According to China’s State Council Information Office, the country is committed to hosting a green Olympic and Paralympic Winter Games. As such, Beijing 2022 has not only made quality ice rinks suitable for respective sports in the competition venues but has also stayed eco-friendly in ice-making.

Behind the process are two types of refrigerants — carbon dioxide (R-744) and R-449A — which the organizing committee chose following careful deliberation and consultation with experts from home and abroad. Of the nine ice rinks in the seven competition venues for Beijing 2022, five used CO2 in ice-making and the other four used R-449A. It is the first time natural CO2 refrigeration system has been used at the Olympic Games.

In fact, R-507 refrigerant was first considered when the organizers started to devise their ice-making plan. R-507 is widely used across the globe and meets the requirement of the Montreal Protocol on Substances that Deplete the Ozone Layer for developing countries. Given that R-507 has a comparatively high GWP of 3,985, Beijing 2022 decided to turn to greener ones.

After looking into global development trends and application of refrigerants consulting with experts, the organizers decided to implement separate ice-making plans with the support of the International Olympic Committee (IOC).

Venues that need to make and maintain ice all year round, including the National Speed Skating Oval, use natural refrigerant CO2. Venues that only occasionally make ice, such as the National Aquatics Center and the National Indoor Stadium, use R-449A refrigerant.

CO2 has zero ODP and a GWP of only one. It is the refrigerant behind the CO2 transcritical refrigeration system, which was put forward as an ice-making solution for the National Speed Skating Oval by a panel comprising a dozen academicians of the Chinese Academy of Engineering and Chinese Academy of Sciences, senior experts from domestic refrigeration associations, and representatives of the construction team.

As pointed out by Zhang Xinrong, professor of Peking University and a renowned expert in thermal engineering and natural refrigerant, CO2 transcritical refrigeration system boasts high security, low energy consumption and operational cost, and environmentally friendliness. In addition, the heat generated from the process can be recycled, which increases the energy management efficiency with integrated cooling and heating. 

"Experts from international federations once told us that using common eco-friendly ice-making practices will be enough for the National Speed Skating Oval to meet Olympic standards. But we spent 18 months studying documents on ice-making from previous Olympic Winter Games and analyzing the pros and cons of every type of refrigerants. Eventually, we were able to come up with better solutions," said Song Jiafeng, an engineer with the Oval's construction team.

According to Song, using carbon dioxide as a refrigerant can increase ice-making efficiency by 30% and save around two million kilowatts of electricity per year.

The choice was applauded by the IOC, which "fully supports" the decision and its implementation.

When it comes to venues that only need occasional ice-making, Beijing 2022 organizers had discussions with equipment suppliers, engineers, and service providers of the venues and decided on using R-449A. R-449A is a lower-GWP alternative for R-507, with a GWP of 1282, which is 68% lower than that of R-507.