Green Junction by Julie Peller, Ph.D.
If you take the time to calculate your personal carbon footprint, you might find that airline travel elevates your carbon dioxide emissions far more than other activities. According to the International Energy Agency (IEA), the global carbon dioxide emissions from air travel are only 2% of the energy sector emissions but are rising. The agency indicates that newer aircraft are up to 20% more efficient than older models, but the growth in airline travel cancels out these emission reductions. Many companies in the airline industry have set a goal of net zero emissions, processes that balance the amount of greenhouse gases removed with the amount released. They hope to achieve this by 2050 but have a long way to go.
According to S&P Global, air travel burns 400 billion liters of jet fuel annually. Ways to reduce fuel consumption include lighter-weight construction materials, more efficient travel routes, and optimized aerodynamics. When you purchase an airline ticket, you may notice information about the amount of carbon dioxide equivalents you add to the atmosphere, an indication of the efficiency of your travel. The other part of the plan to reach net zero emissions is a switch to sustainable aviation fuels (SAF). These fuels are made from renewable raw materials instead of fossil fuels. Currently, these fuels constitute only 0.15% of the global jet fuel.
Sustainable aviation fuels are currently made from plant and animal oils, with expectations of producing the fuel from bio-based ethanol and methanol. Other potential sources include portions of food and yard waste, wood waste, and agricultural waste, but many of these materials can be composted or recycled. More technological approaches for future SAF may include carbon captured from air (carbon dioxide) and/or hydrogen as fuel. While hydrogen burns cleanly since it produces water, the source of the hydrogen gas determines its overall sustainability, most of which is currently sourced from natural gas. This hydrogen fuel is termed gray or blue hydrogen, compared to the term green hydrogen. The latter is made in a sustainable way by passing electricity through water and not relying on fossil fuels.
Beware of the companies that boast SAF technologies that burn non-bio-based waste, such as plastics and other synthetic materials. These processes have been shown to be energy-intensive and release toxic emissions. Keep an eye out for advancing technology in batteries for aviation.
Julie Peller, Ph.D., is an environmental chemist (Professor of Chemistry at Valparaiso University ). Julie has been writing a weekly column for the past ~6 years called the Green Junction and is helping to move the call of Laudato Si to action forward. Her Research Interests are advanced oxidation for aqueous solutions, water quality analyses, emerging contaminants, air quality analyses, Lake Michigan shoreline challenges (Cladophora, water, and sediment contaminants), and student and citizen participation in environmental work.
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