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Cost-effective and reliable hydrogen sensors for facilitating the safe use of hydrogen

Final Report Summary - H2SENSE (Cost-effective and reliable hydrogen sensors for facilitating the safe use of hydrogen)

Executive Summary:
The H2Sense project underpins the effective deployment and availability of reliable hydrogen sensors, primarily but not exclusively for use in applications using hydrogen as an alternative fuel. The objective is to avoid any hazardous events which could hinder the implementation of hydrogen as an alternative fuel by ensuring the availability and optimum use of low-cost and reliable hydrogen sensors.
A survey of hydrogen sensors and sensor manufactures was prepared. It shows that more than 400 hydrogen sensing elements, sensors or sensor systems are commercially available. Commercial sensing platforms are based above all on catalytic combustion, electrochemical reactions, thermal conductivity and electrical resistivity changes. Further types are based on work function as well as on optical and acoustic effects. Many sensor suppliers have their headquarters in USA, Germany, Japan and United Kingdom.
Diverse application areas of hydrogen sensors are identified and compiled. Current and new applications include:
• Room/area monitoring for safety where hydrogen may occur e.g. battery rooms.
• Detection of leaked hydrogen.
• Process monitoring and control e.g. in the petrochemistry industry.
• Stationary and mobile fuel cell applications.
Requirements for cost-effective and reliable hydrogen sensors are specific to the application where they are used. With respect to safety deployment, many requirements are stipulated by appropriate international safety standards. Pertinent requirements on sensor performance include response time, selectivity, robustness and lifetime, in addition to maintenance and capital costs.
Performance tests on three sensors based on different sensing platforms under harsh conditions of high temperature and humidity show that all three fulfil general requirements on accuracy and robustness, even though further optimisation is expedient.
The hydrogen sensors market was evaluated and an analysis was performed to identify the potential turnover and market volume for nine market segments. Barriers which may hinder the commercialisation and widespread deployment of hydrogen sensors were identified. These include a lack of end-user’s knowledge on recent advances of contemporary hydrogen sensors and deficiencies in sensor performance. Other barriers are the cost of purchase, efforts for installation, deployment and maintenance. Approaches to overcome these barriers were developed.
Recommendations for further RTD activities were elaborated. Further efforts should focus on overcoming performance gaps in relation to selectivity, accuracy, robustness, low energy consumption, long term stability, improved production technologies and reduction of manufacturing and maintenance costs.
A survey on hydrogen sensor related standards was prepared and recommendations for new RCS activities to be implemented at national and global level were devised. Although general standards for flammable gas sensors exist, additional sensor standards are needed for specific hydrogen related applications such as for leak detection or for sensor test protocols in automotive applications.
A novel aspect of this project is the ongoing co-operation and joint activities with the National Renewable Energy Laboratory of the US Department of Energy. As a result of this collaboration output from the project was leveraged by the interaction and knowledge transfer between the European and US partners.
The foreground of this project were shared with the hydrogen community through dissemination on the H2Sense project website, in a workshop on “H2 Sensors – the right one in the right place at the right price”, in a brochure on hydrogen sensors, in publications and oral presentations.

Project Context and Objectives:
A.2.1 State-of-the art
The implementation of fuel cells and hydrogen technologies as part of the European low-carbon energy policy is complex and requires stringent consideration of safety aspects. The competitiveness of hydrogen and fuel cell systems depends directly on their safety characteristics and the professional provision of safety in facilities where they are used. For this reason hydrogen safety has been developed as a technical and scientific discipline to ensure the safe use of hydrogen. This includes inter alia hydrogen safety engineering for risk minimization and the development of a system of measures and guidelines for mitigation of fault and accidents.
Hydrogen sensors have been cited as a key-enabling technology for safe hydrogen use. Sensors can alert to the presence of hydrogen before its concentration in air reaches the lower flammability limit (LFL) of 4 vol% in air. When integrated into a risk mitigation strategy, sensors detecting higher than acceptable hydrogen concentrations can be used to trigger alarms or initiate procedures (activation of forced ventilation, system shutdown, etc.) to prevent hydrogen concentration reaching the flammable limit. In this way hydrogen sensors can contribute significantly to the safe use of hydrogen however only if they fulfil specific performance requirements.
There are many types of hydrogen safety sensors available on the commercial market employing different technologies to detect hydrogen. Electrochemical, catalytic metal-oxide, thermal conductivity, semiconductor and field effect based sensors are the most widely available types. Emerging technologies and products may provide faster, more reliable and more sensitive detection of hydrogen under a broader range of ambient conditions. Nevertheless there are still improvements to be made to develop and fabricate cost-effective commercial products.
Hydrogen sensors have been used for decades in industrial applications for the detection of and contribution to mitigation of hydrogen leaks to protect against the potentially hazardous consequences of such leaks. As such a wealth of knowledge has been gathered regarding the deployment and performance of hydrogen sensors in well-defined and controlled industrial environments. However in hydrogen-inclusive economy hydrogen sensors will be used by the public in the domestic market under radically different conditions. Furthermore the potential market for hydrogen sensor use will be extensive as they are foreseen to be required where ever hydrogen will be produced, stored, transported and used. Therefore recommendations have been made to further evaluate and investigate existing and emerging hydrogen detecting technologies to identify and assist development of safer and more reliable detection systems tailored for specific end-use applications. New challenges for the use of hydrogen sensors arise as the scope and range of operating conditions for these devices will expand and diversify.

Project Results:
The description of the main S&T results are given in the attached "Final Report_H2SensePart-A"

Potential Impact:
A.3.8 Potential impact of the project

A.3.8.1 Socio-economic impact and the wider societal implications of the project.
The impact of the H2Sense project can be categorised at three levels (i) impact on the hydrogen community, (ii) social impact and (iii) financial impact.

■ Impacts of the H2Sense projects on the hydrogen community include:

- Dissemination of knowledge and information on hydrogen sensors and their correct use
A common observations from hydrogen sensor end-users is that ‘hydrogen sensors do not work’. In reality however there is a lack of experience using hydrogen sensors, and as a result they are often used incorrectly whereby false readings arise. The H2sense project has provided the hydrogen community with guidelines on the use and requirements of hydrogen sensors, particularly for emerging applications. In addition, a publically available database on commercial hydrogen sensors has been provided.
- Compile existing applications and feedback on real-life sensor performance –
Confidence in hydrogen sensor use and their advantages grows with practical experience. Hydrogen sensors have been used for many decades for safety and process control in the chemical, petrochemical, semiconductor and aerospace industries. In these applications hydrogen sensors have an established track record for reliable and accurate hydrogen detection under the controlled industrial conditions of the application. Understanding and addressing issues related to hydrogen sensor use in these established applications will assist in the development and appropriate use of sensors in emerging markets. Analysis of sensor performance in real-life applications was performed within the H2Sense project. The impact of environmental parameters in industrial environments on sensor performance was evaluated and has provided practical insights into sensor deployment for end-users.
- Identified sensor performance gaps
Despite major technological developments in the gas sensing field an ideal hydrogen sensor does not yet exist. While comparison of a sensor’s specifications against the performance requirements of a specific application can provide an end-user with guidelines on which sensor is suitable, experimental validation of sensor performance is essential to substantiate any sensor’s performance under the specific conditions of the application. Experimental performance validation is also central to identifying gaps between the detection capabilities of sensor’s and the expectations of the end-user. Experimental testing and inter-laboratory comparisons of commercial hydrogen sensors performed within the H2Sense project highlighted shortcomings in commercial product performance with respect to response hysteresis, temperature dependence and cross sensitivity.
- Identified increased requirements on sensors, and on regulations, codes and standards
The availability of robust and harmonised hydrogen sensor-related standards facilitate sensor developers and manufacturers to develop fit-for-purpose products for the industry. While a number of standards exist covering combustible gas sensors and hydrogen sensors for very specific applications H2Sence has identified that additional performance and testing standards would be useful to sensor manufacturers for the development and commercialisation of fine-tuned products for other specific applications.
- Stimulate RTD for sensor improvements for increased availability of low-cost, effective hydrogen sensors
Based on the gaps identified between detection capabilities of current sensor’s and the needs and expectations of end-users, H2Sense has identified areas where focused R&D activities could be focused to address specific performance issues which are of direct relevance to sensor users.
- Facilitate the safe use and implementation of hydrogen as an alternative fuel by ensuring correct use of effective hydrogen detection devices
Adoption of hydrogen as a future energy carrier is ultimately reliant on its safety for the consumer. Hydrogen sensors are enablers for safe hydrogen use. Their ability to detect and alert to the presence of leaked hydrogen and their integration into safety systems to activate mitigating procedures to avoid formation of potentially dangerous hydrogen gas mixtures is fundamental to their contribution to hydrogen safety. Through its activities H2Sense strives to make more cost-effective and reliable hydrogen sensors available to customers, thereby increasing the safety of hydrogen applications in the industrial, public and private sectors and facilitating adoption of hydrogen as low-carbon energy carrier for the future.

■ Social impact is created by:
- Support to the safe use of hydrogen and the transition to a hydrogen inclusive economy
- Contributions to minimizing the release of hydrogen into the atmosphere
- Support the competitiveness and growth of European industry, particularly SMEs, by identifying and proposing means to diminish barriers to sensor development and innovation. A stronger market for hydrogen sensors will enable job creation and further job security.
- Establishment of strong links between research and industry through collaboration, as well as between European and US – based entities.

■ Financial Impact is made by:
- Suggested approaches to overcome barriers of new technology commercialisation
- Increases opportunity for product sales
- Support competitiveness of European SME – supporting the innovative capabilities of European sensor enterprises
- Improves technological expertise of SME

■ External factors influencing impacts - Collaboration with NREL:
A specific novel dimension to this project is the co-ordination of the activities with the National Renewable Energy Laboratory lead by the US Department of Energy. The interaction and knowledge transfer between the European and US consortia leverages the output of this project. The knowledge that exists on either side of the Atlantic regarding the state-of-the-art of hydrogen sensors, sensor technology developments, deployment strategies and commercialisation aspects was pooled and a larger audience can be obtained. These benefits will be continued by a synergetic trans-Atlantic inter-laboratory sensor testing programme in which EU and US laboratories will perform complementary tests and exchange the results to maximise the output to both the US and EU stakeholders.

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