The opportunities for CO2 technology to be applied in China over the next few years are abundant. Yet additional research into specific CO2 technology applications still needs to be done, heard participants in the 2nd International Symposium on Natural Gas CO2 Refrigeration and Heat Pump Technology held in Hefei, China on 30-31 July.

China is now moving into the second stage of its HPMP (Hydrochlorofluorocarbons Phase-Out Management Plan). The purpose of the discussion at the symposium was to put more focus on the use of CO2 systems as a key alternative technology, and to identify and address the technological and economic challenges inhibiting their wider adoption.

“In China, the refrigeration industry has chosen natural working fluids as the main alternative technologies including R290 and CO2,” said Shaofeng Hu from the United Nations Environment Programme.

“The challenge is with high costs, [but CO2] is an opportunity […] for us because it will help us make the transition much better,” Hu said.

World-class CO2 research in China deals with efficiency

Several presentations focused on research being done to improve the efficiency of CO2 systems with respect to compressor and heat exchanger design, as well as in other applications such as heat pumps for mobile air conditioning and residential heating.

Dr. Prof. Ma Yitai, director of the Thermal Energy Research Institute, Tianjin University, talked about his work to develop a new type of “combined expander and condenser” which increases efficiency significantly, especially when combined with heat recovery.

Dr. Prof. Yitai also commented on why CO2 has such an advantage these days over other alternatives. “There are new alternatives on the market, but from the perspective of cost, it is very difficult to use these new materials. That is why we choose CO2 as one of the best solutions,” he said.

“CO2 is very abundant and we can even foresee one day where it will cost nothing.”

“CO2 is very abundant and we can even foresee one day where it will cost nothing.”

Dr. Prof. Ma Yitai, Tianjin University

Opportunities for CO2 technology in Singapore

Victor Nian from the Energy Studies Institute, National University of Singapore spoke about the opportunities for energy-efficient and low-GWP heating and cooling solutions in Singapore.

Nian said that around 35% of electricity consumed is needed for cooling and refrigeration alone in Singapore. In addition, the government is considering taking action to phase down HFC use in the near future.

“The licensing regime for HFCs in Singapore is expected to come into force on 1 January 2019.”

Victor Nian, National University of Singapore

Nian highlighted the fact that, with the possible energy efficiency gains and environmentally friendly benefits of CO2 technology, there is a significant opportunity to use it in Singapore.

Heat pumps, a single solution for domestic heating in China

One of the main discussion themes centered around the potential for CO2 heat pumps to play a very important role in China’s domestic, commercial, and industrial sectors for heating and hot water.

Professor Shengchun Liu conducted an analysis comparing CO2 air-source heat pumps to traditional heating methods for domestic heating in China.

“In order to alleviate air pollution, it is necessary to adopt an environmentally friendly heating method, especially for rural areas,” said Professor Liu.

“Thus, one promising strategy is to use heat pump systems which are considered by the Chinese government as a renewable energy technology. Transcritical CO2 air-source heat pumps used for heating may have some benefits to offer.”

Professor Liu included major costs, including initial capital costs, annual operation costs, and lifecycle costs, as well as the emission values of polluting gases of the two heating methods, in his analysis.

“At an ambient temperature of 0°C […] 72% of the total heating energy is converted from renewable energy (the energy in the ambient cold air), which is about two times as that of coal boilers. Therefore, it can be concluded that the application of CO2 heat pumps for heating is an energy-saving method.”

High initial investment costs, however, were seen as the main limiting factor currently.

“The [CO2] compressors are the most expensive components of the system,” said Professor Liu.

“Therefore, if we can lower the cost of the compressors we can lower the cost of the system as a whole and there will be many advantages in the market. This is the future trend. Heat pump systems would become the single solution for heating. Right now, for R22 systems, costs are on the rise, so when we think about the right technology, we have to think longer term.”

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