While the study was commissioned by the “Förderinitiative Wasserstoff der Gesellschaft zur Förderung des Energiewirtschaftlichen Instituts an der Universität zu Köln.” (Note: EWI = Energiewirtschaftliches Institut an der Universität zu Köln), it looks to me like it has scientific merit.
I also noticed the EWI more on the academic side of think tanks.
My main criticism with the reported results would be, that it uses a cycle number of 2 per year (the cavern theoretically stores and releases all its hydrogen twice a year.) while true seasonal storage would have a cycle number of 1 so the cost per kg of hydrogen would be up to 3.5€/kg.
Investment cost for their model caverns would be 0.3-0.8€/kWh_th which is the best comparison to the price for battery installations (above 200€/kWh_el). Of course for hydrogen the electrolyzer and power plants are expensive but these have cost per kW capacity so they should amortize well for large amounts of stored hydrogen. Also hydrogen power plants will probably only be 40-60% efficient. So pure storage cost would be 0.5-2€/kWh_el (again margins for electrolyzer and power plants not included).
Also interesting a large proportion of the cost would be CAPEX for creating the caverns. Implying that repurposed NG caverns would be significantly cheaper.
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the actual study is here (in German): [https://www.ewi.uni-koeln.de/cms/wp-content/uploads/2024/03/EWI_Die-Bedeutung-von-Wasserstoffspeichern.pdf](https://www.ewi.uni-koeln.de/cms/wp-content/uploads/2024/03/EWI_Die-Bedeutung-von-Wasserstoffspeichern.pdf)
While the study was commissioned by the “Förderinitiative Wasserstoff der Gesellschaft zur Förderung des Energiewirtschaftlichen Instituts an der Universität zu Köln.” (Note: EWI = Energiewirtschaftliches Institut an der Universität zu Köln), it looks to me like it has scientific merit.
I also noticed the EWI more on the academic side of think tanks.
My main criticism with the reported results would be, that it uses a cycle number of 2 per year (the cavern theoretically stores and releases all its hydrogen twice a year.) while true seasonal storage would have a cycle number of 1 so the cost per kg of hydrogen would be up to 3.5€/kg.
Investment cost for their model caverns would be 0.3-0.8€/kWh_th which is the best comparison to the price for battery installations (above 200€/kWh_el). Of course for hydrogen the electrolyzer and power plants are expensive but these have cost per kW capacity so they should amortize well for large amounts of stored hydrogen. Also hydrogen power plants will probably only be 40-60% efficient. So pure storage cost would be 0.5-2€/kWh_el (again margins for electrolyzer and power plants not included).
Also interesting a large proportion of the cost would be CAPEX for creating the caverns. Implying that repurposed NG caverns would be significantly cheaper.
1€/kg_H2 = 3ct/kWh_th