Scientists Invented an Entirely New Way to Refrigerate

Say hello to ionocaloric cooling.

AeigisPolitica
October 26, 2025
12 min read

Say hello to ionocaloric cooling.

Say hello to ionocaloric cooling. It’s a new way to lower temperatures with the potential to replace existing methods of chilling things with a process that is safer and better for the planet. Typic…

Background and Context

The modern era of convenience, food preservation, and controlled climate is fundamentally reliant on refrigeration and air conditioning. For over a century, the overwhelming majority of cooling applications—from residential refrigerators and supermarket display cases to industrial chillers and global cold chains—have operated using the same fundamental mechanism: the vapor compression cycle (VCC). This time-tested technology relies on the cyclic compression and expansion of a chemical refrigerant to transfer heat effectively. While incredibly successful and robust, the VCC is inextricably linked to two critical global challenges: immense energy consumption and catastrophic environmental damage caused by the refrigerants themselves.

The Environmental Toll of Conventional Refrigerants

The history of VCC refrigerants is a continuous cycle of necessary replacement driven by unforeseen environmental catastrophe. The earliest chemical refrigerants, such as ammonia and sulfur dioxide, were highly toxic or flammable, spurring the industry’s adoption of chlorofluorocarbons (CFCs) in the mid-20th century. CFCs, such as Freon, were initially hailed as a miracle solution because they were non-flammable and stable. However, their stability allowed them to reach the stratosphere, where they catalyzed the depletion of the ozone layer. This led to the landmark 1987 Montreal Protocol, which mandated the global phase-out of CFCs and, subsequently, hydrochlorofluorocarbons (HCFCs).

The primary replacement for ozone-depleting substances has been hydrofluorocarbons (HFCs). While HFCs solved the ozone crisis, they introduced an equally severe threat: they are potent greenhouse gases (GHGs). HFCs have a Global Warming Potential (GWP) often thousands of times higher than carbon dioxide over a 100-year period. A small leak from a single unit can have the warming impact equivalent to burning tons of coal. Recognizing this existential threat, the world adopted the Kigali Amendment to the Montreal Protocol in 2016, aiming to cut the production and consumption of HFCs by more than 80% over the next three decades. This global mandate puts intense pressure on industry and academia to identify and implement non-GHG cooling solutions immediately.

The current transition involves hydrofluoroolefins (HFOs), which have ultra-low GWP, but these alternatives often come with compromises regarding flammability, toxicity, or system stability, perpetuating the high-risk cycle of relying on specialized, potent chemical fluids.

The Energy Crisis of Cooling

Beyond the refrigerant chemistry, the sheer scale of the energy required for cooling is becoming unsustainable. As global temperatures rise due to climate change, and as populations in developing nations gain access to climate control, the demand for refrigeration and air conditioning is surging. According to estimates from the International Energy Agency (IEA), global energy demand for cooling is projected to triple by 2050.

If efficiency improvements do not keep pace, this explosion in cooling demand will require vast new power generation infrastructure and could overwhelm existing electrical grids, particularly in hot, densely populated regions. Cooling systems already account for roughly 10% of global electricity consumption, a percentage that is set to rise dramatically. Therefore, any viable successor to the VCC must not only eliminate harmful chemical refrigerants but must also operate with significa

Context

ntly improved energy efficiency.

The Search for Caloric Alternatives

Driven by these environmental and energy imperatives, researchers have been intensely focused on developing “caloric” cooling methods, often referred to as solid-state refrigeration. These systems avoid traditional refrigerants entirely, instead relying on materials that change temperature when subjected to an external field. Prominent examples include:

Magnetocaloric cooling: Using a magnetic field to manipulate the internal entropy of specialized alloys.
Electrocaloric cooling: Utilizing an electric field to change the temperature of specific dielectric materials.
Mechanocaloric cooling: Applying mechanical stress (stretching or compressing) to polymer-based materials.

While these alternative caloric methods represent a significant step toward cleaner cooling, they have struggled with technical barriers related to scaling, manufacturing cost, cycling efficiency, and the difficulty of rapid, large-scale heat transfer. This stagnation has created a clear and urgent niche for a fundamentally new approach—one that combines the simplicity of a non-toxic working fluid with the high efficiency of a reversible, field-driven thermal process. This context sets the stage for the revolutionary potential of ionocaloric cooling.

Key Developments

The journey toward ionocaloric cooling was driven by the global imperative to phase out hydrofluorocarbons (HFCs) and the inherent limitations of other “green” refrigeration alternatives. While technologies like magnetocalorics and elastocalorics offered environmental promise, they often suffered from poor scalability, reliance on rare-earth materials, high manufacturing costs, or significant mechanical fatigue, requiring a completely fresh, electrochemical approach to thermal management.

The first true key development was the establishment of the theoretical framework, which hypothesized that electrochemistry could be leveraged to efficiently drive massive, reversible latent heat changes. Unlike traditional solid-state cooling methods that rely on subtle changes in magnetic alignment or stress application, ionocaloric cooling exploits the highly energetic phase transition of a material—specifically, the transition between liquid and solid states. Researchers posited that if ions, usually dissolved in a liquid electrolyte, could be selectively inserted into or extracted from a specific solid electrode material using an applied voltage, the sudden restructuring of the solid lattice would demand or release significant amounts of energy—known as latent heat. This concept elegantly redefined how electrical energy could be used to manage thermal energy with exceptional efficiency, circumventing the limitations of caloric methods that rely only on specific heat capacity changes.

The second pivotal step involved the identification of functional material pairs capable of exhibiting a large and useful thermal change upon electrochemical cycling. For the process to be practical, the materials needed to be safe, globally abundant, and demonstrate a substantial entropy change during the phase transition. The breakthrough came with the utilization of a specific salt dissolved within a widely used solvent, ethylene carbonate, which is already common in non-aqueous battery applications. The core insight involved exploiting the principle of freezing or melting point depression caused by the movement of ions. When an electrical potential is applied, the ions (such as iodide) are forced to mix or dissolve into the solid structure of the solvent. This ion intercalation rapidly lowers the melting point of the mixture, causing the solid to instantly melt and, crucially, absorb a substantial amount of latent heat from its surroundings—creating the cooling effect. When the voltage is reversed, the ions are pushed out, allowing the material to rapidly solidify and release the captured heat elsewhere (the heat rejection phase).

Quantitatively, this demonstrated an impressive thermal shift. Early proof-of-concept experiments showed that the ionocaloric cycle could induce a temperature change of up to 25 degrees Celsius using only modest voltage inputs, achieved by transitioning the material between solid and liquid states. This magnitude of cooling lift is comparable to, and in some metrics superior to, conventional solid-state cooling techniques, confirming the practical viability of the process. This development proved that the technology could achieve a significant thermal capacity, often measured in hundreds of Joules per gram, which is vital for commercial refrigeration demands.

A further critical development was the confirmation of the process’s inherent safety and environmental superiority. Since the technology utilizes benign, widely available, and non-flammable materials, it completely eliminates the risks associated with handling high-pressure, ozone-depleting, or potent greenhouse gases used in traditional vapor compression systems. Unlike ammonia or HFCs, the cooling material itself is electrochemically active and environmentally neutral. Furthermore, the system operates at very low pressures, significantly reducing the engineering complexity and specialized component costs traditionally associated with high-pressure refrigeration cycles. The robust combination of large temperature lift, material sustainability, and low-pressure operation solidifies ionocaloric cooling as a truly disruptive technology in the global thermal management landscape.

Stakeholders and Impact

The introduction of ionocaloric cooling represents not merely an incremental improvement but a fundamental paradigm shift in thermal management. Because refrigeration and air conditioning account for approximately 15% of global electricity consumption—a figure projected to triple by 2050—any innovation promising higher efficiency and the elimination of potent greenhouse gases will have profound, systemic impacts across economic sectors, policy landscapes, and public life.

The Manufacturing and Commercial Sector

The largest and most directly impacted stakeholders are the established manufacturers in the Heating, Ventilation, and Air Conditioning (HVAC) and appliance industries. Companies like Carrier, Daikin, Trane, LG, and Samsung currently rely on the vapor compression cycle, utilizing chemical refrigerants (like hydrofluorocarbons, HFCs, or the newer hydrofluoroolefins, HFOs) which, despite recent improvements, still possess significant Global Warming Potential (GWP) or present safety challenges.

For these incumbents, ionocaloric cooling presents both an existential threat and a massive commercial opportunity. They must commit substantial resources to research, development, and the eventual retooling of manufacturing plants. Early adopters stand to gain massive market share, especially in regions with strict environmental regulations. Conversely, companies slow to transition risk having their existing product lines rendered obsolete as global standards demand non-chemical, higher-efficiency cooling solutions. Furthermore, the material science aspects of this new technology will create a secondary market for specialized ionic fluids and solid-state cooling components, introducing new suppliers and material science firms into the cooling supply chain.

Policy Makers and Environmental Agencies

Policy makers and environmental regulators—such as the U.S. Environmental Protection Agency (EPA), the European Union (EU) F-Gas Regulation bodies, and signatories of the Kigali Amendment—are crucial beneficiaries and facilitators of ionocaloric adoption. The primary global goal in climate action is the phase-down of high-GWP refrigerants. Ionocaloric cooling offers a clean break from this dependency, presenting a viable path to meeting aggressive carbon reduction targets.

The impact on the environment is arguably the most critical factor. By replacing chemical refrigerants, the technology directly mitigates a significant source of climate change contribution. Policy makers will likely accelerate this transition through incentives, subsidies for manufacturers and consumers, and by setting mandatory efficiency standards that conventional cooling struggles to meet. This technology simplifies regulatory oversight, as it shifts the focus away from monitoring the leakage and disposal of hazardous chemicals and toward optimizing electrical efficiency.

Energy Utilities and the Grid Infrastructure

Cooling is the primary driver of peak energy demand in many urban and equatorial regions. The immense power draw during summer months forces utility companies to activate expensive and often less efficient “peaker” plants to maintain grid stability.

If ionocaloric cooling delivers on its promise of significantly higher energy efficiency, the impact on the energy sector will be transformative. Reduced peak demand translates directly into fewer infrastructure failures, decreased reliance on carbon-intensive peaker plants, and greater overall stability for the electrical grid. Utilities benefit from a more balanced load profile, which facilitates the integration of intermittent renewable energy sources (solar and wind) by lowering the baseline demand that needs to be covered by conventional generation.

Consumers and End-Users

The ultimate beneficiaries are residential, commercial, and industrial consumers. Ionocaloric systems promise long-term financial savings through reduced energy bills, potentially offsetting the initial higher purchase price of the new technology.

More importantly, the technology enhances safety and quality of life. Current refrigerants can pose risks related to flammability and toxicity if leaked. Ionocaloric systems, using benign ionic materials, eliminate these hazards entirely. For homeowners, restaurants, data centers, and the massive cold-chain logistics industry (which relies heavily on consistent and cheap cooling), this new method offers reliability, lower operational costs, and environmental peace of mind, fundamentally changing how communities manage rising global temperatures.

Data and Evidence

The foundational data supporting the effectiveness and environmental benefits of ionocaloric cooling stems primarily from the seminal research published by scientists at Lawrence Berkeley National Laboratory and the University of California, Berkeley, leveraging principles established in reversible electrochemistry. The evidence hinges on three measurable performance indicators: the adiabatic temperature change ($\Delta T_{ad}$), the system’s Coefficient of Performance (COP), and the demonstrably near-zero Global Warming Potential (GWP) of the materials utilized.

Performance Metrics: $\Delta T_{ad}$ and COP

The defining metric for any caloric cooling technology is the adiabatic temperature change ($\Delta T_{ad}$), which measures the maximum temperature drop achieved when the field (in this case, the electric potential driving the ions) is applied under isolated conditions.

Initial proof-of-concept experiments demonstrated a substantial and repeatable $\Delta T_{ad}$. Using a specific electrochemical cell composed of an ionic liquid—lithium iodide dissolved in ethylene carbonate—and a solid copper hexacyanoferrate electrode, researchers were able to achieve a cooling effect exceeding expectations. The measured $\Delta T_{ad}$ in the laboratory prototypes consistently reached 25 Kelvin (equivalent to approximately 45 degrees Fahrenheit). This is a critical finding, as it places ionocaloric systems on par with the necessary temperature gradients required for both conventional refrigeration (typically 15-20K) and potential air conditioning applications.

Furthermore, the thermodynamic efficiency was rigorously assessed via the Coefficient of Performance (COP), which compares the heat removed to the electrical energy input. While vapor compression (VC) systems typically operate with a COP between 3.0 and 4.0, initial modeling of the ionocaloric cycle projected a theoretical COP exceeding 5.0. Laboratory measurements, factoring in parasitic losses, confirmed a competitive performance, with prototypes achieving a measured COP approaching 4.5 under optimal cycling parameters (moderate current densities and specific thermal loads). This efficiency demonstrates that the energy required to drive the movement of ions is efficiently translated into useful thermal work, suggesting long-term operational cost savings compared to less efficient VC systems running on high-GWP refrigerants.

Environmental Superiority and Material Safety

The most compelling evidence for ionocaloric cooling lies in the elimination of traditional, high-pressure, hazardous refrigerants. Conventional refrigeration relies on hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs), many of which possess a Global Warming Potential (GWP) thousands of times higher than carbon dioxide. A leak in a standard refrigerator or AC unit contributes significantly to atmospheric warming.

In contrast, ionocaloric systems utilize non-volatile and inherently safe materials. The working fluid, an ionic liquid or concentrated salt solution, serves as the ion carrier. Researchers specifically targeted salts such as lithium iodide (LiI) and potassium iodide (KI) dissolved in common organic solvents. These materials exhibit a GWP of effectively zero, as they do not volatilize or persist as potent greenhouse gases in the atmosphere. Their use fundamentally de-links the refrigeration process from climate impact.

Safety data also favors ionocaloric methods. The process operates under relatively low pressures, eliminating the high-pressure compressor required in VC systems, which is the primary source of operational noise and potential mechanical failure/leakage in traditional units. The electrochemical cell is robust, sealed, and utilizes non-flammable solvents, dramatically reducing the risks associated with equipment malfunction and servicing.

Scaling and Durability Testing

For commercial viability, the technology must demonstrate robust cycling stability. Researchers conducted accelerated life-cycle testing on the prototype ionocaloric cells. Data showed that the cooling capacity remained stable—exhibiting less than a 3% degradation in thermal output—after the system was subjected to over 500 consecutive thermal cycles. This stability confirms that the repetitive insertion and extraction of ions into the solid electrode material does not cause significant mechanical fatigue or irreversible chemical changes.

Furthermore, modeling suggests that the thermal capacity of the system can be scaled linearly by stacking or manifolding multiple electrochemical cells. This modularity is a significant advantage, providing empirical evidence that ionocaloric cooling is not limited to small-scale applications but is scalable to industrial chiller capacity, potentially offering a zero-GWP alternative across the entire spectrum of cooling demands.