Hydrogen blending of natural gas widens deep decarbonization road

"Promote the construction of zero-coal cities. By 2030, we will pilot low-carbon technologies such as mixing natural gas with hydrogen in gas-fired power generation and heating." The "Chongming World-class Ecological Island Carbon neutral Demonstration Zone Construction Implementation Plan (2022 version)" issued recently proposed the above key tasks, and Shanghai Chongming became the first region to clarify the time point of hydrogen mixing of natural gas, causing concern in the industry.

Mixing natural gas with hydrogen can not only expand the application scenario of hydrogen energy, but also improve the combustion performance of terminal equipment, reduce carbon dioxide, nitrogen oxides and other emissions, and green and low-carbon characteristics make it more and more popular. According to Peng Suping, an academician of the Chinese Academy of Engineering, the team predicts that if the proportion of hydrogen mixing is 10%-20% and the life cycle cost of "production, storage and transportation" is calculated (30 yuan/kg), the output value of the whole industry chain will reach 80-180 billion yuan/year. In the face of broad market prospects, how to seize the development opportunities?

■■ Provide new ideas for carbon reduction

Among the many hydrogen-related technologies, the popularity of hydrogen blending of natural gas is not accidental.

"The integrated development of the two is an important choice to achieve deep decarbonization." At the 18th China Distributed Energy International Forum held recently, Zhu Xingshan, deputy chief economist of the Development Planning Department of China National Petroleum Corporation, said that the addition of hydrogen to natural gas is equivalent to an increase in supply, which will greatly reduce carbon emission intensity while easing the pressure on the latter supply. At present, hydrogen energy storage and transportation is still a "stuck neck" link, and mixing is conducive to the low-cost storage and transportation of hydrogen and large-scale utilization. "Natural gas and hydrogen energy have similar characteristics in the transport, transport, use and other industrial chain links, and can find a lot of integration opportunities in power generation, construction industry and other application scenarios."

Wang Hongjian, chief engineer of Daoshi Research Institute of Beijing Gas Thermal Engineering Design Institute, further confirmed: calculated at 10%-20% hydrogen mixing ratio, the carbon emission reduction of equal calorific value is 3.5%-7.6%; Making full use of the existing gas pipeline network infrastructure, the cost of large-scale and long-distance hydrogen transport is 0.3-0.8 yuan/kg per 100 kilometers. "Since the international research began in 2000, there are more than 40 demonstration projects around the world, and about 2,900 tons of hydrogen are incorporated into the natural gas pipeline network every year, and the proportion of hydrogen is up to 20%." In China, as the hydrogen energy medium - and long-term plan is clearly proposed, pilot demonstrations such as hydrogen-doped natural gas pipelines are carried out, and research work and demonstration demonstrations are accelerated."

In addition to the regional level, some enterprises are also trying first. The reporter learned from the State Power Investment that Jingmen Green Movement Energy Co., LTD., a subsidiary of the group, successfully achieved 30% hydrogen-doped combustion transformation and operation at the end of September. This is the first time that China has carried out high-proportion hydrogen-doped combustion transformation tests and scientific research on heavy-duty gas turbine commercial units, and it is also the first demonstration project in the world to carry out high-proportion hydrogen-doped combustion in natural gas combined cycle and cogeneration commercial units. Only a 54 MW gas turbine in Jingmen can reduce carbon dioxide emissions by more than 18,000 tons per year with 30% hydrogen mixing.

■■ The industry is still in its infancy

The value is widely recognized, but there is still a long way to go to really mix natural gas with hydrogen. Zhang Bo, a professor at the China Institute of Energy Policy at Xiamen University, said that although some provinces have issued local plans as a breakthrough in hydrogen energy storage and transportation and terminal applications, the national level has not yet issued development plans, and the industry as a whole is still in its infancy.

"This is a complex system engineering, both to consider the technical feasibility, but also subject to safety, economic constraints." Some key issues must be addressed before it can be used on a large scale." Zhang Bo said that taking safety as an example, compared with methane, the main component of natural gas, hydrogen has a larger explosion limit range, is more likely to leak spontaneous combustion, and the risk of explosion after mixing is correspondingly expanded, which puts forward higher requirements for natural gas long-distance pipelines, urban gas pipe networks and terminal energy use equipment. It is important to study the law of leakage diffusion and safety risk control of hydrogen-doped natural gas.

Zhu Xingshan also said that there are not many mature projects at this stage, coupled with the lack of planning and standard system, resulting in unclear security risks and other problems. "For example, the adaptability of in-service pipelines to different hydrogen mixing ratios, and how to improve the hydrogen mixing ratio of storage and transportation and terminal equipment have not been studied enough and not deep enough." Without a lot of research and experimentation, pipeline operators are often afraid to do it. According to the different proportion of hydrogen mixing, the terminal energy use equipment in the design, manufacturing, operation, maintenance, testing and other aspects, the standard specification is also lacking."

Then there are the economics. Hydrogen transportation in natural gas pipelines can realize long-distance and large-scale transportation of hydrogen energy with relatively little investment in a short period of time. However, the calorific value of the same volume of hydrogen is only 1/3 of that of natural gas, and in order to ensure that natural gas provides the same calorific value at the terminal after mixing hydrogen, the hydrogen price should theoretically be 1/3 of the gas price. "According to the current price of natural gas gate station, the hydrogen price obtained is far lower than the cost of hydrogen production at this stage." In other words, from the perspective of the whole industry chain, the commercial application of natural gas hydrogen blending project is not currently economically feasible." Mr. Zhang said.

■■ Urgent need to strengthen the top-level design

In the view of many industry insiders, strengthening top-level design and strategic research is a top priority. "The development of hydrogen blending of natural gas is related to the high-quality development of the entire hydrogen energy industry and the transformation of the natural gas industry, and its technical route and key tasks should be deeply analyzed, covering basic research, equipment research and development, technical demonstration, applied research, norms and standards, performance testing, and business model innovation." At the same time, we will improve the management model of the natural gas hydrogen blending industry and establish relevant incentive mechanisms." Zhang Bo said.

How to promote it? For example, it is necessary to carry out the safety and emergency management system construction of the hydrogen blending industry of natural gas with high standards, and explore the establishment of an industrial safety supervision platform based on information technology and digital technology. Strengthening communication and cooperation between management departments can continue the management model of the natural gas industry, and clarify the regulatory authorities and responsibilities of each link of natural gas hydrogen mixing. On the basis of the current natural gas pipeline network regulatory framework, improve the regulatory approval process for the construction of hydrogen-doped projects, sort out the key points of industrial standardization, and maintain the coordinated development of hydrogen-doped natural gas and hydrogen energy, natural gas and urban gas standards.

Wang Hongjian believes that from the perspective of the future space, with natural gas as the key trend of fuel, hydrogen storage and transportation can be achieved with the help of gas pipe networks, and then diversified fuel supply can be achieved, from hydrogen to hydrogen energy and natural gas. "Through evaluation at this stage, the proportion of hydrogen mixing in terminals and pipelines is 10%-20%, and the technology is completely feasible, and it can even be increased to 20%-30% after partial transformation." However, higher hydrogen mixing ratio still needs verification analysis, and there is a lack of systematic evaluation methods and databases. Including the law of pipe performance deterioration, integrity management and risk assessment, leakage monitoring and other links, need to be further studied and improved."

"First make full use of the existing infrastructure, and then consider new hydrogen-doped applications, and hydrogen-doped gas turbines should be prioritized in new large-scale constructions." Zhu Xingshan suggested that major demonstration projects of hydrogen mixing in natural gas be organized at the national level, and different application scenarios be selected, including pipeline hydrogen mixing and hydrogen gas turbine, to carry out demonstrations according to local conditions, accumulate experience and explore paths.