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High Performance PEM Electrolyzer for Cost-effective Grid Balancing Applications

Periodic Reporting for period 3 - HPEM2GAS (High Performance PEM Electrolyzer for Cost-effective Grid Balancing Applications)

Reporting period: 2019-04-01 to 2019-09-30

The large-scale deployment of wind power and solar energy sources will strongly contribute to the implementation of Europe’s energy policies objectives. However, these resources are characterised by intermittent behaviour and their fluctuations affect the stability and reliability of the electrical grid. Consequently, there is a strong need for rapid-response, cost-effective and scalable energy storage systems capable of absorbing the electrical power exceeding the capacity of a transport and distribution line. This will considerably reduce the investments needed to build a new grid infrastructure.
Hydrogen produced from water electrolysis can play a significant role as energy storage medium. Electrolysis can support the electricity grid in terms of power quality, frequency and voltage control, peak shaving, load shifting and demand response. In this regard, electrolysers are designed to follow the variable energy generation profile of renewable power sources locally available and to adapt to the intermittent profile of electricity supply.
The overall objective of the HPM2GAS project was to develop, validate and demonstrate rapid-response self-pressurising PEM electrolyser technology based on advanced cost-effective components with dynamic properties for interfacing to the grid. The project addressed both stack and balance of plant innovations with the field test of an advanced 200 kW PEM electrolyser in Emden (Germany). In particular, the electrolyser developed consisted of an advanced BoP and improved stack design and components (e.g. bipolar plates, membranes, electrocatalysts).
Several strategies have been applied to lower the overall cost to enable widespread utilisation of the technology. These primarily have dealt with a three-fold increase in current density (resulting in the proportional decrease in capital costs) whilst maintaining cutting edge efficiency and applying a material use minimisation approach in terms of reduced membrane thickness whilst keeping the gas crossover low and reducing the precious metal loading.
The field-testing activity was carried out with the aim of evaluating the power-to-gas process as a means to store the surplus of renewable energy and to provide grid balancing service. The proof-of-concept of power-to-gas was demonstrated for the new electrolysis system and significant knowledge was acquired about the operation of this type of advanced electrolyser at high current density.
Advanced catalysts and membranes were developed in the first period of the HPEM2GAS project by CNR-ITAE and Solvay, respectively. Short-side chain (SSC) perfluorosulfonic acid (PFSA) Aquivion® membranes and ionomers were developed and scaled up for this application. Utilizing a nanosized Ir0.7Ru0.3Ox solid solution anode catalyst and a supported Pt/C cathode catalyst, in combination with the Aquivion® membrane, gave excellent electrolysis performances exceeding 3.2 A·cm-2 at 1.8 V terminal cell voltage (~80% efficiency vs. HHV at cell level) at 90 °C. A degradation rate as low as 8 μV/h after 4,000 h operation at 3 A cm-2 at 80 °C was recorded at cell level. Stack development activities at ITM produced an efficient and compact design. The novelty of the stack design developed in HPEM2GAS lies in the gas generation part of the stack being de-coupled from ancillary services with a unique single acting hydraulic cylinder providing compression to the stack. In the second period, advanced ITM 75 cells stack, equipped with 415 cm2 active area MEAs produced by IRD, was assembled and tested.
Stack and electrolyser assessment was carried out by ITM in the second phase. Hydrogen production capacity of about 80 kg/d was demonstrated for the system at 3 A cm-2. Best efficiency at system level of 72 % vs HHV H2 was achieved at 3 A cm-2, at an operating temperature of 55°C. Differential pressure operation was demonstrated for the novel stack geometry at 20-50 bar across a wide range of the load curve.
The electrolysis plant was subjected to field-tests in Emden (Germany). The proof-of-concept of power-to-gas for the injection of the produced electrolytic hydrogen into the local gas grid was demonstrated. Regarding the exploitable results, the consortium included developers of materials, components and devices for PEM electrolysers and an end-user (SWE) that is involved in the supply of renewable power, especially from wind plants. Exploitable knowledge regarded in particular: the scaling-up and optimization of PEM electrolysis components, advanced stack design, coatings and cost effective bipolar plates, innovative compact PEM electrolysis system for grid-balancing service.
Regarding the project communication and dissemination, the public website was organised to inform interested stakeholders, as well as the general public of ongoing and finalised project activities. This also occurred through flyers, newsletters and technical project publications.
The progress beyond the state of the art has regarded tripling the electrolysis current density with respect to conventional commercial PEM electrolysers (from 1 to 3 A cm-2) with an efficiency higher than 80 % (HHV) at 75 °C, at stack level, materials use minimization with total PGM catalyst loading < 0.3 mg PGM catalyst/W, development of thinner (90 µm) short side chain PFSA membranes with reduced cost, demonstration of a novel stack geometry and coated stack components allowing a reduction in stack hardware costs while showing excellent stability at 3 A cm-2.
The potential impact of the HPEM2GAS project is related to the sustainable hydrogen production which can meet an increasing share of the hydrogen demand for energy applications from carbon-free or lean energy sources. The project addressed materials research, technology development and reduction of the total life cycle costs related to present PEM electrolysers. This was accomplished by replacing current commercial materials for membranes, catalysts with higher performance and lower cost materials as well as addressing advances in stack manufacturing and system development for grid-balancing service and power to gas applications. The innovative membrane, low noble metal loading electrocatalysts and novel stack architecture developed in the project can significantly contribute to reduce the present costs of PEM electrolyser components. These systems can be matched with high coupling efficiency to local grids sharing large fraction of renewable energy from wind turbines and find suitable application for power-to-gas processes by feeding the produced hydrogen into the gas grid.
The impact of the project thus covers several different sectors and targets:
i) Industrial impact: new PEM electrolyser system/model for different clients in EU and worldwide
ii) Scientific impact: research on new MEAs, polymers and catalysts.
iii) Economic impact: new market possibilities
iv) Environment: more possibilities for industries and cities to use renewable energy sources
In addition to the hydrogen injection into the gas grid, other potential uses for the electrolytic hydrogen produced from the surplus of renewable energy include methanation of CO2 from waste water or biogas plants, storage at high pressure and use as fuel for fuel cell electric vehicles, storage at medium pressure and use of the hydrogen to generate electricity and heat via a gas turbine or a stationary fuel cell, and use as feed-stock chemical in the industry.
HPEM2GAS ITM Power Electrolysis stacks
HPEM2GAS CNR-ITAE Anode catalyst and Solvay Aquivion ionomer for water electrolyis
HPEM2GAS CNR-ITAE anode catalyst for water electrolyis
HPEM2GAS CNR-ITAE anode catalyst-ionomer interface for water electrolyis
HPEM2GAS ITM Power Electrolysis full stack
HPEM2GAS ITM Power Electrolysis system
HPEM2GAS Electrolysis Field Testing