Safeguarding the Hydrogen Economy: A Focus on Leak Detection and Mitigation

The use of fixed gas detectors can play a crucial role in mitigating the environmental impact of hydrogen leakage and help protect workers in the hydrogen value chain

Governments, industry sectors and companies seeking sustainable energy sources to reduce greenhouse gas (GHG) emissions are increasingly turning to hydrogen. In a recent survey of 500 global energy and utilities-sector executives and 360 executives from end-user sectors (including heavy transportation, aviation, maritime transport, steel, chemicals and petroleum refining), 64% said they plan to invest in low-carbon hydrogen initiatives by 2030, and 9 out of 10 plan to do so by 2050 [1].

“Low-carbon hydrogen will play a key role in the decarbonization of several industries whose emissions are difficult to abate, such as basic chemicals, aviation, steel production, shipping and long-haul road transportation,” stated Boston Consulting Group (BSG), authors of the March 2023 Building the Green Hydrogen Economy report [2].

On the surface, hydrogen appears to be an ideal energy source to help pave the path to a more sustainable future. However, since H₂ is the smallest molecule in existence, it can easily pass through and embrittle materials and sealings. Therefore, potential for leakage presents significant challenges and risks throughout the hydrogen value chain.

While hydrogen emits no carbon dioxide when burned or used in a fuel cell, its leakage into the atmosphere has an indirect impact on global warming by extending the lifetime of GHGs, such as methane, ozone and water vapor, resulting in indirect warming [3, 4].

Global energy experts are calling for increased research and development to “improve hydrogen leakage detection, prevention and mitigation,” noting how “hydrogen sensors must be able to detect leakage at much lower detection thresholds than those existing and among various types of applications [3].”

This technology exists today in the form of fixed gas detectors that can monitor for small leaks before they become more significant, and initiate automatic ventilation, engine room shutdowns and other actions as required for larger releases and accidents (Figure 1).

When used throughout the hydrogen value chain, from production and delivery to storage, tank maintenance and power generation, fixed gas detection can help mitigate the potential environmental impact of unintentional hydrogen leakage and help protect workers who are enabling the steps in the value chain.

 

Current and future H₂ applications

The most common industrial uses of hydrogen today are for chemical feedstocks, petroleum refining and fertilizer production. More than 90% of the world’s hydrogen is used for three industrial applications: by petroleum refineries to lower sulfur content in diesel; to produce methanol used by fuel blenders; and make ammonia for fertilizers and chemicals [5]. A small percentage of hydrogen is consumed directly in steel production [6].

There are four main types of hydrogen production [3, 7, 8], as follows:

1. Brown or black hydrogen produced from coal. It is the most environmentally damaging form of hydrogen production because both the CO₂ and CO generated during the process are not recaptured, creating significant air emissions
2. Gray hydrogen produced from natural gas using a process known as steam reforming, which releases carbon emissions. It typically generates a somewhat smaller amount of emissions than black or brown hydrogen
3. Blue hydrogen produced using the same process as gray hydrogen, but is augmented with carbon capture, utilization and storage (CCUS) technology to mitigate emissions. It is sometimes referred to as “carbon neutral, as the emissions are not dispersed in the atmosphere,” but a more accurate description is “low-carbon” because around 10–20% of the generated carbon cannot typically be captured
4. Green hydrogen produced using renewable energy, usually through water electrolysis. This results in no emissions

Gray hydrogen is the most common form of hydrogen production today (over 90%) but there has been growing interest and significant investments in low-carbon and emissions-free hydrogen production across the globe [9]. The Center on Global Energy Policy predicts blue and green hydrogen to comprise 97% of the total supply by 2050 [3].

Some targeted use cases for clean hydrogen and recently announced initiatives are described in the following sections.

Steel production. The steel industry produces more CO₂ than any other heavy industry, comprising about 8% of total global GHG emissions [10], making it a prime target for clean hydrogen-based initiatives. In April 2023, India’s largest steelmaker, Tata Steel, announced that it had begun a trial of injecting hydrogen gas at its blast furnace to cut carbon emissions [11].

Fertilizer production. The production and use of nitrogen fertilizers accounts for up to 5% of total GHG emissions [12]. Research published in 2023 found that changing the source of hydrogen for ammonia production from steam reforming (gray hydrogen) to water electrolysis (green hydrogen) could reduce 75% of production emissions by 2050 [12]. Fertilizer company Yara, utilities company Engie and investment and trading company Mitsui & Co. are collaborating on the Yuri Renewable Hydrogen to Ammonia Project, scheduled for completion in December 2027 [13].

Petroleum refining. The refining sector is a major energy user and contributes to approximately 4% of GHG emissions. It is the third-highest emitter amongst industrial sectors (excluding energy production), making it another prime target for clean hydrogen adoption [14]. In July 2022, Irving Oil announced that it was expanding its green hydrogen capacity with investment in 5-megawatt hydrogen electrolyzer [15].

 

Trouble spots for H₂ leakage

While low-emission and emissions-free hydrogen production has significant potential to reduce carbon emissions and support global sustainability efforts, hydrogen leakage during production, transport, storage and end use could negate the benefits and potentially result in enduring climate impacts [16]. Because hydrogen production and use are limited today, and the infrastructure does not yet exist to broaden its use to the levels anticipated by 2050, there is uncertainty around the risk for hydrogen leakage throughout the value chain. Researchers have relied on estimates based on current usage, and projections based on the value chain of other gases like natural gas.

 

Production

When hydrogen is produced via electrolysis, the most significant mechanism for leakage is operational purging as part of the purification process, with leakage as high as 10%. During CCUS-enabled hydrogen production, similarly to electrolysis, hydrogen can potentially be released from leakage or purging. Even if waste hydrogen is “sent to flare rather than vented to atmosphere,” there will be residual hydrogen emissions, estimated at between 0 and 0.5% of the hydrogen produced [17].

Hydrogen leakage during production seems to vary by production method. Leakage during gray hydrogen production (via steam reforming) is estimated at less than 1%. Leakage during blue hydrogen production (with CCUS technology) is estimated to be approximately 1.5% because of the “added complexities of its production system [3].”

Because green hydrogen production is very limited today, researchers struggle to estimate its leakage, but it is an important research topic, given predictions that its use will expand. Looking at studies on green hydrogen “losses,” which means measuring the “difference between the theoretical, calculated quantity of hydrogen that is supposed to be produced and the amount that is actually measured,” the total loss could be as high as 4% [3].

 

Delivery, transport and storage

While most hydrogen consumed today is obtained locally, it can be transported to terminals via pipelines, trucks, trains or ships. Hydrogen is stored in liquid (cryogenic) or gaseous (compressed) phases in terminals until it is distributed to end-users at petroleum refineries, chemical plants and so on.

According to the Center on Global Energy Policy, “pipelines, including both dedicated hydrogen pipelines and natural gas blending systems, are the most important systems for hydrogen delivery” and “in and of themselves, these systems demonstrate a low risk of leakage [3].”

Studies published in recent years have found “roughly 0.4% leakage for hydrogen simply passing through a pipeline [ 18].” But this does not consider the full hydrogen delivery systems that will be required to support the future hydrogen economy, including storage facilities, which could experience mechanical loss. Researchers estimate a 2% lifecycle loss of hydrogen from integrated transportation and storage systems [3].

The delivery of hydrogen to fueling systems via trucks is “leakier,” according to the Center on Global Energy Policy, with an estimated 5% average leakage for truck transport and storage systems. Leakage of hydrogen for particularly small facilities (<100 kg/d) is estimated to be above 20%, and average-sized fueling stations (several hundreds to several thousands of kilograms per day), between 3 and 6% [3].

 

End use

The end users for hydrogen are expected to expand with greater investment in the production of blue and green hydrogen. The challenge is that “end-use leakage risks are the least understood especially in terms of future hydrogen end uses that do not exist today [3].” Described below are current and anticipated use cases and estimated risks for leakage.

Electricity generation. The process of converting hydrogen to power based on gas-turbine technology has around 3% hydrogen leakage [3].

Fuel cells (surface and aviation transport). Fuel cells emit “a similar amount of hydrogen compared to electrolyzers and, when incorporated into transport applications, will also emit hydrogen from the compressed storage [17].” In a study that assumed “road transport leakage is similar to hydrogen storage tank leakage during delivery, with the exception of potential boil-off loss during charging,” researchers estimated road transport leakage at 2.3% [3].

Hydrogen refueling stations. Here, the main emissions are from the compression of hydrogen and the short-term storage of compressed hydrogen prior to injection into vehicles. Experts predict these emissions “should be relatively low (at 50% confidence) but there are some uncertainties that push up the upper limit (99% confidence) [17].”

Industry (to decarbonize industrial processes such as steel and chemicals). While it has not been “possible to predict the emissions from industry at this stage and this will require further consideration,” researchers assume an “emission of between 0 and 0.5% of the hydrogen used [17].”

 

Risks to the environment

New research from Princeton University and the National Oceanic and Atmospheric Association (NOAA) found “a leaky hydrogen economy could cause near-term environmental harm by increasing the amount of methane in the atmosphere. The risk for harm is compounded for hydrogen production methods using methane as an input, highlighting the critical need to manage and minimize emissions from hydrogen production [16].”

As the Center on Global Energy Policy pointed out in its report, the more hydrogen produced, the more leakage into the atmosphere if mitigation measures are not put in place. The estimated 2.7% economy-wide leakage in 2020 could jump to 5.6% leakage in 2050 based on hydrogen production milestones (528 million metric tons by 2050) outlined in the International Energy Agency (IEA) net-zero scenario [3].

The Princeton and NOAA researchers have established the following leakage thresholds for green and blue hydrogen in Ref. 16.

Green hydrogen: critical threshold for emissions is around 9%.“If more than 9% of the green hydrogen produced leaks into the atmosphere — whether that be at the point of production, sometime during transport, or anywhere else along the value chain — atmospheric methane would increase over the next few decades, canceling out some of the climate benefits of switching away from fossil fuels.”

Blue hydrogen: critical threshold for emissions is around 4.5%. “Because methane itself is the primary input for the process of methane reforming, blue hydrogen producers have to consider direct methane leakage in addition to hydrogen leakage. For example, the researchers found that even with a methane leakage rate as low as 0.5%, hydrogen leakages would have to be kept under around 4.5% to avoid increasing atmospheric methane concentrations.”

 

Risks to workers

While hydrogen itself is not toxic and does not impose major new risks compared to other gases, leakage can impact the safety of people involved in tasks along the hydrogen value chain, from production to use. Below are some of hydrogen’s characteristics that employers and workers must take into consideration when building a safety infrastructure.

Permeation. Hydrogen can easily permeate materials and in some cases embrittle them. For this reason, stainless steel and composite materials are typically used for storage tanks.

Leakage. Owing to its small molecules and low viscosity, hydrogen can leak from pipelines and other structures more easily than denser gases. In fact, when it leaks from a pipe at sufficiently high pressure, hydrogen can even self-ignite. As well as with pipelines engineered to hydrogen-ready specifications, regular inspection is imperative to detect leak points at joints and along pipelines.

Explosion. Unlike actual explosives, pure hydrogen cannot explode. The risk comes when it hits the air. For hydrogen to cause an explosion, oxygen needs to be present. But if hydrogen is allowed to escape, even a static spark from clothing would be enough to set off an explosion.

Invisible flame. Hydrogen burns with a very pale flame that is invisible in daylight. Because it emits little of the infrared radiation that humans perceive as heat, it cannot be sensed as heat. The hydrogen flame does however emit substantial ultraviolet radiation.

Odorless and colorless. Hydrogen has no smell and no color, so it is undetectable for humans. With methane, this issue is mitigated by adding odorants, and research is in progress to determine whether this will also be possible with hydrogen.

 

Gas detection requirements

Given its propensity for permeation and leaks, inability of humans to detect in their environments and risk for explosion, hydrogen must be continuously and reliably monitored throughout its value chain. The ability to detect small leaks can help organizations prevent the escape of large “fugitive emissions” into facilities and out into the atmosphere [17].

If systems are designed correctly, such very small leaks will not pose issues, because the amount of hydrogen gas released will typically be too small to create a flammable mixture with air. Risks (including asphyxiation or the creation of a flammable mixture) only arise when hydrogen gas accumulates in a confined area over time [19].

Due to the properties of hydrogen, explosion protection via early leak detection is key to ensuring plant and personal safety. Gas detection is regarded as the primary way to protect against explosion by preventing explosive atmospheres from building in the first place (Figure 2).

Organizations in the hydrogen value chain must engage in risk control, including deployment of gas measuring and warning systems, to comply with standards, codes and regulations. A few examples are outlined here.

ISO 26142 Hydrogen Detection Apparatus – Stationary applications. This is an international standard that “defines the performance requirements and test methods of stationary hydrogen detection apparatus that is designed to measure and monitor hydrogen concentrations.” It sets requirements “applicable to a product standard for hydrogen detection apparatus, such as precision, response time, stability, measuring range, selectivity and poisoning [20].”

H-14: HYCO Plant Gas Leak Detection and Response Practices. This applies to plants producing large amounts of hydrogen and carbon monoxide. It covers methodologies for prevention of, detection of, and response to flammable and/or toxic gas leaks that occur within the fence line of these facilities, including typical leak detection technologies (for instance, personal monitoring, fixed monitoring, and specialized detectors) [21].

UL 2075 Standard for Safety Gas and Vapor Detectors and Sensors. This applies to fixed, portable and transportable toxic and combustible gas and vapor detectors and sensors intended for use in ordinary (non-hazardous) locations for use in indoor or in unconditioned areas [22].

 

Fixed hydrogen gas detection

Fixed gas-detection systems provide instant alerts in the event of hazardous leaks or risks of combustion. Organizations can leverage several different hydrogen detection technologies to build efficient and effective protection layers.

Catalytic bead sensor. This sensor type detects hydrogen below its lower explosive limit (100% LEL). With good long-term stability and fast response time, these devices are mainly used for continuous area monitoring of the ambient air.

Flame detectors. This type of device detects hydrogen-based fires, which are barely visible to the human eye. Those with sensor technology and programming specially designed for hydrogen or its combustion product (H₂O) ensure rapid detection of the dangerous flames and, at the same time, very high immunity to false alarms, which, for example, multifunction devices cannot provide to the same extent.

Ultrasonic gas-leak detection. Ultrasonic detectors “listen” to high-pressure leaks and can detect even small leaks very fast. They serve as early warning area monitors, responding earlier than conventional gas detectors because they register the sound of leaking gas instead of measuring the concentration of accumulated gas clouds.

Electrochemical sensor (EC). These devices are a good choice when selective measurements of hydrogen on the parts-per-million (ppm) concentration level are required. They offer many advantages, such as fast response, high accuracy, great stability and a long service life. This technology is useful for point leak detection and personal air monitoring.

 

Safe and effective detection

Hydrogen detection systems are only as effective as the planning that goes into them. The organization and its detection system technology partner should first conduct an on-site risk assessment to know exactly where to place sensors, how sensitive they must be and what happens in the event of an alarm. Fixed gas detectors with a modular design can be flexibly integrated into an existing infrastructure, combined with each other, and extended into a seamless safety network.

One key consideration during the risk assessment is determining where hydrogen will go in the event of a leak. Like ammonia and methane, hydrogen is less dense than air and forms gas pockets below indoor ceilings when leaking. The presence of hydrogen will not be perceived at ground level, even when dangerous amounts are accumulating beneath the ceiling. When hydrogen and methane are mixed, hydrogen can form gas pockets above methane. Hydrogen detectors are therefore typically placed at a higher level than methane detectors.

It is also important to note that CO sensors are cross-sensitive to hydrogen. If used near possible hydrogen exposure, CO sensors should be compensated for hydrogen so that cross-sensitivity and false alarms are reduced to a minimum.

An organization should work with its technology partner to incorporate fixed hydrogen detection devices into its broader alarm and emergency response network. Advanced technology, such as flame and gas mapping, help to develop suitable solutions for specific organizational needs.

 

Digitalization in gas detection

As compliance requirements become stricter, organizations are mandated to maintain detailed records — for example, of measured gas values or alarms — to demonstrate adherence to safety standards. Manual, paper-based recording and tracking of data in the hydrogen value chain cannot support safety measures at the scale in which hydrogen use is predicted to grow.

In a bid to raise the efficiency of documentation tasks and make use of the large amount of data generated, organizations are turning to solutions with smart data analytics. Data captured by hydrogen detectors are processed in a single, automated workflow for record keeping, and turns raw data into valuable insights for operational safety.

Digital technologies will be essential to the hydrogen value chain, including for system surveillance, early detection of faults and leaks and continuous optimization of costs [1]. The digital records are more accurate and can be made available faster during audits. Predictions and improvements can also be derived from data patterns. Impending failures can be prevented before they occur, and leaks and defects can be detected before they lead to serious damage.

 

Portable gas detection

Mobile hydrogen-detection devices serve as an adjunct to fixed hydrogen detection monitors. Small, robust and ergonomic, these devices are usually attached to a worker’s clothing near the breathing area, but in a way as to not limit their movement. Portable gas detection instruments can be equipped with sensors to detect hydrogen alone or other gases as well — for instance, O₂, CO, H₂S, NO₂ and SO₂ (Figure 3).

As with the fixed hydrogen-detection monitors, mobile detection devices should feature the ability to wirelessly transmit measured data to a central gas detection system. That way, the organization has a central, digital repository of measured gas values, alarms and other data for analytics, documentation and reporting.

Hydrogen is increasingly being recognized as a key player in the transition towards a more sustainable future. Governments, industry sectors and companies are planning significant investments in low-carbon hydrogen initiatives to reduce emissions in industries that are difficult to decarbonize.

However, the potential for hydrogen leakage presents significant challenges and risks throughout the hydrogen value chain, indirectly impacting global warming. Therefore, there is a need for increased research and development to improve hydrogen leakage detection, prevention and mitigation. ■

 

References

1. Capgemini Research Institute, Low-carbon hydrogen: A path to a greener future, April 2023.

2. Schmundt, W., others, Building the Green Hydrogen Economy, Boston Consulting Group, March 2023.

3. Center on Global Energy Policy, Hydrogen Leakage: A Potential Risk for the Hydrogen Economy, Columbia University, July 2022.

4. Ocko, I. and Hanburg, S., For hydrogen to be a climate solution, leaks must be tackled, Environmental Defense Fund, March 2022.

5. Maguire, G., How realistic is a hydrogen-powered economy?, Reuters, March 2023.

6. DNV, Hydrogen Forecast to 2050 report, 2022.

7. El Sayed, T., others, The clean hydrogen opportunity for hydrocarbon-rich countries, McKinsey & Company, November 2022.

8. Marchant, N., Grey, blue, green – why are there so many colours of hydrogen? World Economic Forum, July 2021.

9. U.S. Dept. of Energy, Biden-Harris Administration Announces $750 Million to Advance Clean Hydrogen Technologies, March 2023.

10. Ellerbeck, S., What is green steel and why does the world need more of it?, World Economic Forum, July 2022.

11. India’s Tata Steel begins hydrogen gas injection trial in blast furnace, Reuters, 2023.

12. Gao, Y. and Cabrera Serrenho, A., Greenhouse gas emissions from nitrogen fertilizers could be reduced by up to one-fifth of current levels by 2050 with combined interventions, Nature Food, Vol. 4, May 2022, pp. 170–178.

13. Australian Renewable Energy Agency, Yuri Renewable Hydrogen to Ammonia Project, February 2023.

14. Nurdiawati, A. and Urban, F., Decarbonising the refinery sector: A socio-technical analysis of advanced biofuels, green hydrogen and carbon capture and storage developments in Sweden, Energy Research & Social Science, Vol. 84, February 2022.

15. Irving Oil, Irving Oil to introduce hydrogen for the regional market – a first-of-its-kind investment from a Canadian refiner, press release, July 2022.

16. Poore, C., Switching to hydrogen fuel could prolong the methane problem, Andlinger Center for Energy & the Environment, Princeton University, March 2023.

17. Frazer-Nash Consultancy, Fugitive Hydrogen Emissions in a Future Hydrogen Economy, March 2022.

18. Understanding Hydrogen Leakage Today and Tomorrow, Hydrogen Forward, August 2023.

19. U.S. Dept. of Energy, Hydrogen Leaks, Hydrogen Tools, https://h2tools.org/.

20. ISO 26142 Hydrogen Detection Apparatus – Stationary applications, 1st Ed., June 2010.

21. Compressed Gas Association, H-14: HYCO Plant Gas Leak Detection and Response Practices, September 2018.

22. Underwriters Laboratories, UL 2075: Standard for Gas and Vapor Detector and Sensors, March 2017.

 

Authors

Mark Heuchert is the senior marketing manager for safety equipment at Dräger North America (Email: [email protected]). Prior to his current role, he held management roles at Cembrit Holding, Flowserve, Hilti and Xylem. He is a Certified Safety Professional (CSP) and is also accredited as an Advanced Qualified Safety Sales Professional by the International Safety Equipment Association.

 

Ronak Patel is a senior marketing manager for strategy at Dräger North America (Email: [email protected]). He has worked with Dräger for 9 years, and previously held engineering roles at Baker Hughes. He holds a B.S. in electrical engineering from Purdue University and an M.B.A. from Rice University.