Above all, considering their characteristics and properties, they justify the suitability of proposing technological development paths that make both solutions go hand in hand and complement each other.

This approach is endorsed by the strategies that entities such as the EU itself have been launching in recent years, where the joint and coordinated deployment of both technologies can be seen.

Thus, the first strategy deployed by the EU in this regard dates back to 2017, when the initiative known as Batteries Europe was launched. Through it, the EU seeks to move from 3% of the European market share of batteries in 2018 to 25% in 2028.

In addition, the EU has also launched its own green hydrogen strategy, which aims to produce hundreds of tons of renewable hydrogen per year by 2050, with a strong presence in sectors such as transport, building and industry.

This plan has been defined with a clear vocation to "complement" the battery strategy already defined by focusing on the decarbonization of sectors of the economy that could not achieve the desired energy transition only through electrification based on batteries and renewable energy sources.

This is demonstrated, for example, in the first "Green Deal" call published in May 2020 at the EU level, where it already speaks in its area 5 ("Sustainable and Smart Mobility") of hydrogen and battery hybridization in demonstrators for future maritime and air means of transport.

Similarly, the International Energy Agency (IEA), in its document "Batteries and hydrogen technology: keys for a clean energy future", reveals that it will take more than renewable energy and efficiency to put the world on track to meet climate and other sustainability goals. It identifies both batteries and hydrogen as keys to a low-carbon society.

BATTERIES AS A KEY FACTOR IN BOOSTING GREEN HYDROGEN

As indicated above, this joint approach between the two technologies is largely based on the similarities and complementarities between the two technologies.

Not surprisingly, batteries and electrolyzers (how coveted green H₂ is obtained) are based on similar electrochemical principles, making it possible to take advantage of the knowledge generated in one technology for the benefit of the other as the use of similar components and elements.

It is therefore expected, for example, that given the increasing maturity of the battery industry, the future large-scale industrialization of electrolyzers will take advantage of this knowledge and experience, reducing the time to scale and the associated costs. This also explains why more and more players are working on both technologies, taking advantage of existing synergies to offer innovations that benefit both.

But beyond these common principles from which both batteries and H₂ can benefit, other elements justify the need to propose a technological roadmap that considers these solutions’ complementarity.

As detailed in previous posts in our blog, the efforts of the H₂ industry are currently focused on boosting the production of H₂ through the electrolysis of water based on renewable energies (such as wind or solar energy). This will make it possible to generate a sustainable, emission-free production process, which will further strengthen the commitment to this technology with a view to the energy transition.

However, as it is based on "intermittent" energy sources such as those mentioned above, green H₂ poses the challenge of establishing a stable production system that guarantees its production without having to depend on weather conditions at any given time. This is where the potential of batteries to increase hydrogen production through electrolyzers arises.

Thanks to their storage capacity, batteries make it possible to eliminate the uncertainty and dependence associated with the availability of renewable energies depending on the time of day or the weather forecast. Thus, potential energy surpluses can be stored for later times when a deficit occurs. This avoids losses or waste of energy, thus achieving greater efficiency in its use.

Until a few years ago, this approach was not considered within the electrolyzer sector due to the high price of batteries, which meant a significant increase in the final cost of electricity obtained from hydrogen. This is why it was considered a more profitable option to reduce the degree of utilization of electrolyzers to only those times when renewable energy was available.

However, this scenario is not the same today, where the reduction in the price of batteries has reached such a level that their commissioning in electrolyzer plants is beginning to be profitable, also making it possible to increase the degree of utilization or plant factor of the installation thanks to the storage of energy in surplus phases for later use in times of deficit of renewable sources. 

Electrolyzer plants such as the one being developed by Iberdrola in Puertollano (Spain) already contemplate this approach, which aims to boost the attractiveness and growth of the green H₂ production industry worldwide.

H₂ WILL ADDRESS CURRENT BATTERY LIMITATIONS

So far, we have seen the possibilities offered by battery technologies to boost the green H₂ industry. But the latter is also expected to provide a solution that complements and meets the needs that, due to its nature, batteries will not be able to meet.

Above all energy density is a key factor for using one technology or another in a specific application. It should be noted that current lithium-ion batteries have a density of ≈250 Wh/kg, with this figure expected to increase to ≈400-450 Wh/kg thanks to future solid-state generations.

These figures are sufficient to answer, for example, the challenges that small electromobility (such as a car) may present. However, they are insufficient to meet the needs of heavy transport (such as trucks, trains, ships and airplanes).

This is where the possibilities of H₂ come in since it reaches densities close to 2,500 Wh/Kg in a gaseous state. This factor, together with the fact that heavy transport has fewer space or capacity limitations to use H₂ as fuel (through fuel cells), makes it a high potential alternative for this type of vehicle.

H₂ is also a key energy carrier for stationary applications, thanks to its large-scale storage capacity. Therefore, it is expected that in the future, hydrogen and batteries will be used together wherever grid applications are required in combination for an effective storage and demand management system, grid support or generation balance according to the needs of the moment.

THE CHALLENGES OF ACHIEVING THIS SCENARIO

This promising joint future between the two technologies depends on meeting the challenges presented by both solutions, especially in the case of hydrogen, which, as mentioned, is still an incipient technology compared to batteries.

On the one hand, one of the major areas for improvement is associated with the aforementioned cost of hydrogen production in order to provide it at a cost that is competitive with current alternatives. Approaches such as the aforementioned use of batteries can facilitate the industrialization and cost of obtaining H₂.

Likewise, its storage also presents challenges in terms of durability, recharging and life cycle, on which work is already underway to optimize its efficiency, a key factor for its future use and employment as a real alternative to other technologies.

As for batteries, the industry´s efforts are focusing on developing new technological generations to meet the needs of industries such as electric vehicles, renewable energies and consumer electronics.

This mainly involves increasing the energy densities of the devices, something that batteries such as the aforementioned solid-state batteries are expected to achieve, together with other advances that are being made in relation to the compositions of cathodes and anodes or the configuration of the cells.

The evolution of both hydrogen and batteries will depend on the response to these challenges, which in turn will determine the future consolidation of the new energy model to which we aspire in the future. Therefore, the importance of implementing technological approaches that include the development of these solutions in combination, taking advantage of the synergies and possibilities they offer each other in order to accelerate their maturity. All this is a first step towards establishing, in the long term, a flexible and hybrid energy model that will allow us to take advantage of the best of both worlds.