While a quarter of the population is still off the grid, in urban areas demand for electricity often outpaces supply. We are supporting the extension of Pakistan’s biggest hydropower facility to meet peak demand and increase access to renewable energy.
Opportunity
We are working with Pakistan’s Water and Power Development Authority (WAPDA), and the World Bank to expand the generation capacity of the Tarbela Dam hydro plant.
Originally built in 1976, Tarbela is the world’s largest rockfill dam. It was designed to control water in the Indus River for irrigation of farmland downstream, but over the years, hydropower capacity has been added to capture the energy of water released from the dam. We are currently leading the fifth extension project, which will increase the power plant’s total peak generating capacity by 1530MW, from 4888MW to 6418MW.
However, alongside this project we are also working on Pakistan’s first floating photovoltaic (FPV) project, adding a further 325MW of generating capacity, split between Tarbela’s reservoir and the head ponds of the downstream Ghazi Barotha hydropower project.
Solution
FPV employs the same technology as land-based photovoltaics. But because PV performance is better at low temperatures, it generates more power, thanks to the cooling effect of the water. Ideal locations for FPV are static water bodies without vessel navigation: quarry lakes, cooling ponds, and reservoirs – such as at Tarbela.
Coupling FPV with the existing hydroelectric facilities enables use of established transmission infrastructure, minimising capital and operational costs.
Another attraction is that operating solar alongside large hydropower enables the two technologies to work symbiotically, with solar reducing the need for hydropower production during the day, and hydro kicking in as the sun sets, and to fill spikes in demand.
Our solar team is using an innovative solution to cope with the reservoir’s depth and variable height, which presents a challenge for anchoring FPV. The initial 25MW pilot installation will use PV modules mounted on unanchored rafts that self-locate to given GPS co-ordinates, using small motors.
Outcome
Construction of the fifth hydropower extension is still in its early stages. The powerhouse is scheduled for commissioning in early 2025 and works on the intake will stretch to early 2027.
Harnessing the energy of irrigation releases from the existing tunnel will enable the project to be built for roughly 80% less than the typical cost of a purpose-built hydropower facility of the same size. Adding the FPV component as well will enable additional renewable energy to be supplied at a competitive price, helping Pakistan to meet the country’s energy needs and reducing reliance on gas and coal-fired electricity production. It will supply power to tens of millions of people on the grid, alleviate outages and support socio-economic development for generations.