Four major technologies help distributed energy to develop in a “blowout” manner

In recent years, thanks to the rapid development of power technology, information technology, control technology and energy storage technology, global distributed energy projects have shown a "blowout" development. The maturity of renewable energy generation and small gas turbine technology has led to a rapid decline in the levelized cost of energy (LCOE), and the economic feasibility of distributed energy projects has leapt from a development obstacle in the past to a driving force; energy storage technology has brought greater flexibility to distributed energy, and the use of renewable energy can be unconstrained by its intermittent characteristics, and excess electricity and heat can also be stored; the application of information and communication technology in the power grid has greatly improved the ability to access real-time energy data, and the development of the Internet of Things as a communication infrastructure has promoted the evolution of distributed energy systems from simple mechanical equipment to intelligent and digital. Under the guidance of technological innovation, the advantages of distributed energy systems compared to the traditional centralized "power generation-transmission-power consumption" model have been strengthened: higher comprehensive energy utilization efficiency, less pollutants and greenhouse gas emissions, enhanced system stability and energy supply security, and lower energy costs. The power, communication, and energy storage technologies that distributed energy technologies rely on have fully entered the mature stage and are very close to the balance point of breaking the cost barriers of traditional energy technologies. Today, we are about to usher in the "technological singularity" of distributed energy development.

Distributed energy supply technology

Distributed energy supply technology is the core of distributed energy systems, including various power generation technologies and cogeneration technologies. For example, the basic module of a distributed photovoltaic power generation system is a photovoltaic array that performs photoelectric conversion, and the core of a distributed natural gas cogeneration (CHP) system is a gas turbine or internal combustion engine (other fuels or technologies, such as biomass and fuel cells, can also be used). Technological innovation has enabled distributed energy supply equipment such as photovoltaic modules and natural gas turbines to adapt to various energy needs, while costs have also been significantly reduced, creating objective conditions for the popularization of distributed energy.

Natural gas distributed energy technology is based on equipment such as gas turbines or gas internal combustion engines. While generating electricity, it uses the waste heat generated by the gas turbine to provide heating and cooling for users. Using the energy cascade utilization model, the comprehensive energy utilization efficiency of natural gas CCHP units is much higher than that of independent power generation and heating systems. For example, the fuel utilization efficiency of Siemens SGT-300 gas turbine units in CCHP projects can usually reach more than 80%, and the energy cost can be reduced by about 40%. On the other hand, higher efficiency also means less emissions. Compared with traditional coal-fired power generation and coal-fired boilers, natural gas distributed energy has inherent advantages in the emission of nitrogen oxides, sulfur dioxide and smoke, and the carbon dioxide emissions of gas-fired power generation are only half of those of coal-fired power generation. In addition, the unique fuel flexibility of gas turbines also makes them very suitable for the field of distributed energy. Recently, China Power (Chengdu) Integrated Energy Co., Ltd.'s distributed energy station project located in the Western Park of Chengdu High-tech Industrial Development Zone, Sichuan Province, adopted this equipment. As Sichuan has unique natural gas resources, the company plans to use the fuel flexibility of two Siemens SGT-800 gas turbines to further reduce energy costs.

Around the world, developed countries still dominate the design, testing and manufacturing of core power equipment such as gas turbines and gas internal combustion engines, and continue to introduce new technologies in the manufacturing process of key components. Among them, 3D printing (also known as "additive manufacturing") has become the next technological breakthrough for gas turbine manufacturers. Using 3D printing technology, Siemens and other companies have completed the trial production and full-load testing of components such as blades, and are expected to apply 3D printing to the design and mass production of other gas turbine components. 3D printing technology can significantly shorten the R&D cycle of equipment, improve the performance of components, improve the operating efficiency of equipment, and give full play to the potential of technological innovation.

In the field of distributed photovoltaic power generation, driven by technological innovation, both the fundamental development goals of photovoltaic systems, namely, “cost reduction” and “efficiency increase”, have made positive progress. Thanks to the continuous research and development of traditional crystalline silicon materials and breakthroughs in new material technologies such as cadmium telluride, copper indium gallium selenide, and perovskite, the energy conversion efficiency of photovoltaic modules has been continuously improved, and the performance of anti-aging, anti-ultraviolet, thermal conductivity, and flame retardancy has also been greatly improved. Diamond wire cutting and passivated emitter rear cell (PERC) technology have become hot words in the industry and have been gradually recognized by the market; at the same time, high-efficiency battery technologies such as full back contact battery (IBC), heterojunction battery (HIT), and metal wrapped back contact battery (MWT), which were rarely involved by enterprises before, have also attracted the attention and investment of more and more enterprises. The “13th Five-Year Plan” photovoltaic technology innovation plan proposes to increase the efficiency of crystalline silicon solar cells to more than 23% by 2020, and realize the localization of HIT, IBC and other batteries. From the perspective of cost, the cost of a distributed household rooftop photovoltaic power station of the same 3KW scale has been reduced to less than RMB 30,000, a 50% decrease from the cost ten years ago. The era of "grid parity" for distributed photovoltaics is getting closer.

It is worth mentioning that the multi-energy complementarity of distributed natural gas and distributed renewable energy has synergistic benefits and will become an important direction for the future development of distributed energy supply technology. Taking the natural gas CCHP unit coordinated distributed photovoltaic project as an example, the addition of renewable energy has further improved the system's comprehensive energy utilization efficiency and emission reduction benefits; the multi-energy complementary system is not limited by a single energy type, and natural gas and solar energy complement each other, enhancing the security of the system's energy supply; in a system equipped with energy storage facilities, the volatility of photovoltaics can be suppressed, and gas units can also be flexibly dispatched within an appropriate range to ensure the stable operation of the energy supply area and the power grid.

Energy Storage Technology

Energy storage is a vital part of distributed energy systems. The existence of energy storage units makes it possible to flexibly apply electricity and thermal energy that could only be "generated and used immediately". At present, the application scenarios of energy storage are mainly divided into two parts: thermal energy storage (cold storage and heat storage) and electrical energy storage. Cold storage and heat storage facilities can optimize the operation of natural gas distributed systems and improve the economic benefits of projects, while electrical energy storage can make up for the volatility and intermittency of distributed renewable energy and ensure the stable output of the system. From the perspective of energy storage media, it can be divided into batteries, hydrogen, tank heat, geothermal, ice heat, etc.

With the rapid development of renewable energy such as wind power and photovoltaics, the importance of energy storage is increasing. Energy storage technologies such as flywheels, supercapacitors, lithium batteries and flow batteries can smooth the output curve of distributed photovoltaics and provide support for the stable operation of the system. When the photovoltaic output is greater than the user's demand, the excess electricity can be stored. If the solar panels stop working, or there are peak loads, insufficient power supply, power outages, etc., the stored electricity can be released to meet the user's electricity needs and improve the comprehensive utilization rate of distributed photovoltaics. With the promotion of electric vehicles and the rise of the concept of energy Internet, technologies that incorporate electric vehicles into energy storage networks have also emerged. Among them, power battery manufacturers, automobile manufacturers and universities have carried out relevant research to explore the technical feasibility and economic benefits of using waste power batteries for energy storage in distributed energy systems. Thermal storage is a simple but basic technology that is usually used in buildings and industrial processes. On the one hand, it can improve system efficiency by optimizing the heating, ventilation and air conditioning (HVAC) system; on the other hand, it can also avoid electricity price premiums during peak hours.

In addition, hydrogen energy has gradually become the next innovation point in the field of energy storage and distributed energy. As a major country in the use of renewable energy, Germany has currently built dozens of "wind power hydrogen production" projects: through water electrolysis equipment, hydrogen is produced using wind power that cannot be absorbed by the power grid, and then the hydrogen is mixed into the local natural gas pipeline in an appropriate proportion for use by nearby users. This method uses the huge natural gas network as an energy storage medium to further reduce the wind abandonment rate of wind farms. In May of this year, the hydrogen production station of the first wind power hydrogen production project in China was officially started. On the user side, water electrolysis hydrogen production can be fully combined with distributed photovoltaics to produce hydrogen while storing energy, and no pollutants and greenhouse gases are emitted during the whole process. With the promotion of technologies such as fuel cells and hydrogen energy vehicles, distributed energy networks with hydrogen as the core will also usher in greater development space.