Dimensioning of an energy storage system on a MWh scale for the standby operation of an off-shore and off-grid Power-to-X system

The production of e-fuels and chemicals via Power-to-X (PtX) processes offers a promising approach to long-term energy storage. "Green" hydrogen produced by electrolysis serves as a raw material for the synthesis of chemicals and fuels such as methane, ammonia, methanol and synthetic hydrocarbons. Offshore and off-grid PtX plants use areas on the high seas where wind farms could not previously be built due to a lack of economically viable cable or pipeline connections. One advantage of PtX is the use of existing storage infrastructures and the linking of all energy sectors, e.g. transportation, industry and heating, with wind and solar energy.

As part of the German flagship project H2Mare, the PtX-Wind consortium aims to develop experimental, research-based and productive offshore PtX platforms that are directly connected to wind energy in the North Sea.

The challenge is that a CO2-free energy storage unit must provide enough energy to operate the electrolysis and PtX systems as well as important platform instruments in the event of no wind, storms, maintenance or system failures.

Our task, together with industrial and academic partners, is to dimension a battery storage system for a research PtX platform comprising a 5 MW electrolysis unit and a 1.7 MW PtX platform.

Step 1: Suitable battery technologies such as PbAc, PbGel, LFP, NMC and supercapacitors are tested to verify the battery characteristics specified by the manufacturer. The results of the preselection at module level (0.5 kWh) are presented.

Step 2: The battery characteristics were implemented in the "System Advisor Model (SAM)" software, combined with a year-round wind power generation profile.

Results: A minimum battery capacity (0.52 MWh) for standby operation (0.47 MW) was determined based on the 1C rate of modern LFP batteries. Initial economic considerations are also presented.

Curriculum vitae

Willi Peters received his diploma in chemical engineering from the University of Erlangen-Nuremberg and contributed to research on hydrogen storage in liquid organic hydrogen carriers (LOHCs), which store hydrogen by reversible & chemical bonding, from 2011 to 2105. As a researcher and project coordinator, he expanded his scope in the field of energy storage by investigating new battery technologies such as the aluminum-ion battery (2015) and the zinc-ion battery (2018). He is currently a research associate at the DECHEMA Research Institute in Frankfurt am Main.

His research focuses on the development of novel, cost-effective and non-toxic cell components and processes, in particular the synthesis of cathode materials and electrolytes for non-lithium-ion batteries for use in stationary energy storage systems.