Hydrogen shows significant promise as an enabler of the green energy transition, particularly in industrial sectors where electrification is challenging. Anu Pulkkinen, Senior Strategy and Business Development Manager at Vaisala, discusses the current state of play in the hydrogen economy and the key role of accurate measurement in making the green transition possible.

The hydrogen economy refers to the use of hydrogen to decarbonize economic sectors that are hard to electrify, such as transportation, shipping and aviation, and heavy industry. In the same way as other fossil-fuel alternatives, hydrogen is categorized by color according to the way it is produced:

• Green hydrogen is produced through the electrolysis of water using renewable electricity such as wind or solar.
• Blue hydrogen is produced by splitting fossil natural gas into hydrogen and CO2 and then capturing and storing or using the CO2 produced.
• Gray hydrogen, the most common form produced today, is created in the same way as blue hydrogen except the CO2 is released into the atmosphere rather than being captured.

Both blue and green hydrogen will play their part in helping to scale up the hydrogen economy. 
 

Hydrogen is a key player in the global energy transition

With production technologies evolving and new applications for hydrogen being uncovered all the time, the hydrogen economy is making great inroads. Hydrogen is already used widely as a feedstock or fuel in processes like oil refining and ammonia and methanol production, and as a reducing agent in steel production. These are all industries where moving towards cleaner, green hydrogen holds significant potential for emissions reduction.

Hydrogen is also used in fuel cells to power electric motors in buses and trucks, and as an energy storage medium and energy source in power generation. Furthermore, hydrogen and hydrogen-based fuels could offer potential low-carbon solutions for shipping and aviation, where decarbonization is particularly challenging. For more insights about the future of fuel cells, watch my presentation Fuel cell R&D – Future trends, drivers and applications.
 

Why reliable measurement matters to the hydrogen economy

At Vaisala we take a broad view of decarbonization that encompasses process optimization, carbon capture utilization and storage (CCUS), electrification, and new technologies and improvements. The accurate measurement of parameters such as humidity, carbon dioxide, and methane is critical to advancing the hydrogen economy and accelerating the green energy transition.

Vaisala’s instruments for measuring these parameters offer stable, real-time on-line measurement without the need for manual sampling. They also offer a fast response time and are exceptionally easy to install and maintain, with a long calibration interval and no moving parts or consumables that need to be replaced.

Vaisala measurement probes are capable of sending a direct current signal (4–20 mA) and fieldbus (Modbus) to a plant’s automation system without the need to install any additional software or hardware. All Vaisala instruments have a wide temperature range, and we also offer options for robust weatherproofing and Ex-certification to enable installation in highly challenging, explosive environments. Let’s look at a few examples of how Vaisala technology is being used in hydrogen-related applications.
 

Fuel cells depend on reliable humidity measurement

Hydrogen is used in a wide range of fuel cell applications, where humidity control is critical due to the fuel cell proton exchange mechanism. Inside fuel cells is a polymer electrolyte membrane (PEM), which conducts protons between the anode and cathode. The humidity of the reactant gases – hydrogen on the anode side and air on the cathode side – must be controlled to preserve membrane integrity.

When humidity is kept at the optimal level, the PEM exhibits high proton conductivity and low electrical resistance, but if it becomes too dry conductivity drops drastically, severely limiting the cell’s power output. On the other hand, excessive humidity can cause mechanical damage to the membrane, leading to increased electrical resistance and reduced voltage.

Vaisala technology has been supporting hydrogen fuel cell development since its inception in the early 1990s. Leading players in the automotive and shipbuilding industries use Vaisala’s HUMICAP® technology in their fuel cell development processes. Vaisala humidity sensors are also widely used by VTT Technical Research Centre of Finland in hydrogen-related research projects. VTT experts are researching both low-temperature (PEM) and high-temperature (solid oxide) fuel cell technologies, and Vaisala instruments are installed before and after the fuel cell stack to monitor and control process gas humidity. Vaisala instruments are also used to measure the humidity levels of ambient air in hydrogen purification and production. 

Learn more about the instruments developed for high-humidity conditions and join our Fuel Cell Humidity Lab webinar series to hear more about humidity insights at vaisala.com/fuelcell.
 

Measuring CO2 and humidity in CCUS applications

CCUS will play an essential role in the global push for carbon neutrality. In sectors where greenhouse gas (GHG) emissions are hard to abate, CCUS may be the only path forward to decarbonization. CCUS will also be needed in energy-intensive industries that still rely on fossil fuels.

Continuous, on-line CO2 concentration measurement in incoming and outgoing gas streams enables real-time performance monitoring and process optimization in plants where the CO2 is being captured. Accurate CO2 and humidity measurement is also critical when researching and developing new capture technologies as they provide valuable insights into process kinetics and performance.

Vaisala technologies are being applied in point-source CO2 capture at the CopenHill waste-to-energy plant in Amager, Denmark. The plant converts 560,000 tons of waste into electricity, heat, and ash every year. Its carbon capture process relies on the Vaisala Multigas Probe MGP261 to measure humidity and the concentration of captured CO2. The captured CO2 can then be used together with hydrogen to produce green fuels and chemicals. Learn more at vaisala.com/CCUS.
 

Measuring CO2, methane, and humidity in SOEC applications

Solid oxide electrolysis (SOEC) co-electrolysis is used to produce hydrogen and methane from CO2, water, and electricity. Although the technology is still at the pilot-plant stage, it is forecast to play a major role in Japan's transition to 90% renewable gas by 2050.

The CO2 used can be captured from industrial emissions, directly from the atmosphere, or from processes used to upgrade biogas to biomethane. The SOEC process typically uses renewable energy and does not require precious metals or rare earth elements, which reduces its environmental impact.

Accurate CO2 measurement in carbon capture processes helps to maximize the efficiency of the SOEC process and minimize GHG emissions. It is also becoming more and more important in the face of increasingly strict regulations.

The Vaisala Methane, Carbon Dioxide and Humidity Multigas Probe MGP261 is used in SOEC co-electrolysis processes to measure feedstock (CO2, humidity) and products (methane) in real time to enhance efficiency and optimize the process. Learn more about the instrument at vaisala.com/MGP261.
 

Industrial measurements are at the heart of the green transition

Renewables and clean energy production are at the heart of every industrial decarbonization and green transition pathway, and the innovative technologies and processes that will enable the transition need reliable measurements. Vaisala technology is helping to accelerate decarbonization with trusted instruments that offer reliable and stable real-time measurement of humidity, carbon dioxide, and methane. Together we can advance the hydrogen economy and enable real sustainable change.