Hydrofluorocarbons (HFCs)

Haloalkanes containing no chlorine or bromine, the elements whose presence are known to cause damage to the ozone layer. Although HFCs are not ozone-toxic, they do contribute to the greenhouse effect. Hydrochlorofluorocarbons (HCFCs) contain hydrogen instead of some chlorine and fluorine and as a result are far less harmful to the atmosphere. These gases replace Chlorofluorocarbons (CFCs) in refrigeration and air conditioning equipment, though they are also inadvertently emitted during some manufacturing processes. HFC-23 (Trifluoromethane) is an abundant and very potent greenhouse gas. About 98% of HFC-23 emissions are created as a byproduct in the production of HCFC-22, a refrigerant used for stationary refrigeration and air conditioning, and generally are vented to the atmosphere. Nearly half of the credits awarded to developing countries under the Kyoto Protocol come from HFC catch-and-destroy processes that are considered industrial gas projects. Some have argued that the CDM has led to perverse incentives; firms may produce more HCFC-22 in order to make money for reducing HFC-23 emissions. This may flood the market with no clear environmental or sustainable development benefits.  Because of this, some standards do not credit projects that destroy HFCs from new facilities.  

Further reading: 'The Credit for Destruction,' Carbon Finance