Chemical Solar Storage Emerges as Option for Grid Flexibility

Researchers have developed a system that stores solar energy in liquid form and releases it later as hydrogen without external electricity, a laboratory advance that highlights new options for energy storage as Mexico faces rising power demand, grid constraints and ambitious clean-generation targets.

“This system demonstrates a notable efficiency in storing solar energy as electrons,” wrote researchers in their study published in Advanced Materials, describing a process that separates the capture, storage and release of solar energy and allows hydrogen to be produced on demand in the absence of light.

The research arrives as Mexico’s electricity system approaches a period of stress. Demand is projected to grow steadily over the next two decades, driven by industrial activity, electrification and climate-related increases in peak consumption. According to recent analysis by the Institute of the Americas, cited by MBN, gross electricity consumption reached nearly 360 terawatt-hours in 2024 and is expected to grow at an average annual rate of about 2.5% through 2039, with peak demand rising faster. At the same time, investment in generation, transmission and distribution has lagged behind demand growth, creating risks for reliability and affordability.

Mexico has committed to increasing clean electricity generation to 38% by 2030 under its national planning framework, yet clean sources accounted for about 23.4% of total generation in 2024. Solar and wind capacity are expected to expand, but their variability has underscored the need for storage solutions that can provide flexibility and resilience. Grid congestion, transmission losses above 12% of net consumption and declining hydroelectric output due to droughts have further complicated the transition.

Within this context, the ability to store solar energy chemically and transport it without relying on high-pressure hydrogen infrastructure addresses two persistent challenges: intermittency and storage risk. While the technology remains at an early stage, it reflects a broader push to diversify storage options beyond conventional batteries.

The system described by the researchers integrates commercially available materials: graphitic carbon nitride, which acts as a photocatalyst, and ammonium metatungstate, a polyoxometalate compound capable of accepting and storing electrons. When exposed to blue light, the photocatalyst generates electrons that are transferred to the tungsten-based clusters, where they are stored chemically. The process is visible as a color change in the solution, signaling that solar energy has been captured in the form of reduced tungsten states.

A small amount of methanol plays a supporting role by stabilizing the charge separation and preventing rapid recombination of electrons. The stored energy can later be released in the dark by adding a platinum-on-carbon catalyst, which enables the electrons to combine with protons from water to produce hydrogen gas. In laboratory conditions, the system achieved a hydrogen evolution rate of 3,220µmol/g per hour without illumination, and 954µmol/g per hour under natural sunlight, without relying on external electricity, explains the study.

The authors argue that separating energy capture from energy release allows solar energy to be transported in liquid form from regions with high irradiation to areas with lower solar resources. They note, however, that challenges remain, including reliance on methanol and the need to demonstrate long-term stability beyond laboratory timescales.

Although the research is not specific to Mexico, it aligns with national discussions about storage and system flexibility. Industry participants increasingly view storage as essential rather than optional. Ernesto Nájera, Development Director for Latin America, Pytes has said that storage systems are becoming central to grid stability and distributed generation, particularly as users seek resilience against outages and rising peak demand. He has emphasized that proper system design and professional installation are critical as storage supports essential loads and interacts more directly with grid operations.

Policy planning reflects this shift. Mexico’s long-term electricity development plans envision the addition of thousands of megawatts of storage capacity by 2030 to support renewable integration and reduce stress on the grid. Andres Friedman, Co-Founder and CEO, Solfium, notes that storage is also tied to competitiveness, as companies face growing pressure to reduce emissions across their value chains and demonstrate progress on Scope 3 targets.

Distributed generation combined with storage has gained momentum as a way to bypass transmission bottlenecks and bring capacity closer to demand centers. Market participants argue that decentralization, supported by digital platforms and new financing models, could accelerate clean-energy deployment more quickly than centralized projects alone. Private capital has shown interest in these approaches, particularly in energy-as-a-service models that reduce upfront costs for users.

Chemical storage systems that convert solar energy into transportable fuels represent a different, longer-term pathway, but one that addresses similar constraints. If future research extends storage duration from hours to weeks and reduces dependence on sacrificial components, such systems could complement batteries and other storage technologies, particularly for seasonal balancing or remote applications.

For Mexico, where demand growth, grid limitations and clean-energy targets converge, the advance underscores the range of solutions under development. While commercial deployment remains distant, the research highlights how innovation in storage could expand the options available to policymakers, utilities and businesses as the country works to align reliability, competitiveness and decarbonization over the coming decade.