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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - MEMPHYS (MEMbrane based Purification of HYdrogen System)

Teaser

Summary

Project MEMPHYS, MEMbrane based Purification of HYdrogen System, targets the development of a stand-alone hydrogen purification system based on a membrane hydrogen purification module. Applications are for instance hydrogen (H2) recovery from biomass fermentation, industrial pipelines, storage in underground caverns, and industrial waste gas streams.
The project MEMPHYS thereby supports the policy of the EU to decarbonise the energy system respectively to reduce the carbon dioxide emission. It increases the value of hydrogen as a new carbon free energy carrier because the recycling as well as the storage of hydrogen becomes more attractive.
The MEMPHYS project utilizes an electrochemical hydrogen purification (EHP) system. These systems have been proven to produce high purity hydrogen (99.999 %), while they consume a very low amount of energy, because the purification and compressing processes are electrochemically driven and operate at almost constant temperature.
In principle, an EHP is an electrochemical cell, which consists of an anode, an electrolyte, and a cathode. Therefore, an EHP uses almost the same materials like a hydrogen fuel cell, which is one of the most promising energy conversion systems for future electric mobility.
The purification process itself runs as follows: As long as you connect the anode and the cathode to a direct current power source, hydrogen is quasi pumped from the anode side to the cathode side through the electrolyte. Because only hydrogen is pumped and other components like nitrogen (N2) are not pumped, the hydrogen is cleaned. And if you would close the cathode and if you would simultaneously go on with pumping the pressure on the cathode would increase.
In detail in the MEMPHYS project, the purification process is in fact a two-step process. The EHP is assisted by another membrane, which acts like a pre filter.
Overall the project MEMPHYS is one of the many, many steps to convert the European energy system to an environmental friendly and sustainable system, which helps to become independent from fossil fuels and to secure our standard of living.

Work performed

During the first phase of the project MEMPHYS small details have been investigated separately.
One of the smallest and most expensive part is the catalyst, which is used at the anode and at the cathode. Therefore, several catalysts have been investigated regarding their capability to split and to merge hydrogen into its components. Especially for the anode catalyst it was also important to know which catalyst can withstand different poisoning components of the input gas.
In parallel to the catalyst development another component of an EHP was investigated separately: The so called bipolar plate. This plate is necessary for constructing an EHP stack, which is an electrical series connection of several electrochemical cells. The bipolar plates are made of steel and a number of different steel types and of different coatings have been tested. The bipolar plates are also necessary for the transport of the anode input gas as well as the transport of the cathode output gas, therefore the plates have channels, which are stamped into the metal sheet.
Different kinds of a flowfield (which consists of the channels) have been tested with a CFD program. Thereby, it is important that the gases are well distributed over the electrochemical cell and in parallel that it is possible to produce it with a process, which does not increase the costs so much.
Finally, at the end of the project, all the parts will come together and work as a complete EHP system. The structure of the complete system has already been designed in the first half of the project. So, it was possible to test different sensors and actuators, and to develop a first strategy for the operation and the diagnostic of the EHP system. Therefore, a lab style EHP system was constructed on a table, which gives access to all the components. Hereby, it was easier to exchange components and modify the system. For example, for the heart of the system, the EHP stack, an older version was used which does not contain the in parallel developed catalyst and bipolar plates. In the second part of the project it will be exchanged.
With the lab system in the first phase of the project it was possible to run the first tests with a complete system and to check how far we are away from our targets. We found that it is really hard to reach all the targets in parallel or simultaneously. For example, we reached the target of the recovery rate of 95 % (percentage of recycled H2), but according to Pareto rule the energy consumption (17.3 kWh/kgH2) is much higher than the target of 5 kWh/kgH2. Vice versa, it is possible to reach the energy consumption of 5 kWh/kgH2, but only if you recover just 18 % of the supplied hydrogen.
In parallel to the technical investigations, we looked also for the economic aspects of an EHP system. Detailed analyses showed that the electrochemical cell itself is the main driver for the costs of the system. Like in a fuel cell you have also the same tradeoff between investment and operating costs. You could buy a very large EHP system, which leads to a high investment and very low running costs. On the other hand, you could buy a very small EHP system, which leads to a low investment but to high running costs.
Most of the results of the project MEMPHYS are shared with the public via different communication channels: The traditional ways of communication as well as the modern ways of communication are used to inform about what is going on in the project.

Final results

Until the end of the project, it is expected that the efficiency of the electrochemical hydrogen purification (EHP) system will be increased further. In detail, the target is to reach an overall efficiency of 5 kWh/kg, which means that only 15 % of the hydrogen energy content is used for the purification and compression process or, in other words, that 85 % of the gained hydrogen energy content is saved.
For sure, it is also a question of money or investment into an EHP. Today the cheapest hydrogen you can buy is generated from natural gas using a so called steam reformer. For example if you run a large refinery which needs a huge amount of hydrogen for refining you have to pay 1 â‚¬/kgH2, including the operation and capital costs. But in this case, you also emit carbon dioxide from the natural gas, which leads to greenhouse gas emissions. If you use power from renewable energy sources like sunlight or wind power and produce hydrogen via an electrolyser you end up with something about 4 â‚¬/kgH2 and your hydrogen is greenhouse gas emission free.
The target in the MEMPHYS project is to reach also roughly 4 â‚¬/kgH2. Therefore, for an operator of an industrial plant it would be more attractive to recycle the consumed hydrogen instead of buying new hydrogen from a supplier.
Because only a very, very small number of groups in the world are working on the topic EHP, the MEMPHYS project will give the EU a push for this technology. Moreover, resulting here from, it will create jobs and lead to an advance over Asia and North America, which are also very active in the field of electrochemical converters.