Improving lifetime of electrolyzers to store energy using hydrogen
02-11-2015
With a rapidly increasing share of renewable electricity, electricity generation will periodically be much higher than the demand. A recent European study confirms hydrogen as one of the more attractive options to store vast amounts of renewable energy. However, cost and lifetime of electrolyzers are important barriers to the large-scale implementation of this switchable capacity. Within VoltaChem's Power-2-Hydrogen program line, ECN is focusing on improving lifetime of electrolyzers. What are the lessons learned?
Lifetime of electrolyzers currently comes at a cost
Current PEM electrolyzers are able to achieve 40.000 hours of lifetime or more. But this lifetime literally comes at a cost. Using higher catalyst loadings, thicker membranes and high-performance separator plates can increase lifetime. Use of these materials however adds excessively to the cost of the electrolyzer. Lack of durability thus has a double impact on the electrolyzer economics. It increases capital cost because of shorter depreciation periods and because more expensive materials have to be used.
Lifetime needs to be assessed in different conditions
It is not sufficient to evaluate lifetime under full-load conditions. This is one of the important lessons to be learned from the PEM fuel cell development, in which ECN has more than 15 years of experience. It has been extensively shown that loss of performance occurs much quicker under impact of rapid load changes, start-stop cycles and operation close to open cell voltage. Although there are a number of important differences between fuel cells and electrolyzers, both have in common that lifetime needs to be assessed both under full-load and under transient and off-design conditions. In particular if the electrolyzer is used to manage a varying supply of renewable energy, it will be operated under highly variable loads.
Determining durability can be challenging
Assessing the impact of the way the electrolyzer copes with the variable operation conditions is important, but also quite challenging. A single lifetime measurement is time-consuming. To determine the impact of several variables rapidly becomes very costly. It is necessary to develop methods to accelerate degradation in such a way that it allows prediction of the durability of components under real conditions. Such Accelerated Stress Testing approaches can only be developed based on a good understanding of the degradation process. And by very close cooperation of the stakeholders to cope with the wealth of fundamental and practical issues to address.
Setting up the framework & bringing stakeholders together
To be able to make progress on understanding the degradation process in order to reduce it requires a considerable investment in bringing together knowledge, infrastructure and a strong partnership. To that purpose Shared Innovation Program VoltaChem recently launched its Community.
Please join VoltaChem's Community, read more about VoltaChem's Power-2-Hydrogen program line or contact Yvonne van Delft to discuss how the electrolyzer research can benefit your company or project.
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