Why Is the Floating Photovoltaic Solution Essential?
Many countries focus on floating photovoltaic solutions.
Beyond the desert, the tentacles of photovoltaic power plants have extended to lakes and seas. The floating photovoltaic solution have their own advantages, as they can utilize existing reservoirs, lakes, and seas without occupying agricultural land. And it can also be raised underwater to increase income.
In the past two years, some coastal provinces in China have noticed floating photovoltaic solutions. The most radical is Shandong, which has stated its intention to build tens of millions of kilowatts of offshore photovoltaic bases along the Bohai Sea and Yellow Sea coasts. The planned sites have already reached 57, with a total installed capacity of over 40 million kilowatts.
Jiangsu, Zhejiang, Liaoning, and Guangdong all have offshore photovoltaic projects, with Jiangsu province having 18 of them.
As a major photovoltaic country, although western China has a large area of centralized photovoltaics, it is difficult to absorb such a huge amount of electricity locally, and the cost of "West East Electricity Transmission" is high. Installing photovoltaic panels directly on the water surface near the major province for power generation is certainly more cost-effective in terms of transportation costs.
However, the difficulty of water-based photovoltaic technology is high, and the climate is more unstable compared to inland areas. Therefore, it has not yet formed a scale. If technological bottlenecks can be overcome, water-based photovoltaic projects will undoubtedly enable countries lacking land resources to invest more in centralized photovoltaic projects. For the global energy transition, these countries are also important links that cannot be ignored.
How to build a water-based photovoltaic project?
At present, water-based photovoltaics are divided into two types: one is pile foundation fixed type, and the other is floating type like the Sirindhorn Reservoir in Thailand.
Pile foundation type is actually using a pile driver to drive reinforced concrete pipe piles with a diameter of 30-50 centimeters into the water bottom, similar to a foundation, and then installing corrosion-resistant metal photovoltaic brackets on the piles. Piling can only be carried out within 5 meters of the water depth, and there is no geological hazard in the area with small water level change, so the fixed power station with pile foundation can only be installed in the mudflat and intertidal zone.
Pile-based waterborne PV is also the most mainstream mode at present. At present, China's offshore PV is mainly offshore. For example, the offshore PV project in Xiangshan, Zhejiang Province, is located in the mudflat area of Xiangshan County, with 630000 PV panels and an annual power generation of 350 million KW.
Pile-based water-based photovoltaics may not be very new in form, but construction is quite challenging. In Xiangshan County, typhoons are inevitable, and an additional wave dissipating wall was built to block the erosion caused by the wind and waves.
Compared to the already mature pile-based water photovoltaics, floating photovoltaic solutions have attracted more attention in recent years. Photovoltaic panels and inverters are installed on floating pipes or floating boxes. It is suitable for medium and far sea areas with a water depth greater than five meters and no typhoons.
If we want to make the most efficient use of water resources, we must go deeper into the ocean. However, compared to fixed pile foundation water photovoltaic solutions, floating photovoltaic solutions face more complex and variable environments. In Bohai Bay, the ice age lasts for more than three months every year, and flowing ice will drift around. It is difficult to produce floating photovoltaic solutions in this type of sea area. Therefore, many floating photovoltaic solutions are still built in environmentally stable reservoirs.
The deep-sea project still carries experimental characteristics. In October 2022, a floating photovoltaic project in a deep sea area of Shandong Province officially started generating electricity. This is the world's first floating offshore photovoltaic project with a depth of 30 meters and an offshore distance of 30 kilometers. In extreme cases, the wave height can reach ten meters.
This power station has advanced technology stacked on top, and in order to better adapt to ocean currents, it has used the elastic film patent and anchoring system of Norwegian floating photovoltaic technology company Ocean Sun.
Such investment certainly costs lots of money. Even if put into use, this power station is only a demonstration, with only 770 components installed and a power generation of only 500KW, which is only a small fraction of the fixed water photovoltaic project in Zhejiang.
Pile foundation and floating photovoltaic solutions have not yet broken through their limitations, and the material cost of offshore floating photovoltaic solutions is 10 to 30% higher than conventional photovoltaics, not to mention the cost of operating in Shanghai. Only with a significant increase in installed capacity can there be economies of scale, reducing the cost of anchoring systems and floating bodies. For example, when the installed capacity reaches 500MW, the cost per kilowatt is reduced by half compared to 10MW.
However, when the cost of electricity transportation remains high, offshore photovoltaics will inevitably be put on the agenda of coastal provinces. Moreover, not all countries in the world have vast and sunny Gobi like China.
Compared to China, countries with limited land such as Singapore and Japan are more interested in water-based photovoltaics. Japan built the world's first floating water photovoltaic power station in Aichi Prefecture in 2007.
For a long time, floating photovoltaic systems were only sporadically distributed in countries such as France and Spain, with a combined capacity of only 10MW from over 20 power stations. They were mainly used for experimental or demonstration projects and have not been truly put into large-scale use.
It was not until the Johor Floating Power Station in Singapore that floating photovoltaic solutions were considered a successful large-scale case. This 5MW floating offshore photovoltaic power station officially started operation in 2021, with 13,000 solar panels and 40 inverters, becoming the largest offshore floating photovoltaic system at that time. It can generate 6.02 million kilowatt hours of electricity annually, which is approximately equivalent to the annual electricity consumption of 1,250 four-bedroom public housing units.
Japan, on the other hand, is the country with the most applications of floating photovoltaic solutions in the world, but their power plants are mostly built in reservoirs. The Yamakura Dam in Chiba Prefecture has the largest floating photovoltaic power plant in Japan, which was put into use in 2018 with an installed capacity of 13MW.
Floating photovoltaic solutions on the sea surface are important technologies for resource scarce countries such as Singapore and Japan. They all have vast sea areas, coupled with abundant sunlight on the water surface, making them more suitable for the national conditions than existing centralized photovoltaics.
South Korea is even more ambitious. Ocean Sun, which supplies technology for Shandong projects, has signed an agreement with South Korea, which plans to develop a 2.1GW floating waterborne photovoltaic complex in Saemangeum, a mudflat along the Yellow Sea coast.
In China, floating photovoltaic power stations carry more social significance than actual supplementary electricity. For example, the original intention of building a floating photovoltaic power station in Huainan City, Anhui Province was to manage the abandoned subsidence areas after coal mining.
Water photovoltaic projects have become exemplary in many regions, but they are still far from large-scale application. How to fix the floating body in large floating power plants? How to solve dampness and surges, and how to stably connect to the power grid? These hard core problems that are inevitably encountered in the process of scaling up have not been solved.
How to protect the environment during implementation is also a difficult problem. In May 2022, the Ministry of Water Resources issued a special document stating that projects such as photovoltaic power stations and wind power generation are not allowed to be constructed in rivers, lakes, and reservoirs.
As land resources become scarce and carbon neutrality approaches, photovoltaics are bound to enter the sea from land. However, the road that water-based photovoltaics have to go through will be much more difficult than that of land-based photovoltaics.
Beyond the desert, the tentacles of photovoltaic power plants have extended to lakes and seas. The floating photovoltaic solution have their own advantages, as they can utilize existing reservoirs, lakes, and seas without occupying agricultural land. And it can also be raised underwater to increase income.
In the past two years, some coastal provinces in China have noticed floating photovoltaic solutions. The most radical is Shandong, which has stated its intention to build tens of millions of kilowatts of offshore photovoltaic bases along the Bohai Sea and Yellow Sea coasts. The planned sites have already reached 57, with a total installed capacity of over 40 million kilowatts.
Jiangsu, Zhejiang, Liaoning, and Guangdong all have offshore photovoltaic projects, with Jiangsu province having 18 of them.
As a major photovoltaic country, although western China has a large area of centralized photovoltaics, it is difficult to absorb such a huge amount of electricity locally, and the cost of "West East Electricity Transmission" is high. Installing photovoltaic panels directly on the water surface near the major province for power generation is certainly more cost-effective in terms of transportation costs.
However, the difficulty of water-based photovoltaic technology is high, and the climate is more unstable compared to inland areas. Therefore, it has not yet formed a scale. If technological bottlenecks can be overcome, water-based photovoltaic projects will undoubtedly enable countries lacking land resources to invest more in centralized photovoltaic projects. For the global energy transition, these countries are also important links that cannot be ignored.
How to build a water-based photovoltaic project?
At present, water-based photovoltaics are divided into two types: one is pile foundation fixed type, and the other is floating type like the Sirindhorn Reservoir in Thailand.
Pile foundation type is actually using a pile driver to drive reinforced concrete pipe piles with a diameter of 30-50 centimeters into the water bottom, similar to a foundation, and then installing corrosion-resistant metal photovoltaic brackets on the piles. Piling can only be carried out within 5 meters of the water depth, and there is no geological hazard in the area with small water level change, so the fixed power station with pile foundation can only be installed in the mudflat and intertidal zone.
Pile-based waterborne PV is also the most mainstream mode at present. At present, China's offshore PV is mainly offshore. For example, the offshore PV project in Xiangshan, Zhejiang Province, is located in the mudflat area of Xiangshan County, with 630000 PV panels and an annual power generation of 350 million KW.
Pile-based water-based photovoltaics may not be very new in form, but construction is quite challenging. In Xiangshan County, typhoons are inevitable, and an additional wave dissipating wall was built to block the erosion caused by the wind and waves.
Compared to the already mature pile-based water photovoltaics, floating photovoltaic solutions have attracted more attention in recent years. Photovoltaic panels and inverters are installed on floating pipes or floating boxes. It is suitable for medium and far sea areas with a water depth greater than five meters and no typhoons.
If we want to make the most efficient use of water resources, we must go deeper into the ocean. However, compared to fixed pile foundation water photovoltaic solutions, floating photovoltaic solutions face more complex and variable environments. In Bohai Bay, the ice age lasts for more than three months every year, and flowing ice will drift around. It is difficult to produce floating photovoltaic solutions in this type of sea area. Therefore, many floating photovoltaic solutions are still built in environmentally stable reservoirs.
The deep-sea project still carries experimental characteristics. In October 2022, a floating photovoltaic project in a deep sea area of Shandong Province officially started generating electricity. This is the world's first floating offshore photovoltaic project with a depth of 30 meters and an offshore distance of 30 kilometers. In extreme cases, the wave height can reach ten meters.
This power station has advanced technology stacked on top, and in order to better adapt to ocean currents, it has used the elastic film patent and anchoring system of Norwegian floating photovoltaic technology company Ocean Sun.
Such investment certainly costs lots of money. Even if put into use, this power station is only a demonstration, with only 770 components installed and a power generation of only 500KW, which is only a small fraction of the fixed water photovoltaic project in Zhejiang.
Pile foundation and floating photovoltaic solutions have not yet broken through their limitations, and the material cost of offshore floating photovoltaic solutions is 10 to 30% higher than conventional photovoltaics, not to mention the cost of operating in Shanghai. Only with a significant increase in installed capacity can there be economies of scale, reducing the cost of anchoring systems and floating bodies. For example, when the installed capacity reaches 500MW, the cost per kilowatt is reduced by half compared to 10MW.
However, when the cost of electricity transportation remains high, offshore photovoltaics will inevitably be put on the agenda of coastal provinces. Moreover, not all countries in the world have vast and sunny Gobi like China.
Compared to China, countries with limited land such as Singapore and Japan are more interested in water-based photovoltaics. Japan built the world's first floating water photovoltaic power station in Aichi Prefecture in 2007.
For a long time, floating photovoltaic systems were only sporadically distributed in countries such as France and Spain, with a combined capacity of only 10MW from over 20 power stations. They were mainly used for experimental or demonstration projects and have not been truly put into large-scale use.
It was not until the Johor Floating Power Station in Singapore that floating photovoltaic solutions were considered a successful large-scale case. This 5MW floating offshore photovoltaic power station officially started operation in 2021, with 13,000 solar panels and 40 inverters, becoming the largest offshore floating photovoltaic system at that time. It can generate 6.02 million kilowatt hours of electricity annually, which is approximately equivalent to the annual electricity consumption of 1,250 four-bedroom public housing units.
Japan, on the other hand, is the country with the most applications of floating photovoltaic solutions in the world, but their power plants are mostly built in reservoirs. The Yamakura Dam in Chiba Prefecture has the largest floating photovoltaic power plant in Japan, which was put into use in 2018 with an installed capacity of 13MW.
Floating photovoltaic solutions on the sea surface are important technologies for resource scarce countries such as Singapore and Japan. They all have vast sea areas, coupled with abundant sunlight on the water surface, making them more suitable for the national conditions than existing centralized photovoltaics.
South Korea is even more ambitious. Ocean Sun, which supplies technology for Shandong projects, has signed an agreement with South Korea, which plans to develop a 2.1GW floating waterborne photovoltaic complex in Saemangeum, a mudflat along the Yellow Sea coast.
In China, floating photovoltaic power stations carry more social significance than actual supplementary electricity. For example, the original intention of building a floating photovoltaic power station in Huainan City, Anhui Province was to manage the abandoned subsidence areas after coal mining.
Water photovoltaic projects have become exemplary in many regions, but they are still far from large-scale application. How to fix the floating body in large floating power plants? How to solve dampness and surges, and how to stably connect to the power grid? These hard core problems that are inevitably encountered in the process of scaling up have not been solved.
How to protect the environment during implementation is also a difficult problem. In May 2022, the Ministry of Water Resources issued a special document stating that projects such as photovoltaic power stations and wind power generation are not allowed to be constructed in rivers, lakes, and reservoirs.
As land resources become scarce and carbon neutrality approaches, photovoltaics are bound to enter the sea from land. However, the road that water-based photovoltaics have to go through will be much more difficult than that of land-based photovoltaics.
