Singareni Collieries said this week it will begin developing floating solar projects, starting with installations totalling 500 MW, co-ordinated with the Telangana State Renewable Energy Development Department (TSRED), which has already run a feasibility study.
The Singareni Collieries is a coal mining company which also owns some coal plants. It is 51% owned by Telangana state, and 49% by the federal government, and produces 9% of national coal output. Like several other coal and fossil fuel companies in India, it has begun to deal in renewables, engaging with solar last year – it expects to have 220 MW ground-based PV installed by the end of August.
It is now considering whether to have all 500 MW floating solar capacity installed in one place, or to split it between five 100-MW locations. Some of the largest floating solar plants in the world are on flooded disused mines in China.
India’s first large-scale floating solar project, a 150 MW installation at the Rihand Dam in Uttar Pradesh, saw a 50 MW segment awarded to the Shapoorji Pallonji Group in December 2018.
The majority of floating solar plants are constructed on the nation’s many state-owned dams. Hydroelectric dams are the ideal location for floating solar, as they can make use of the existing transmission infrastructure, and are safer than offshore or large lakes, where winds or waves may damage the installation.
Another useful location will be the reservoirs used by India’s vast coal power fleet. The largest floating solar tender seen this year in India is for a 100 MW installation on the Ramagundam Thermal Power Plant’s balance reservoir – also in the state of Telangana.
Telangana is a mountainous state on the southern part of the Deccan Plateau, and is powered roughly three-quarters by coal and one-quarter by hydroelectric plants. That includes the historic Nagarjuna Sagar dam constructed in the 1950s and 60s, which has 816 MW capacity.
The state is looking at a massive upgrade of both its coal and its hydroelectric capacity in the coming years, including a 4 GW hydroelectric dam at Ippagudem, up from a current hydroelectric capacity of 2.7 GW. Water use will be moderated by irrigation needs and by the state’s semi-arid nature, which is why coal plants will remain the majority of the state’s power.
This calls to mind another advantage of hydroelectric-located floating solar, which is that whenever solar output is high, less water needs to be used to run the dam, acting as a form of storage.
A recent report by the Energy and Resources Institute (ERI) pegged India’s maximal floating solar capacity, using such reservoirs, at 280 GW. As of March, the country had a floating solar pipeline of 1.7 GW.
India is considered likely to install 2.8 GW of floating solar, out of a total 50 GW solar over the next five years, according to forty Indian CEOs surveyed by Bridge to India. That proportion is in line with the 6.9% of current Indian solar capacity which was found to be floating in the ERI’s report.
That 50 GW figure in five years also represents about a quarter of what is needed each year to meet India’s official 175 GW renewables targets for 2022 – the country has less than 40 GW of wind and solar each right now.
The country’s largest proposed array is a 1 GW setup at the Indira Sagar Dam, the country’s largest reservoir – a size only rivalled in floating solar, by the 2.1 GW Saemangeum proposed in South Korea.
Another noteworthy project is the 70 MW phase 2 of the Kayamkulam floating solar project, at the Rajiv Gandhi Combined Cycle power plant. That project, granted to Tata Power Solar last September, boasts a new record low price of $0.46 per watt according to the Energy and Resources Institute (ERI). The ERI attributed this to improvements in floater design and manufacture, other technical improvements, and India’s aggressive bidding – but said the costs had fallen so low that quality may be a concern.