The International Day of Clean Energy is a good moment to say out loud what many already know but have not yet translated into concrete decisions: the conversation is no longer renewables yes or no.
Spain has a real advantage. We have demonstrated deployment capacity and a solid industrial ecosystem. But if we aspire to genuinely electrify industry, attract data centres, sustain the growth associated with digitalisation and artificial intelligence, and keep tariffs competitive, we need to take the next step — to anchor the transition with firmness. This is not achieved with a single ingredient. It is achieved with a complete menu: renewables, grids, storage of different durations, demand flexibility, and market signals that reward the value each asset actually provides.
Clean energy 24/7 is not a slogan. It is a technical and economic specification. When a manufacturer decides to electrify a furnace or a chemical plant, the question is simple: can it operate continuously, and at a predictable cost? When a data centre evaluates a site, it looks at availability, price and quality of supply. In practice, they ask for the same thing system operators ask for: power when it is needed, not just energy when there is sun or wind.
The novelty is that the need for firmness is growing very fast. The January 2026 EPRI technical report, prepared with the LDES Council, makes precisely this point: rising consumption from data centres, the use of artificial intelligence, and the broader trend toward electrification are pushing the search for scalable and dispatchable sources of both electricity and heat.
The good news is that storage is no longer the expensive piece that only covers peaks. It is evolving into a set of technologies with different cost and service profiles. And here it pays to be precise: in energy planning, what is not measured well is decided badly.
From "cheap kWh" to "valuable capacity"
For years we have compared technologies by the levelised cost of energy (LCOE), and more recently by the LCOS of storage. That is reasonable: it simplifies. But over-simplification can lead to expensive errors. The EPRI report itself warns that LCOS can undervalue long-duration systems oriented to reliability and resilience because, by design, they are used only a few times per year. A 100 MW, 40-hour system may discharge only during prolonged stress events, and its value is not how much energy it delivers in a normal year — it is that it prevents loss of load, avoids emergency actions, and in some cases substitutes for firm capacity.
In Spain, concentrated solar power went from being the star to being the "ugly duckling," when in fact it continues to provide a valuable capacity: clean dispatchable energy for hours, exactly when the system needs it most. While the discussion here has narrowed, China — today the world's largest battery manufacturer — is building a CSP fleet that already exceeds, in capacity, everything historically installed in the rest of the world combined. Spain was once the world leader, and it retains the industrial and technical knowledge to lead again, provided we define long-duration storage policy at utility scale and above twelve hours that is genuinely technology-neutral and that pays for the service the system actually demands: clean firmness.
To talk rigorously about clean energy 24/7, then, two concepts must be brought back to the centre:
- firm power, available when the system needs it;
- and total installed cost together with cost structure, not only cost per MWh produced.
The right indicator for comparing technology categories is the Total Plant Cost (TPC). The logic is straightforward: it allows capital-intensive options to be compared, and it reveals how cost evolves with duration.
What the numbers say, without makeup
Storage is not one thing. There is intraday storage, designed to shift energy within the day and provide system services. There is multi-day storage, which protects against prolonged events or adverse weather patterns. And there is thermal storage, central to decarbonising industrial heat, which is too often the elephant in the room.
A very practical message follows: this is no longer about betting on a winning technology — it is about building portfolios. Just as the electricity system does not rest on a single type of generation, clean firmness will not come from a single type of storage either.
Firmness is not only electricity — it is also heat
When we discuss industrial competitiveness, we tend to focus on the price of electricity. But for many industries, process heat carries equal or greater weight. Thermal storage and the electrification of heat — through resistive elements, heat pumps and high-temperature solutions — have enormous potential, because they decouple the moment electricity is purchased from the moment heat is used. This makes it possible to capture renewable surpluses, reduce peaks and stabilise costs.
In thermal energy storage, many solutions depend on integration with existing cycles or industrial processes. Certain costs — for example the cost of a new cycle — may not be included in aggregated ranges. That is important, because it forces projects to be designed with proper integration engineering, not as boxes plugged into the grid.
For Spain, this connects directly with heat-intensive industry, with industrial clusters, and with a clear opportunity: if we can deliver clean, cheap electricity when it is abundant, and convert it into firm and dispatchable heat, we win twice. We reduce emissions and we reinforce competitiveness.
If the technology is advancing, then the question is why it is so hard to accelerate the transition toward clean firmness. The answer is that the bottleneck is less technological than systemic — markets, regulation, permitting, grids and coordination.
Five lines of action
First — remunerate firmness and flexibility transparently.
Today the market rewards energy, and at times it rewards services. But clean firmness — understood as the ability to sustain power in critical hours and during prolonged events — needs a stable framework. Long-term planning and contracting, with technology-neutral criteria, can accelerate investment in long-duration storage and in hybrid solutions.
There is a trap to avoid here: assessing these investments only by hours of use, or by a standard LCOS, can make them look expensive. But the value of insurance is measured when the loss occurs. There are cases of low annual utilisation but high systemic relevance. No one wants blackouts.
Second — accelerate grids and interconnection as competitiveness infrastructure.
Without grids, there is no transition, no industry, no data centres. Spain has made progress, but demand is growing and the integration of more renewables requires reinforcement, digitalisation and management capability. Every project that stays in the queue is not only a lost investment; it is an industrial opportunity that moves to another geography.
Third — bet on storage portfolios, not on a single clock.
Think in layers:
- the intraday layer, which balances the day and provides system services;
- the multi-day layer, which protects against prolonged events and reduces the need for fossil backup;
- the thermal layer, which decarbonises heat and improves system efficiency.
There are technology families with distinct cost trajectories and complementary services.
Fourth — integrate demand into the solution, especially industry and digital.
Clean energy 24/7 becomes much easier when demand can also be flexible. This is not about stopping a steel mill at will; it is about redesigning processes, incorporating thermal storage, modulating auxiliary loads, using electricity at moments of surplus, and monetising that flexibility. In data centres, for example, there is room with load management, demand-response agreements, behind-the-meter storage and intelligent redundancy design.
Fifth — improve data quality and cost standards.
Without a common language for CAPEX, TPC, OPEX and normalisation assumptions, we will be comparing pears with screws, and decisions will be delayed. This kind of benchmarking adds genuine value because it normalises and aggregates data in a comparable way, while still protecting commercially sensitive information.
A practical view for Spain
Clean energy 24/7 is a competitiveness strategy, not just a climate policy.
It means being able to tell an industrial customer: "you can electrify with continuity, with predictable cost, and with a low footprint." It means being able to tell an investor: "there is a framework where firmness is remunerated and where projects are bankable." It means being able to tell the citizen: "there will be a transition without surprises and without improvisation."
Spain can lead this if it brings together three things:
- renewable deployment capacity;
- industrial and engineering muscle;
- a market architecture that turns clean firmness into a bankable asset.
And here I return to the meaning of the International Day of Clean Energy. Celebration is fine. But the best celebration is to advance on what is missing. Clean energy is already here. What we have to build now is clean energy always — with storage, with flexibility, and with clear rules.
That is the path to a more reliable system, a more competitive industry, and a transition that feels like an opportunity, not a risk.