[ electrolysis ]
Table 1 . State-of-the-art characteristics of different electrolysis technologies and LCOH values based on the CAPEX and OPEX values specified . A system is defined as equipment including stacks , power electronics and balance of the system components ( gas separators , electrolyte tanks , etc .), and excluding balance of plant .
2023
Parameter Units AWE PEM SOEC AEM Critical raw materials Chemical elements Ni , Ru , Ir Pt , Ti , Ir Co , Ni Ni Stack size MW | kg / h 5 | 100 1 | 17 0.04 | 1 0.0025 | 0.043 Maximum system size GW 1 1 0.05 N / A Average system efficiency kWh / kg 54 60 40 N / A Average degradation h 80,000 60,000 20,000 5,000 Average system CAPEX €/ kW | € 1,000 per kg / h 500 | 25 750 | 44 800 | 32 N / A LCOH with electricity price € 60 / MWh €/ kg 4.6 5.4 4.3 N / A LCOH with electricity price € 40 / MWh €/ kg 3.2 3.9 3.19 N / A
quality of the Ni coating over carbon steels is improved . Balance-of-system components , such as electrolyte tanks or gas separators , are mainly made of Ni-plated carbon steel , but due to the corrosion characteristics of the electrolyte , some stainless-steel components may also be needed . In addition , stainless steel is also used for system tubing . Finally , non-expensive catalysts such as Raney Ni , but also Ni , Fe and / or Cu-containing alloys , are the more common materials used as catalysts . In some cases , the use of Ru and Ir can also be found , allowing the operation of the stack at higher current densities , leading to smaller footprints , although without much improvement in electrical efficiencies .
As can be seen from Table 2 , with the expected projections for 2030 and lower renewable electricity prices (€ 15 and € 30 / MWh as reference ), the LCOH can already be quite interesting , and the improvement is much more significant when OPEX ( both electricity consumption and durability ) is improved . Therefore , it seems an interesting approach to focus less on reducing costs when a good CAPEX level is reached (€ 300 –€ 400 / kW ) and instead to improve both electricity consumption and degradation of the AWE stacks . Highquality Ni coatings on carbon steel components leading to lower Ni content will result in good
CAPEX levels . Likewise , longer component durability will lead to lower OPEX and , therefore , lower LCOH . Finally , achieving higher electrical efficiency and cost-efficient catalysts with larger surface area will bring electricity consumption down , which will contribute to improving the LCOH ( lower OPEX ), even without such favourable electricity prices .
PEM water electrolysis
Proton exchange membrane water electrolysis ( PEMWE ) is characterised by having a solid electrolyte and by operating at much higher current densities , resulting in a significantly smaller system footprint . With a relatively high output pressure of ca . 30 bar , it produces highpurity hydrogen ( 99.999 %). The second column of Table 1 summarizes the main characteristics of this technology , as well as the LCOH calculations for electricity at both € 60 and € 40 / MWh . Rather large stacks can also be achieved , with current sizes averaging 1 MW and 17 kg / h of produced hydrogen . Lower footprints of 25 kg / h per m 3 , compared to 7 kg / h per m 3 in the case of AWE , can be achieved . These large stacks in hydrogen output and small footprints allow PEM manufacturers to currently reach system sizes in the GW range . In terms of CAPEX , PEMWE is about 50 % more expensive on average than AWE . This value is € 750 / kW or € 44,000 kg / h , and has slightly higher electricity
32 Hydrogen Tech World | Issue 9 | April 2023