Carbon Dioxide and Ionic Liquid Refrigerants

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Notre Dame, Indiana
Project Term:
10/01/2010 - 09/30/2013

Technology Description:

The University of Notre Dame is developing an air-conditioning system with a new ionic liquid and CO2 as the working fluid. Synthetic refrigerants used in air conditioning and refrigeration systems are potent GHGs and can trap 1,000 times more heat in the atmosphere than CO2 alone—making CO2 an attractive alternative for synthetic refrigerants in cooling systems. However, operating cooling systems with pure CO2 requires prohibitively high pressures and expensive hardware. Notre Dame is creating a new fluid made of CO2 and ionic liquid that enables the use of CO2 at low pressures and requires minimal changes to existing hardware and production lines. This new fluid also produces no harmful emissions and can improve the efficiency of air conditioning systems—enabling new use of CO2 as a refrigerant in cooling systems.

Potential Impact:

If successful, Notre Dame would decrease the use of conventional, polluting refrigerants and increase the energy efficiency of air conditioners.


Increased energy efficiency would decrease U.S. energy demand and reduce reliance on fossil fuels—strengthening U.S. energy security.


Refrigerants with polluting emissions could account for up to 10%-20% of global warming by year 2050. Notre Dame's technology could eliminate the use of these refrigerants.


Widespread adoption of this technology could reduce energy consumption for air conditioning of buildings—providing consumers with cost savings on energy bills.


ARPA-E Program Director:
Dr. Dane Boysen
Project Contact:
Prof. William Schneider
Press and General Inquiries Email:
Project Contact Email:


Creative Thermal Solutions

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