[ electrolysis ] abate industries such as steel manufacturing , which is responsible for emitting over 200 Mt of CO 2 eq , or 7 % of total EU emissions . Therefore , the EU has set an ambitious target through RePowerEU to produce around 20 Mt of renewable hydrogen by 2030 , which could help eliminate a significant portion of these emissions associated with grey hydrogen use and steel production .
The cleanest manner to produce green hydrogen is through electrolysis , which splits water molecules into hydrogen and oxygen in a device called electrolyser . If the electricity powering the electrolyser comes from renewable sources , the process is fully green . Therefore , the more available and affordable renewable energy makes green hydrogen a very competitive solution to both replace grey hydrogen and manufacture green steel . However , the cost of both electricity and electrolysers determines the cost competitiveness of green hydrogen projects , impacting the so-called levelized cost of hydrogen ( LCOH ). The LCOH takes into consideration both capital and operating expenditures ( CAPEX and OPEX ) of a certain green hydrogen project and is expressed in €/ kg or $/ kg .
As key equipment in green hydrogen projects , electrolysers have a major impact on the LCOH , along with the electricity price . Different electrolysis technologies can be used for water electrolysis , each with different characteristics in terms of CAPEX and OPEX . These are alkaline water electrolysis ( AWE ), proton exchange membrane ( PEM ) water electrolysis , solid oxide electrolysis cells ( SOEC ), and anion exchange membrane ( AEM ) water electrolysis . For all of them , CAPEX is heavily influenced by the materials used , while the electrical efficiency of each technology determines the OPEX associated with carrying out the electrochemical reaction . This article will review the main characteristics of these technologies as well as the key materials forming part of the different electrolyser types . Finally , the article will present LCOH values for state-of-the-art examples of each technology in 2023 , as well as expected LCOH values in 2030 , based on future projections of electricity prices and improved CAPEX and OPEX for each technology .
Alkaline water electrolysis
Alkaline water electrolysis ( AWE ) is the most mature electrolysis technology , which uses a liquid electrolyte ( KOH ). The main characteristics of AWE , along with the current LCOH values that can be obtained with two commonly used reference electricity prices (€ 60 and € 40 / MWh ), are presented in the first column of Table 1 . Both large stacks and systems can be achieved with the use of pressurized alkaline technology : stacks as large as 5 MW with an output pressure of 100 kg / h and systems close to 1 GW . In terms of CAPEX and OPEX , an average CAPEX for an AWE system is around € 500 / kW or € 25,000 kg / h , and the average OPEX is around 54 kWh / kg , with a stack lifetime of 80,000 h . 3 , 4
Regarding the materials used in AWE , both pure Ni and Ni-plated carbon steel are the more common materials , with the use of some expensive and rare-earth metals such as Ru or Ir being significant in some of the solutions offered in the market . Recent calculations made by the International Energy Agency estimate that AWE uses around 800 kg / MW of Ni . 5 Pure Ni and Ni-plated carbon steel are used as components of different parts in the electrolyser stack , such as bipolar plates and electrode supports , or even as catalysts in the case of Ni . Ni-plated carbon steel is intended to replace pure Ni in all components where less harsh conditions allow that , and as the
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