What refrigeration method will be used in Beijing 2022 Winter Olympics?

At the historic Winter Olympics, Beijing used carbon dioxide as refrigerant for the first time, striving to implement "frugality". Green and wisdom ".

This measure will be applied to some Winter Olympics venues, including but not limited to speed skating track, short track speed skating track and figure skating track. It is precisely because of this measure that the overall carbon emissions of the Winter Olympics will be greatly reduced, equivalent to planting 6,543,800+2,000 trees.