When you think of “cool car,” you probably don’t have an image of a practical family sedan in mind. But Nissan, the Japanese automaker behind these SUV models, is trying – quite literally – to be one of the coolest cars on the market.
Nissan is testing a heat-reflective white paint that can cool the outside temperature of its cars by as much as -5 degrees Celsius and the inside temperature by -4 degrees Celsius, the automaker said. The aim is to avoid the inevitable heat build-up in Nissan vehicles that usually occurs when parking a car in the blazing sun, and allow users to use the air conditioning less. It’s part of a drive by the company – and the wider auto industry – to increase the efficiency of cars amid growing concerns about sustainability in a warming climate.
“My dream is to build cooler cars without consuming energy,” said Susumu Miura, senior manager of the advanced materials and processing laboratory at the Nissan Research Center, in a press release Wednesday. “This is especially important in the age of electric cars, where the burden of running air conditioning in the summer can have a significant impact on the charge level.”
Nissan unveiled the paint, which is six times thicker than typical car paint, at the Tokyo International Air Terminal in Haneda in November 2023 for a 12-month test. In collaboration with energy technology company Radi-Cool, the company has applied its cooling paint to airport service vehicles. Miura hopes Nissan will also extend the paint to commercial vehicles.
The technology has become increasingly attractive given efforts to make vehicles more climate-friendly. Toyota is also experimenting with paints that can lower interior temperatures. In 2021, a team of engineers at Purdue University developed the world’s whitest paint, which can reflect over 98% of sunlight. A year later, the team developed a thinner version of the paint that can be used to coat airplanes, cars and space shuttles.
The key to the effectiveness of Nissan’s cooling paint are two particles: one that reflects near-infrared rays that normally cause normal paint to absorb heat, and another that generates electromagnetic waves to dissipate the heat.
“Basically, you combine light of different wavelengths so that the light is reflected at all sorts of angles at different wavelengths,” said Shu Yang, a professor of materials science and engineering at the University of Pennsylvania. Assets.
Yang compared the paint to sunscreen, which absorbs and reflects UV rays from the skin. Even the materials in the paint have similarities to sunscreen, such as titanium oxide, the basic compound in many cooling technologies that reflect heat. Although the paint appears white, Yang said that is not due to a pigment added to the paint, but rather to the structural particles from which the paint itself is made.
A bright future lies ahead of us
Although more automakers are adopting reflective white paint as a cooling solution, there are many unanswered questions about how the technology can be improved in the future. Environmentally conscious Nissan customers, for example, can save themselves the trouble of giving their cool cars a colorful coat of paint, Yang said. The cooling paint will remain white as materials scientists continue to determine the optimal particle size for reflecting light and heat. The end goal will likely be developing an effective translucent paint that can be used to coat colorful car pigments, she said.
The problem is simply figuring out how to do it. Even after the development of cooling color, there are still too many scientific unknowns about how and why certain colors reflect and absorb heat. While the general scientific rule is that light colors reflect heat and dark colors absorb it, there are still anomalies, such as the deep purple eggplant red.
“If you touch the skin of the eggplant, it’s actually cool,” she said. “There are a lot of questions: Why and what happened?”
However, materials scientists warn that even technological discoveries and improvements in these technologies have limited benefits in combating climate change. Compounds such as barium sulfate must be mined and extracted, leading to higher carbon emissions.
Jeremy Munday, a professor of electrical and computer engineering at the University of California, Davis, said painting cars reflective white paint is essentially just a drop in the bucket when it comes to combating the effects of greenhouse gases pumped into and trapped in the atmosphere.
“This is definitely not a long-term solution to the climate problem,” Munday told the New York Times“This is something you can do in the short term to mitigate worse problems while you try to get everything under control.”
