Floating photovoltaic panels may have found a place. In recent years, severe drought has disrupted power which supplies several hydroelectric dams in Africa and the hot sun has reduced the evaporation from reservoirs. Therefore, some researchers asked why not utilize photovoltaics. The floating photovoltaic panels could add power to existing hydroelectric turbines while providing shelter to the water surface and reducing evaporation.
There is growing interest in installing floating photovoltaic panels on reservoirs and other bodies of water like mudflats, flooded open-pit mines, etc.
A. Africa has the richest solar energy resources in the world.
In January, researchers at The European Commission's Joint Research Center in Ispra, Italy, published a study to explore the huge potential of hybrid hydropower and solar power plants in Africa. Rossio Gonzalez Sanchez, lead researcher, believes that 1% of the photovoltaic panels of only the Africa continent reservoir area can be doubled the capacity of the reservoir, which can reach 58 GW, improving a quarter of the total generating capacity of the African continent.
Some of the African continent's biggest reservoirs could benefit from the floating PV systems
. These include The High Aswan Dam on The Nile in Egypt, where The Sahara sun causes the reservoir to lose about a quarter of its water each year to evaporation, the Kariba and Cahora Dams on The Zambezi River in southern Africa Bassa) and the Ako-Sombo dam in Ghana. Sanchez said this option is cheaper than building more dams. It does not have the environmental and social bad influence of flooding the land with reservoir water.
Africa has a serious shortage of electricity. Many homes cannot be connected to electricity and a rapidly growing economy is unable to meet the demand for electricity. Hydropower has long been the mainstay of electricity in many African countries, but a prolonged drought has made it difficult to maintain access to it. Sanchez says Africa has the most solar energy in the world, which is twice as much as Europe. After studying surface data from 146 large reservoirs across the continent, she sees floating photovoltaic panels as an important opportunity to maximize electricity generation from existing water resources.
In addition, shading the water with solar panels can reduce evaporation. She estimates that this approach could help the continent save nearly one billion cubic meters of water a year. It is enough to increase the amount of electricity produced by hydroelectric turbines by 170 gigawatt-hours a year.
Many of Africa's hydropower dams have reservoirs that once flooded large areas of flat land. Therefore, building dams not only takes up large amounts of land, but also it is highly susceptible to evaporation and water depletion. However, floating photovoltaic panels over large areas of water can turn a disadvantage into an advantage. Kenya is planning to build floating photovoltaic power plants in three reservoirs on the Tana and Turkwel rivers.
B. Floating photovoltaic power generation is becoming increasingly popular around the world.
The deployment of floating PV panels is becoming increasingly popular worldwide. Some experts predicted that they will soon become the "third largest" solar deployment model after distributing rooftop and ground-based ones. It is estimated that 350 floating solar systems
are now in place in more than 35 countries. However, most of them are small, says Frank Haugwitz of Apricum, a German clean-technology consultancy. By the end of last year, the total installed capacity of these floating solar systems was just 2.6 gigawatts.
Japan pioneered the model more than a decade ago, but China has taken the lead. The world's largest operational floating solar project with a total capacity of 150 megawatts, is located in a submerged former coalmine in Anhui Province, China. Interest in the technology is growing elsewhere in Asia.
The largest floating solar power project under construction is in Saemangeum, South Korea, on what was once a beach. The $4 billion project, with a total installed capacity of 2.1 gigawatts, will be operational by 2025. The floating solar photovoltaic project in Kerala, India, is located in the Banasura Sagar reservoir. The state of Maharashtra has also mentioned deploying a 600MW floating photovoltaic project at the Koyna power Station reservoir, one of India's largest hydropower projects.
Singapore is reportedly exploring the idea of installing floating solar panels at sea to power data centers. Technicians are considering installing floating solar panels between offshore wind turbines to take advantage of their grid connections. Other Asian countries, including Taiwan, Thailand and Vietnam, also have such programs.
European countries are also becoming more interested. A German renewable energy company called BayWa completed a 27-megawatt project on a flooded sandpit in the Netherlands last year. A study carried out for the company last year by the Fraunhofer Institute for Solar Energy Systems recommended deploying floating photovoltaic panels in flooded open-pit lignite mines. There are 500 such pits across 470 square kilometers of rural eastern Germany. The institute estimates that the potential deployment size of the mines could theoretically reach 56 gigawatts, with even 5 per cent coverage generating 2.74 gigawatts of installed capacity.
C. Water photovoltaics could help Africa
It seems that the cost of deploying solar panels on water is typically about 10 to 20 percent higher than that on the ground. However, floating photovoltaic panels have their advantages. They do not take up land. They do not pollute with dust. They do not need to level land, and they do not need to cut down trees or demolish buildings. The water is cooler than the land, so the energy yield is usually higher.
Floating photovoltaic panels in dams and reservoirs have other benefits. Grid-connected transmission lines are readily available. The two types of power generation can complement each other by using solar power during the day and saving water to generate electricity at night.
However, the biggest added benefit, especially in the tropics, is that the solar panels that cover the water's surface reduce water evaporation, boosting the hydropower potential of reservoirs. Reservoirs in much of the tropics drop as much as two meters a year, which is equivalent to a third of their capacity.
The Kariba Dam reservoir in southern Africa lost a quarter of its water as a result. The Akosombo Dam reservoir in Ghana has lost more than half. While no feasible solution has been found to reduce the huge loss of water storage, solar panels may be the answer.
There have been no environmental impact studies or other detailed analyses of the potential impacts of floating PV panels on wildlife or the wider environment. Sanchez says there could be potential damage to fisheries from reduced light or changing water temperatures. These changes will also reduce algae growth, which could be beneficial for freshwater ecosystems plagued by algal blooms. In Africa, crocodiles or hippos may attack some floating panels. Similarly, such infrastructure can hinder access to water for these and other animals.
A World Bank report three years ago said floating photovoltaic panels opened up new frontiers for global solar power generation, especially in land-constrained countries, as the land becomes increasingly restrictive for solar development. The World Bank is now considering financing hybrid hydroelectric and solar power plants in Pakistan, Turkey, Ukraine, Mali and Cote d 'Ivoire, Mr. Hogwitz said.
Land restrictions on solar deployment are spurring other options, too. BrandiMcK-uin of the University of California, Santa Barbara, says California could turn its network of more than 6,000 km of irrigation canals (the world's largest water delivery system) into "solar canals" that would replace the diesel generators that power irrigation pumps.
The fast-moving water in the irrigation canal makes it impossible for the solar panels to float on the water, so they need to be mounted on metal mounting structures or suspensions above the canal. Their roles in shading the sun remain largely intact. Floating panels and hanging solar panels can reduce water evaporation from irrigation canals and potentially reduce weed growth, according to a study by McKuhn published in March in the journal Nature Sustainability.
What is clear is that solar panels look set to function in a way that has never been done before, whether it is the floating type or suspended ones.