Technology: Electrolysers – part 2

Electrolyser technology

Alkaline, PEM and Solid Oxide electrolysers produce hydrogen using different technologies. In this part of the technology series, we will present application areas for electrolysers and hydrogen. We will also present the suitability of the technologies to each application.

Did you miss «Technology: Electrolysers – part 1»? Read it here.

Hydrogen is a potential key factor to address the energy transition, and water electrolysis is the cleanest and most sustainable way to produce hydrogen. If hydrogen is produced from renewable energy sources, e.g. solar or wind power, it is a zero-emission energy carrier. Hydrogen can be used in sectors that are difficult to decarbonize through electrification.

Electrolysers can produce Hydrogen that can be used in:

  • Transport
  • Off Grid
  • Grid Balancing
  • Industry 

In the following paragraphs we will discuss some of the application areas for electrolysers in general.


This is the rather obvious application electrolysers can be used for. Hydrogen can be used not only for light-duty vehicles such as the Toyota Mirai, but also heavy-duty vehicles such as the Nikola Tre. Hydrogen can be used beyond these areas of transport in applications such as trains & maritime. Airbus is even looking to fuel a plane with hydrogen!

How an electrolyser can help electrify & decarbonize the transport sector is by producing hydrogen from water & electricity which when used in transport is a zero emission fuel. Hydrogen for transport can be produced locally at the dispenser or centralized and then distributed & dispensed in compressed or liquid form.

Illustration of Electrolysis/Hydrogen use in transport:


Off-grid production and use of Hydrogen as a solution is possible with electrolysers. Here, we must consider fluctuations in the electrolyser operating conditions when using Variable Renewable Energy (VRE) such as wind or solar power.

Another configuration is an off-grid solution combining electrolysers, storage and fuel cells. This solution can be used to supply energy to remote areas with no connection to the electricity grid. Normally in these situations you want to have a short-term storage based on batteries, and a long-term storage based on hydrogen. However, the round trip efficiency is low, and the investment cost is high compared to alternatives like pumped hydro and battery storage.

Illustration of Electrolysis/Hydrogen direct use in an off-grid Scenario:

Illustration of Electrolysis/Hydrogen in a micro electricity grid:

Grid Balancing*

Electrolysers are systems that can typically be turned on and off and ramped up and down in unilization levels which can increase or decrease it’s electricity consumption and thereby providing grid balancing services. Grid balancing has been given an asterix(*) because it is a service that can be provided but it unlikely justifies the case on its own. Here it is possible to have multiple benefits at the same time. Electrolysis can be used to balance the grid by only taking the surplus electricity from the grid when it is available. This way the system is always in balance and no excess electricity production from VRE is wasted.

The hydrogen that is produced from the electrolyser for grid balancing can be added back into the grid as electricity through use in turbines or fuel cells as described in the Off-Grid application or used in transport or industrial applications.

Illustration of Electrolysis/Hydrogen use in grid balancing:


Within industrial applications hydrogen is mostly used as an «ingredient» in a chemical process, rather than an energy carrier (or “source”). For instant when making ammonia (which in the next step can be used to make fertilizers) hydrogen is added to a chemical process that combines hydrogen with nitrogen into ammonia, NH3. In smelters hydrogen can replace carbon (typically from coal) as a reductant in the chemical process of removing the Oxygen from the oxidised metal-ore (the reduction process). In that case the resulting product of the reduction process is the pure metal and clean water (vapor) instead of CO2.

Hydrogen can also be made into other energy carriers, based on hydrocarbons, like methanol, jet fuel, diesel etc. This is called “Power-to-X” meaning that electricity (the “power”) can be turned into different fuels (the “X”) by first making hydrogen in an electrolyser and then adding carbon (for instance from CO2 in the air) into the preferred hydrocarbon fuel. This process will “re-use” carbon/CO2, but not eliminate it.

Illustration of Electrolysis/Hydrogen use in industry:


Suitability of Different Electrolyser Technologies

While many hydrogen users do not care what the source of Hydrogen is, it is important to note that there are certain attributes to each electrolyser technology that make it more suitable within certain applications.

In the case of Transport for instance there is no noticeable difference between the suitability of the technology however economic conditions or electricity sources may dictate that one is better than the other.

In the case of Off Grid and Grid Balancing, there are clear differences in the suitability of different electrolysers due to technological limitations.

In the case of Industry, we have the same scenario as with Transport where there is no noticable difference in the suitability however specific conditions may dictate one is more suitable than another.

The suitability of the different electrolyser technologies: Alkaline (ALK), Proton Exchange Membrane (PEM) and Solid Oxide Electrolyser (SOEL) to the applications is summarised in the illustration below:

Next week, we will compare between the different electrolyser technologies and highlight the trade-offs between each other, their perfect applications and actual economic implications.

Do you want more details regarding the applications for the different electrolyser technologies?  Contact us at Did you miss «Technology: electrolysers – part 1»? Read it here.