How much space is there to reduce the cost of submarine cables in the era of offshore wind power subsidies?

SMM News: 2022 offshore wind power state subsidies will be fully withdrawn, the post-subsidy era put forward higher requirements for enterprises'R & D and innovation capabilities. As one of the three main hardware equipment juxtaposed with wind turbine, foundation and tower tube, the submarine cable accounts for about 10% of the total cost of offshore wind power. Where is the cost reduction space for this part, and how big is it?

The global offshore wind power cost and electricity price are still decreasing. In 2019, the lowest bid price of offshore wind power projects in France and Britain reached 0.39 yuan per kilowatt hour (connected to the grid in 2026) and 0.35 yuan per kilowatt hour (connected to the grid in 2023 / 25), respectively. Compared with the feed-in electricity price of 0.75 yuan per kilowatt-hour (2020) in China, this figure still has a lot of room for decline.

The high-tech content of submarine cable determines its high cost. A group of figures from the General Institute of Water Regulation show that the prices of 35kV submarine cables are between 60 and 1.5 million yuan per kilometer, and those of 220kV submarine cables are between 400 and 5 million yuan per kilometer.

Different from onshore wind power, offshore wind power projects need to collect the power generated by wind turbines scattered in the site to the offshore booster station through 35kV submarine cable, and then send the offshore booster station to the land centralized control center with 220kV submarine cable. From 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 greater the proportion of submarine cable investment cost is.

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

The industry generally predicts that during the 14th five-year Plan period, with the policy of offshore wind power in China and the gradual increase in volume, the kilowatt cost of offshore wind power in China will be reduced from the current 16000 yuan to about 13000 yuan, with about 20% room for cost reduction.

Coincidentally, Zhao Shengxue, deputy chief engineer of East China Survey and Design Research Institute of China Electric Power Construction Group, pointed out that at present, the system kilowatt-hour cost of 1 million kilowatt offshore wind farms in China is more than 0.15 yuan / kWh. If the installed scale reaches more than 200 ~ 3 million kilowatts, the kilowatt-hour cost of the delivery system will be reduced to less than 0.1yuan / kWh.

He also pointed out that in the case of replacing copper cores with aluminum cores in submarine cables and localization of insulating materials, the cost of submarine cables will also have room for a reduction of 12% and 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 a level that can be borne by the industry under the support of "quantity".

On the other hand, technological innovation is also recognized as one of the ways to reduce costs in the industry.

According to the calculation of the East China Hospital, the electricity price level of offshore wind power during the 14th five-year Plan period should be between 0.5 yuan and 0.55 yuan per kilowatt-hour. In the field of power collection lines and submarine cable prices, it should be realized by optimizing the layout of 220kV collection lines, adopting 66kV collection lines, localization of insulation materials and reducing line investment. The above measures can reduce the overall unit kilowatt cost of the project by 400 to 500 yuan.

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

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