We’re pretty used to our creature comforts here in the US, and air conditioning has become more of an expectation than a luxury. In fact, around 85% of homes in America have air conditioning. Unfortunately, A/C uses up a LOT of energy, as the electricity to run our cooling systems consumes at least 5% of the primary energy in the country. We use more electricity for cooling than the entire continent of Africa uses for anything.
In early March of 2015, as part of President Obama’s Climate Action Plan, the Environmental Protection Agency approved an expanded list of more climate-friendly refrigerants for air conditioners and refrigerators. This is a great step in the overall plan to reduce our harmful impact on the environment, but the long-term goal is to develop technology that will completely eliminate the need for toxic refrigerants. Luckily, there are several cooling methods in development that could significantly improve our energy efficiency and reduce our reliance on environmentally unfriendly chemicals.
One such method uses magnets–specifically the magnetocaloric effect–to cool the air in an enclosed space. Magnetic materials heat up when exposed to a magnetic field and cool down when removed from the field. Magnetic air conditioners use this principle by quickly and repeatedly exposing a magnetocaloric alloy to a magnetic field. The alloy heats up, then cools down when it passes through a gap in the field, thereby cooling the water that surrounds it. This eliminates the need for any sort of refrigerant, and uses much less electricity than a traditional air conditioning unit.
Ever heard of thermoacoustics? Air conditioners employing this principle use the soundwaves from a loudspeaker to push helium–an environmentally benign gas–back and forth in a resonator. The gas absorbs heat when compressed and releases it when expanded, thus cooling the surrounding air. This technology has already been used to cool a Ben & Jerry’s ice cream freezer, and the researchers at University of Pennsylvania are now working on improving its overall energy efficiency.
The option that’s possibly closest to being realized is the Desiccant-Enhanced Evaporative (DEVap) air conditioner. This technology combines the principle of evaporative cooling with properties of water-resistant membranes and a desiccant, which absorbs moisture from the air. This method produces cool, dry air with no refrigerant and significantly less energy expenditure than cooling systems on the market today. Researchers are currently working on optimizing the system to get the cost of materials and production down. If all goes according to plan, we should start seeing the DEVap units for sale in the next few years!