A Brief Introduction to the Development Prospect of Hydrogen Energy Distributed Energy System

Distributed energy is not far away from us

When we talk about the concept of distributed energy, you may feel a little strange, but when it comes to the power department and heating of the factory, you may feel very familiar. In China, energy supply existed in a distributed form for a long time, but because its general supply objects and forms are relatively single, and mainly for factories and factory houses instead of everyone, everyone may feel unfamiliar. But in recent years, with the development of energy technology and the increase of energy supply forms, distributed energy has gradually penetrated into our lives. Whether it is gas floor heating used in residential homes or photovoltaic power generation panels installed on the roofs of many residential buildings, they are all emerging forms of distributed energy. Increase the scale of distributed energy supply to multiple households or an entire community, then a small distributed power station can be built. Power stations generally generate heat during the process of generating electricity, so this energy supply can be combined with heat and power. However, in the current distributed energy, the main purpose is to use natural gas in municipal pipelines as a fuel source to generate electricity in the form of thermal power, and the main purpose is to supply heat.

The demand for distributed energy has emerged

At the end of 2020, an extreme cold wave swept across the land of China, and electricity curtailment measures were adopted in many parts of the country, and major factories' “crazy grab” of diesel generators became a temporary wave. Although the National Development and Reform Commission has pointed out three major reasons, namely, the rapid recovery of industrial production to drive the growth of electricity consumption, the increase of electricity load due to extreme cold weather, the limited external power receiving capacity and the failure of the unit to increase the difficulty of power supply, but the deeper level The reason is that my country's energy supply method is relatively simple, and most of it is centralized energy supply. When the centralized power supply reaches the upper limit of capacity, or there is a shortage of single power generation fuel, it is difficult for each region to respond quickly according to local demand and supply electricity through other fuels. The exposure of the disadvantages of centralized energy means that our demand for distributed energy is more pressing than we thought.

Distributed energy has many advantages

Before talking about the advantages of distributed energy, we need to think about this question: What determines the fundamental structure of power? There are many factors that determine the power structure, but the most important one is the uneven distribution of power demand in space and time. , Which determines the fundamental structure of the power system. For China, in more developed areas, there will be centralized power stations with larger power generation capacity. As the population of the area increases, the number and scale of power stations will continue to increase. It means that our electricity demand will increase in the future, and the area and scale that the grid needs to cover will also continue to expand. These changes will have a huge impact on the cost and quality of energy supply. To put it simply, when the scale of the power grid increases to a certain extent, power grid security issues such as line loss of centralized energy supply, disaster tolerance, and demand fluctuations become increasingly prominent.

The existence of distributed energy can just make up for the many shortcomings of centralized energy. First, it is close to the demand side, and the line loss is very small. Secondly, because its installed capacity generally meets the size of a family to a community or several communities. When energy demand fluctuates, this small installed capacity can quickly and better respond to such fluctuations. Finally, in the event of a disaster or accident, on the one hand, distributed energy sources can supply energy for isolated islands without affecting each other; on the other hand, the spread of a single distributed energy source is small, which ensures the safety of the overall power grid.

Hydrogen power generation system is one of the advantageous options of distributed energy

In terms of its technical characteristics, the fuel cell itself is a device that converts hydrogen energy into electrical energy through an electrochemical reaction without burning, and the hydrogen-to-electricity conversion efficiency can reach about 60%. There are no moving parts in the whole conversion process, so no noise is generated. And its working temperature is generally 80~90℃, and the requirements for the thermal management system are not very high. If the generated heat is fully utilized, the daily heating or hot water demand of residents can also be met. In terms of fuel sources, similar to electrical energy, hydrogen is also a non-natural energy carrier. In addition to the well-known hydrogen production by electrolysis of water, its source can also come from fossil fuel reforming hydrogen production and industrial by-product hydrogen. Even if it is electrolysis of water to produce hydrogen, the electric energy used for electrolysis can also be clean wind, light or water energy. Therefore, the source of hydrogen can get rid of the dependence on fossil fuels such as coal or gasoline and diesel, and it is less restricted by regional resource endowments.

In terms of current technical conditions, fuel cells and electrolyzers are like twin brothers. The fuel cell can be used to convert hydrogen energy into electrical energy, and the electrolytic cell can be used to convert electrical energy into hydrogen energy. If the fuel cell and the electrolytic cell form a system, the system can be used to generate electricity and store energy. Then this will be a complete power generation and energy storage system whose scale can be determined by design.

The system can be built in areas where power demand is large, such as factories and islands, supplemented by wind or photovoltaic power generation. In the daytime or when the wind is strong, the excess electric energy can be stored well, and when there is a demand gap, the fuel cell power generation can be used to meet the power supply demand. It can also be built in residential communities to convert electricity from the grid into hydrogen for storage during the low electricity price period of the electric wave valley at night. During the peak hours of electricity consumption during the day, electricity is generated to make up for demand, and the heat generated can also heat the community.

On the other hand, with the development of fuel cell vehicles, hydrogen energy has become more and more possible as a wide range of distributed energy sources. The fuel cell vehicle itself is a complete hydrogen power generation system that can operate stably and independently. Japan has also taken the lead in proposing the concept of using fuel cell vehicles to provide electricity to a house. Generally speaking, a full-power fuel cell vehicle generates more than 100 kW, which is more than enough to meet the daily electricity needs of most ordinary households in China. And because of the mobility of the car itself, the energy is stored in the high-pressure cylinder of the car with hydrogen as the carrier, which can make the use of energy more free in time and space. It can not only quickly respond to immediate energy demand, but also stably ensure the stability of its own power generation performance.

The latest developments in the hydrogen energy industry imply opportunities for the development of hydrogen energy distributed energy systems

According to research conducted by research institutes, more than 9 countries have promulgated national hydrogen energy strategies, 11 are under formulation, 14 support demonstrations, and 17 are under discussion. In these countries, for the current market of distributed energy, its annual load growth rate has reached 33%; and for the overall market size in 2030 and 2050, it is estimated that it will be around 20G watts to nearly 100G watts. The current short-term growth It is 20 times to 40 times. Europe’s target for 2021 is to install more than 25,000 units in 2021 and 2.5 million units in 2040, which means that it will take 20 years to install an average of 250,000 units per year and replace natural gas with hydrogen; in 2030, the amount of natural gas used in buildings will be increased. 7% was replaced by hydrogen, which solved the heating demand of 2.5 million or 11 million respectively. The prospect of hydrogen as an energy source rather than a chemical product is relatively clear, and the development opportunity of the hydrogen energy distributed energy system is about to come.

In September 2020, the Ministry of Finance, the Ministry of Industry and Information Technology, the Ministry of Science and Technology, the National Development and Reform Commission, and the National Energy Administration jointly issued the "Notice on Carrying out Fuel Cell Vehicle Demonstration Applications", clearly pointing out that it will take four years to gradually achieve Breakthrough in the key core technologies of fuel cell vehicles, focus on technological innovation, identify application scenarios, build a complete fuel cell vehicle industry chain, and further promote the large-scale industrial development of fuel cell vehicles. At present, the results of the model city clusters have come out. Beijing, Shanghai, Guangzhou, Zhengzhou and Zhangjiakou, as the leading cities of the model city clusters, will lead the rapid development of the fuel cell vehicle industry.

Summarize

Looking at the background of the times, policy status, industry dynamics and technical characteristics, on the one hand, distributed energy, especially the hydrogen energy distributed energy system, is developing steadily on a global scale. On the other hand, domestic policies, industries, and technologies are promoting the scale and industrialization of fuel cell vehicles. The author believes that in the next ten years, the hydrogen energy distributed energy system and fuel cell vehicles will eventually overlap and merge to a certain extent. The form of distributed energy is more flexible than we think, and our understanding of fuel cell vehicles will no longer just be a means of transportation. After years of development, we may live in a world where centralized and distributed hydrogen energy and electric energy jointly guarantee energy supply (as shown in Figure 1).

Figure / Schematic diagram of the future hydrogen energy industry structure

additional materials

Distributed energy system refers to a small and medium-sized energy conversion and utilization system that produces and supplies energy on-site according to user needs, directly faces users, has multiple functions, can operate independently, or can be connected to the grid, and can meet multiple goals. As a new generation of functional methods, there are four main features: (1) Directly facing user needs, arranged near the user, reducing energy transmission costs. (2) Compared with the traditional centralized energy supply system, it has medium and small capacity, which is flexible and economical. (3) The multi-functional trend not only includes multiple energy inputs, but also meets the multiple energy needs of users at the same time. (4) Alternative technologies are also increasing, such as the combination with fuel cells, through system optimization and integration, to achieve multiple functional goals. The core and important part of the distributed energy system is the distributed combined cooling, heating and power system, which can be combined with wind energy, solar energy, and biomass energy. According to the type of heat engine, there are mainly gas turbines, internal combustion engines, steam turbines, Stirling engines, and fuel cells and other distributed combined cooling, heating and power. Among them, the hydrogen-oxygen fuel cell combined heat and power generation system, if heat production is included, the system efficiency can reach 70-80%, and the reaction product is only water, which is currently one of the cleanest distributed energy systems.