Siemens Energy will provide a hydrogen production system for a fueling station in Beijing, China. The company said it will be the “first megawatt green hydrogen production project in China.”
“The decarbonization of the energy systems is a challenge that every country must face. Siemens Energy is the company that can provide its customers with significant support in this process—no matter if they are states or companies,” Christian Bruch, CEO of Siemens Energy, said in a statement.
Siemens’ deal is with Beijing Green Hydrogen Technology Development Co. Ltd., a subsidiary of China Power International Development Ltd. (China Power). The hydrogen fueling station will be located in the Yanquing District of Beijing. The location is significant because it is one of three main competition areas for the 2022 Winter Olympics. The “green” hydrogen system is expected to provide fuel for public transportation during and after the event.
‘Grey,’ ‘Blue,’ ‘Pink,’ and ‘Green’ Hydrogen
Although hydrogen is the most abundant element in the universe, it is found mostly in molecular form on Earth, such as in water and methane. Therefore, to get hydrogen gas or liquid, it must be produced.
Hydrogen is classified into various types based on how it is produced. Today, the majority of hydrogen (about 95% according to some estimates) is produced from natural gas through a process called steam-methane reforming. This is currently the least expensive way to produce hydrogen, but it generates significant carbon emissions. As a result, hydrogen produced in this way is considered “grey.” When these carbon emissions are captured and stored or reused, the hydrogen is called “blue” hydrogen. Lately, some folks in the industry have started calling hydrogen produced with nuclear power “pink,” which perhaps developed as a nod to the magenta color often used in radiation and contamination warning signs and ropes.
Green hydrogen, meanwhile, is produced from water through electrolysis using renewable energy sources, such as wind farms, solar facilities, hydropower stations, or geothermal power plants. As a result, there are no carbon emissions.
How Electrolysis Works
Electrolysis has been well-understood for centuries. The process uses electricity to split water into hydrogen and oxygen. This reaction takes place in a unit called an electrolyzer. Electrolysis was at one time the dominant technology for the industrial generation of hydrogen, but it has long since been replaced by less expensive methods. That could change again, as the cost for renewable energy continues to decrease and climate concerns continue to increase, electrolysis could again become a significant method of production.
According to a paper authored by Dr. Philipp Lettenmeier, head of product management for Siemens Energy’s New Energy Business, there are currently two commercially relevant electrolysis technologies on the market for hydrogen production in the MW range: alkaline electrolysis and proton exchange membrane (PEM, also sometimes called polymer electrolyte membrane). The technologies differ primarily in the ionic charge carrier that electrically closes the electrochemical process, as well as in the electrolytes used.
Alkaline electrolyzers have a porous separator that physically separates the hydrogen and oxygen gases, while still enabling transport of the liquid electrolyte. The porous separator creates more stringent requirements for alkaline electrolyzers in dynamic operation. Differential pressures that can result in hazardous mixing of oxygen and hydrogen must be prevented in the alkaline electrolyzer.
PEM, on the other hand, includes a solid electrolyte that electronically isolates the anode from the cathode but electrically closes the circuit through its selective conductivity for cations. This nearly gas-tight solid electrolyte offers several advantages. One is that it serves as a physical divider between the anode (oxygen side) and the cathode (hydrogen side), and it prevents mixing of the generated gases. This enables operation with a differential pressure. Unintentional pressure differentials that could result in mixing of the gases, which can create a serious safety hazard, can therefore be handled more easily in the PEM design. Furthermore, the membrane also ensures a high gas product purity in dynamic operation and during part-load operation when the contaminant gas concentration in both electrolysis technologies increases as a function of the gas production rate due to diffusion.
Lettenmeier explained other differences in his paper and compared the efficiencies of alkaline and PEM electrolyzers. He wrote: “The fact is that the selection of the operating point and the associated voltage are decisive for efficiency. The generally low overall resistances in PEM technology result in a broader range of operating modes.”
Siemens’ Silyzer 200
The core equipment of the hydrogen integrated energy station that will be installed in Beijing includes Siemens Energy’s PEM electrolyzer system, known as the Silyzer 200. It can produce high-quality hydrogen at industrial scale. In addition, the company said the system responds quickly, the startup time under pressure is less than one minute, and it can be directly coupled with renewable energy.
“In order to meet customer needs of saving space and being flexible, Siemens Energy has adapted its hydrogen production system into a customized solution, which is also its first skid-mounted megawatt green hydrogen production system in China,” the company said.
Siemens signed a memorandum of understanding on cooperation in green hydrogen development and comprehensive utilization with State Power Investment Corp. Ltd. (SPIC) in September 2019. SPIC is the controlling shareholder of China Power. The hydrogen production project is said to be the result of a close partnership between the two companies. SPIC and Siemens Energy have plans to further expand their cooperation on green hydrogen projects.
“SPIC is committed to working together with Siemens Energy to continue our cooperation in the field of clean energy and to leverage the complementary advantages of both parties. Together we will contribute to the development of clean energy in order to cope with climate change together,” said Qian Zhimin, chairman of SPIC.
“Promoting the application and development of renewable hydrogen is of great significance for China to build a modern and cleaner energy system,” Bruch added.
Dubai Adds Green Hydrogen Plant
Siemens Energy is also deploying similar technology in the Middle East. In the United Arab Emirates, the company is working with the government of Dubai and its state utility the Dubai Electricity and Water Authority (DEWA) to build the region’s first solar-driven hydrogen electrolysis facility at Mohammed bin Rashid Al Maktoum (MBR) Solar Park in Dubai.
The MBR facility will produce hydrogen using solar PV, store the gas, and then deploy it for re-electrification, mobility, or other industrial uses. That plant also features Silyzer 200 technology, along with Siemens’ SIMATIC PCS 7 control system and SINAMICS DCM converters. Each unit uses 1.25 MW of electric power to generate 20 kilograms of hydrogen per hour.
A groundbreaking ceremony for the MBR facility was held in February 2019. The facility was expected to provide hydrogen for mobility purposes during Expo 2020 Dubai beginning in September 2020, but that global mega-event was postponed for a year due to COVID-19. It will now be held from Oct. 1, 2021, to March 31, 2022. Expo 2020 Dubai is expected to be the largest event ever staged in the Arab world, and is set to include 190 participating countries and millions of visitors from across the globe, organizers said.
—Aaron Larson is POWER’s executive editor (@AaronL_Power, @POWERmagazine).