U.S. Environmental Protection Agency (EPA), “Carbon Dioxide as a Fire Suppressant: Examining the Risks”, EPA430-R-00-002, http://www.epa.gov/Ozone/
snap/fire/co2/co2report.pdf 3.1Introduction
Hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), and to a much lesser extent perfluorocarbons (PFCs), have been commercialised as replacements for halons. The development of these chemicals for use in fire and explosion suppression applications, as outlined in Chapter 2, was instrumental in achieving the halon production phase-out mandated by the Montreal Protocol. While the saturated HFCs and PFCs are not ozone-depleting substances, they have been identified by the Intergovernmental Panel on Climate Change (IPCC) as potent greenhouse gases with long atmospheric lifetimes and are part of the basket of six gases included in the United Nations Framework Convention on Climate Change. As part of efforts to reduce emissions of greenhouse gases (GHGs), there are currently under consideration both international and national proposals to control the production or emissions of HFCs, and some type of future regulation of these agents seems likely.
Emissions of HFCs and PFCs currently represent approximately 1% of total GHG emissions. Emissions of HFCs and PFCs from fire protection are estimated at less than 1% of total HFC and PFC emissions (or less than 0.01% of total greenhouse gas emissions) from all sources. The Technology and Economic Assessment Panel (TEAP) update of the Intergovernmental Panel on Climate Change (IPCC)/TEAP Special Report on Ozone and Climate estimates that as of 2009 about 20% of the former halon market for total flooding applications was replaced with HFCs, with about 50% of the market choosing not-in-kind alternatives and about 25% opting for zero/low GWP alternatives such as fluoroketone, inert gases, and carbon dioxide. PFCs made up less than 1% of the former halon market and are no longer installed in new fire protection applications. Annual emission rates for HFCs are estimated to be 2% for total flooding systems and 4% for portable extinguishers. The report concludes that the GHG reduction potential from fire protection is small due in part to the relatively low emission level and the significant shift to not-in-kind alternatives.
3.2Proposed HFC Amendments
In 2009 and 2010 amendments were proposed that would add HFCs to the Montreal Protocol and slowly phase down their production.
The following are key elements of the proposals:
List 20 specified HFCs in a new Annex F to the Montreal Protocol.
-
Use a baseline for non- Article 5 Parties of the average of 2004-2006 annual production and consumption of HFCs and HCFCs.
-
Slowly phase down the production and consumption of HFCs in non-Article 5 Parties beginning with a 10–15% reduction in 2013–2014 and reaching an 85–90% reduction in 2028–2030.
-
HFC phase down in Article 5 Parties would begin 3–6 years later and reach the 85–90% level 6–10 years later.
-
Include provisions to strictly limit HFC-23 by-product emissions resulting from the production of HCFCs (e.g., HCFC 22).
-
Require licensing of HFC imports and exports, and bans imports and exports to non-Parties.
The proposed HFC amendments were discussed but not approved at the 2009 and 2010 Meeting of Parties (MOP) to the Montreal Protocol. Similar proposals are likely to be considered at the 2011 MOP. The Parties may wish to consider that any future HFC amendments or adjustments include provisions for fire protection uses that have no alternatives other than ODS or the high GWP HFCs.
3.3National Regulations and Proposals
Only a few countries such as Switzerland and Denmark currently have restrictions on the use of HFCs in fire protection. The European Union F-gas regulation (Regulation (EC) No. 842/2006) does not restrict the use of HFCs in fire protection, but instead requires containment, leak inspection, labelling, training, reporting, and recovery in order to reduce emissions. This regulation is up for review in 2011. In the United States, legislative proposals are being considered that would slowly phase down the production of HFCs in a manner similar to the proposed Montreal Protocol amendments outlined above.
3.4TEAP Response to Decision XXI/9
In Decision XXI/9, the Parties requested the TEAP to inform them of uses for which low or zero GWP alternative technologies are or will soon be commercialised. The TEAP concluded that alternatives exist for most of the former uses of halons that have low or zero GWP. These alternatives are described in Chapter 2 and include fluoroketone, inert gases, carbon dioxide (non-occupied spaces), and not-in-kind alternatives such as water, dry chemical, and foam. There are a small number of fire protection applications that may still require halons, HCFCs, or HFCs such as Alaskan oil and gas production facilities, crew bays of armoured vehicles, military and civilian flight lines, and portable extinguishers on board civil aircraft.
3.5Considerations
Environmental authorities were aware of the high GWPs of HFCs and PFCs when they were first approved as ODS replacements in the early 1990s. At that time the most important consideration was quickly eliminating the production of ODS so that the ozone layer could begin recovering, and it was necessary to have effective, efficient, and affordable alternatives in order to achieve that goal. Replacing a high ODP agent with a low or zero ODP agent with a similar global warming potential (GWP) was considered to be a good trade-off for the environment. In their 2007 paper, Velders et al., conclude that the phase out of ODS has already achieved significant climate benefits and additional benefits could be achieved by limiting future emissions of high GWP alternatives.
There are a few important fire protection applications such as oil and gas facilities in cold climates and crew bays of armoured vehicles where the only current options are to use recycled halon or a high GWP HFC. From a total environmental impact perspective, is it better to reuse an already produced, recycled, halon or produce a high GWP HFC for the application? This is a challenge that the Parties may wish to consider.
There are other applications such as military and civilian flight lines and portable extinguishers on board aircraft where the current options are recycled halons, HFCs, or a low ODP/low GWP HCFC. In response, the aviation industry is currently developing an unsaturated hydrobromofluorocarbon (HBFC) agent as a possible replacement for halon 1211 in portable extinguishers. It is possible that this agent could have a very low ODP even when released at higher altitudes. The Parties may wish to consider providing guidance on the viability of using a low GWP alternative that may have a non-zero but low ODP.
Dostları ilə paylaş: |
