【Stories behind COP28】Pursuing Innovation in the University Lab: SPACECOOL’s Masahiro Suematsu Introduces Radiative Sky Cooling Materials That Turn Heat into Light

We, the CCCA, first encountered SPACECOOL at COP27 last year, where we learned that it was a startup launched by Osaka Gas.

Suematsu: Yes, that’s correct. I am also an employee of Osaka Gas. Within the company, I have introduced around six business strategies for commercializing photonics research. The most successful idea resulted in SPACECOOL’s new material.

You seem to be a serial entrepreneur, creating one business after another. How did you encounter photonics?

Suematsu: In my first year at the company, I negotiated with the company to be involved in creating a new business theme. From the second year onwards, I launched research and development in photonics, which was not conducted at Osaka Gas, and started working as a researcher in the photonics research laboratory at Kyoto University to achieve joint research for Osaka Gas and Kyoto University in the research field.

So you wanted to challenge yourself to turn research into a business that could have an impact on society, right?

Suematsu: Yes. While I was job hunting, Osaka Gas visited my alma mater, and I learned that they were the first Japanese company to successfully implement open innovation. Eager to contribute to research and development in Japan, I thought, “This is it!” and joined. Even after joining Osaka Gas, I continued to aspire to commercialize new technologies without losing my initial passion. In my second year, Osaka Gas launched the photonics project, and during that time, I had the opportunity to collaborate with Professor Susumu Noda, a world-renowned authority in the field of photonics at Kyoto University. Originally researching a different field, I had to study hard and spend countless nights in the laboratory conducting experiments.

Human bodies emit light.

How can we define the research field of photonics?

Suematsu: In simple terms, photonics aims to freely control the light generated from heat.

Light generated from heat?

Suematsu: It might sound complex, but it’s a familiar phenomenon in our daily lives. With thermal imaging, we can measure human body temperature. Imaging captures the light emitted by our body’s heat, making it visible. The same principle applies to light bulbs: Heat is transformed into light, illuminating the surrounding space.

So the human body emits light?

Suematsu: Exactly.

The light we see with the naked eye is actually only a small part of the spectrum of light. Could we say that photonics controls all types of light—including those we cannot see with our eyes—and put them to use in various applications?

Suematsu: Yes. For example, in anime, you often see laser beams flying straight. That’s an impressive feat. Normally, light doesn’t travel straight like that; it spreads and disperses. Professor Noda, whom I studied under at Kyoto University, successfully made light travel straight using a very small device. His achievement was widely lauded as a technology with the potential to radically change industrial structures.

Radiative sky cooling: Principles and applications

SPACECOOL’s passive radiative sky cooling materials

What is radiative sky cooling, and how does it work in SPACECOOL’s new material?

Suematsu: Radiative sky cooling is a natural phenomenon on our planet. The Earth, warmed by sunlight, emits heat into space in the form of infrared radiation. This occurs because of the law that heat moves from a hot area to a cold area. The temperature in outer space is around -270⁰C degrees, so the light reflected by the Earth’s surface returns to space. However, on its way back, some light remains on Earth, impeded by clouds and greenhouse gases. If there is less light returning to space than sunlight entering, the Earth warms up; if there is more, the Earth cools down. In simple terms, that’s how it works.

How does the Earth release heat into space?

Suematsu: There are specific wavelengths of light, collectively known as the "atmospheric window," that can eventually make their way back to space, overcoming various obstacles in the process. SPACECOOL’s new material converts the received heat into light at wavelengths that can successfully reach space, thus returning the heat to the cosmos.

With SPACECOOL’s product, most of the absorbed heat can be released into space as light, which means the device can be used to cool objects. How much can the temperature be lowered in practice?

SPACECOOL’s distribution board, which applies their passive radiative sky cooling materials.

Suematsu: Currently, the most popular way to use this material is to attach it to a shade board, which protects the distribution board that houses control panels and breakers. Distribution boards can provide electricity but are highly vulnerable to heat. In recent summers, temperatures inside distribution boards have exceeded 50⁰C, and this heat has caused elevator shutdowns and equipment malfunctions. By applying our material, we can lower the temperature inside a distribution board that was above 50⁰C to below 40⁰C.

Distribution boards are essential devices in office buildings and commercial facilities, so the product seems to be in demand worldwide as heat becomes more severe due to climate change.

Suematsu: Yes, our new material can be utilized not only in Japan but also around the world as an adaptive measure against the global warming that is taking place. For example, when a record heat wave hit the UK last year, cooling systems in Google and Oracle data centers failed, causing them to stop functioning. Such large-scale machines inevitably generate heat—but are also vulnerable to heat. I expect that technologies and services that adapt infrastructure to climate change will see increased demand in the future.

What other applications are there?

To ensure the safe storage and transportation of goods, even in hot summers, the material can be applied to containers transported on trucks. In addition, tents using this material have lower temperatures inside, even in summer, making them suitable for use in disaster shelters.

The SPACECOOL tent. Inside, the temperature is lower than in a regular tent, and the air is crisp,
providing a comfortable environment.

COP28: COOL COP? The world urgently needs climate-resilient heat countermeasures.

SPACECOOL's trucks (in the demonstration and testing phase) ensure the safety
of drivers during the summer and maintain the quality of products.

This summer broke records for heat worldwide. The United Arab Emirates, the host country of COP28, announced that it would focus on air conditioning at this COP, as this will become increasingly essential in this warming world. They committed themselves to the Global Cooling Pledge—a promise to transition to cooling systems with low environmental impact. Could SPACECOOL’s products make significant contributions in this context?

Suematsu: Yes. These products not only emit no greenhouse gases but can also cool indoor spaces with zero energy consumption. I hope they can be helpful to people around the world suffering from the serious effects of heat.

📢 Global Cooling Pledge Launched!

Dr. Sultan Al Jaber, COP28 President, joined climate leaders in launching the Global Cooling Pledge to collectively raise ambition and reduce cooling-related emissions. #DrSultanAlJaber #UniteActDeliver #COP28 pic.twitter.com/P2W5axv5NL

— COP28 UAE (@COP28_UAE) December 6, 2023

Do you anticipate an increase in overseas transactions from now on?

Suematsu: Yes, we have already received inquiries from overseas. We were selected as one of the top 50 startups shaping climate change mitigation and adaptation strategies in the Middle East by the PwC Middle East Net Zero Future 50 Initiative. In the EU, we will participate in a joint research project aimed at standardizing passive radiative sky cooling materials. We will contribute to the development of standardized specifications for evaluating the characteristics and performance of radiative sky cooling materials. Through this, I hope to garner even more global attention for these materials, ultimately leading to increased adoption.