In the face of the climate emergency and the need to reduce dependence on fossil fuels, it is increasingly clear that the energy transition cannot be achieved through direct electrification alone. Complementary solutions are necessary, and in this scenario, green hydrogen is emerging as an energy vector with extraordinary potential—especially in sectors where electrification is complex or unfeasible.
Its value lies not only in its versatility of use—from mobility to industry—but also in its ability to act as a large-scale storage system, helping to stabilize an energy system increasingly based on renewable and intermittent sources.
A hydrogen battery at territorial scale
Hydrogen is not a primary energy source but a vector: energy is required to produce it. And that is where its value lies. If it is produced using renewable electricity via water electrolysis, surplus solar or wind energy can be transformed into a storable and reusable form.
Electrolysis technologies have advanced significantly. PEM (Proton Exchange Membrane) electrolyzers, already commercially available, offer efficiencies of 55–65%. But SOEC (Solid Oxide Electrolyzer Cell) technology, still maturing, can reach efficiencies of 75–85% when residual heat is utilized. Moreover, SOECs are reversible: they can also function as fuel cells, generating electricity again. This makes them a kind of smart battery, particularly interesting in markets with high price variability or advanced flexibility systems.
Hydrogen can be reconverted into electricity and heat more efficiently than conventional combustion. Fuel cells, though still costly, are starting to become competitive in settings with access to cheap renewable electricity. Furthermore, in industrial or community applications, they can provide solutions for energy autonomy and demand management with very low environmental impact.
It’s also possible to burn hydrogen directly in boilers or turbines, especially if it is produced on-site, avoiding costs associated with compression and transport. This application makes sense in processes requiring high temperatures and can complement sources like biomass in hybrid heating networks, adjusting generation according to demand and electricity prices.
From hydrogen to synthetic fuels
Another promising field is the synthesis of fuels from hydrogen. If combined with captured CO₂—whether from biogenic or industrial sources—synthetic methane or green methanol can be produced. These molecules are compatible with current natural gas infrastructures and can replace fuels in hard-to-electrify sectors such as maritime or air transport.
Beyond its use as energy, hydrogen also plays a role as a chemical reagent. It enables the production of green ammonia, a raw material for fertilizers and other industrial applications. Moreover, if the CO₂ used comes from biomass, these processes can contribute to negative emissions strategies, a crucial challenge for achieving climate neutrality.
In the field of mobility, hydrogen offers clear advantages for long-range vehicles like trucks or buses: greater autonomy and fast refueling. Fleets are already being deployed in urban and logistics environments where full electrification is not practical. And in the industrial sector, green hydrogen can replace grey hydrogen—produced from natural gas—in chemical processes like the production of methanol, ammonia, or steel, drastically reducing the carbon footprint.
REGENERA: Concrete applications to accelerate the energy transition
As part of the REGENERA project, led by AIGUASOL, we have translated these potentials into real-world cases, with a rigorous technical and economic approach. Specifically, we studied the production and use of green hydrogen from renewable energy generated at a WWTP (Wastewater Treatment Plant) and its applications within the same system.
One of the key conclusions is that injecting hydrogen into the grid in the form of blending is currently one of the most economically viable options. This approach allows hydrogen to be valorized while also obtaining guarantees of origin (GoOs), improving the overall system’s emissions balance. In fact, the project achieved a remarkable result: the plant’s activity recorded negative emissions of –0.4 kg of CO₂ per m³ of water treated.
We also analyzed the potential of the Power-to-Gas-to-Power system, where hydrogen serves as a temporary storage medium. The cost of this storage has dropped to around €300/MWh, about €50/MWh below typical sector costs. This advancement suggests that in scenarios with large hourly price differences or well-developed flexibility markets, hydrogen could become a key tool for optimizing energy management.
At AIGUASOL, we advocate for an intelligent, pragmatic, and data-driven energy transition. Hydrogen is not a magic solution, but it is a vital piece in many decarbonization scenarios. With projects like REGENERA, we are moving toward a cleaner, more resilient, and more inclusive energy model—where technical solutions have real and tangible applications.
Hydrogen potential analysis (REGENERA, AIGUASOL)
