How much space there is to reduce the cost of submarine cables

In 2022, national subsidies for offshore wind power will be completely withdrawn, and the post-subsidy era puts forward higher requirements for enterprises’ R&D and innovation capabilities. As one of the three major hardware equipment along with the fan, foundation and tower, the submarine cable equipment accounts for about 10% of the total cost of offshore wind power. Where is the reduction space in this part and how big is it?

Global offshore wind costs and electricity prices continue to fall, with the newly announced minimum bid for 2019 offshore wind projects in France and the UK reaching 0.39 yuan/KWH (2026) and 0.35 yuan/KWH (2023/25), respectively. Compared with China’s feed-in tariff of 0.75 yuan per kilowatt-hour (2020), this figure still has a lot of room to fall.

The high technology content of sea cable determines its high cost and cost. A set of figures from the Water Planning Board show that the price of 35kV submarine cable is between 600,000 and 1.5 million yuan/km, and that of 220kV submarine cable is between 4 million and 5 million yuan/km.

However, different from onshore wind power, offshore wind power projects need to first collect the generated electricity generated by the scattered fans in the site to the offshore booster station through 35kV submarine cable, and then send it to the onshore centralized control center by 220kV submarine cable from the offshore booster station. In this process, the delivery cost of offshore wind power is much higher than that of onshore wind power, and the farther offshore the project is, the higher the investment cost of submarine cable will be.

It can be said that the decrease of submarine cable cost depends on many factors — material, technology, networking mode, offshore distance and so on, but a very important point is that the increase of construction amount corresponds to the decrease of unit cost.

It is widely predicted in the industry that during the 14th five-year Plan period, as China’s offshore wind power policies push back and the volume gradually increases, the unit kilowatt cost of China’s offshore wind power will be reduced from the current 16,000 yuan to about 13,000 yuan, with about 20% of the cost reduction space.

Similarly, Zhao Shengxiao, deputy chief engineer of the East China Survey and Design Institute of China Power Construction Group, pointed out that the cost per kilowatt hour of the delivery system for China’s 1 million kilowatt offshore wind farms is more than 0.15 yuan per kilowatt hour. If the installed capacity reaches more than 2 ~3 million kw, the cost per KWH of the delivery system will be reduced to less than 0.1 yuan/KWH.

He also pointed out that in the sea cable with aluminum core instead of copper core, insulation materials domestic situation, the cost of sea cable will be reduced by 12% to 18%. This means that in the process of large-scale construction of offshore wind power in China, the cost of each link of offshore wind power can be gradually reduced to the level that the industry can bear with the support of “quantity”.

On the other hand, technological innovation is also recognized as one of the cost reduction paths in the industry.

According to the estimation of East China Institute, during the 14th five-year Plan period, the price level of offshore wind power should be between 0.5 and 0.55 yuan/KWH. In the field of collecting lines and Marine cables, it should be realized by optimizing the layout of 220kV and 220kV collecting lines, adopting 66kV collecting lines, localization of insulation materials and reduction of line investment by aluminum core. And above measure can reduce project whole unit kilowatt cost 400~500 yuan.

In the future, with the development of offshore wind power to the deep sea, floating dynamic cable, 330kV cable, HVDC cable and other technical fields will be the direction of innovation.