[ electrolysis ]
Table 2 . Projected characteristics of different electrolysis technologies for 2030 and LCOH values based on the CAPEX and OPEX values specified
2030
Parameter Units Alkaline PEM SOEC AEM Critical raw materials Chemical elements Ni Pt , Ir Co , Ni Ni Stack size MW | kg / h 20 | 432 10 | 216 0.5 | 13.3 0.1 | 2 Maximum system size GW > 1 > 1 1 0.1 Average system efficiency kWh / kg 50 50 38 55 Average degradation H 100,000 80,000 80,000 20,000 Average system CAPEX €/ kW | € 1,000 per kg / h 200 | 9 400 | 18 400 | 15 400 | 20 LCOH with electricity price € 30 / MWh €/ kg 2.2 2.4 1.9 2.7 LCOH with electricity price € 15 / MWh €/ kg 1.2 1.4 1.1 1.7
high temperatures ( i . e ., 500 – 850 ° C ), making them the most efficient technology of all . Additionally , they are made of cheap and abundant materials ( i . e ., ceramic oxides ). The third column of Table 1 shows the main characteristics of this technology , together with LCOH calculations for electricity at both € 60 and € 40 / MWh . Compared to PEM and AEM , SOECs use much smaller stacks due to the difficulty in scaling up high-quality and reliable ceramic technology . However , these systems can already achieve the MW scale , allowing for their deployment and further development . The main advantage of SOECs over other electrolysis technologies is their much higher efficiency . They operate at the thermoneutral point ( 1.23 V ), resulting in stack efficiency very close to 100 %. An average electricity consumption value for SOECs when feeding steam water at 150 ° C is 40 kWh / kg and 45 kWh / kg when heating of water is considered . 3 , 4 In terms of current LCOH values , this technology offers the best values due to much lower OPEX , even with its shorter lifetime , as its stack replacement is much cheaper than for AEM or PEM technologies .
SOECs are made of cheap and abundant materials , namely ceramic oxides containing inexpensive and readily available materials such as Zr , Fe , Mn , stainless steels . There are also other materials , such as Ce or Y , that are less abundant but still cost-effective and readily available . Special mention must be made of both Ni and Co as both materials are used quite extensively , which could be an issue . However , the current use of Ni and Co is only 200 and 25 kg / MW , respectively , which is four times less than in alkaline technologies in the case of Ni . 5 The use of high temperatures is another material concern as more advanced stainless steels need to be used since the operating temperature is higher ( i . e ., > 750 ° C ) in both stack components and hot boxes . However , recent developments show a trend in decreasing the operating temperature below this critical level (< 700 ° C ), where cheaper stainless steels can be used .
The table highlights the immense potential of this technology as it can enable us to achieve the cost level of € 1 / kg of hydrogen by 2030 , even with relatively high electricity prices . This is due to the possibility of attaining electrical efficiencies close to 95 % if excess heat is supplied to the system . The expected decrease in CAPEX and OPEX (€ 400 / kW , € 15,000 per kg / h , and 38 kWh / kg ), along with increased durability and larger systems , will help to achieve LCOHs close to € 1 / kg .
AEM water electrolysis
Anion exchange membrane ( AEM ) water electrolysis is the least developed of the
34 Hydrogen Tech World | Issue 9 | April 2023