Electrolysers – The Heart of the Hydrogen Economy
By 2030, the H2 industry is aiming to produce between 16 and 24 million tons. Of these between 9 and 14 million tons would be based on electrolysis and between 7 and 10 million tons from fossil fuels with CCUS.
This week we will look at electrolysers that are at the very centre of the H2 economy.
What is an Electrolyser?
H2 can be produced using the technique of Electrolysis. Electrolysis is a method by which electricity passing through a solution of water splits Water into H2 and O2 (Hydrogen and Oxygen). H2 is formed on the cathode side of the setup. At its basic, the electrolysis set-up looks like as in figure 1 and 2 below.
[1]
The solution is Water mixed with some type of electrolyte. The most common electrolyte is an alkaline solution of Sodium or Potassium Hydroxide.
In industrial scales H2 and O2 are split and stored separately. When they combine, they can be explosive and destructive and will form water again.
About 1.2V to 1.5V is needed to split water using this method. In traditional industrial settings it is cheaper to produce H2 from fossil fuels rather than electrolytic methods. However, since green H2 is the end goal, renewable energy powered electrolytic method is gaining prominence. This is especially true in Europe rather than in the USA.
Figure 3: H2 Production using Electrolysers (Source: Mancera, Manzano et al, 2020)[2]
What are the various types of Electrolyser technologies?
Over the years 2 major technologies have been developed in Electrolyser technology. Fig. 4 below highlights the various types:
Figure 4: Various types of Electrolyser Technologies
Brauns & Turek, 2020 highlight some of the advantages of AEL and PEM over SOE. AEL and PEM can operate and produce H2 at lower temperatures, between 50 deg C and 80 deg C and at 30bar pressure. By contrast, SOE operates in high temperature steam at about 700 deg C and 900 deg C. Nominal stack efficiencies are at about 70% for both.
Alkaline water electrolysis uses concentrated lye as an electrolyte and requires a gas-impermeable separator to prevent H2 and O2 from mixing. The electrodes are made of metals like nickel with an electrocatalytic coating. PEMEL uses a humidified polymer membrane as the electrolyte and metals like platinum and iridium oxide as the electrocatalysts.
AEL and PEM can also offer economies of scale. These technologies are available in multi-MW scale capacities.
For example, literature from Danish Green Hydrogen Systems suggest they have solutions with centralised 6MW system that can be added to deliver over 100MW of systems. Similarly Ohmium suggests that their PEM technology can also be used in modular fashion to sized at several hundreds of megawatts.
What are the production capabilities and efficiencies of these technologies?
A Green Hydrogen System alkaline electrolyser of 900kW[3] capacity can produce H2 at about 16 kg/hour rate. It consumes about 33.4 litres of water and 57 kWh of electricity to produce 1kg of H2. This can be increased to several MW using the modular containerised solution they offer.
An H-Tec Systems PEM electrolyser of 10MW[4] capacity produces about 191 kg/hour or 4.6 tons/day. It consumes about 51 kWh of electricity to produce 1kg of H2.
Figure 5: World's largest electrolyte (Source: Hydrogen-Pro, Norway)
Figure 6: H2 production layout (Source: Hydrogen-Pro)
Who are the major producers of electrolysers globally?
Blackridge Research and Consulting suggests the following 20 major Electrolyser Manufacturers:
1. Bloom Energy
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2. China Shipbuilding Heavy Industry Corporation’s 718th Research Institute (PERIC)
3. Cummins Inc.
4. Enapter
5. Green Hydrogen Systems
6. Haldor Topsøe A/S
7. H-TEC SYSTEMS
8. HydrogenPro ASA
9. ITM Power PLC
10. John Cockerill
11. LONGi
12. MAN Energy Solutions
13. McPhy
14. Nel ASA
15. Ohmium International, Inc.
16. Plug Power Inc.
17. Siemens Energy AG
18. Sunfire GmbH
19. Sungrow Power Supply Co., Ltd.
20. thyssenkrupp nucera
Next week we will see some of the CCUS technology that will be deployed by the USA to generate its version of “Green” H2.
With over 18 years of advisory and engineering experience across 25GW of renewables, Arbutus Consultants Pvt Ltd. could be your partner of choice in your renewable energy journey. Please reach out to us at enquiry@arbutus.co.in to find out how we may be of assistance.
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