Unsaturated polyester resins: Emissions
Styrene, glycols and anhydrides carry the carbon
What this tab covers The greenhouse-gas footprint per tonne, split by lifecycle phase (feedstock, production, movement, use, end of life), the global total, other environmental impacts, levers and low-carbon routes, India's position, and where the investment opportunity lies. Emission intensity 2.80 t CO2e per t range 2.3-3.5 · indicative (basis: 0.35 t styrene x 2.8 + 0.27 t propylene glycol x about 2.4 + 0.26 t phthalic anhydride x about 1.5 + 0.18 t maleic anhydride x about 2.0, plus about 0.4 t for batch processing and transport) Global emissions per year 19.0 Mt CO2e per year 2024 · 2.8 t CO2e/t x about 6.8 Mt (indicative)Per t of liquid UPR (with styrene), cradle-to-gate. Intensity: derived from styrene and PO tiles; anhydride footprints indicative. Global total: derived.
Share of footprint by lifecycle phase
Feedstock 85% Production / process 11% Movement 4%Footprint by lifecycle phase
| Phase | Intensity | Share | Main sources of emissions | Notes | Source |
|---|---|---|---|---|---|
| Feedstock | about 2.4 t CO2e per t | 85% | Styrene (about 1.0 t), glycols (about 0.65 t), anhydrides (about 0.75 t) | derived | |
| Production / process | about 0.3 t CO2e per t (indicative) | 11% | Gas or thermal oil heating of batch reactors for 10-20 hours | indicative | |
| Movement | about 0.1 t CO2e per t (indicative) | 4% | Road and short-sea freight in drums | indicative | |
| Use | styrene VOC emissions during moulding | – | Open moulding releases part of the styrene as VOC (indicative) | Light, corrosion-free pipes and car parts can save energy in use | indicative |
| End of life | about 2.3 t CO2 per t of resin if incinerated (indicative) | – | Thermoset composites are landfilled or co-processed in cement kilns | Glass and filler go into clinker; resin acts as fuel (indicative) | indicative (about 63% carbon) |
Other environmental impacts
Styrene exposure for workers; dust from cutting composites; composite waste that cannot be remelted; silica dust in engineered stone fabrication (a serious silicosis risk for stone workers).
Levers to cut emissions
- Recycled-PET glycolysate and bio-glycols in the polyester
- Low-styrene and styrene-free reactive diluents
- Closed moulding (infusion, RTM, SMC) to cut VOCs
- Cement kiln co-processing and mechanical recycling of composite waste
- Renewable heat for batch reactors
India
No Indian UPR footprint is published. Indian resin relies on imported styrene and PG, so most emissions occur abroad. The main domestic lever is in use: GRP pipes and tanks for water supply and sewage, and composite waste handling (indicative).
Emission figures are indicative global averages from the life-cycle studies named; actual footprints vary widely by site, energy mix and method.Low-carbon routes
| Route | Intensity | Cost premium | Status | Source |
|---|---|---|---|---|
| Recycled-PET-based UPR | not published; lower than ortho (indicative) | small or none when flake is cheap (indicative) | commercial at several producers (indicative) | indicative |
| Bio-based UPR (bio-PG, bio-succinic or itaconic acid) | not published | premium (indicative) | small volumes | indicative |