The ins and outs of the three low-carbon tech debuting in 2022 Winter Olympics

The 2022 Winter Olympic Games that ended on Feb 20 in Beijing was touted as the most green Olympics ever, being powered entirely by renewable energy. A number of low-carbon novel technologies made their debut on the Olympic Games’ stage, such as ultra-low energy consumption buildings, carbon dioxide transcritical direct cooling, and cadmium telluride (CdTe) glass solar cells. How do these new climate tech work to reduce carbon footprint? Let’s take a closer look.

1. Ultra-low energy consumption buildings

Five of the eight venues used in the 2022 Beijing Olympics were previously used for 2008 Beijing Summer Olympics, transformed by “water-ice conversion” and “land-ice conversion.” This equates to a reduction in GHG emissions by approximately 30,000 t-CO2e compared to building new venues. There are three ultra-low energy consumption venues covering over 50,000 square meters, spanning from the Polyclinic of the Beijing Olympic Village, the Wukesong Ice Hockey Training Hall and the D6 area of theYanqing Olympic Village. These ultra-low energy buildings have integrated cross-domain energy-saving technologies, such as exterior wall coatings, lighting, energy and HVAC equipment systems. These technologies guarantee significant lower energy consumption intensity than conventional buildings.

Wukesong Ice Hockey Training Hall is now the biggest stadium with ultra-low consumption of energy in China. It was awarded three stars of the China Green Building. Innovative technologies used include:

1. Low carbon design. The venue adopts a simple design conducive to the design of passive building nodes while reducing the shape coefficient, an index in building energy efficiency design. A smaller building shape ratio, or surface area to volume ratio, indicates minimum heat gain and minimum heat loss that translates into energy saving. Natural light is maximized from an optimized building layout, while other designs such as light-transmitting curtain walls, skylights, sunken plazas, etc., all work toward saving energy.
2. Passive energy saving and insulation. The exterior is surfaced with STP vacuum insulation boards that have heat transfer coefficient that could reach lower than 0.006W/㎡K, compared to 0.04W/㎡K of conventional stone wool board. Large parts of the building adopted glass curtain walls with a low heat transfer manufactured with low-e (emissivity) design and filled with argon gas to ensure strict insulation.
3. Energy-efficient HVAC equipment and appliances. High-performance magnetic levitation (MagLev) chillers (centrifugal compressors with magnetic bearings) and other heat recovery devices are installed on air conditioners for significant energy saving. In addition, energy-efficient fans, water pumps and LED lighting are incorporated into the transmission , distribution and lighting systems.
4. New ice rink dehumidification system. Liquid desiccant dehumidification system is used for the ice rink. Compared with the traditional electric rotary dehumidification system, it could reduce energy by as much as 77%.
5. Building Integrated Photovoltaic (BIPV). A 600kW photovoltaic power generation system is installed on the roof, which can achieve an annual power supply of about 700 MWh, meeting part of the electricity demand of the ice center.

2. Carbon dioxide trans-critical direct cooling for ice making

Ice making is central to the construction of artificial ice rinks. Previous Winter Games mainly use synthetic refrigerant technologies such as CFCs (Chlorofluorocarbons) or ammonia refrigeration technology. The former has a significant greenhouse effect that damages the ozone layer, and the latter has security implications.

The Winter Olympics 2022 was able to introduce carbon dioxide refrigerants for ice making on a large scale for the first time, adopted by four venues, namely in the "Ice Ribbon" National Speed Skating Stadium, the Capital Indoor Stadium, the Short Track Speed Skating Training Hall and the Wukesong Ice Hockey Stadium.

Carbon dioxide as a refrigerant has an Ozone Depletion Potential (ODP) of 0 and a Global Warming Potential (GWP) of 1. This means that it will not damage the ozone layer at all, and the greenhouse effect implication is relatively low. Meanwhile, CO2 refrigeration can significantly reduce the power demand of the refrigeration system, saving 20%-30% of electricity. Waste heat generated in the refrigeration process can also be recycled and reused to generate 70°C hot water for domestic water and dehumidification regeneration, which greatly reduces the energy consumption from heating, antifreeze, dehumidification and ice pouring in the venue. Under the full operation mode, the single venue can save 2,000 MWh of electricity a year, which is equivalent to the carbon emission reduction achieved by planting about 1.2 million trees.

This carbon dioxide trans-critical direct cooling technology for ice-making was introduced in China for the first time through industry-university-research collaboration by Tianjin University with industrial players and companies.

There are other application scenarios for carbon dioxide as a refrigerant as well. In the latest Volkswagen electric vehicle series for example, a carbon dioxide heat pump air conditioning system is now an option along with the original electrical resistance heater. With its superior and environmentally sustainable technology, we believe more auto manufacturing companies will start to adopt carbon dioxide refrigerants.

3. Cadmium telluride (CdTe) glass solar cells

These unique curved glass curtain walls made from 22 "ice ribbons" adorning the exterior facade of the National Speed Skating Stadium are quite attention-grabbing. These glass curtain walls are made of 12,000 pieces of sapphire blue cadmium telluride (CdTe) power-generating glass, which not only are beautiful and vibrant, but also continuously generate electricity for over a few decades.

Normal glass can be "transformed" into electricity-generating building material through applying a 4mm-thick CdTe photoelectric film. The cadmium Telluride power-generating glass has good low-light performance and resistance to attenuation and other characteristics, which enables the solar cell to generate electricity during day and night, even in low light conditions.

The application in the Winter Olympics has attracted the mass media’s attention to the CdTe technology. As a type of BIPV (Building Integrated Photovoltaic) power-generating glass, although its price is more expensive than that of conventional glass curtain walls, the generated electricity is sufficient to cover the extra cost after a short payback period. The technology is quite marketable with the prospect of large-scale application in the urban highrise building walls, rural roofs and other scenes.

Only a handful of companies in the world are currently capable of mass producing CdTe thin-film solar cells, and only First Solar in the US could achieve mass production while two other companies, Toledo Solar in the US and Calyxo in Germany could achieve small scale stable production. There are mainly three Chinese companies that could produce CdTe thin-film solar cells, namely Chengdu CNBM Optoelectronics, Longyan Energy and Zhongshan Ruike.

Reference links and image sources:
Beijing 2022 sustainability – All you need to know - Olympic News: https://olympics.com/ioc/news/beijing-2022-sustainability-all-you-need-to-know
Xinhua: https://xinhuanet.com/
Unsplash：https://unsplash.com/
ChinaTimes：https://www.chinatimes.net.cn/

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