One of the most critical considerations in designing an energy system is its material makeup. Different resources have varying levels of thermal performance, so optimizing these choices can lead to significant gains in efficiency and reliability. Phase change materials (PCMs) have emerged as a particularly promising solution in many areas.
What Are Phase Change Materials?
Phase change materials absorb or release thermal energy as they shift between different phases of matter. Water is the most familiar example. When water boils, the liquid remains at 212 degrees Fahrenheit, and the rest of the heat is released as steam. This vaporization carries roughly 2,230 joules of energy per gram, which is why steam is effective as a power source.
In most modern engineering applications, researchers look at PCMs other than water. Alternative materials may shift phases at more accessible temperatures or produce larger thermal energy transfers.
Other common examples include paraffin wax, ice-melting salts, some fatty acids and polyethylene. Many of the most promising come from novel synthetics as researchers look into new material combinations to maximize these qualities.
Benefits of Phase Change Materials in Energy Applications
The heat absorption and release of PCMs make them intriguing resources for various energy system applications. Absorbing thermal power in high-temperature environments could stave off the worst effects of heat damage. Alternatively, releasing it in colder conditions could provide passive heating to reduce power consumption.
PCMs are often not a complete energy solution on their own but complement other systems to maximize their performance. Power storage, insulation and transfer mechanisms all benefit from these materials’ unique qualities. This potential could drive the global PCM market to be worth $4.17 billion by 2027, with energy applications accounting for much of the growing demand.
Applications of Phase Change Materials in Energy Systems
Using PCMs to their highest potential starts with recognizing where they can improve existing energy solutions. With that in mind, here are five leading use cases for phase change materials.
Energy Storage
Phase change materials are particularly advantageous as an energy storage medium. They can absorb excess heat at peak temperature cycles as they solidify and release it later as thermal power when melting during the low part of the cycle.
This use accounts for surpluses and gaps between electrical generation and consumption. Renewables, which are inherently intermittent, stand to gain the most from the application.
One challenge is that many PCMs are poor thermal conductors, leading to waste in the energy transfer process. Combining them with highly conductive materials like steel could resolve the issue. However, the metal must be of sufficient quality, as low-quality steel is prone to cracking amid temperature fluctuations.
Insulation
Another way to integrate PCMs into energy systems is to use them as insulators. The absorption and release of excess heat prevent unwanted thermal transfers to maintain consistent conditions within a building or refrigerated container.
A study across multiple homes in Australia found that combining PCMs with standard insulators could reduce cooling energy by 16.2% despite low costs. The resulting electrical savings led to a payback period of just 1.7 years. Such a quick turnaround makes these resources highly valuable as a way to maximize building efficiency, while larger changes take time to produce results.
The same benefits make PCMs valuable in refrigeration systems. Refrigerated trucks could use them to minimize the trailer’s reliance on the diesel engine to keep food items safe. As a result, overall tailpipe emissions would decline.
Industrial Waste Heat Recovery
The same characteristics that make phase change materials ideal storage media and insulators make them promising waste recovery solutions. Industrial facilities lose 20%-50% of their energy through waste heat, but PCMs could absorb this thermal radiation and redirect it to other purposes.
Insulating a hot water pipeline or high-temperature machine with a PCM could recover much of the lost thermal power. Manufacturers can then shift the phase back later to release the heat and energize other processes.
This twofold usage model prevents waste and reduces the amount of energy needed to power all functions, as waste from one area could go toward another. The thermal transfer would require additional materials like thermally conductive metals, but such a solution could dramatically lower industrial emissions and electrical costs.
Solar Energy
PCMs have also gained traction in solar applications beyond serving as a storage mechanism. Passive solar heating systems are particularly noteworthy.
Lining a water storage tank with a PCM can trap heat inside. That way, a solar collector can warm the water when it’s sunny and the PCM will keep it that way as the sun sets and the air cools. This system provides electricity-free hot water to reduce energy consumption in homes and businesses.
Alternatively, PCMs can divert excess heat away from solar panels during periods of intense sunlight. Such times are ideal for electrical generation, but solar cells perform better at lower temperatures, so the high heat can counteract that opportunity. Passive cooling through a PCM layer mitigates the concern to maximize efficiency.
Electric Vehicles
Phase change materials could improve electric vehicles (EVs) for similar reasons. EVs are crucial to minimize emissions, but lithium-ion batteries require reliable thermal management to enable safe charging cycles and efficient power discharge at varying temperatures.
By absorbing excess heat, PCMs can keep lithium-ion cells cool during peak charging cycles without needing complex cooling mechanisms. As a result, prices fall and automakers can avoid the thermal runaway that leads to EV fires in extreme cases. Preventing such disasters would make faster charging more viable, making EVs more practical.
Insulating PCMs could also keep heat in to prevent performance drops that lithium-ion batteries typically experience in extreme cold. Consequently, range anxiety would not increase in cool weather and EVs would remain a convenient alternative to gas and diesel cars.
Phase Change Materials Could Drive Energy Savings
With so many potential use cases available, phase change materials’ potential in energy applications is significant. As the industry seeks to drive efficiency and cut waste, it should consider how these resources could complement other, more technologically advanced solutions.
Additional research and development could lead to new PCMs or PCM-reliant systems that meet higher standards. Implementing the technology could unlock needed power savings to ease the transition to sustainable electricity
