Perfluorocarbons (PFCs)
Some greenhouse gases fade in a decade. A few effectively never leave. Perfluorocarbons are the second kind: molecules so chemically inert that nothing in the atmosphere breaks them down. A tonne of the most common one, emitted from an aluminium smelter today, will still be trapping heat when the year is 50,000 CE.
PFCs are fully fluorinated industrial greenhouse gases — extraordinarily potent and effectively permanent.
Perfluorocarbons (PFCs) are greenhouse gases of only carbon and fluorine — CF₄, C₂F₆ — from aluminium smelting and semiconductor manufacturing. With no natural sinks they are extraordinarily persistent: CF₄’s 100-year GWP is 7,380. In inventories they are Scope 1 process emissions.
Definition — What PFCs Are
Perfluorocarbons are compounds of carbon and fluorine only — hydrocarbons in which every hydrogen atom has been replaced by fluorine (the prefix “per-” means “completely”). That complete fluorination makes them exceptionally stable: colourless, non-flammable, and almost chemically inert. The same inertness that makes them useful industrially is what makes them a climate problem, because nothing in the lower atmosphere destroys them.
With no significant sinks, PFCs accumulate and persist for thousands of years. Like HFCs, they contain no chlorine and so do not deplete the ozone layer — but they are potent greenhouse gases and one of the group of fluorinated gases (“F-gases”) covered by international climate agreements and corporate inventories. The most important PFCs are the small ones: CF₄ (tetrafluoromethane), C₂F₆ (hexafluoroethane), and C₃F₈ (octafluoropropane).
PFCs combine two extremes: a very high global warming potential and an atmospheric lifetime measured in millennia. That combination makes a PFC emission effectively irreversible — unlike CO₂ or methane, a substantial fraction of which is removed over time, PFCs released today are still warming the planet thousands of years from now.
Where PFCs Come From
Unlike HFCs, which leak from refrigeration and air-conditioning, PFCs are overwhelmingly industrial process emissions from two sectors:
- Primary aluminium smelting. PFCs are produced during “anode effects” — brief upsets in the electrolytic reduction of alumina, when the ore in the bath runs low and the process starts reacting with the carbon anode and its fluoride electrolyte, releasing CF₄ and C₂F₆. This is historically the single largest source.
- Semiconductor manufacturing. PFCs (CF₄, C₂F₆, C₃F₈) are used to etch circuit patterns and clean deposition chambers; a fraction passes through unreacted and is emitted. As chip demand grows, so does this source.
Both industries run dedicated abatement and reduction programmes, because with lifetimes in the thousands of years there is no margin for “dealing with it later” — every tonne avoided is a tonne kept out of the atmosphere essentially forever.
The GWP and Lifetime Numbers
PFCs pair very high global warming potentials with extreme longevity. The values below are the live IPCC AR6 figures (the reporting default) alongside the older AR5 values.
| PFC | Main source | Lifetime | AR5 GWP-100 | AR6 GWP-100 |
|---|---|---|---|---|
| CF₄ (PFC-14) | Aluminium, semiconductors | ~50,000 yr | 6,630 | 7,380 |
| C₂F₆ (PFC-116) | Aluminium, semiconductors | ~10,000 yr | 11,100 | 12,400 |
| C₃F₈ (PFC-218) | Semiconductors | ~2,600 yr | 8,900 | 9,290 |
Live GWP values from the GreenCalculus data layer · lifetimes from IPCC AR6 · complete AR6 GWP dataset →
Because their lifetimes run to millennia, the 100-year GWP actually understates their true long-term impact — over a 500-year horizon PFC values are higher still. Heavier PFCs used in electronics, such as c-C₄F₈ and C₆F₁₄, carry similarly high GWPs. As with all gases, AR6 revised the values upward from AR5, so inventories on the older basis understate PFC emissions.
PFCs vs HFCs
PFCs and HFCs are both fluorinated greenhouse gases, often mentioned together, but they differ in ways that matter for both chemistry and policy.
| PFCs | HFCs | |
|---|---|---|
| Composition | Carbon + fluorine only (fully fluorinated) | Hydrogen + fluorine + carbon |
| Main source | Aluminium smelting, semiconductor fabrication | Refrigerant leaks (fridges, A/C, heat pumps) |
| Atmospheric lifetime | Thousands of years (CF₄ ~50,000) | Years to a few decades |
| Ozone impact | None | None |
| Main control regime | Climate agreements + industry programmes | Kigali Amendment phase-down |
The headline difference is time. HFCs are powerful but relatively short-lived, so cutting them buys near-term climate benefit quickly. PFCs are essentially permanent, so preventing them in the first place is the only real control — there is no waiting for them to decay.
PFCs in Greenhouse-Gas Accounting
In a corporate inventory, PFCs appear as process Scope 1 emissions — released directly by aluminium smelting or chip fabrication, rather than leaking from equipment like HFCs. The mass emitted is multiplied by the gas’s GWP to convert it to CO₂-equivalent, the common unit that lets it be summed with CO₂, methane, and nitrous oxide.
Given GWPs above 7,000, even modest PFC quantities dominate the CO₂e total from these processes — which is why aluminium and semiconductor firms track them closely. Our converters apply the live IPCC AR6 values under the GHG Protocol — for example CF₄ to CO₂e and C₂F₆ to CO₂e.
Common Confusions
- Confusing PFCs with HFCs. PFCs are fully fluorinated (carbon + fluorine only), longer-lived, and come from industry; HFCs contain hydrogen and come mostly from refrigerant leaks.
- Assuming Kigali covers PFCs. The Kigali Amendment phases down HFCs only. PFCs are addressed through climate agreements and industry reduction programmes, not Kigali.
- Underrating their permanence. With lifetimes of thousands of years, PFC emissions are effectively irreversible — there is no “later” in which they decay.
- Thinking they harm the ozone layer. Like HFCs, PFCs contain no chlorine and do not deplete ozone — their harm is purely climatic.
- Missing them in aluminium or chip inventories. PFCs are process emissions, not fuel or electricity, so they can be overlooked despite dominating a facility’s Scope 1 CO₂e.
- Using AR5 GWPs. AR6 raised PFC values and is the reporting default since 2023; older figures understate the impact.
Related Terms, Standards, and Tools
PFCs sit alongside HFCs among the fluorinated gases, are ranked by their global warming potential from IPCC AR6 — like methane and nitrous oxide — reported as process Scope 1 emissions under the GHG Protocol, and convertible to CO₂e with our PFC converters.
Frequently Asked Questions
Perfluorocarbons (PFCs) are a family of greenhouse gases made of only carbon and fluorine — fully fluorinated compounds such as CF₄ (tetrafluoromethane), C₂F₆ (hexafluoroethane), and C₃F₈ (octafluoropropane). Because they contain no hydrogen and no chlorine, they do not deplete the ozone layer, but they are extremely stable and long-lived, with atmospheric lifetimes of thousands of years and very high global warming potentials. They are emitted mainly from primary aluminium smelting and semiconductor manufacturing, and are one of the fluorinated “F-gases” covered by climate agreements and greenhouse-gas inventories.
Overwhelmingly from two industrial processes. The largest historical source is primary aluminium smelting, where PFCs (CF₄ and C₂F₆) are produced during “anode effects” — process upsets when the alumina in the electrolytic bath runs low. The second major source is semiconductor manufacturing, where PFCs are used to etch circuits and clean equipment and a fraction escapes unreacted. Unlike HFCs, which leak from refrigeration and air-conditioning, PFCs are process emissions, so both industries run dedicated programmes to reduce them.
Under IPCC AR6, the 100-year global warming potentials are approximately: CF₄, 7,380 [GreenCalculus gwp.PFC_CF4.ar6_100]; C₂F₆, 12,400 [GreenCalculus gwp.PFC_C2F6.ar6_100 · IPCC AR6 WGI Ch 7 Table 7.SM.7 (2021) — AR6 GWP-100]; and C₃F₈, 9,290 [GreenCalculus gwp.PFC_C3F8.ar6_100 · IPCC AR6 WGI Ch 7 Table 7.SM.7 (2021) — AR6 GWP-100]. In other words, one tonne of CF₄ traps as much heat over a century as roughly 7,380 tonnes of CO₂ [GreenCalculus gwp.PFC_CF4.ar6_100]. These are the reporting defaults, and they are higher than the older AR5 values. Because PFCs persist for thousands of years, their impact over longer horizons is greater still. The full dataset for every gas is in our IPCC AR6 GWP values.
Thousands of years. CF₄ has an atmospheric lifetime of around 50,000 years, C₂F₆ about 10,000 years, and C₃F₈ roughly 2,600 years. Because there are no significant natural processes that break them down in the lower atmosphere, PFCs are effectively permanent on any human timescale — a tonne emitted today will still be warming the planet for millennia. This is the key difference from HFCs, which last years to decades, and it means the only meaningful control for PFCs is to prevent the emissions in the first place.
Both are fluorinated greenhouse gases that spare the ozone layer, but they differ in chemistry, source, and longevity. PFCs are fully fluorinated — carbon and fluorine only — and come from aluminium smelting and semiconductor manufacturing, with lifetimes of thousands of years. HFCs also contain hydrogen, come mainly from refrigerant leaks, and last only years to decades. Policy differs too: HFCs are being phased down under the Kigali Amendment, whereas PFCs are managed through climate agreements and industry reduction programmes. In short, HFCs are shorter-lived refrigerants; PFCs are near-permanent industrial gases.
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