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INNOVATIVE CELL AND STACK DESIGN FOR STATIONARY INDUSTRIAL APPLICATIONS USING NOVEL LASER PROCESSING TECHNIQUES

Final Report Summary - LASER-CELL (INNOVATIVE CELL AND STACK DESIGN FOR STATIONARY INDUSTRIAL APPLICATIONS USING NOVEL LASER PROCESSING TECHNIQUES)

Executive Summary:
In project LASER-CELL, the partners set the overarching goal of achieving a novel alkaline fuel cell (AFC) and stack that deliver competitive performance at a commercially-viable cost.

The technology at the heart of the project is the Coordinator’s AFC technology, which had been produced in limited volumes. Project LASER-CELL is funded by the FCH-JU, and will play a key in transitioning the technology from lab-based prototype stage to industrial-scale commercial deployments.

The partners assessed a range of innovative materials and laser-based manufacturing processes to achieve a design and manufacturing process suitable for large-volume production. For the purposes of this project, the partners focused on one specific application: a large-scale industrial fuel cell system running on hydrogen available as a by-product of the chlor-alkali process.

The Consortium assembled experts in advanced manufacturing, carbon technology, laser processing, computational modelling, life-cycle analysis, Hydrogen and fuel cells. Research was undertaken in two main areas:

1. During the project two distinct material sets for substrates were investigated:

a) metals were investigated due to their high electrical conductivity and chemical resistance but had the drawback of being more difficult to process.

b) Polymer matrices were combined with conductive carbons and metal powders to provide substrate materials which were more responsive to laser excitation thus allowing faster manufacturing speeds.

2. In order to evaluate laser-processing of substrates, the project investigated an additive and a subtractive manufacturing routes: laser drilling and laser sintering.

At the end of the second year of the project, one material and one process was selected and used to build a prototype fuel cell stack, based on technology developed during the project. Technology readiness proved to be the decisive factor and the more mature technologies of laser drilling and metal substrate were chosen. It is noteworthy however that the partners obtained very promising results with the other two technologies and carried out further work on these also.

In order that the prototype electrodes had the best chance of success, several modifications were made to the design and function of the fuel cell technology, most notably by reducing the ionic leakage in the electrolyte circuit using an ingenious decoupling method.

In addition, significant modelling and analysis was carried out to evaluate the environmental, economic and market implications of the project’s results. Improvement in global warming score and cost of cartridge are reported. Market penetration within the EU was assessed in a report that also considered regulatory incentives that would improve the availability of of by-product Hydrogen.

In the final phase of the project, a prototype built from selected technological advances achieved in the project was tested and was found to perform at a level consistent with AFC Energy plc (AFCEN) contemporary technology. The cost reduction and improved environmental impact are also key successes of the project.

Project Context and Objectives:
CONTEXT OF PROJECT LASER-CELL

Project LASER-CELL focuses on the Coordinator’s proprietary low-cost alkaline fuel cell technology. The alkaline fuel cell (AFC) is one of the most efficient devices for converting hydrogen into electricity. The main advantages of this technology are:

- Very high energy conversion efficiency

- Use of very low-cost catalyst materials in the fuel cell

- Liquid electrolyte, which can also be employed as a cooling agent, results in simplified systems with high operating efficiencies.

At the outset of project LASER-CELL, the Coordinator was beginning its transition from a research and development company to a commercial company. Only relatively small numbers of fuel cells had been built, and these were produced using expensive, labour-intensive processes.

In order to compete with mature power-generation technologies, the move to mass production of fuel cell systems must be achieved at a commercially viable price. The purpose of project LASER-CELL is to test and assess the potential contribution that novel substrate materials and laser-based manufacturing processes could make to this goal.

Production of the substrate plate was chosen as the project focus because this is the most expensive component of the fuel cell system by some margin. The substrate is a complex and highly-refined component, high volumes of which will be used in each large-scale system. For example, a 250 kWe system will require in excess of 3,000 substrate plates. The project addressed these issues in 2 ways:

1. MASS MANUFACTURING TECHNIQUES

At the start of the project, no mass-manufacturing techniques existed that could produce substrates of sufficient quality, without substantial modification of the process. Before the project began, the partners surveyed a range of mass-manufacturing techniques and determined that due to their high precision and speeds, laser-based processes would have the best chance of achieving the porosity requirements while achieving manufacturing speeds needed to make mass manufacture commercially viable.

Of the laser-based processes available, the partners decided that the project would develop and study laser-drilling and laser-sintering technologies with the aim of determining their suitability to mass produce substrates of high quality.

Laser drilling is the more mature of the two processes, and at the outset of the project had been used in other industries, notably the photovoltaic industry.

Laser sintering technology is at a much earlier state of development. It uses powder-like materials which are fused into a mass, layer by layer. This is achieved by exposing the surface of a powder bed with a laser or other energy beam. This process can potentially be improved by exploiting pulsing, but this makes the process more complicated since there are many more parameters that must be controlled. Sintering is nevertheless attractive due to the additive nature of the process. In drilling, the material which is drilled by the laser is vaporised. A high proportion of the substrate surface area is porous, and a correspondingly high proportion of the substrate material is therefore wasted. In contrast, sintering is an additive process in which porosity is primarily achieved by the powdered nature of the starting material, which means that little or no material is lost in order to achieve the desired porosity. In addition, powdered materials tend to be cheaper and easier to store and transport compared to sheets or rolls of materials that are the starting point of the laser-drilling process.

2. SUBSTRATE MATERIALS

In addition to manufacturing method, the choice of material used to manufacture the substrate is critical to the commercial viability of the fuel cell systems. AFCEN currently uses a metal alloy that contains Ni. AFCEN is always keen to consider alternative alloys or other materials and a range of innovative conductive nano-composites not previously available were investigated during the project to improve substrate properties including lower cost and reduced weight.

Here, the key challenge was to achieve sufficiently high electrical conductivity through the addition of carbon nano-tubes (CNTs) to the polymer matrix, while maintaining sufficient mechanical strength of the material. This can also be achieved using a combination of metals and polymers to reduce total substrate costs. In project LASER-CELL, Nanocyl of Belgium has optimised their CNT-based materials for use in alkaline fuel cells. Polymers were considered, based on their suitability for use in a corrosive alkaline environment. Production trials using very high loadings of CNTs have been carried out. This way, conductivity of the materials could be significantly increased. In addition samples of metal and polymer composites were successfully produced.

THEORETICAL MODELLING, ANALYSIS AND COSTING TOOL

The use of conductive polymers and composite metal/polymer materials in combination with the two laser processes offers a wide the range of possible outcomes, many of which have not previously been evaluated in depth. In order to efficiently assess the potential of the different combinations in terms of fuel cell performance and cost, the University of Duisburg-Essen (UDE) developed fuel cell modelling and cost analysis tools. The fuel cell and cost models allow the partners to predict the performance and cost of different substrate and fuel cell stack designs and provide vital supporting information for the second phase of the project.

A tool able to predict performance and cost of a range of AFC designs was also produced and provided design rationale for material selection and geometric design. This tool is applicable other low-temperature fuel cell technologies.

An analysis of the stationary power generation market for industrial applications was conducted to identify the market potential of the novel stack design, and availability of hydrogen fuel at a range of potential applications for the technology.

SELECTION MILESTONE

In order to maximise the substrate development during the project, a selection milestone at the mid-point of the project was used to focus the consortium on a limited technology set during the second half of the project. Laser drilling was compared to Laser sintering and polymer matrices were compared to metallic ones.

When considering the impact on cell and stack design, the parameters which were assessed included: safety; reduced part count; ease of assembly; durability; optimised performance; recyclability; and increased volumetric power density.

CELL AND STACK DESIGN

The stack design may be significantly impacted by the choice of substrate design and manufacturing process: the thickness of the plate, the potential to integrate components and reduce part count will be greatly affected by the process that will be used. Substrate conductivity dictates whether the stack should be of a monopolar of bipolar design. To realise the project vision, proprietary cell and stack features that have never before been incorporated into an AFC system are used to deliver a functioning stack.

Most fuel cells are very sensitive to changes in operating conditions and this is also true for alkaline fuel cells. Changing one component in a fuel cell stack or fuel cell system usually has knock-on effects that must be addressed by design modifications. The impact on stack output caused by the selection of manufacturing process was determined and the results of the fuel cell modelling undertaken by UDE incorporated through refinements to the current fuel cell stack design. As part of this Work Package, the laser-processed substrates were made into electrodes, combined with the novel stack design and then tested. This represents culmination of the project.

OBJECTIVES

The overarching goal of the project is to deliver a novel alkaline fuel cell and stack that will deliver competitive performance and that can be economically produced in volume for large-scale stationary applications. In order to achieve this ambitious goal, the partners agreed the following set of objectives:

PROJECT LASER-CELL OBJECTIVES

1. Designing a novel AFC based on laser-processed substrates that provide optimised technical and commercial characteristics.

2. Assessing and adapting state-of-the-art laser manufacturing techniques and incorporating their benefits (while taking account of their restrictions) in the fuel-cell design.

3. Designing an innovative fuel-cell stack to operate in industrial stationary settings, which delivers safety, mass manufacture, ease of assembly, recyclability, serviceability and optimal performance.

4. Combining the above objectives in order to establish the cost-competitiveness of the AFC technology in comparison with all competing technologies – confirming for the first time the commercial viability of AFCs in large-scale stationary applications.

Project Results:

SELECTION MILESTONE

At the end of the first phase of the project, the combinations of material and process were evaluated, and the partners proceeded to create a fuel cell stack using laser drilling of metal substrate plates.

Although significant advances were achieved during the project in both laser-sintering and conductive polymers, the Coordinator believed that these options had to be ruled out for the second half of the project due to their relatively early stage of development.

Tests conducted on small-sized samples confirmed many positive attributes of both of these options; their future inclusion in AFCEN’s future development plans is not ruled out. However, by the end of M22, it was not certain that it would be possible to use sintering or polymers to produce the full-sized substrate plates (620 – 280 mm) that were needed for the second half of the project.

Purely practical considerations played an important part in the considerations and it was eventually decided to proceed on the basis of selecting the option which provides the greatest chance of completing the second phase of the project on time and within budget.

AFTER THE SELECTION – PROTOTYPE STACK

To realise the project vision, proprietary cell and stack features that have never before been incorporated into an AFC system were used to deliver a functioning stack.

Most fuel cells are very sensitive to changes in operating conditions and this is also true for alkaline fuel cells. Changing one component in a fuel cell stack or fuel cell system usually has knock-on effects that must be addressed by design modifications. The impact on stack output caused by the selection of drilling was determined. The current cell and stack designs were developed with metal substrates, which was the material that was retained for the second half of the project. Therefore, there was no need to make adjustments as a result of the choice of substrate material.

In parallel, results of the fuel cell modelling undertaken by UDE were incorporated through refinements to the current fuel cell stack design.

CLEARLY SIGNIFICANT RESULTS OF THE PROJECT

Throughout the project, the consortium partners have consistently delivered high quality research and commercially driven outcomes. The success of project LASER CELL is largely down to the strength of the individual partners and the strength of the collaboration between partners. The key aspects of the project have been outlined in above and the results of the project are discussed below within similar terms.

OVERALL

• Material and process selected for laser processed substrate

• Successful, ‘product-like’ stack testing was used to generate data on Laser cell stack performance.

• The refined, final substrate was not found to make any negative contribution to fuel cell performance.

• Electrode substrate costs decreased by ca. 70 % over the project

o It would be straightforward to reduce that by a further 50% by recycling and optimisation

• Stack production costs were reduced by 31 %.

• The Global Warming Scores of the alkaline fuel cell system production were determined for the end of project Laser Cell.

Good GW-Scores for system production seen to be possible with further refinement, in particular by:

o using regenerative hydrogen

o using by-product hydrogen

o achieving recycling targets

• Market analysis was carried out showing the European landscape for by-product hydrogen.

• The project was discussed at high profile academic and industrial events.

FUEL CELL TECHNOLOGY

• Development of humidified gas delivery for single cell test stands

• Development of suitable test protocols for single cell testing using humidification

• Stack produced according to novel design

• Ionic decoupler refined and finalised design produced

• Stack manufactured from LASER CELL substrates and tested

• The natural variation in fuel cell testing was determined and used to improve experimental design and sampling methodologies throughout the final phase of the project.

• The beta system was upgraded to test stand status

• Ionic decoupling was investigated and ‘shower-head’ design completed

• The scaled, single-cell test stand was further refined to provide better, more reproduceable data.

• Quality of all testing and stack components was assured through baselining and method definitions.

LASER DRILLING

• Prototype laser drilling machine completed

• Laser-drilling target speed for single laser source and 250 micron nickel achieved

• Significant advances in laser-drilling technology for metal sheets demonstrated and drilling speeds above project targets were achieved.

• Laser Drilling workstation completed and used successfully by Cencorp to produce 50 full-size prototype electrodes.

• Drilling Time Calculator completed – this is a tool that estimates drilling time taking a range of production-related variables into account.

• Laser multi-spot drilling setup with SLM element achieved at VTT

• Laser-drilled samples with multispot optical system achieved by VTT

• Reproducibility of scaled-substrates demonstrated.

LASER-SINTERING

• Prototype laser processing machine completed

• Laser-sintering of small porous nickel substrates was successful

• Laser-sintering of small porous nickel substrates achieved using a cylindrical lens. Although not all aspects of this novel sintering process are ready to be incorporated into a mass production method, this result highlights the potential of sintering in terms of manufacturing speed.

• Laser-sintering of conductive polymers poses significant challenges due to the high thermal conductivity of the CNTs.

• Small porous nickel substrates were successfully produced; novel methods for laser-sintering were evaluated and potential of this technology in terms of manufacturing speed has been shown.

• Laser-sintered part by VTT was achieved with sintering speeds many times faster than what can be achieved with commercially available equipment

THEORETICAL MODELLING

• Parameterisation of the substrate completed

• UDE completed of the substrate conduction model

• Modelling was used to show the major influences on the polarisation of alkaline fuel cells

• Modelling was used to investigate the effects of substrate conductivity on polarisation response

• Selection milestone was confirmed through modelling of polarisation response

CONDUCTIVE AND HYDROPHILIC POLYMERS

• Suitable polymers for the production of non-metal substrates were identified

• Successful compression moulding and sheet extrusion trials for high-CNT content polymers was achieved

• Conductive polymer sheet material was shown to be suitable for laser-drilling

• Rolled tubes of carbon-filled polymers was achieved; a wide range of polymers evaluated; and significant improvements in conductivities achieved; laser-processing of some varieties was demonstrated for the first time.

Potential Impact:
IMPACTS

1. PROGRESS TOWARD COMMERCIALISATION OF ALKALINE FUEL CELLS

A substrate and stack design that can be mass produced at a commercially viable cost is the key development step that is needed to all the technology to progress to the next development phase.

The LASER-CELL achievements have lain the foundations for the commercially-viable mass manufacture of alkaline fuel cell substrate plates.

Specifically, (i) improvements to manufacturing processes, (ii) refinement of materials and stack design modifications (iii) economic analysis, (iv) life cycle analysis and (iv) computational modelling have combined to make an invaluable contribution that enabled the Coordinator to advance its technology to the commercial demonstration level.

The LASER-CELL stack is designed to cost, and the Coordinator has achieved a reduced part-count. The new substrate and other stack components are compatible with the use of low-cost plastics in non-electrochemically active parts, which brings additional costs savings through reductions in weight.

The technical targets for the new stack design have been achieved, including easier thermal management and reduced possibility of thermal shock, improved seals. These were largely achieved by improved flows of the electrolyte and other system fluids.

The successful completion of a stack suitable for mass manufacture confirms both the technical and commercial viability of the Coordinator’s deployment strategy of using a common base (fuel cell stack) deployed in a Balance of Pant that can be tailored to specific power applications.

The substrate and stack design, which are the successful foregrounds from project LASER-CELL, will be demonstrated on a commercial scale in project POWER-UP. Project POWER-UP is the first time an alkaline fuel cell system has been demonstrated on an industrial scale anywhere in the world. The project’s commercial-scale Balance of Plant has been successfully installed and commissioned. The system is expected to begin operating at capacity by the end of 2015.

As further proof of the versatility of the AFC technology at the heart of project LASER-CELL, the Coordinator will demonstrate a small-scale (3-5 kWe) version of its AFC system in project ALKAMMONIA, in which a proof of concept system is being developed which is designed to provide power in remote applications, in particular to power telecommunication towers in remote and inhospitable locations. Project ALKAMMONIA takes as its starting point the improved substrate and stack design achieved in project LASER-CELL, and will publish its final results in 2017.

Achieving the performance targets for the AFC technology in terms of power density, efficiency and reliability has enabled the Coordinator to provide the reassurance required by future end-users and regulators of the technology. Commercial preparations have already been completed which will enable the first large-scale systems to be deployed on commercial terms soon after the technology has been successfully demonstrated.

MARKET ANALISYS
Successful commercialisation of AFC technology will depend not only on technically and economically efficient manufacture of the systems themselves. Sourcing hydrogen fuel at a commercially viable prices will also play a critical role.

Increasing demand for hydrogen, and the difficulties inherent in the managing large volumes of colourless/odourless flammable gas are issues which Europe’s nascent fuel cell and hydrogen industries must confront if it is to successfully compete with the advances being made in other parts of the world, notably SE Asia and North America.

The market analysis contained in deliverable report D6.6 will make an important contribution to planning for the future commercialisation of AFC systems. This study was undertaken by Air Products, the world’s largest industrial gas company. It provides a professional assessment of the current industrial H2 markets and gives an indication of the available hydrogen that could be valorised and therefore deemed attractive propositions for AFC installations.

The study identifies the types of target sites where by-product hydrogen (often but erroneously termed ‘waste’ hydrogen) is produced at a suitable scale, and where regulatory incentives would encourage valorising the available hydrogen.

* * *

Scientific knowledge has also been increased by the project. The Consortium partners further increased the impact of the project by sharing results in scientific papers and conferences and by running workshops for interested parties.

In spite of the project’s relatively narrow focus on one component of an electrode for an alkaline fuel cell system, the advances made during this project show promise for a wide variety of applications. Consortium partners are seeking to exploit advances made during this project in other types of fuel cell, redox flow batteries, other battery electrodes, filtration applications, noise reduction/absorption, electromagnetic shielding, fire proofing and others.

The information and improvements made during this project have gone beyond fulfilling the consortium’s objectives and have provided, not only an improved fuel cell system, but also solid platforms on which many other technologies will be built.

IMPACTS, AWARENESS AND WIDER SOCIETAL IMPLICATIONS

During work package 7, the consortium have striven to ensure that the project was communicated to as wide an audience as possible with the available resources.

This continued into the post-funding period, with a keynote speech featuring project outcomes being given to a conference for UK based early career fuel cell scientists and engineers at Birmingham University in December 2014.

Increasing awareness of this project within the fuel cell community has helped to bring alkaline technology to academics who had considered that nothing new could be done with it. While it cannot be attributed to LASER-CELL it is worth noting that there were more than 50% more publications made through Elsevier’s ScienceDirect on the subject of alkaline fuel cells in the three years of the project as compared to the preceding three.

Not only does LASER-CELL impact the fuel cell and hydrogen sphere, it can offer significant benefits to other fields of sustainable energy generation. The improvement of laser drilling technology will have a real impact on the world of low-cost Photovoltaic technology.

The strides forward in conductive plastics and their processing could not be fully exploited in project LASER-CELL but these advances have considerable potential benefits for a wide range of applications where a low-cost conductive polymers are needed. Dissipation of static for electronics is one application but with further development, the materials will likely be able to be used as a replacement for traditional compressed graphite plates in batteries and in PEM fuel cells. Combined with an additive manufacturing route, such as laser sintering, a truly cost effective could result in mass-producible components which could potentially improve the economics of a variety of technologies.

ENVIRONMENTAL BENEFITS
The provision of low-cost, Alkaline fuel cells has great potential to reduce reliance on fossil fuels but this will only be sustained if the overall consumption and processing of materials is also addressed. It has been shown through the project that the innovations made have greatly improved the overall environmental footprint of the system.

The market for fuel cell systems running on waste hydrogen has also been assessed by AIRP. The reported analysis suggests that some straightforward actions would improve the viability of alkaline fuel cells systems in Europe running on by-product Hydrogen. LASER-CELL and POWER UP go a long way toward addressing the key aspects of performance and cost but the issue of a policy framework is highlighted. Potential benefits of using fuel cell technology for stationary power may well be outweighed by uncertainty in the technology so if cost is not addressed then potential early adopters of this technology will not find that final push that they need.

DISSEMINATION ACTIVITIES

The laser-cell project identity was established at the beginning of the project. The key elements are
1. Project logo
2. Project poster in pdf format – this can be printed at A4, A3 and larger by the partners at the own website.
3. Project flier – double sided A4 flier that summaries the project, its goals, the Consortium members, contact details.
4. A project website was set up.
An outside company was subcontracted for the design work of these items.

ACADEMIC PAPERS
Two academic papers were produced:
1. Conference paper: “Extending Lifetime of Alkaline Fuel Cells via Efficient Water Management Strategies” published by the European PEFC and Hydrogen Forum. This paper received the "best scientific paper" award at the 2013 PEFC & H2 Forum in Lucerne, Switzerland, Europe's most respected fuel cell event.
2. J P Garibay, J.J.J. Kaakkunen, R Penttilä, J Harris, J McIntyre, P Laakso and V Kujanpää. Rapid laser sintering of alkaline fuel cell substrates using integrating mirror. J. Laser Appl. 27, S29207 (2015)

WORKSHOPS
The Coordinator ran two workshops entitled “From Lab to Manufacturing Challenges in the mass manufacture of AFCs”. These workshops were led by Dr Vivien Chapman, AFC Energy’s Senior Fuel cell Scientist. These workshops were run in the final months of the project, firstly during the programme review days of the FCH-JU, and then at Lancaster University.

CONFERENCE
At the mid-term review, the assessors recommended that the Coordinator present its technology at an event for the chlor-alkali industry, since it is anticipated that this industry will play an important role in the deployment of the technology, due to the large volumes of by-product hydrogen available.
The Coordinator presented its technology and an exhibition booth at EuroChlor, 9th International Chlorine Technology Conference and Exhibition which took placed in Madrid 1-3 April 2014.
There were more than 300 participants from Europe and other regions of the world. With around 40 speakers, the conference provides a valuable forum sharing information to improve safety, health, environment protection performances in technical matters related to the aspects of production, transportation and use of chlorine.
The presentation given by the Coordinator focused on project POWER-UP (and costs have been reported to that project), however a summary of project LASER-CELL was presented, and the coordinator showed videos of the both Cencorp’s laser drilling and VTT’s laser sintering achievements.

List of Websites:
www.laser-cell.eu