Complex Made Simple

4 innovative technologies that can replace ACs and refrigeration

Buildings account for 38% of the world’s greenhouse gas emissions. Among the factors is wasteful energy use tied to heating and cooling. Scientists are working on innovative solutions to combat this issue

Traditional air conditioners also spew millions of tons of CO2 worldwide daily A new, lower-energy alternative to air conditioning works by sucking the body heat out of nearby people This paint is so white that coating a building with it could reduce or even eliminate the need for air conditioning

As incomes in developing countries continue to rise, demand for air conditioners is expected to triple by 2050. Air conditioning is currently responsible for almost 20% of electricity use in buildings around the world.

United Nations report published late last year found that buildings account for 38% of the world’s greenhouse gas emissions, a percentage that’s rising. Among the factors for the uptick is wasteful energy use tied to heating and cooling.

Most air conditioners use refrigerant gases called hydrofluorocarbons (hfcs). Though these do not deplete Earth’s ozone layer in the way the chlorofluorocarbons they replaced back in the mid-1990s did, but they have up to 11,700 times the warming potential of carbon dioxide, and the United Nations has warned that not addressing HFC use could mean “we essentially cook ourselves.” 

Still, according to the IEA, traditional air conditioners also spew millions of tons of CO2 worldwide daily. The global commercial refrigeration equipment market is forecast to reach $53.23 billion by 2026, according to a new report by Reports and Data. Here we look at global solutions to solve cooling-related environmental problems, starting from Saudi.

Salt crystals

A new experimental electricity-free cooling system is under development at Saudi Arabia’s King Abdullah University of Science and Technology (KAUST), a press statement revealed. All the system requires is salt and sunlight to cool a space or refrigerate food at temperatures of 3.6ºC.

The KAUST electricity-free cooling system is detailed in a paper in the journal Energy and Environmental Science.

The machine takes advantage of a natural “phase-change” phenomenon that sees energy absorbed when salt crystals dissolve in warm water which rapidly cools as the salt dissolves.

Ammonium nitrate crystals have high water solubility and cooling power, are cheap, and are already widely used in fertilizers, meaning they are commercially viable. I

Scientists found that ammonium nitrate could be used to cool the space surrounding an ammonium nitrate-filled metal cup from room temperature at 25º C to 3.6º C in about 20 minutes. The temperature then remained 15º C for more than 15 hours.

The KAUST team believes their system can be used for cooling rooms as well as for food refrigeration. The salt can be crystallized and reused once again after it is dissolved by evaporating the water via solar heat. The water can also be reused via a solar still.

Emissions free heat pump

Exergyn, a clean-tech specialist, has attracted global attention by developing and patenting an emissions-free heat pump that contains no refrigerant gases, one of the main causes of global warming.

Technologies such as Exergyn’s are seen as key to decarbonizing the sector, which is estimated to be worth $1 trillion.

The company has teamed up with Carrier in an attempt to bring the technology to market. It is also understood to be in talks with the US company about a possible buyout.

In a recent memo to the board, clean-tech expert Chas Anders Hall, who sits on Exergyn’s advisory council, said the company’s technology could be worth in excess of $500 million.

 Geothermal heat pumps are a poorly named appliance because they heat and cool buildings. They also don’t require fossil fuels like propane, oil, gas, or coal, all fuels used to heat buildings today. 

They run solely on electricity, so there is still that element of a power grid that is still powered by coal and natural gas, but by itself, it’s not a major pollutant.

A heat pump can be cost-prohibitive and run anywhere from $6,500 to $13,000. 

Radiant cooling

A new, lower-energy alternative to air conditioning works by sucking the body heat out of nearby people using membrane-assisted radiant cooling.

Researchers tested a “cool tube” pedestrian pavilion in tropical Singapore and found 79% reported feeling comfortably cooled by the pavilion despite air temperatures of 85 to 87 degrees Celsius.

Radiant cooling is maybe best known today as a part of smart home engineering: panels in the floor or ceiling, filled with circulating cool water, that absorb ambient heat and create a cool effect.  

The cooling effect of the “cool tube” worked even at a high relative humidity in the tropical climate.

“Very” white paint

Researchers from Purdue University developed a paint so white that coating a building with it could reduce or even eliminate the need for air conditioning in a building, a press statement revealed.

It’s so white, in fact, that it has been awarded a Guinness World Record title for the world’s whitest paint.

paint
Image Source: Interesting Engineering

Purdue team’s latest white paint formula reflects up to 98% of light. It uses a chemical compound called barium sulfate, which is typically used to make photo paper and white cosmetics.

The team also used a wide range of different barium sulfate particle sizes in their paint, allowing it to scatter a higher range of light spectrum from the Sun as different sizes scatter different sunlight wavelengths. 

The team developed their paint so as to reflect sunlight away from buildings. Because the paint they developed absorbs less heat from the Sun than it emits, it can even cool the surface on which it is coated, reducing the need for air conditioning.

The Purdue team claims that covering a roof area of approximately 92 square meters would allow the equivalent cooling power of 10 kilowatts.