A range of alternatives to halon with no or low GWP, such as water-based technologies, dry powders, inert gases, and carbon dioxide, have displaced about 75% of previous halon use in countries classified as developed under the Montreal Protocol. About 5% of the existing and new halon applications are considered critical, with no technically or economically feasible alternatives. These critical uses include military vehicles, civil and military aircraft, and other high-risk explosion scenarios involving unacceptable threat to humans, the environment, or national security. Recovered and recycled halon is being used to meet these needs (IPCC/TEAP, 1999).
Relatively small, but important, quantities of HFCs and PFCs are being used as substitutes for halon in fire protection. About 20% of the systems that would have used halons in the absence of the Montreal Protocol currently use HFCs and only about 1% use PFCs (UNEP, 1998c, 1999b).
Growth in HFC use is limited by high cost compared to other choices. PFCs are not technically necessary as halon replacements except in rare and special circumstances (UNEP, 1999b). However, relatively strong growth of HFC/PFC use in developing countries and countries with economies in transition is being driven by aggressive marketing, and is producing a new dependency that could lead to a rapidly growing market in applications where other alternatives are available. Awareness campaigns involving fire protection experts and their customers could help limit uses that are not technically justified (UNEP, 1999b).
The Montreal Protocol prompted various improvements in the management of halons and their replacements, resulting in a fourfold decrease in annual emissions. Testing and training with halon and HFC was eliminated and the unintended discharges of systems were greatly reduced through intensified maintenance and operational improvements. With only 20% of new fire protection systems using HFCs and with the fourfold decrease in emissions, HFC emissions are 5% compared to those from halon systems before the Montreal Protocol (UNEP, 1999b; McFarland, 1999).
Emissions of HFC from the installed bank of fire protection equipment, including necessary emissions to suppress fires, are estimated to be about 4%6% per year (UNEP, 1999b). These emissions could be reduced by up to 50% through continued improvements to eliminate unnecessary discharges and by increased recycling of the HFCs (IPCC/TEAP, 1999). There are no estimates of the cost-effectiveness of such measures.
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