installed bulb type turbines along with generators, similar to those at a hydroelectric power station.

Alternately, tidal power stations are based on the concept of a windmill — a tidal energy unit functions like an underwater windmill. Electric power is transmitted through a sub-sea cable connected to the grid. Research and development continues in its design, installation and maintenance, with a view to mainstreaming these technologies to make them cost effective. A new installation method developed recently will reduce installation time significantly.

South Korea is constructing a 1,320MW tidal power plant (to be commissioned by 2017), whereas another plant of 520MW is being planned. Likewise, Russia, which currently operates a 1.7MW tidal power station, plans to construct three mega tidal power stations of 3,640MW, 8,000MW and 8,710MW capacities. Canada operates a 20MW power station.

The UK currently operates a 1.2MW power station, and has constructed a 10.5MW plant. It now plans to establish a 300MW power generation facility. Western Australia recently approved construction of a 40MW tidal power plant. A Massachusetts (US) tidal power project of 20MW is under construction.

Scotland is the world leader in the commercial development of wave and tidal energy, having commenced power generation in November 2000. Meanwhile, a 2,200MW tidal power project is being developed in the Philippines. China recently established a 3.2MW tidal power station, and has signed an agreement with the Netherlands to develop the world’s largest tidal power project based on a new tidal technology.

Construction of a 50MW power plant has been undertaken by India in the Gulf of Kutch. More plants are planned in India, as there is a potential of generating 8,000MW by exploiting tidal and wave energy.

However, Pakistan has yet to move in this direction, despite having various strategic locations with high tidal current velocities or strong ocean currents along its 990km coastline. According to a study conducted by the National Institute of Oceanography, creek network in the Indus deltaic region, extending over 70km along the Arabian Sea, can alone generate 900MW tidal power.

A detailed study testing and assessing tidal energy across the coastline could show a huge potential for marine energy resources, which could be exploited for power generation on a commercial scale.

Grid-based or off-grid tidal power stations could be constructed, depending on site conditions. In our case, off-grid power stations would be more advantageous for meeting rural needs of electricity.

A proper policy on tariff and commercial development of these resources, as well as providing an enabling environment to investors, both domestic and foreign, will be helpful.

—Engr Hussain Ahmad Siddiqui

The writer is the former chairman of the State Engineering Corporation, Ministry of Industries and Production

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