Reflecting its relatively mature stage of development, onshore wind turbine technology at the 3 MW level has been in extensive application. Currently, the world’s largest onshore wind farm is located in Alta Wind Energy Center in the United States state of California. With an installed capacity of 1.02 GWh, the facility is under expansion to bring total capacity to 1.55 GWh. Offshore wind power has also moved into the stage of commercial operation, with an offshore wind turbine boasting a single-unit capacity of 8 MW and a blade diameter of 164 m currently in trial operation in Denmark’s National Testing Center. Offshore wind turbine installation vessels are a core technology requirement for constructing offshore wind turbines. The world’s biggest installation vessel of its kind, the Pacific Orca, has a loading capacity of 8400 tons, capable of carrying and installing 12 × 3.6 MW wind turbines at one go. China is reputed as the world’s largest builder of large wind farms, with 16 provincial-level wind power grids each with an interconnection capacity of over 1 GW, together with nearly 200 large wind farms of over 100,000 kW concentrated mainly in the “Three North” region covering Inner Mongolia, Hebei, Gansu, Liaoning, and Xinjiang.

Wave energy is a more extensively researched form of ocean energy. The first wave energy generating unit for commercial operation was successfully developed in Japan in the early 1960s. Since the 1980s, the target of wave energy development has shifted from power supply covering near-shore and coastal areas to far-away coastal locations and sea islands, demonstrating the successful practical application and commercialization of this technology on a small to medium scale. There are now over 30 wave energy stations in the world available for demonstration and operational purposes.

Tidal current and ocean current energies generate electricity by using the mechanical power from the horizontal movement of seawater. An experimental generator with a capacity of 2 kW was installed 50 m under the sea in the United States state of Florida in 1976. A 20 kW ocean current generator was developed by United States-based OEK Company in 1985, followed by the undersea installation and operation for a year of a 1.5 m diameter, 3.5 kW ocean current power generator by University of Yam in Japan in 1988. Research on tidal currents was conducted in the Strait of Messina by experts from Italy in 1996 and an experimental power station with a capacity of 120 kW was put into operation in 2004. A 300 kW tidal current generator for experimental purposes was installed on the west coast of the United Kingdom in 2003. In the 1970s, experiments were conducted for the first time on tidal current power generation in Zhoushan, Zhejiang Province. In the mid-1980s, generating equipment with a capacity of 1 kW were built, with the completion of experiments on generating units with a capacity of 70 kW in the late 1990s. China’s first tidal current power station, with a capacity of 600 kW was developed in Daishan County, Zhoushan City, Zhejiang Province in 2002.

The utilization of temperature differences to produce energy dates back nearly a century, but substantial progress has only been achieved over the past 40 years. The world’s first temperature gradient power generating equipment for practical application was developed in the United States waters of Hawaii in 1979, with a rated power of 50 kW. The maximum power output can reach 53.6 kW when the temperatures of the upper and lower levels of the sea are 28 and 7°C, respectively. Power output was improved to 210 kW in 1993. Over 10 countries, including the United States, Japan, the United Kingdom, France, the Netherlands, South Korea, India, the Philippines, Indonesia, Russia, and Sweden, are conducting research on temperature gradient energy. China has just started to utilize temperature gradient energy, with equipment for practical application yet to be built.

The utilization of salinity gradient energy has a relatively short history. Application technology in this area is basically at the experimental stage. No substantial progress has yet been achieved because of inhibitive costs due to formidable technical challenges.

Rapid growth of coordination and control technology for future distributed generation. It is expected that by around 2020, a host of technologies will basically become mature to adapt to the control requirements on distributed generation under complicated work conditions of interconnection operation as well as static and fault islanding. These technologies include the simulation technology for high-concentration, multisource coexisting systems at the distributed generation level, multisource complementary control for distributed generation, source charge coordination and control technology, equivalent virtualization technology for distributed generation and microgrids. In around 2030, equivalent simulation technology for centralized access to distributed generation will be mastered to realize flexible, interactive support for distributed generation and main grid power. Coordination and control technology based on flexible load control, energy storage devices and distributed generation will be acquired to exercise effective control over random power fluctuations and power quality in respect of distributed-generation, high-penetration grids. Intelligent recovery control technology and adaptive protection technology can support self-recovery and network reconfiguration after a breakdown of a distributed-generation, high-penetration grid. In around 2050, key information on the global geographical distribution, cluster size and output characteristics of distributed generation will be studied to realize flexible control over the equivalent virtual system for large-scale distributed generation. Based on a high-speed, globally interconnected telecommunication system, coordinated control across zones and layers can be realized over state-level grids, continent-level grids and globally interconnected grids to support efficient backup across different regions and times in response to typical load changes among the large clean energy bases in the Arctic and equatorial regions and across the ocean, relative to a global network of energy interconnections.

Research and manufacture of key equipment such as high-reliability converter transformers, converter valves, sleeves, and DC filters. DC transmission technology, key to achieving ultradistance and ultralarge capacity transmission, represents one of the major technological means to connect large energy bases with load centers. Recently, breakthroughs have been achieved in the research on the topography of ±1100 kV modular transmission-source converter valves and also in converter valve technology. An all-round breakthrough is expected around 2018 in ±1100 kV UHV DC transmission technology to realize engineering applications to achieve transmission distance of over 5000 km and transmission capacity, 12 GW.

Research and manufacture of UHV transmission equipment suited for extremely hot and cold climates. Currently, UHV projects operate at temperatures as low as −50 to −40°C and as high as 50–60°C. However, the Arctic region’s lowest temperature is −68°C and the equatorial region’s highest ground temperature is over 80°C, both temperatures beyond the tolerance limits of existing UHV transmission equipment. The insulation performance of electric materials will weaken under extremely high and low temperatures. Therefore, research shall be conducted on the key technologies of equipment well suited for operation in such extremely hot and cold climates. By around 2030, a breakthrough will be achieved in the development of a full set of UHV DC equipment with the properties required. The UHV DC compact converter station concept will go into practical application to meet the export requirements of large clean energy bases in the Arctic and equatorial regions and elsewhere.

Currently, the cost of 1000 kV UHV transmission is only about 72% of that of 500 kV EHV transmission. With the construction of a global energy network, the transmission cost will further decrease subject to successful production of UHV equipment on a large scale.

Since the 1990s, among the world’s submarine cable transmission projects, 15 AC transmission projects have been developed, including five at a voltage grade of 500 kV or above. Since 2000, three 500 kV AC submarine cable transmission projects have been put into operation, compared with 67 DC transmission projects, which include 13 HVDC transmission projects under construction or planning. DC submarine cable technology is becoming an important means of building cross-sea grid interconnections and also connections with offshore renewable energy generation. The Norway–Netherlands submarine cable transmission project, featuring HVDC transmission, is scheduled for operation in 2016–2018. The design capacity is 1.4 GW. The 600 km submarine cable across the North Sea is the world’s longest submarine cable. Under the North America Power Grid, there are 14 submarine cable transmission projects, with a design transmission capacity of 5.762 GW and a total cable length of 1718 km underwater. The Neptune Project in the United States is based on a ±500 kV DC submarine cable network, with a maximum water depth of 2600 m as the world’s deepest submarine cable.

In response to the development requirements of a globally interconnected energy network, research and manufacture of UHV AC and UHV DC cables must be completed before 2030. After 2030, conditions will be in place for large-scale application of UHV AC/DC cables and submarine cables to better support the construction of cross-sea projects forming part of the future global energy network.

In around 2020, a basic theoretical framework for DC grids will be initially established, with the completion of the economics analysis of DC grid technology involving interconnections at two voltage grades and associated engineering work. Looking forward to 2030, with the growing maturity of DC grid-related technologies, economics analysis of the technology involving DC grid interconnections at several voltage grades will have been completed, with the relevant projects moving into actual implementation. By around 2050, DC grid technologies will enter a period of active promotion and render strong support to large-scale grid access for renewable energy.

Technology for optimizing coordinated operation of microgrids and large power grids. The wide variety of microgrid equipment gives rise to variance in control methodology and operational characteristics. The complexity of operation control and protection for microgrids calls for research into design standardization in terms of control system structures, communication networks, and control technology, in order to standardize and modularize complete equipment, while improving the universality and expandability of the coordination and control systems for microgrids and large power grids.

Technology for managing microgrid energy optimization. A microgrid incorporates multiple energy sources like solar, wind, and biomass energy, together with a variety of energy conversion devices such as fuel cells and energy storage systems to provide customers with different energy products, like cooling, heating, and electricity. Given the greater uncertainty and time variance involved, more in-depth research is required on the technology for managing microgrid energy optimization so as to optimize microgrid operations and improve overall operational efficiency.

With the development and integration of microgrids and distributed generation technology, plug-and-play distributed power, flexible interactions at the grid level with the demand side as well as coordinated operation with large power grids will be realized and become an integral part of ubiquitous smart grids at the national level.

Into the twenty first century, the method of zone and layer-based control has become relatively mature. Control technology has improved significantly, evidencing a move from “off-line forecasts and real-time matching” on a precontrol basis toward “online forecasts/decision-making and real-time matching” and further to “real-time calculation and real-time control”.

Real-time/super real-time simulation and decision-making technology. Offline, online, real-time, and super real-time operations have progressed in chronological order. The growth of grid capacity imposes ever-higher requirements on the timeliness of grid operation analysis and decision-making. In the early days, power system control was based on off-line calculations due to the constraints of computer technology. However, with the progress of information technology, more and more calculations can be performed online or even on a real-time basis. Dynamic security assessments and prewarnings can be conducted online. Through online transient stability analyses, we can not only assess the security level of current systems, but also develop prevention and control strategies to help dispatchers with operational adjustments and improve grid operational safety. Through real-time simulation, we can simultaneously simulate the actual running state of grids. Super real-time simulation is achieved if the simulation results can be obtained before the occurrence of a real incident. In the future, the development of grid-based real-time and super real-time simulation technology will further improve the security control of large grids at the operational level.

Fault diagnosis, recovery and automatic reconfiguration technologies of power grids. On the strength of technology innovations, such as online fault monitoring and diagnosis, new relay protection and wide-area backup protection, fault recovery strategy optimization and smart reconfiguration technology, power grids demonstrate strong security, stability and fault self-recovery capability in different operating environments and in the face of different types of fault. These technologies can greatly improve the defense capability of large grids against cascading faults, extreme weather conditions, and harmful external conditions. With the development of computer technology and control theory, operational control at the grid level is gradually moving in the direction of forecasting, prewarning, and automatic fault recovery. Highly automatic operational control, expected to materialize after 2030, can support day-ahead forecasts for renewables-based power generation within a 5% margin of error and help achieve a global dynamic equilibrium among renewables, traditional energy and demand loads.

Compressed-air energy storage operates on the principle of transforming electric energy into potential energy storable in compressed air by using surplus electricity produced in low-demand periods to drive the air compressor and press the air into a large-capacity air reservoir. At times of power undersupply, the compressed air is burnt with oil or natural gas to drive the combustion gas turbine for power generation and meet the requirements of system-level peak load regulation. Compressed-air energy storage has the advantages of high capacity, long service life, and good economics. But the generation process requires burning fossil fuels, which results in pollution and carbon emission. Currently, compressed-air stored energy technology is basically at the laboratory modeling or small-scale demonstration stage.

Flywheel energy storage works by accelerating a rotor (flywheel) to a very high speed and storing the kinetic energy generated. The rotor becomes a generator when energy is extracted from the system. Featuring low energy density and instead of large-scale energy storage, this energy storage technology is suitable for short-term energy storage to resolve problems of power quality and impulse-type electricity consumption.

With a history of 140 years, lead–acid cell storage is the most mature technology of its kind, currently accounting for more than half of the battery market. A low-cost and safe storage option, this technology is used mainly on electric bicycles. But lead–acid cells are not suitable for grid energy storage due to their low energy density, massive size, and also the poisonous materials involved in production.

With a high energy density, the sodium–sulfur cell is well-attuned to modular manufacturing and easy on transportation and installation. It is suitable for providing emergency backup to meet special load demands. The sodium–sulfur cell was invented by Ford Motor Company in the United States in 1967. Getting a head start on sodium–sulfur cell research, Japan developed successfully in the mid-1980s, a sodium–sulfur cell with a high energy density of 160 kWh/m³. In 1992, Japan carried out a demonstrative operation of the world’s first sodium–sulfur cell energy storage system. As at the end of 2002, more than 50 sodium–sulfur cell energy storage stations were in demonstrative operation in Japan. In July 2004, the world’s largest sodium–sulfur cell energy storage station with a power rating of 9600 kW and a capacity of 57,600 kWh was formally inaugurated in an automatic system plant under Hitachi Limited. In 2009, State Grid Corporation of China completed a medium-sized 2000 kW pilot production line for sodium–sulfur cells, making China the world’s second country after Japan to master the core technology of high-capacity, single-cell sodium–sulfur batteries.

Flow cells feature high capacity and a long recycling life, with recyclable electrolytic solutions and separately designable capacity and power. Flow cells are bulky and use vanadium, a toxic compound, as a raw material for production. As early as in 1974, NASA successfully developed the world’s earliest flow cell. Currently, the full vanadium flow electricity storage system and the sodium polysulfide/bromine flow electricity storage system are two relatively mature cell types already at the stage of demonstrative operation.

Lithium ion cells use a Li ion-containing compound for the positive pole and a carbon material for the negative pole. The lithium ion battery features large energy density, high average output voltage and low self-discharge. It has no memory effect and operates in a wide temperature range from −20°C to 60°C. Known as a green product, the long-life cell demonstrates superior recycling performance without using any toxic or harmful substance. Currently, the lithium ion battery is used extensively on cell phones, laptops, electric vehicles and other equipment. However, economically it is not well-placed for use on power systems or large-capacity energy storage devices, as a charge–discharge cycle costs more than RMB 1 per kWh.

The metal–air cell is a new fuel cell type that uses metal fuels rather than the hydrogen energy in traditional fuel cells. Nonpoisonous and pollution-free, it offers many advantages, like steady discharge voltage, high energy density, low internal resistance, long service life, relatively low costs, and low requirements on process technology. It is an electricity generating device that incorporates oxygen and metals like zinc and aluminum, with the potential to open up a new generation of green energy storage batteries on account of the low cost, abundance and recyclability of the raw materials used for production. It is also structurally simpler compared with the hydrogen fuel cell.

Hydrogen energy storage technology has commanded widespread international attention as a source of clean, efficient and sustainable carbon-free energy. National plans for hydrogen energy development have been developed in the United States, Japan and some European countries, with a number of large-scale demonstrative applications of hydrogen energy storage already in place. These include an energy storage demonstration system designed for renewable energy integration, a hydrogen refueling station for fuel cell-powered cars, as well as hydrogen-based methane and natural gas–hydrogen blends. The hydrogen cell developed by the National Renewable Energy Laboratory can sustain a driving range of over 1500 km by using 15 kg of liquid hydrogen fuel. The scope of application of hydrogen energy storage technology has expanded from motorized transportation to the energy field. But ion exchange membranes for the fuel cell are still costly. Technology breakthroughs have to be achieved in cost reduction and in hydrogen production and storage before commercial operation can be realized.

Utilizing the zero electric resistance of a superconductor, a superconductive electromagnetic energy storage device offers the advantages of large instantaneous power, light mass, small volume, zero loss, and quick response. It can be used to improve power system stability and power quality. However, prospects for the future application of this technology are clouded by low energy density, limited capacity, and the fact that it is subject to the development of superconducting materials technology.

Optical fiber communication technology fulfils the function of communication based on transmission through optical fiber lines. It serves a backbone for information networks, with the advantages of rapid transmission speed, small transmission loss, and high signal quality and safety. Commercial networks currently run at a speed of 400 GB/s. In August 2014, Danish scientists achieved data transmission of 43 × 10³ GB/s (5300 GB of data/s) in laboratory conditions using a single optical fiber and a laser generator. This technology makes it possible to download a movie of 1 GB in just 0.2 ms. Experts expect virtually unlimited broadband for users with the continued development of optical fiber over the next 10 years.

Mobile communication technology integrates the newest technology of wired and wireless communications, realizing information transmission between mobile devices as the fastest developing technology of the twenty-first century. Since the advent of 1G (first generation) communication technology in the 1970s, we are now moving into the 4G (fourth generation) era. 4G technology can achieve a downlink peak data rate of 1GB/s and an uplink peak data rate of 500 Mb/s in the 100 MHz broadband. At the same time, 5G technology has become the focus of research around the world. Compared with 4G, 5G can transmit 1000 times more data volume at a data rate, 100 times faster, of 10 GB/s. The number of network-connected devices will also increase by 100 times, and end-to-end delays will shorten by 80%. 5G technology will meet the needs brought on by the fast-increasing intelligent terminals and rapid growth of the mobile Internet.

Satellite communication technology realizes communication between two or more earth stations by using artificial earth satellites as a relay station to retransmit radio waves. Comprised of satellites and earth stations, a satellite communication system is known for its wide coverage and high reliability, not being subject to the restrictions of complex geographical conditions between two communication points or calamities on earth. Satellite communication is good for multipoint transmission and reception, with the capability of providing broadcasts and multiple access communication economically. However, the technology also has its disadvantages, including long time delays, limited communication access in high-latitude regions, and the impact of space radiation on space communications. With technological improvements and lower costs, the launch and application of satellites is now practically possible for corporations.

Apart from improving transmission speed and quality, how to ensure communication security is also an important direction of communication technology research. Based on the principles of quantum mechanics, quantum communication technology can achieve, within extreme physical limits, high performance communication by using quantum effects to physically ensure the absolute security of communication. This brand new technology can resolve problems otherwise unresolvable by other communication technologies, making it the major focus of communication technology research around the world. Currently, quantum communication technology can cover a maximum transmission distance of 300 km and achieve a security rate of 1 Mb/s subject to a communication distance of 50 km. The development of quantum communication technology will ensure information security for important infrastructures, including national defense and military facilities and large grids.

The Internet of Things (IoT). An extension of the Internet into the physical world, the IoT is built on an integration of sensor technology, communication technology, and information service technology. It is a dynamic networking infrastructure with self-organizing capability based on standard rules and interoperable communication protocols. Every physical and virtual object in the IoT has its own identification tag, physical attributes and smart interface, enabling seamless integration of the object with the existing information network. IoT technology will bring about full informatization of the real-world physical environment, realize “network ubiquity,” and play a significant role in the future development of the global energy network.

The ubiquitous Internet. The Internet, or the worldwide web, was originated in the United States in 1969. With the development of personal computers and smart phones, the Internet has become a household phenomenon and an important ICT platform for work and life. Based on conventional Internet technology, the ubiquitous Internet has extended its reach to facilitate the exchange of information with any people or objects anytime, anywhere. It can provide a variety of information services in response to different demands. Simply put, it is an omnipresent form of the Internet that provides mutual access to information among different objects.

Sensor technology. A detection device and a key technology for gathering information, a sensor converts, based on certain rules, a measured object into electrical signals or other forms of information output as required. Sensor technology started to catch growing attention in the 1980s with the rapid growth of integrated circuit technology and computer technology. It has now evolved into a backbone technology for ICT development. Sensor technology is supported by fundamental research on sensors and research on sensor network systems. Currently, fundamental research on sensors is focused on new materials, with the adoption of micromachining and bionics technologies to improve the sensitivity, accuracy and stability of sensors. The focus of sensor system research is placed on applying near field communication technology to build a stub network with sensors and the information they collect, forming an important foundation for the IoT.

Image recognition technology. Image recognition technology enables computer-based processing, analysis and interpretation of images to identify targets and objects of different shapes and forms. The recognition process includes image preprocessing, image segmentation, feature extraction, and judgment and matching. Simply put, image recognition refers to the computer reading of image contents like the human mind. Image recognition equips machines with the power of sight in place of human-based monitoring of equipment conditions and prewarning of potential danger. This technology provides intelligent navigation for unmanned vehicles, with the capability to judge road conditions in real time based on satellite data.

Cloud computing and cloud storage technology. Cloud computing refers to software sharing, computing and data acquisition on an Internet platform. Cloud storage technology brings together a large collection of storage equipment on the Internet to provide shared data storage and service access capabilities. The development of cloud computing and cloud storage will lead to the formation of a hardware system to accommodate the integrated operation of servers, storage devices and Internet equipment, which will maximize the expandability of software applications. In the area of cloud computing technology, virtualization development and breakthrough will not only enhance the utilization efficiency of computing resources, but also provide dynamic migrations and resource scheduling to allow more efficient management and expansion of cloud computing loads and contribute to the flexibility of cloud computing services.

Big data technology. Big data technology enables the extraction of important information of value from the massive data that is beyond the processing capacity of a traditional database. As big data technology involves enormous volumes of data, the requirements on data processing capacity and transmission rates are far more stringent compared with conventional data processing technology. With the phenomenal growth of the Internet, data and information flows have continued to increase. For the future global energy interconnection, information flows on resources, grid operation and users are expected to extend locally from a single location (a country or region) to the whole world, accompanied by dramatic data growth. This situation will warrant the application of big data technology with important real-life implications for improving the management and operation of the future global energy network.

For the IoT, the power communication network will incorporate communication, information, sensor, automation and other technologies, together with sophisticated sensors, to extensively deploy a variety of smart devices with sensing, computing, and actuation capabilities in power generation, transmission, consumption, and management. Through a power sensing network and IoT technology, real-time surveillance can be conducted on grid operation status, intelligent substations, distribution lines, users and power plants to realize panoramic sensing, mutual information access, and intelligent control for the global energy network. The IoT is the foundation for developing the global energy network; only by means of real-time monitoring and sensing can the global energy network operate securely and efficiently based on an established control strategy.

For image recognition technology, surveillance images of power plants and substations, cruise images of aircraft as well as satellite images can be transmitted back to the surveillance and control center of the electricity system to diagnose equipment operation status through image recognition technology and analyze and prewarn damage to insulation materials, corona discharge, short-circuit, icing, and filth. In the icy cold Arctic and scorching equatorial regions, forested and mountainous areas and other locations with unfavorable conditions for work, image recognition technology can recognize equipment conditions intelligently to improve reliability and reduce labor and material resources.

For cloud computing and cloud storage technology, efforts should be devoted to remove bottlenecks in analyzing and processing speed in operation control and power trade management of the global energy interconnection, such that the speed and accuracy of big data analytics can be improved and power scheduling and trading on a global level realized. As the coverage of global energy interconnections expands, power trading technology will mature. With the establishment of a trading system, the complementary nature of resources due to spatial–temporal differences among the electricity markets across different countries and continents will manifest itself more prominently. The evaluation system for power trade through a network of globally interconnected grids and the platform for verifying power trade will be more widely applied, generating strong computing and storage demand. Cloud computing and cloud storage can fully leverage existing global computing resources and supercomputing technology to schedule computing resources according to tasks from time to time to meet the demand for computing and storing global energy data and information.

Big data technology can be employed, given its strong forecasting performance, to conduct fast-time real-time simulation for the electricity system and improve the intelligence level of analytical decision-making. Variables such as temperature, atmospheric pressure, humidity, rainfall, wind direction, wind force, and radiation, are taken into full account to arrive at more accurate forecasts of volatile power sources. Energy and electric power system modeling technology, incorporating big data analytics and numerical weather forecasts, can improve the smoothness of wind and solar photovoltaic power supply. With big data technology, power dispatchers can work out scheduling arrangements ahead of time and contribute to the consumption of more renewable energy.