Cooling / Refrigeration

These past years have seen a succession of substances used for cooling and refrigeration. In the 1990’s CFCs (chlorofluorocarbons, such as Freon) were banned in most countries due to their proven damaging effect on the ozone layer. Instead, HFCs (hydrofluorocarbons), were taken into widespread use. But, while they do not harm the ozone layer, HFCs are potent greenhouse gases, and contribute to global warming. In many countries, steps are being taken to phase out HFCs.

CO2 a viable alternative
Natural refrigerants, such as CO2 are viable alternatives to HFCs, and actually effective in reducing carbon emissions as the CO2 technology is less energy consuming. Thus, the global warming potential of natural refrigerants is significantly lower than that of the synthetic gases, and they do not harm the ozone layer.

Denmark was the first country in the world to ban all synthetic gases as refrigerants, effective from 2007 – and businesses, such as supermarkets, have been quick to adopt the new technology using CO2 as a refrigerant. This is partly due to economic incentive, as the use of greenhouse gases for refrigeration is taxed.

CO2 can be used as a refrigerant or working fluid in a wide range of applications, such as air-conditioning for buildings and vehicles, commercial refrigeration and vending machines.

Magnetic refrigeration
Another alternative method of refrigeration, in which Denmark also holds a leading position, is magnetic refrigeration. This promising new technology, which is still in the early stages and not yet commercially applicable, is based on temperature changes in materials subjected to a strong magnetic field (magnetocaloric effect).

The Risoe National Laboratory for Sustainable Energy (Risø, DTU) in Denmark has built a prototype magnetic refrigeration device which is able to cool 8 degrees C. The goal is to be ready with a commercial application within a few years.