Working Group III: Mitigation

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A3.4 Solvents and Cleaning Agents

Less than 3% of projected demand for CFCs solvents has been replaced by HFCs and PFCs (McFarland, 1999).The high cost of fluorocarbons, regulatory prohibitions on HFC and hydrofluoroethers and hydrofluoroesters (HFE) solvents, and investment in emission reduction measures are expected to maintain carbon equivalent use and emissions in 2010 to current baseline levels. Annual PFC solvent emissions are estimated at 3,000–4,000 tonnes (UNEP, 1999b; Harnisch et al., 1999) and HFC emissions are estimated to be 1,000–2,000 tonnes (UNEP, 1999b). These values convert to less than 7.5MtCeq for PFCs and less than 1 MtCeq for HFCs.

Perfluorocarbons (PFCs such as C5F12, C6F14, C7F16, and C8F18) were introduced in the early 1990s as substitutes for ozone-depleting CFC-113 solvents and are also used in some applications where ODS solvents were never used. HFC-43-10mee and its azeotropic blends with alcohol, hydrochlorocarbons, and hydrocarbons were introduced in the mid-1990s to replace CFC-113 and PFCs. HFE solvents became commercially available in the late 1990s to replace PFCs, CFCs, HCFCs, and HFCs.

HFCs and HFEs are used in specialized cleaning of delicate materials, oxygen systems, and precision parts; as a flush fluid for particulate removal in precision cleaning; as a rinsing agent in a co-solvent process for cleaning printed circuit boards and mechanical components; and to dry electronics and precision parts after aqueous or semi-aqueous processing. In some circumstances, HFC drying may have a lower LCCP than thermal drying. HFCs and HFEs are also replacing PFCs and CFC-113 as carrier fluids for specialized fluorocarbon lubricants, as dielectric and heat transfer fluids, in developing latent fingerprints off porous surfaces, in rain repellent sprays for aircraft windshields, and in other applications demanding unique solvency properties (UNEP, 1998e, 1999b).

The four emission reduction options are: (1) changing production processes and product designs to avoid the need for fluorocarbon solvents (e.g., “no-clean” soldering and aqueous cleaning); (2) switching to lower GWP fluorocarbon or non-fluorocarbon solvents; (3) reducing emissions through process improvements (UNEP, 1999b); and (4) utilizing solvent recovery and recycling where possible. Progress is being made in each of these options.

One source estimates that process improvements could reduce fluorocarbon solvent emissions in the European Union by 20% by 2010 at a cost effectiveness of about US$160/tCeq and that an 80% reduction could be achieved at about US$330/tCeq (March, 1998).

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