The Future of Aviation: Sustainable Fuels on the Horizon

This article highlights one of the major problems with environmentally-friendly solutions to existing problems. In this case, the BBC look at whether sustainable aviation fuels are likely to succeed. The issue is that they're currently expensive, and cannot be produced at scale. However, both the UK and the EU have introduced targets for sustainable fuel use as a proportion of total aviation fuels.

In the outskirts of Sheffield, researcher Ihab Ahmed is at the forefront of a revolution in aviation. Within the Sustainable Fuels Innovation Centre (SAF-IC) at Sheffield University, Ahmed tests synthetic fuels on a modified jet engine, originally designed as an auxiliary power unit for commercial airliners. This cutting-edge research facility is dedicated to developing and evaluating sustainable aviation fuels (SAFs), synthetic alternatives to traditional fossil fuels that are made from renewable sources like waste cooking oils, agricultural residues, and captured carbon dioxide.

Unlike fossil fuels, burning SAFs does not increase the overall carbon dioxide load in the atmosphere. The carbon released when these fuels are burned was recently removed from the atmosphere by plants or chemical processes, making SAFs a potential game-changer for reducing the aviation industry's carbon footprint. Beyond carbon dioxide, these fuels also reduce harmful particulates and other pollutants that affect air quality and human health.

Aviation's Environmental Challenge

The aviation industry faces a major challenge: how to continue growing while reducing its environmental impact. Forecasts from Airbus and Boeing indicate that the global airliner fleet will more than double in the next two decades, driven by rising demand for air travel in emerging markets like India and China. Meanwhile, the International Air Transport Association has committed to reaching net zero carbon emissions by 2050. Achieving this will require substantial innovation and investment in new technologies.

Replacing older aircraft with more fuel-efficient models will help, but it won't be enough. New technologies like hydrogen power and electrification are promising, but significant hurdles remain. Hydrogen, for instance, is difficult to store and transport, requiring either high pressure or extremely low temperatures. Additionally, sustainable hydrogen production from renewable sources is currently limited. Batteries, another potential solution, are currently too heavy for use in large aircraft or long-haul flights.

This is where sustainable aviation fuels come in. Unlike hydrogen or batteries, SAFs can be used in existing aircraft with minimal modifications. Recent demonstrations, such as Virgin Atlantic's transatlantic flight powered entirely by SAF, show that the technology is viable. However, there are still limitations: current regulations allow SAFs to be blended with conventional jet fuel, with the SAF component not exceeding 50%.

Scaling Up Sustainable Fuel Production

Despite their promise, SAFs face significant challenges in scaling up. Currently, SAFs account for just 0.05% of the fuel used in the European Union, and they cost three to five times more than conventional jet fuel. Governments and regulators are beginning to address these issues with mandates and subsidies. For example, the UK has introduced a SAF mandate requiring 2% of all jet fuel supplied to be SAF by next year, increasing to 10% by 2030 and 22% by 2040. The EU has set similar targets, aiming for 63% SAF use by 2050.

Production methods for SAFs are diverse. They can be derived from biomass sources, including waste oils, agricultural residues, and even human waste. However, not all feedstocks are ideal; some could contribute to deforestation or compete with food production. An alternative approach is the power-to-liquid process, which uses renewable electricity to split water and carbon dioxide, then combines the resulting hydrogen and carbon to create liquid fuel. While this method could theoretically produce limitless supplies of SAF, it is currently expensive and energy-intensive, requiring a significant increase in renewable electricity production and carbon capture.

Environmentalists argue that the aviation industry's commitment to sustainable fuels is not sufficient, pointing out that many new planes currently on order will continue to rely on fossil fuels for decades. However, recent announcements at the Farnborough Airshow suggest that the industry is taking steps in the right direction. A consortium of major companies, including Airbus, AirFrance-KLM, and Qantas, has committed $200 million to invest in SAF-producing projects, while Boeing has partnered with Clear Sky to promote a novel SAF production method pioneered by the British company Firefly, which uses human waste as a feedstock.

Conclusion

The transition to sustainable aviation fuels is a critical step in reducing the aviation industry's environmental impact. While the road ahead is challenging, with significant technical and economic hurdles to overcome, the potential benefits of SAFs make them a promising solution for a more sustainable future in air travel.

Glossary of Key Economic Terms

• Biomass: Organic material that comes from plants and animals, and can be used as a renewable energy source.
• Carbon Capture and Storage (CCS): A technology used to capture and store carbon dioxide emissions from sources like power plants, preventing CO2 from entering the atmosphere.
• Economies of Scale: Cost advantages that businesses obtain due to the scale of their operation, with cost per unit of output generally decreasing with increasing scale as fixed costs are spread out over more units.
• Feedstock: Raw material used to supply or fuel a machine or industrial process; in the context of SAFs, feedstocks can include waste oils, agricultural residues, or captured CO2.
• Fossil Fuels: Natural fuels such as coal, oil, and gas formed from the remains of living organisms that release carbon dioxide when burned.
• Net Zero: The balance between the amount of greenhouse gas emissions produced and the amount removed from the atmosphere; achieving net zero means that any emissions are balanced by absorbing an equivalent amount from the atmosphere.
• Power-to-Liquid (PtL): A technology that converts electricity (preferably renewable) into liquid fuels, typically by splitting water into hydrogen and oxygen, and then combining the hydrogen with carbon dioxide to create hydrocarbons.
• Renewable Energy: Energy from sources that are naturally replenishing and sustainable over the long term, such as solar, wind, and hydroelectric power.
• Sustainable Aviation Fuel (SAF): A type of fuel that is produced from renewable resources and has a lower carbon footprint than traditional jet fuel.
• Synthetic Fuels: Fuels made from chemical processes that do not rely on natural fossil fuel extraction, often created from biomass or through chemical synthesis involving captured CO2 and renewable hydrogen.

Retrieval Questions for A-Level Students

1. What are sustainable aviation fuels (SAFs) and how do they differ from conventional jet fuels?
2. Why is the aviation industry interested in using SAFs, and what are some of the environmental benefits?
3. What are the main challenges associated with scaling up the production of SAFs?
4. How do hydrogen and battery technologies compare to SAFs for use in aviation?
5. What are some of the current government initiatives to increase the use of SAFs in aviation?

This article highlights the potential of sustainable aviation fuels to transform the aviation industry, addressing both the opportunities and the significant challenges that lie ahead.