Magnetic Air Conditioners: A Futuristic Approach to Staying Cool

As global temperatures continue to rise, those of us living in already warm climates may increasingly feel the need to turn up the air conditioning. However, traditional air conditioners are notorious for their high energy consumption: According to the U.S. Department of Energy, residential air conditioning accounts for 16 percent of all household electricity usage in the United States.

In the near future, magnetic air conditioners may provide a solution to cool our homes without raising outdoor temperatures. Traditional air conditioners work by transforming a liquid refrigerant into a gas (absorbing heat from the air in the process), then compressing and cooling the gas to convert it back into a liquid. Magnetic air conditioners use magnets instead of compressors and refrigerants, offering a completely different method for cooling the surrounding air.

The Magnetocaloric Effect

Magnetic air conditioners utilize a phenomenon called the magnetocaloric effect. Magnetic materials heat up when exposed to a magnetic field and cool down once the field is removed. This effect was first discovered by German physicist Emil Warburg in 1881 through experiments with iron, but the temperature change was too small for practical use. In recent years, however, researchers have created magnetocaloric metal alloys that generate a significantly larger effect at room temperature.

How will magnetic air conditioners function?

Magnetic air conditioners cool the air by rapidly and repeatedly subjecting a magnetocaloric material to a magnetic field. In one prototype, developed by Astronautics Corporation of America in collaboration with the U.S. DOE's Ames Laboratory, a wheel containing the rare Earth element gadolinium spins through a stationary magnet's field. As the wheel turns, the gadolinium heats up and cools down as it passes through a gap in the field, cooling the water surrounding it during its rotation.

Eco-Friendly Technology

In a magnetic air conditioner, the alloy serves as the refrigerant, while plain water acts as the heat transfer medium, eliminating the need for harmful hydrochlorofluorocarbons (HCFCs) found in traditional air conditioners. Although the first magnetocaloric alloys were either toxic or too costly, recent advancements have produced cost-effective, environmentally friendly materials.

Magnetic air conditioners do require electricity, but the motor that drives the disk containing the magnetocaloric alloy is expected to be far more energy-efficient than the compressor used in traditional air conditioners. A 2011 article in Scientific American noted that Astronautics aims to have a prototype by 2013 that uses only two-thirds of the electricity consumed by a conventional air conditioner while providing the same cooling performance.

Could a magnetic air conditioner be in your future?

Along with Astronautics and the U.S. Department of Energy, numerous private companies, universities, and government organizations across the globe are investigating magnetic cooling technology for various applications, including air conditioning, refrigeration, and climate control for both industrial and domestic purposes.

The National Laboratory for Sustainable Energy at the Technical University of Denmark leads its own 'MagCool' initiative, while research at institutions like Penn State and other U.S. universities has expanded our understanding of magnetocaloric principles, shedding light on why certain materials cool more effectively than others. In 2009, BASF and Delta Electronics partnered to develop new magnetocaloric cooling systems and explore the potential of magnetocaloric power generation. Despite the excitement surrounding this technology, magnetic air conditioners are still a few years from commercial availability, and the first applications will likely be industrial rather than residential.