The Development Roadmap of  
High Voltage and Large Capacity  
DC Submarine Cable Technology  
( B r i e f
 
V
e r s i o n )  
Global Energy Interconnection  
Development and Cooperation Organization  
(GEIDCO)  
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
PREFACE  
Cross-sea power transmission has been an important method for  
offshore wind power development and cross-sea interconnection.  
More than 7000km of cross-sea transmission projects have been built  
up around the world at present, mainly in Europe, Middle East and  
Southeast Asia，Among which Europe has the almost 95% of the  
global market. Meanwhile, there are many island and peninsula  
countries in Asia, having a great potential of offshore power and  
economy development, which will make the demand of cross-sea  
transmission increase rapidly.  
Compared with that of power transmission on land, the total capacity  
of cross-sea transmission is less than 1%. While compared with that  
of submarine communication cable and petroleum pipelines, the total  
length is less than 1% and 10% respectively. Considering rapid  
increasing demand of clean energy at sea and regional cross-sea  
interconnection, it is believed that the global cross-sea power  
transmission will have a great market potential in the future, which  
means higher technical and economic requirements are necessary for  
submarine cable.  
With the advantages of large capacity, long distance and high  
efficiency, DC transmission technology has become the main proper  
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The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
method for cross-sea power transmission. Due to its importance in  
submarine power transmission subjects, the submarine cable has been  
the key and main bottleneck of cross-sea transmission technology.  
Globally,  
the  
DC  
submarine  
cable  
has  
reached  
±500kV~±600kV/1500MW~2500MW. However, the average  
market price of submarine cable still remains high, about 5~10 times  
higher than that of the overhead lines. Driven by the global energy  
interconnection, the demand will become stronger for offshore wind  
power and long-distance cross-sea power transmission with large  
capacity, which means that the current EHVDC submarine cable may  
not meet the new demands any longer. Looking back on the evolution  
of AC/DC transmission technology, from high voltage to Extra high  
voltage, even to Ultra high voltage, it is proved that higher voltage,  
longer distance and larger capacity usually mean a better economy,  
which is also suitable for submarine cable. Therefore, suggestion of  
developing ±800kV~±1100kV/4000MW~12000MW UHVDC  
submarine cable is officially proposed in this study, which mainly  
focus on the background, future demand and potential comprehensive  
benefits. Based on the current technology and economy status, the  
technical and economic factors, challenges of UHVDC submarine  
cable in the future are analyzed first, and a possible technical route  
and the economy evaluation of UHVDC submarine cable are  
presented, finally the R & D roadmap of UHVDC submarine cable  
II  
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
are offered, which could provide support for relevant research  
institutes and governments, also for promoting the technical  
development and engineering practice of UHVDC submarine cable.  
This study could also promote the construction of global energy  
interconnection, facilitating the sustainable development for human  
beings.  
The report is divided into 5 chapters.  
Chapter 1 introduces the current development of cross-sea power  
transmission and DC submarine cable, including engineering  
application, technical level and economic level.  
Chapter 2 analyses the demand for the cross-sea HVDC transmission  
projects in the future, based on the regional energy development,  
power grid interconnection and the future global energy  
interconnection construction demands, and offers specific technical  
and economic index for the UHVDC submarine cable.  
Chapter 3 analyses and introduces main technology, economy, market  
and policy challenges for the development of UHVDC submarine  
cable.  
Chapter 4 comes up with the prediction and evaluation for the  
development trend of UHVDC submarine cable, as well as the  
economy level. The specific R & D plan is proposed as well, and the  
corresponding development roadmap is offered.  
Chapter 5 presents the comprehensive benefits of technical, economic,  
III  
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
social and political aspects which would be brought by developing  
UHVDC cable.  
Overall, UHVDC submarine cable technology is considered to be a  
key technology to realize long-distance and large capacity power  
transmission across the sea, which would have a bright application  
prospects and huge comprehensive benefits in the future. However,  
the development of UHVDC submarine cable is also facing many  
technical challenges, such as materials, manufacturing, designing and  
installing, which need to be overcome and realized step by step, and  
under cooperation of everyone from the whole industry.  
Considering the current situation and trend of technology  
development, it is predicted that the application of ±800kV/4000MW  
UHVDC submarine cable could be realized in 2025, and  
±800kV/8000MW UHVDC submarine cable could be achieved in  
2035. With further breakthroughs in materials, ±1100kV / 12000MW  
UHVDC submarine cable might be effected in 2050.  
IV  
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
CONTENTS  
1. Development Status ..............................................................................2  
1.1 Overview of Cross-sea Transmission ...................................................2  
1.2 Overview of Global Submarine cable...................................................3  
1.3 Technical Status ....................................................................................4  
1.4 Economic Status ...................................................................................7  
2. Demands and Targets .........................................................................11  
2.1 Demands Analysis...............................................................................11  
2.2 Development Targets ..........................................................................12  
3. Bottleneck ............................................................................................15  
4 Research Plan and Roadmap..............................................................18  
4.1 Overall Evaluations.............................................................................18  
4.2 R & D Plans ........................................................................................20  
4.3 Roadmap .............................................................................................22  
5. Development Prospect........................................................................26  
5.1 Comprehensive Benefits.....................................................................26  
5.2 Recommendations...............................................................................26  
1
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
The GEI is an important platform for clean energy  
production, widespread energy allocation and electrification of  
energy consumption. It will provide systematic solutions for the  
sustainable development of economy, society and environment.  
Submarine cable is the indispensable way for power  
interconnection to span five continents, connect the four oceans,  
traverse the East and the West, the North and the South and cover  
the entire world, which helps realize multiple energy global  
allocation, cross-time-zone and cross-seasonal complementary.  
1. Development Status  
1.1 Overview of Cross-sea Transmission  
Submarine cable, cross-sea bridge cable, submarine tunnel  
cable and cross-sea overhead line are the four ways of  
realizing cross-sea connection and offshore wind power  
transmission, of which the submarine cable is the most  
common. In 1850, the first cross-sea project in the world—  
English Channel submarine cable project from Britain to France,  
was put into operation, starting the beginning of the development  
of cross-sea power transmission technology and projects. Over 90%  
of global cross-sea projects are submarine cable projects, mainly  
for island power, offshore platform power, renewable energy  
development and power grid interconnection.  
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The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
(a) Island Power Supply  
(b) Offshore Platform Power Supply  
(c) Offshore Wind Power Development  
(d) Grid Interconnection  
Fig. 1.1 Application Status of Cross-sea Transmission  
1.2 Overview of Global Submarine cable  
In the whole transmission capacity including on land and  
offshores, the proportion of power transmitted by submarine  
cable is less than 1%. Developments of large-scale offshore  
wind power and massive grid interconnection have provided  
positive motivation for DC submarine cable, which may have  
a great potential in the future. By 2019, the total electric power  
demand of the world had reached 28000TWh/year, and the global  
power grid had transmitted over 3000GW, of which the submarine  
cable transmitted about 26GW, accounting for less than 1%. As  
the earliest region to develop offshore wind power, Europe has  
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The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
most submarine cable projects and the largest scale around the  
world, with the total length of over 6200km and the total  
transmission capacity of over 22GW. Driven by the rapid  
development of economy, fast increase of clean energy and  
regional cross-sea grid interconnection demand, Asia has  
gradually become a more and more important market for high-  
voltage submarine cable.  
Fig. 1.2 Global Submarine Cable Projects and Market Distribution  
1.3 Technical Status  
Through 4 developing stages of oil filled, impregnated paper  
insulation, crosslinked extruded insulation and non  
crosslinked extrude insulation, the EHVDC submarine cable  
is becoming mature, while the accessories are still the  
weakness. HVDC submarine cable is a complex and systematic  
integration, involving the cable itself, accessories, tests and  
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The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
installing, O&M, which are the keys to realize the cross-sea  
power transmission. The current EHVDC submarine cable is  
almost mature, mainly including two technical routes,  
impregnated paper insulation (MI/PPLP) and extruded  
insulation(XLPE/P-Laser),200kV~±600kV/1000MW~2500MW.  
Accessory technology is the key to realize the long length  
submarine cable, the relevant materials and manufacturing  
process are extremely complex, which makes it pretty difficult.  
The installing is greatly affected by the sea condition, geology,  
weather, ocean current and other unexpected situations, and has a  
huge impact on the reliability and economy of submarine cable  
projects. Human activities have been always the main causes for  
submarine cable failure, and the emergent repairing has always  
been the most difficult for submarine cable projects.  
Fig. 1.3 Classifications of Submarine Cable  
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The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
Insulating materials are the key technology for DC submarine  
cable technology advancement and cost reduction.  
Impregnated paper insulation and extruded insulation are the two  
main technical routes. The former includes traditional adhesive  
impregnated paper (MI) and impregnated PPL paper insulation  
(MI-PPL) and the latter mainly includes crosslinked  
polyethylene(XLPE) and thermoplastic polypropylene(P-Laser)  
insulation. Currently, all above types have reached extreme-high  
voltage level. The technology of MI insulation tends to be mature,  
whose highest technical level is ± 525kV/2400MW. MI-PPL  
insulation is made by adding polypropylene material between two  
layers of insulating paper, whose highest level in lab is up to ±  
700kV/3000MW. XLPE insulated submarine cable adopts a  
crosslinked extrusion process, whose highest operating  
temperature in the project is 70℃, and the highest technical level  
is ± 640kV/3000MW. P-Laser insulated cable uses thermoplastic  
insulation material, whose highest technology level is  
±600kV/3200MW, but no practical project yet.  
6
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
(a) Adhesive Impregnated Paper Insulation (b) Polypropylene-impregnated Paper  
Composite Insulation  
（a）XLPE  
（b）P-Laser  
Fig. 1.4 Schematic Diagram of the Typical Structure of Submarine Cable  
1.4 Economic Status  
Submarine cable projects, usually customized designed, are  
more expensive than overhead lines. The price is normally  
affected by such factors as technical parameters, seabed  
environment, installing ability and market capacity.  
According to analysis of practical projects price composition, the  
cost of cable generally accounts for 40-50% of the overall  
comprehensive price (about 60% for conductor, 20-30% for  
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The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
insulation, and 10-20% for armor and shielding). The unit price  
of accessories such as joints and terminals are still high, but  
considering the small quantity, the cost proportion is generally  
less than 5%. As to installing, for those areas of less than 1000m  
deep, the current installing cost accounts for about 50-60% of the  
whole cost, but for those areas of more than 1000m deep, there  
are few references available. However, according to the  
preliminary analysis, for the sea area of more than 2000m deep,  
it is believed the installing cost will account for more than 70%,  
becoming the most important part of the overall price of  
submarine cable.  
Fig. 1.5 Price Composition of Submarine Cable Project  
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The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
Fig. 1.6 Current Single Circuit Comprehensive Price Level of DC Submarine Cable  
The price of submarine cable increases with the increase of  
voltage level and conductor cross-section, while the unit price  
of submarine cable decreases with the increase of voltage and  
capacity. After analyzing a large number of cost data of  
submarine cable, for the same cross-section and the same  
insulated material, the price of DC submarine cable increases by  
10% for each 100kV increase of voltage. For the same voltage  
level and the same insulation, the price increases by 15% for each  
500mm2 increase of conductor cross-section. For the same  
voltage level of high and extra-high voltage, the larger cross-  
section the larger the capacity, the higher the unit price, but the  
lower the unit price of unit power. This is because more power,  
lager cross-section leads to less material consumption for unit  
power and lower installing cost. The cost level and trend of partial  
9
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
voltage grade submarine cable capacity are shown in Figure 1.38.  
In general, high-voltage and large capacity DC cable are more  
economical than low-voltage and small capacity ones.  
Fig. 1.7 Law of Unit Power of DC Submarine Cable  
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The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
2. Demands and Targets  
2.1 Demands Analysis  
With the rapid developments of large-scale offshore clean  
energy and cross-sea grid interconnection, the demands of  
promoting the transmission capacity, distance and economy  
have been gradually increasing, which made the demand of  
UHVDC submarine cable increase. It is predicted that in the  
next 30 years, the total transmission distance of cross-sea projects  
in Asia, Europe, North America and Africa will be up to 1000km,  
8000km, 5000km and 4000km respectively, and the total capacity  
will reach 120GW, 110GW, 40GW and 50GW correspondingly.  
The transmission capacity of most projects will be up to  
4000MW-8000MW, and the distance of some projects would be  
over 2000km-3000km, which is difficult for current EHVDC  
cable. Therefore, developing ± 800kV or higher voltage of  
UHVDC submarine cable is urgently necessary. In terms of  
economy, the market price of ±200kV~±600kV submarine cable  
for a bipolar EHVDC is about $1~2.6 million/km, which is 5~10  
times as much as that of overhead line of the same level. However,  
with the increase of voltage level and conductor cross-section, the  
unit power price of DC submarine cable decreases, which means  
UHVDC submarine cable will be more economical than EHVDC  
submarine cable, and will have a better prospect.  
11  
   
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
Fig.2.1 Typical projects for Demands  
Fig.2.2 Demand Analysis  
2.2 Development Targets  
Compared with EHVDC submarine cable, UHVDC  
submarine cable has a much higher technical standard while  
a better economic level. Technically, considering the current  
manufacturing, equipment ability and demands in the future, , it  
is proved that the voltage resistance of insulation material for  
±800kV～±1100kV/ 4000MW～12000MW UHVDC submarine  
cable (extruded insulation) should not be less than 43kV/mm～  
65kV/mm, the endurance temperature should not be lower than  
12  
 
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
110℃, and the cross-section of conductor need to be around  
1250mm2～4500mm2. In terms of construction, the submarine  
cable ship needs to carry 20,000 tons of cable (twice the current  
level), and needs to be equipped with DP-2 and above dynamic  
positioning systems and towing with a tension of 3 million  
newtons (twice the current level). Subsea trenchers, robots, and  
exploration equipment all need to adapt to a working depth of  
3000 meters (twice the current level), with a pressure resistance  
of 298 atmospheres (twice the current level).  
(a) Temperature Distribution  
(b) Electric Field Distribution  
Fig. 2.3 Operating Characteristics of Rated Power in Seawater for ±800kV/8000MW cable  
Table 2.1 Technical Targets of UHVDC submarine cable  
Voltage class（kV）  
±800  
±1100  
4000  
8000  
43  
12000  
Transmission capacity（MW）  
Voltage  
endurance  
（kV/mm）  
Heat resistance  
Index of  
insulating  
material of copper  
conductor  
20  
75  
21  
65  
110  
33  
110  
39  
submarine cable  
（°C ）  
Index of  
Voltage  
insulating  
endurance  
material of  
aluminum  
conductor  
submarine cable  
（kV/mm）  
Heat resistance  
（°C ）  
68  
110  
110  
13  
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
Figure 2.4 Conceptual model of multi-purpose seafloor trencher  
In order to achieve a wider range of applications and  
promotion, UHV DC submarine cables have higher  
requirements on comprehensive economic indicators. In order  
to be economical, the overall transmission cost of a cross-sea  
project (including the converter stations at both ends, cross-sea  
lines, and overland overhead lines) should not exceed the  
electricity price difference between the first and the end of the  
project. Economically, it is estimated that the price of ±  
500kV/2000MW  
~
3000MW, ±600kV/4000MW and  
±800kV/8000MW submarine cable needs to be less than 2.5, 3.0  
and 7.0 million USD/km respectively, in order to have a better  
market competitiveness.  
Table 2.2 Economic targets of future UHV / EHVDC submarine cable  
14  
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
Expected economic  
goal (Single circle,  
US $10k/km)  
Price spread（cents  
/ kWh）  
voltage（kV）  
capacity（MW）  
2000~3000  
4000  
0.78~3.53  
1.01~3.43  
1.25~6.32  
1.25~6.32  
250  
300  
380  
700  
±500  
±600  
4000  
±800  
8000  
3. Bottleneck  
Such technical promotions as the increases of voltage,  
capacity, distance and water depth would be the main  
challenges. Developing UHVDC submarine cable needs to  
overcome such barriers as insulation materials, manufacturing  
process, accessory, installing, O&M technology. Among them,  
electrical performance, structural design and manufacturing  
process of insulating materials are the bottlenecks for voltage  
promotion. Conductor cross-section and thermal characteristics  
of insulating materials are the main challenges for capacity  
promotion. Accessory technology is the key to realize long-  
distance transmission, which is also the weakness. O&M ability  
has a great effect on the reliability and maintenance efficiency  
during operation. Installing technology and auxiliary equipment  
will directly affect the construction efficiency and project quality,  
as well as the price. Therefore, with the rapid increase of  
submarine cable projects globally, more professional installing  
15  
 
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
and O&M teams are needed in the future.  
Fig. 3.1 Three-layer co-extrusion equipment for HVDC submarine cable  
Fig.3.2 3000mm2 large cross-section conductor manufacture  
Economic improvement is one of the most important  
motivations to promote the practical application. Compared  
with the overhead lines, the economy is one of the most important  
factors limiting the large-scale application and development of  
submarine cable, but still the submarine cable has an obvious  
16  
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
advantage of less land occupation. Thus, improving the economy  
would be very important for the wide application of UHVDC  
submarine cable.  
While market and policies could be the catalyst to further  
promote the development of UHVDC submarine cable. Due  
to the complexity and uncertainty of submarine cable projects, the  
market will be more cautious while choosing power transmission  
solutions, but meanwhile, a lack of incentive policies on  
submarine cable issued by government will also affect the  
development of submarine cable technology and the  
improvement of economy.  
17  
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
4 Research Plan and Roadmap  
4.1 Overall Evaluations  
By evaluation, ± 800kV / 4000MW submarine cable could be  
achieved in a relatively short term, while ± 800kV/8000MW  
expected to be available in a longer term. Impregnated paper  
insulation technology is being mature and reliable, while  
extruded insulation technology has been developing rapidly, both  
could be the options to realize low capacity UHVDC submarine  
cable in the near future. But for the medium and long term,  
extruded insulation technology has a better potential to achieve  
larger capacity and higher voltage level, attributing to its  
simplicity and reliability. Based on improving and optimizing the  
design of insulation structure, it is expected that ± 800kV /  
4000MW could be achieved and applied to practical use in 2025.  
With further improvement of heat resistance of insulating  
materials, ± 800kV/8000MW would be achieved in 2035. And  
±1100kV level might come true by 2050, if significant  
breakdowns are made for the properties of conductors and  
insulation materials.  
Impregnated  
Paper  
and  
Extruded insulation  
Extruded insulation  
Extruded insulation  
18  
   
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
Fig. 4.1 Technical Research Evaluations  
With further development and application, the economy of  
UHVDC submarine cable will be greatly improved, meeting  
the expectation. It is estimated that in 2050, the unit price of  
±800kV/4000MW and 8000MW DC submarine cable will be no  
more than 2.6 million USD/km and 4.4 million USD/km, and the  
unit price of ±1100kV/12000MW DC submarine cable is  
expected to be no more than 5.8 million USD/km, which will have  
good economic benefits and a better market competitiveness.  
（1）2025  
（2）2035  
19  
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
（3）2050  
Fig. 4.2 Comprehensive price of Submarine cable  
4.2 R & D Plans  
Developing UHVDC submarine cable is a systematic project,  
which needs to overcome such key difficulties as materials,  
designing and manufacturing process step by step.  
As studied, before 2025, research should be focused on  
optimizing the insulation structure design , constructing the basic  
theory of DC submarine cable insulation structure design  
involving space charges, temperature, electric field, conductivity,  
dielectric constant and other parameters, reducing the impact of  
space charges through nano doping and base resin purification,  
studying the electric field reversal mechanism and inhibition  
method, and improving the manufacturing process and operation  
reliability of cable and accessories, building UHVDC test  
terminals and UHVDC systematic tests site to meet the  
requirement of ±800kV/4000MW UHVDC submarine cable  
projects.  
20  
 
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
Fig.4.3 Design of prefabricated joint structure  
During 2025-2035, the manufacturing process of insulating  
materials should be improved. The high-purity insulating base  
resin is Developed to raise the long-term withstand temperature  
to 110℃, and raising the insulation strength to 43kV/mm, as well  
as the matching semiconductor shielding materials. The potential  
of all kinds of thermosetting and thermoplastic insulating  
materials for the improvement of thermal and insulation  
properties is explored so as to prepare for the research and  
development of new insulating materials. Detection and salvage  
robots and other equipment suitable for 2000m deep-sea  
operation are developed.  
Fig.4.4 Structure of non-crosslinked extruded insulation material-  
polypropylene  
21  
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
During 2035 to 2050, having a deeper research on potential  
insulating material and developing new insulation materials with  
working strength up to 65kV/mm. Based on the performance  
characteristics and structure of submarine cable, improving the  
water resistance, compression resistance and deformation  
resistance of submarine cable, forming an industrial mass  
production ability. The deep sea operation equipment, especially  
the submarine robots, is developed to improve the compressive  
capacity and maneuverability of the equipment, to realize the  
ability of installing for 3000m deep sea and 2000km long distance,  
and meeting global submarine cable application demands.  
Fig. 4.5 Conceptual Model of Large-size Ocean Submarine Cable Ship  
4.3 Roadmap  
Key Technology - Insulation materials: It is estimated to achieve  
800 kV / 4000-8000MW by nano-doping and purification of base  
materials by 2035, and to achieve ± 1100 kV by developing new  
22  
 
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
materials with high-purity and high-clean base materials by 2050.  
Fig. 4.6 Development Roadmap of the insulation material  
Key Technology - Installing: It is estimated to achieve  
transmission distance of 1000km by increasing reliability and  
length of a single cable before 2025, and to improve construction  
ability to 2000km in length and 3000m in deep by improving  
cable properties and installing capacity by 2050.  
Fig. 4.7 Development Roadmap of the Installing  
23  
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
Key Technology - O&M: It is estimated to develop the optical  
time domain analysis technology based on the existing embedded  
optical cable method to improve the accuracy of monitoring by  
2025, and to develop other new online monitoring methods  
without optical cable during 2025 and 2050.  
Fig. 4.8 Development Roadmap of O&M  
Industry ： For submarine cable of ±800 kV/4000MW,  
engineering practice needs to be implemented as soon as possible  
under the promotion of the governments and the market. For ±800  
kV/8000MW, it is necessary to focus on overcoming the  
difficulties of insulation materials and structures designing, and  
improving the capabilities of installing and O&M at the same  
time. For ±1100 kV/12000MW, new solid insulation material  
needs to be developed and gradually promoted for the application  
of the large-scale, long-span cross-sea transmission projects.  
24  
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
Fig. 4.9 Development Roadmap of the Industry  
25  
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
5. Development Prospect  
5.1 Comprehensive Benefits  
Developing UHVDC submarine cable will bring huge  
technical, economic, social and political benefits. On one hand,  
it can promote the technological progress of materials,  
manufacturing process, automation control and other related  
industries, bringing about 150 billion US dollars investment for  
UHVDC submarine cable subjects. On the other hand, it can  
improve the safety of regional energy supply, and increase an  
employment of about 14 million in related industries. At the same  
time, it can promote the development of clean energy, effectively  
deal with the climate change, and reduce land resources  
occupation by more than 100000 square kilometers. In addition,  
it can also promote the new mechanism of energy and power trade,  
accelerate the process of clean energy development at sea and  
global energy interconnection, enhance the level of energy  
interconnection, improve the power supply reliability of island  
countries, improve the safety of energy transmission, and  
promote regional coordinating development.  
5.2 Recommendations  
Developing UHVDC submarine cable needs extensive  
cooperation of enterprises, universities and research  
institutes all over the world. On one hand, countries all over the  
26  
     
The Development Roadmap of High Voltage and Large Capacity DC Submarine Cable Technology  
world should pay more attention to the technical, economic and  
social benefits of UHVDC submarine cable, and make  
preparations, to take the market opportunities in time. On the  
other hand, for those advanced countries and institutions, it is  
recommended to issue promulgate policies and guidance  
documents to promote the development of new materials and  
equipment before 2025. During 2025-2035, it is recommended to  
issue relevant supporting policies, such as tax relief and export  
subsidies, to support construction of demonstration cross-sea  
projects and investments. Also, research institutions and  
manufacturers are suggested to actively participate in the study of  
the development roadmap, refining R & D planning and  
developing together.  
27