Welcome! Let’s grow the hydrogen economy together. Let’s grow the hydrogen community! Questions & Answers Power supply / controls for renewable-powered electrolysis?

  • Joseph Lawrie

    Member
    March 2, 2023 at 22:43

    Hi Shane – please may I ask whether I understand your example correctly?

    Are you interested in the electronic equipment that would be required to take the direct current (DC) output of the photovoltaic array and pass this directly to an electrolysis plant without involving an electricity grid?

    Or is it permitted for your example for an electricity grid to be involved in the transmission of power generated by the solar panels and then required by the electrolyser?

    Thanks!

    • Shane Mulligan

      Member
      March 31, 2023 at 12:08

      Hi Joseph, thanks for replying. You asked:

      Are you interested in the electronic equipment that would be required to
      take the direct current (DC) output of the photovoltaic array and pass
      this directly to an electrolysis plant without involving an electricity
      grid?

      Yes, this is exactly what I’m interested in. It seems there could be large savings here, but few are looking at it, and I’m just not clear on why.

      • Joseph Lawrie

        Member
        March 31, 2023 at 14:34

        Hello Shane,

        thanks for helping me to understand your question.

        I think it is not common to see the configuration of linking the DC output of a photovoltaic array directly to the DC input of a photovoltaic array because connecting these two assets via a public electrical grid means that when it isn’t sunny, but it is windy, the electrolyser can still be operated, and if the electrolyser is turned off for maintinence on a sunny day, the PV array does not have to be turned off as well (because there is nowhere for its power to go).

        One could imagine that any mismatch between the DC power generation (PV array) and the DC load (the electrolyser) could be handled by an electrochemical storage battery (also DC) and thus save the cost of the DC -> AC -> DC conversion steps invovled with connecting to a public electrical grid.

        The costs of a sufficiently sized storage battery, as well as the losses involved in the DC/DC conversions and the charging and discharging of the battery have been compared and constrasted with the benefits of being connected to a larger electrical grid and the cost (financial and efficiency) of the AC/DC conversions many times in academic literature on this topic. If you are interested in some suggestions specific papers to look at, please let me know and I will dig out some notes.

        Furthermore within Europe there is now a regulatory framework around installing electrolyser capacity and how it is required to be supplied with power. I found the following overview of the recently introduced changes to be helpful:

        https://www.bakermckenzie.com/en/insight/publications/2022/07/eu-hydrogen-policy-developments

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        Regarding the specific components and their cost for connecting a 200 MW solar array to a 150 MW electrolyser without using a public electricity grid, I’m not sure that it would be that easy to find this information out since I would imagine it is usually confidential to a specific project.

        Perhaps another member has worked on a project like this in the past who might be able to address this part of your question with more detailed answers than I can.

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        I hope that this information helps a bit with your question. Thanks!

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