Greenhouse Gas Emissions Assessment in Petroleum Refining Systems

Petroleum refineries rank among the largest industrial sources of greenhouse gas emissions, driven by energy-intensive operations such as crude distillation, catalytic conversion and steam cracking. Comprehensive assessment of these emissions requires a life-cycle perspective, encompassing upstream crude production, feedstock transport, refinery processes and downstream product distribution. Methodologies range from physics-based bottom-up estimators to top-down carbon accounting and bio-physical modelling. Allocation of emissions to specific products (for example, gasoline, diesel, petrochemical feedstocks and refinery hydrogen) employs mass-based, energy-based or economic-value approaches, each carrying implications for policy and regulatory compliance. Recent advances in high-resolution supply-chain tracing, data analytics and systems optimisation have revealed significant variability in emissions intensity both within and between refineries. Simultaneously, integration of heat and power networks, adoption of low-carbon process fuels, implementation of carbon capture technologies and shifts in product slate have emerged as the primary routes to emissions mitigation. At a global scale, targeted engagement with super-emitting facilities and refined quantification of “well-to-refinery-entrance” intensities can unlock gigatonne-scale savings, underscoring the strategic importance of refinery decarbonisation in meeting long-term climate goals.

Research from Nature Portfolio

Recent studies have employed high-fidelity datasets and optimisation algorithms to map “well-to-refinery-entrance” carbon intensities across global crude trade pathways. Results demonstrate a wide range of emissions intensities—spanning from approximately 4 to over 200 kg CO2-equivalent per barrel—with a volume-weighted average near 50 kg CO2-equivalent per barrel. By integrating these granular emissions profiles with supply forecasts under stringent climate scenarios, it has been shown that prioritising low-carbon crude pathways alone could realise between 1.5 and 6.1 Gt CO2-equivalent reductions by mid-century. These findings highlight the potential for non-capital-intensive mitigation through strategic crude sourcing and supply-chain transparency, offering an actionable complement to onsite energy-efficiency and carbon-capture investments.

Greenhouse Gas Emissions Assessment in Petroleum Refining Systems publication trend

The graph below shows the total number of articles in greenhouse gas emissions assessment in petroleum refining systems across all publications each year (not limited to Nature Index journals).

Technical terms

Carbon intensity: Emissions of CO2-equivalent per unit of energy output or product, expressed in kg CO2e per barrel or g CO2e per MJ.

Well-to-refinery entrance: Life-cycle segment covering crude extraction, transport and pre-refinery processing up to the refinery feed inlet.

Life cycle assessment: Systematic evaluation of environmental impacts across all stages of a product’s life, from extraction through processing to end use.

Allocation methods: Techniques for apportioning shared emissions among multiple outputs based on mass, energy content or economic value.

Decoupling index: Ratio indicating the relationship between economic growth and changes in GHG emissions, used to assess progress towards carbon peaking.

References

1. Analysis of standard and innovative methods for allocating upstream and refinery GHG emissions to oil products. Applied Energy (2017).
2. Carbon intensity of global crude oil trading and market policy implications. Nature Communications (2023).
3. Unraveling economic-environmental coupling in China's petrochemical industry towards carbon peaking. Resources Conservation & Recycling Advances (2024).
4. Global oil refining's contribution to greenhouse gas emissions from 2000 to 2021. The Innovation (2022).