PROJECT OVERVIEW
Large scale use of industrial quality hydrogen for power generation and heat
Achieving the European Green Deal target of becoming the world’s first climate-neutral continent by 2050 will require deep cuts to emissions across all aspects of the economy, including the power generation and heating sector. This, combined with the REPowerEU plans, places hydrogen as a clean energy carrier in a unique position. It can be used in, and thereby couple, all sectors like; power & heat, transport and industry. Hydrogen offers long term storage, it can be transported over large distances and it can be produced and used without, or with very low emissions. A central part of the EU climate strategies is the target of domestic renewable hydrogen production of 10 million tons by 2030, in addition to the same amount imported. This volume of hydrogen requires massive amount of geological storage as well as transportation by pipelines. Large scale use of hydrogen requires infrastructure for distribution to end users all over Europe.
Hydrogen storage in underground salt caverns structures is very limited, all of which three are in the USA and the one in the United Kingdom. Since the hydrogen mainly origins from steam methane reforming (SMR), the purity is around 95%. Rock caverns (sealed) are being developed, one of them within the HYBRIT project in Sweden, where clean hydrogen from electrolysis will be stored. In most geological storages and pipelines hydrogen will be already, or become, contaminated with substances not suitable for use in all types of fuel cells (like N2, CO, CO2, HC, sulphurs etc). Hydrogen produced via electrolysis is considered “clean”, the only impurities are oxygen and water. However, other sources of hydrogen, like from natural gas reforming, have impurities remaining from the production process.
While re-purification of this H2 can, and should be done for some applications by e.g. Pressure Swing Adsorption (PSA), it adds cost and complexity, and is not in all use cases economically feasible. Currently, there is no standard for the quality of H2 coming from geological storages or pipelines, and the knowledge about which contaminants are present in hydrogen from these storage sites is extremely limited.
Large-scale stationary fuel cells in the MW-range should be able to operate on such industrial quality H2 without repurification. They can offer a low-cost clean alternative for both large scale (peak) power and heat production, as well as for small, medium and large-scale back-up power units for the critical infrastructure, thereby also improving the resilience of the energy system. The H2 quality standard under development is expected to become around 98%, whereby the main relevant poisoning impurities are CO and sulphurs, in addition to inert gases like CO2 and N2, thus the fuel cell systems most tolerate these. With this background, the CLEANER consortium intends to develop a stationary 100 kW PEMFC module capable of operating on industrial quality hydrogen.
Objectives and ambition
The overall objective of the CLEANER project is to develop and demonstrate for more than 5000 hours a >100 kW PEM fuel cell system operating on industrial quality hydrogen. In doing so, this will contribute to the required decarbonization of the power generation and heating sectors by using highly efficient technology to produce clean energy with zero emission. This overall objective leads to a series of sub-objectives which are discussed below.
Objective 1 - Development of a >100 kW PEMFC system tolerant of impurities in industrial H2
In a PEM fuel cell system, it is the actual fuel cell which is sensitive towards contaminants such as CO and sulphur available in the hydrogen fuel. How the type and concentration of contaminants influence the fuel cell durability is known, but the actual impact for a full-size stack operated in a full system on impure hydrogen is not well investigated.
The fuel cell system delivered to VTT will be an upgraded version of PowerCell’s commercial 100kW system module which is designed for usage in marine and stationary MW system installations (already delivered MW-size systems). PowerCell’s fuel cell systems are designed to run for 20,000 hr with maximum 10% degradation, but the degradation rate is mainly validated with hydrogen from electrolysis. Thus, in the first testing period of about 500 hrs at VTT, the system’s state of the art lifetime in the presence of amounts of all relevant contaminants will be analysed. The delivered system will be prepared for system optimization at the site, including potential valves and equipment. A decrease in system degradation rate will be targeted by for instance, tuning the hydrogen recirculation loop, potential air bleed on anode side and/or nitrogen protected start-up. The initial test results will guide us towards further suited upgrades for durability enhancement, among which comes filter installation/regeneration on the feed hydrogen, regeneration strategies of the stack and tuning purge strategies.
Thus, in the project, improved strategies for the mitigation of performance losses associated with the use of low-quality hydrogen will be developed, allowing significant increases in the lifetime of fuel cells, and enabling the design of future-proof strategies for a low total cost of ownership (TCO). The system improvements will also integrate other outcomes of testing of stacks, single cells, as well as newly developed components and materials, see further objectives below.
When the first test campaign of both system and stack/single cell is finalized, there will be a decision on what updates to include in the second system test campaign of at least 4500 hrs. If system tuning during the first campaign is sufficient to reach the targeted degradation rate, investigation of the influence of a hydrocarbon-based (HC) membrane on system durability might also be implemented in the second test campaign. It is necessary to find alternatives to today's commonly used fluorine-based membranes for future generations of PMEFCs since the use of these materials will likely be banned in the EU. Since other types of membranes may require different contamination mitigation strategies, it is important to be prepared and understand the difference. PowerCell has identified a promising hydrocarbon-based membrane, which will initially be tested in a lab scale, and depending on the results, maybe further validation also in stacks. In this setting, the fuel cell system will start at TRL 3, end at 5 and be ready for TRL 6 and demonstration.
Objective 2 - Demonstrate more than 5000 hours for a > 100 kW PEM fuel cell system operated with industrial quality hydrogen
In CLEANER we will operate a dedicated fuel cell system > 100 kW for more than 5000 hours. The system tests will be conducted first shortly (500 hours in 2025) at VTT's facility in Espoo/Otaniemiusing followed by longer (> 4500h) testing at VTT's facility in Espoo/Kiviruukki 2026-2027. Long-term testing at Espoo/Kiviruukki will bedone using industrial quality by-product hydrogen supplied from KemiraSastamala/Äetsä sodium chlorate factory to VTT using SoA hydrogen tube trailers. There are currently no standards for testing stationary fuel cell systems operating on industry grade hydrogen, and especially not with an anode recirculation loop, which is necessary to optimize hydrogen utilization. Currently, only a few institutes (including SINTEF, VTT) or industries are carrying out tests on the impact of contaminants using different systems (open system, single cell with recirculation loop, stack testing with recirculation loop), even fewer have investigated the impact of high concentrations of impurities up to 5% and hardly anything of this work is published.
The CLEANER project aims to progress beyond the state of the art in terms of analysis of the impact of previously non-considered impurities on fuel cells operated in a realistic manner i.e., with hydrogen recirculation in dead-end mode. Full classification of the anode recirculation loop composition when the fuel cell is operated in this way has not previously been published. In addition, we will further classify the recirculation loop composition with the presence of contaminants from low grade hydrogen, aiding in the understanding of contamination mechanisms and providing important input into future standards for the quality of low-grade hydrogen.
Objective 3 - Increase tolerance of impurities in hydrogen while reducing cost of catalyst
State-of-the-art PEMFC catalysts are based on Pt. These however have limited tolerance to impurities such as CO and sulphurs and contribute to the high capital expenses (CAPEX) of fuel cell systems.
One way to enhance the CO tolerance at the anode, is to design hydrogen oxidation catalysts with decreased CO adsorption strength and/or improved CO electrooxidation activity. An example of such a catalyst are PtRu nanoalloys supported on carbon (PtRu/C). However, their suffer from limitations regarding stability. Other materials showing promising performance with respect to high impurity tolerance are under investigated, and little is known about material reproducibility as well as performance under realistic fuel cell conditions.
Another method that allows fuel cell operation on fuels containing impurities takes advantage of internal air bleeding, i.e. oxygen diffusion through the membrane from the cathode, as is known from automotive fuel cells. By using so-called preferential oxidation (PROX) catalysts, contaminants such as CO could directly be oxidized to CO2 which cleans and recovers the catalyst surface.
Finally, a third strategy towards high impurity tolerance is the recovery of the catalyst activity by applying high potential (at the anode site). In this way, the contaminants can be oxidized and removed from the catalyst surface. A challenge however is that high potentials can degrade the catalyst support material which eventually lowers the performance of the fuel cell stack. Therefore, carbon supports with improved stability at high potential need to be employed.
Summarized, three strategies for improved impurity tolerance will be pursued within CLEANER:
- Development of anode catalysts with increased CO tolerance and improved electrochemical CO oxidation. Here both metal-oxide-mediated and single site approaches will be explored.
- Implementation of fuel cell compatible PROX catalysts to improve oxygen utilization during air bleeding (i.e. by direct chemical CO oxidation).
- Development of stable carbon supports and thereof derived Pt/C catalysts to allow for high potential catalyst recovery strategies.
For a better assessment and understanding of the degradation processes that take place inside the fuel cell, a variety of experimental techniques will provide detailed performance and durability characteristics of the catalysts under investigation in-operando. In this context, advanced diagnostic materials and strategies will be developed and used at both single-cell and short-stack level.
The project will therefore progress through different technology readiness levels, reflecting the development from initial lab-scale testing to (short) stack operation..
Objective 4 - Reduce TCO through lower cost materials, modelling and increasing efficiency
To be able to reduce the use of fossil fueled CHPs, the overall TCO of the clean alternatives must be competitive. Currently both CAPEX and OPEX of fuel cell technologies are considerably higher than its fossil counterparts. A reduction of CAPEX will be realized through lower cost materials (less amount of noble metals), increased system lifetime and design for mass manufacturing through modular and automated production of stacks/systems. OPEX is reduced by optimizing control strategies for life-long increased efficiency, based on development of dynamic models and state-of-health monitoring. Exploitation of waste heat from the fuel cell, potentially via a heat pump, will be included in the modelling for further improving the overall system efficiency and economics, see more under objective 5. The study on utilization of heat will use input from the technical development in the REFHYNE 2 (GA101036970) project, where Linde is developing technology suitable for PEM technology. Allowing the use of low-cost industrial quality hydrogen will itself reduce the OPEX considerably. The techno-economic activities will cover the whole value chain from hydrogen supply to end use, and thus be able to highlight the cost bottlenecks and prepare documentation on actual costs for end-users and other stakeholders.
Objective 5 - Assure economically and environmentally sustainable development
An objective of the project is to assess and understand viable business cases for the use of industrial hydrogen in the power generation and heating sector. In addition to the performance, the actual CAPEX and OPEX costs of the system in operation will be assessed and used as input to case studies of Schiphol Airport (the Netherlands) and Ferrexpo's Black Sea port (Ukraine, for export of iron products). These techno-economic results will be used to populate a mathematical economic model15, which represents the performance of a system (single application or a full value chain) under different specifications on system size/components, overall energy economics and flows, as well as end use requirements. This model will be able to analyse under which conditions viable business models can be made for other end users and locations of industrial quality hydrogen.
Environmental impacts of the new technology and its use will also be important to understand. Often environmental impacts are shifted between system elements or between different types of impact categories. For example, this could be shifting the environmental burden to upstream processes (such as electricity or materials production. In CLEANER there may be a trade-off between implementing new materials and technological solutions and how the fuel cell system is operated. An assessment is needed to identify these trade-offs and potential shifts to support informed decision. Once the technology is assessed in isolation, it will then be included during the case analysis, where the techno-economic assessment will be extended to include environmental impacts. The case analysis will then be able to estimate the overall environmental impacts of each scenario and allow a more holistic comparison to be performed.
Objective 6 - Exploit project results through dissemination to and dialogue with key stakeholders
The project is designed to support the use of hydrogen as a key part of the energy transition. A final objective of the project is to ensure the conclusions from the activities are wrapped up into clear messages for industry research society, regulators and policy makers to stimulate further development and demonstration of large-scale stationary fuel cells. The conclusions will also be disseminated by the end user partners, who cover the sectors aviation, maritime, heavy-duty industry, and pipeline distribution to reach new stakeholders and markets.