Solar energy is plentiful, clean and green, and is key in reducing carbon footprint. The conventional renewable energy farms like solar and wind needs space – a lot of it. We require about five acres of land for setting up a one MW solar photo-voltaic plant on ground.
There are many advantages in going for ‘Floating Solar Power Plants’. The main advantage is that they do not take up any valuable land consumption, except for the limited area required for electrical panels and grid connections.
The Floating Solar Panel Structure provides a large area of Shade for the water – and thus reduces evaporation of water from these reservoirs / lakes /dams. This is particularly beneficial to areas susceptible to draught, since continuous water loss to evaporation over a time contributes to water shortage. The shades provided by these Floating Solar Systems also help in reducing the presence of algae blooms in bodies of fresh water, thus improving the quality of water.
The significant benefit of Floating Solar Plant is that it does not take up the valuable space on land, meaning that it can be used for other purposes such as agriculture, Construction of Buildings, development of Industry etc.
Another advantage is that the presence of water exerts a cooling effect, which improves the performance of Solar PV Panels by 5-10%. Solar PV Panels being themselves water proof, rain or floating water can’t damage them.
Floating solar PV system on Tengeh reservoir
Singapore is one of the smallest countries in the world, and it is also among the biggest per capita carbon dioxide emitters in Asia. Renewable energy is a challenge for this country with no rivers for Hydro Electricity & no wind that is strong enough to power Wind Turbines. In a bid to tackle climate change, the country is building one of the world’s largest floating solar farm.
The conventional renewable energy farms, like Solar and wind, need space – a lot of it. This important factor places a bottleneck on the green energy ambitions of Singapore, an island state with a population of 5.63 million and a land area of 724 sq. kms. The high levels of urbanization and the towering metropolis are not favourable to solar and wind farms.
Singapore’s National Water Agency, & Sembcorp Floating Solar Singapore, which are partnering to build a 60 Mega Watt- peak (MWp) Floating Solar PV system on Tengeh Reservoir, with 122,000-panels solar farm, will be one of the biggest in South-East Asia covering an area, the size of about 45 football pitches.(Fig.1). Despite there is some delay in the project execution due to the pandemic situation, it is likely to be commissioned before end of 2021.
To ensure operational excellence, sustainability and safety of the large scale project, every component of the Floating Solar System has been carefully chosen & designed. This includes the need to maximise energy generation, minimise environmental impact, and be durable enough to last its entire life span of 25 years.
Another very important factor in selection of this project was to overcome Singapore’s Land Constraints in pursuit of greater renewable energy generation, thus contributing to the national climate change mitigation. The aim is to reduce reliance on fossil fuels, cut emissions and build climate resilience. The Singapore Government recently unveiled a wide-ranging ‘green plan’ that includes steps such as planting more trees, reduce the amount of waste sent to landfills and build more battery charging points to encourage the use of electric cars.
The energy generated from this floating Solar project is sufficient in greening the Singapore’s water works, that is, the energy generated is sufficient to meet the needs of Singapore’s water works, which will be one of the few in the world to be 100% green. This is equivalent to the reduction of carbon emission equivalent to 7000 cars.
The floats are made of UV-resistant High Density Polyethylene (HDPE), and the solar panels are made of double-glass modules to increase their durability and life span. PV panels are tilted for efficient energy generation and rainwater drainage. They are also coated with anti-reflective materials to minimize glare. The floats are anchored to the reservoir beds using steel cables / chains.
Currently, many countries are going in for Floating Solar PV projects. Kyocera Corp. of Japan, has come up with a smart way to build and deploy floating solar power plants without gobbling up precious agricultural land in space-challenged Japan, by building the plants on freshwater dams and lakes. This Japanese 13.7 MWp floating photovoltaic plant sits behind the Yamakura Dam at Ichihara in Chiba Prefecture. It can power nearly 4,700 homes and is saving more than 7,800 tonnes of CO2 a year. It consists of 50,000 solar panels. It is located in 13 ha of water area. This project, which is Japan’s largest floating PV power plant, was inaugurated by Kyocera in March 2018 at the Yamakura Dam in Ichihara City, Japan. (Fig.2)
Unfortunately, during the second week of September 2019, part of the above Floating Solar Plant at Yamakura Dam was damaged by the 125 mph wind brought by the Typhoon Faxai. Then it caught fire. It was suspected that the high speed wind, tore several floating modules of the project and stacked them one above the other. This is suspected to be an anchor failure. The fire fighters were of the opinion that the contact between live loose panels and those that remained moored to mounting structures, might have caused short circuit / overheating of the modules, creating the conditions for a fire. This incident need to be kept in mind when planning Floating Solar PV Plants in areas experiencing high speed winds & typhoons. Properly designed and strengthened anchoring of the panels is a must to avoid such incidents. (Fig.3)
After the outermost row had ripped off, the wind-facing edge did not have any ballast anymore to counter uplift from wind. The modules and floaters began to curl-up with the result of an electrical fire. (Fig.4)
India’s biggest floating solar power plant is coming up in Telangana
National Thermal Power Corporation (NTPC) has a 2,600 MW Super Thermal Power Station at Ramagundam, Telengana. This project has its own water Reservoir meeting the requirements of the Thermal Power Plant. Now NTPC is setting up India’s biggest Floating Solar Power Plant in this reservoir, with a capacity of 100 MW, which is expected to become operational in Telengana soon. This floating solar project, spread over 450 acres, will have 4.5 Lakhs PV panels, at a cost of Rs.423 crores.
Conventional Solar PV plants when located on land, require about five acres of land per MW capacity. Given the challenges in land acquisitions, NTPC is going for the floating method.Further, NTPC is planning a 92 MW Floating Solar plant at Kayamkulam Gas plant in Kerala, as well as a 25MW Floating Solar Plant at Simhadri Power Plant in Vizag. This is in line with our country’s commitment towards development of Renewable Energy. As per NTPC officials, setting up Floating Solar units on water bodies and huge reservoirs help them in cutting down on the costs. Floating Solar Units prove to be cost effective when compared to Ground- Mounted solar plants.
NTPC in its enthusiasm to expand its power generation by introducing Floating Solar PV Projects, has to keep in mind the damages caused by the typhoon in Japan – and ensure that proper anchoring designs are followed in the Floating Solar Plants to prevent such mishaps.
According to the researchers at the US Department of Energy’s National Renewable Energy Laboratory (NREL), hybrid systems of Floating Solar Panels & Hydro Power Plants will hold the technical potential to produce a significant portion of the electricity generated annually across the globe. Floating solar farms on existing hydropower reservoirs could cut solar costs and meet 40% of the world’s energy needs, they found.
Following are the technical potentials of the hybrid systems using Hydro Power Reservoirs for Floating PV panels, instead of using lakes or ponds.
The most important one is that the solar power system can use the existing infrastructure and transmission lines of the hydropower facility, which cuts capital costs. Plus, the two technologies can balance each other since solar power has the most potential during dry seasons – while rainy seasons are best for hydropower. So, at a hybrid plant, operators could store excess solar power using pumped storage hydropower, where electricity is used to pump water to a higher elevation. (Fig.5)
Usage of Floating Solar PV Panels on the reservoirs of Thermal Power Plants, as conceived by NTPC, can also form an Hybrid version which will save lot of land acquisition costs as well as develop Renewable Energy to cut down Carbon Emission. “Putting Solar Panels on Water Is a Great Idea—Yes, it will work.”
C.V. Govinda Raju is a former Executive Director of Karnataka Vidyuth Karkhane Ltd., Bangalore & the Former President of ISPAT group of Company.