国际可再生资源机构-利用可再生能源实现零排放：生物喷气燃料（英）-2021_96页_2mb

Summary of "Reaching Zero with Renewables: Biojet Fuels"

Core Content

This report, published by the International Renewable Energy Agency (IRENA) in 2021, outlines the role of biojet fuels in achieving the decarbonisation of the aviation sector by 2050. It highlights the need for sustainable aviation fuels (SAFs) as a critical component in reducing the carbon intensity of aviation, which currently accounts for 2% of global CO₂ emissions and 12% of all transport emissions. The report also discusses the challenges and opportunities in scaling up biojet production and the importance of supportive policies and technological innovation.

Main Points

Aviation Emissions and Climate Goals

• Aviation emitted 915 million tonnes of CO₂ in 2019, projected to double by 2050 under a business-as-usual scenario.
• The sector has committed to a 50% reduction in CO₂ emissions by 2050, but this may not be sufficient to meet net-zero goals, especially if offsetting plays a large role.
• IRENA's 1.5°C Scenario (1.5-S) projects that aviation emissions need to fall by about 90% by 2050 to align with the goal of limiting global temperature rise to no more than 1.5°C.

Biojet Fuels as a Decarbonisation Tool

• Biojet fuels, derived from biomass, are the most approved type of sustainable aviation fuel currently available.
• They can be produced from various feedstocks, including used cooking oils (UCO), which are a key source.
• Current biojet production is limited, with global output at about 140 million litres in 2019, up from 7 million in 2018.
• Biojet fuels are typically blended with fossil jet fuel in low ratios, and their cost is 3–6 times higher than conventional jet fuel.

Technology Pathways

• The main pathway for biojet fuel production is the hydrotreatment of fats, oils, and greases (FOGs), known as HEFA (hydrotreated esters and fatty acids) or HVO (hydrotreated vegetable oils).
• Other technologies, such as gasification, pyrolysis, and hydrothermal liquefaction (HTL), are under consideration for long-term production.
• Advanced biojet fuels from non-food biomass are seen as more sustainable and less carbon-intensive than those from food-based feedstocks.

Policy and Market Considerations

• Policies are essential to create market demand and support the development of biojet fuels.
• Current transport policies that promote low-carbon fuels need to be adapted for aviation.
• A low-carbon fuel standard and incentives such as tax credits and exemptions could help bridge the cost gap between biojet and conventional jet fuels.
• The report emphasizes the need for regulatory frameworks that support the commercialisation of biojet technologies and ensure their sustainability.

Challenges

• The high cost of feedstocks and production infrastructure is a major barrier to biojet scale-up.
• The limited availability of sustainable feedstocks, such as UCO, and the competition with other applications (e.g., food production) pose challenges.
• The long lifespan of aircraft (20–35 years) means that technological alternatives like electric or hydrogen-powered planes will not significantly reduce emissions in the short to medium term.

Long-Term Prospects

• To meet 2050 targets, large volumes of biojet fuel and e-fuels (synthetic fuels) will be required.
• IRENA estimates that over 200 billion litres of biojet fuel may be needed annually by 2050 under the 1.5°C Scenario.
• The cost of biojet is expected to decrease over time as more facilities come online and supply chains become more efficient.
• The report calls for increased investment in biojet production, estimated at USD 5 billion per year, and for policies that support both "market pull" and "technology push".

Key Information

• Current Biojet Production: Approximately 140 million litres per year (2019), mainly from UCO via HEFA/HVO processes.
• Future Demand: Over 100 billion litres per year of biojet may be needed by 2050 to meet emission reduction targets.
• Cost: HEFA-based biojet fuel costs around USD 2124 per tonne (USD 1.7 per litre) in 2020, significantly higher than conventional jet fuel.
• Feedstock Availability: UCO and other waste oils are the most readily available feedstocks, but more sustainable sources such as lignocellulosic biomass, algae, and waste gases are also under exploration.
• Policy Recommendations:
  • Implement low-carbon fuel standards.
  • Encourage the repurposing of oil refineries for biofuel production.
  • Provide financial incentives and tax credits to support biojet development.
  • Establish effective feedstock and supply chain policies to ensure sustainability and cost-effectiveness.

Conclusion

Biojet fuels are a key solution for decarbonising the aviation sector, especially in the short to medium term. However, significant investment, supportive policies, and sustainable feedstock supply chains are essential to achieve the necessary scale and cost competitiveness. The report highlights the importance of integrating biojet into broader climate strategies and ensuring that the aviation industry aligns with global net-zero goals.