The key to deploying decarbonized hydrogen is to reduce costs, industrialize and mass-produce electrolyzers. What technologies should be used, and how can they be made economically acceptable? Some answers.
LThe European Union (EU) has set ambitious targets for reducing greenhouse gas (GHG) emissions, aiming for carbon neutrality by 2050, and -40% by 2030. Hydrogen is a major pillar of this strategy, and its share in the European energy mix is expected to increase from less than 2% (including use as a raw material) in 2018 to 13/14% in 2050.
Today, however, almost all hydrogen in the EU-28 (94%) is produced from hydrocarbons, and is therefore a significant source of GHG emissions. Therefore, in addition to CO capture2 on the one hand and the production of hydrogen by biomass on the other, the production of hydrogen by electrolysis is one of the main pillars of the “green” strategy in terms of hydrogen. However, it should be remembered that the level of GHG emissions from electrolysers depends heavily on their electricity supply, with only renewable (“green” hydrogen) or nuclear (“turquoise” hydrogen) energies being considered decarbonized.
Between objective and reality
Objective: The construction of electrolysers of 2 x 40 GW by 2030 in the EU and an additional 40 GW in neighbouring countries (Ukraine, North Africa – mainly for export), coupled with an additional capacity of 80 to 120 GW of renewables, is divided into two phases:
In the first phase, by 2024, 6 GW of electrolysers, capable of producing up to 1 Mt of hydrogen, for targeted applications in the chemical industry and “heavy” mobility.
In a second phase, by 2040, 40 GW+ of electrolysers should be built, making it possible to produce 10 Mt of hydrogen for more advanced applications such as electricity production and storage. In addition, the plan also provides for the deployment of an infrasgas station construction for mobility applications.
But between the announced roadmap and the reality of production, a gap remains to be crossed. Indeed, the deployment is slow. After the demonstrators, manufacturers are barely laying the first stones of industrial production and the economic model with the cost of electricity is complex when production from fossil gas remains much cheaper today. The costs of electrolysis are still prohibitive compared to conventional processes (by steam reforming 2 to x4) but the variation in the price of gas (and our dependence) can change the situation.
What economic model?
Electrolysers are therefore one of the main options for producing “green” hydrogen in the medium term, if they are combined with competitive renewable energy sources. However, difficulties persist today in their implementation. Manufacturers are currently working on the automation of production lines, with in particular a development on 4 to 5 MW modules, especially in PEM and alkaline mode, with developments in progress on SOEC technology (reversible e, PC), AEM or high temperature developed in particular by the CEA.
The economic competitiveness of electrolysers – even if it should improve significantly in the medium term – also depends on the end uses, and consequently on the technologies used and the scale on which they are implemented. The production/consumption ratio on the same site or in the vicinity of a territory improves competitiveness (transport and storage are very costly). The development of such territorial ecosystems of varying sizes seems to be the model that could be developed. Not all sites are equal in terms of renewable potential (wind, photovoltaic) or access to a decarbonized network, with the share of decarbonized electricity production (including nuclear) differing significantly from one country to another in Europe.
In the short to medium term, there is economic space for medium to large-sized electrolysis units (10 to 50 MW) made up of standardized MW modules, supplying hydrogen mobility hubs strategically positioned across the territory.
The preferred operating model is based on the establishment of multimodal units, located in the immediate vicinity of the main road logistics corridors, combining long-distance freight trucks and intercity buses, captive fleets of municipal vehicles (garbage trucks, buses) and hydrogen trains or boats, allowing to achieve sufficient scale (Capex and electricity supply).
Access to a decarbonized and economically competitive electricity supply, either from the grid or from renewable energies, is fundamental.
Another possible model is very large electrolysers for industrial applications and small electrolysers (1 MW) which can constitute a technically interesting solution for powering light mobility applications in locations far from major transport routes. But the economic model remains to be defined.
Performance and costs
In a report from May 2012 (Hydrogen technologies at the CEA), the CEA published a graph (Fig. 8) comparing the performances of the three technologies: low-temperature electrolysis (alkaline type in yellow, PEM in blue) and high-temperature electrolysis (in red). At a given voltage at the terminals of the cell, hydrogen production is proportional to the intensity of the current (horizontal) and the efficiency (Nm3/kWh) is inversely proportional to the voltage (vertical).
Discussing the use of a new energy vector, even at a preliminary stage, requires not only a life cycle analysis, but also an overall economic analysis (capital cost, operating costs and maintenance). The cost of hydrogen produced by electrolysis is linked to that of electricity, and therefore to its production method. DIn the case of “green” electricity, it is the capital costs of the renewable system (photovoltaic, wind, etc.) that will have an influence. The figures vary, depending on the authors and the assumptions used (size and performance of the unit, capital cost, etc.), between €2.5 and €6/kg, with a fairly broad consensus around €3.5 to €5/kg of hydrogen, for an operating time of more than 7,000 h/year (Figure 10).
These figures should be considered with caution, given the low feedback on the actual performance of these systems and the associated costs, but they show that an economic analysis, even preliminary, does not disqualify this new sector which still needs to be developed, particularly for captive applications.
These costs can be compared with the results of the work of the national HyFrance3 project. For example, in the event of massive production of hydrogen from a wind farm, coupled with storage in deep cavities, in the PACA or Rhône-Alpes regions, the prospective cost, in 2050, of hydrogen produced by electrolysis could be in the range of 0.5 to 0.7 €/kg.
For its part, the CGSP (General Commission for Strategy and Foresight) published in September 2014 the results of a study on the subject (Figure 10).
