Aviation accounts for two percent of global greenhouse gas emissions. Two percent may not sound like much, but if aviation were a country, these levels would make it the seventh largest emitter in the world. Moreover, these emissions are expected to rise significantly in coming years. In the United States, the Federal Aviation Administration estimates U.S. aviation emissions will rise by 100 percent by 2050 under a “business-as-usual” scenario, due primarily to increases in air travel.

Stakeholders are taking these projections seriously, at the national and international level. The U.S. Environmental Protection Agency recently issued an endangerment finding for aircraft, indicating that greenhouse gas emissions from aircraft are hazardous to public health. This finding requires the EPA to begin crafting regulations for aircraft emissions. At the global level, the International Civil Aviation Organization (ICAO) will be making decisions to finalize a market-based measure, designed to help stabilize future emissions at projected 2020 levels, at their meeting beginning September 27 in Montreal. Biofuels will be able to play a large part in meeting these standards and reducing overall aviation emissions.

The Importance of Biofuels for Aircraft

Projections suggest that improvements in aircraft efficiency will only go so far in decreasing emissions. Much of the required emissions reductions will have to be met by improving the fuel itself. Aircraft are difficult to decarbonize, since they require energy-dense fuels. While strides in electric and hybrid jets have made progress, it’s assumed that liquid fuels will be required for aircraft for the foreseeable future. As airlines look to decarbonize their fuel sources, biofuels are the natural choice.

Various feedstocks can be used to make sustainable bio-based jet fuel, including crop residues, cereal and sugar crops, oils and fats, algae, and cellulosic plant matter. ICAO estimates that replacing traditional kerosene jet fuel with jet fuel produced from an energy crop like miscanthus can reduce greenhouse gas emissions by as much as 90 percent, assuming no land use change. Land use change could have a positive or negative effect—converting annual crop land to perennials could increase soil carbon storage, while replacing forested land with annual crops would decrease soil carbon. The global trade group International Air Transport Association (IATA) has said that the use of biofuels in aircraft, compared to traditional jet fuel, could reduce CO2 lifecycle emissions by up to 80 percent.

In addition to reducing greenhouse gas emissions, jet fuel containing biofuels also has lower volumes of aromatics. Aromatics have been shown to have negative health effects, including developmental, reproductive, and immunological problems. Combustion of aromatics also contributes to ultra-fine particulate matter and polycyclic aromatic hydrocarbons (PAHs), both of which lead to health problems as well. Blending biofuels into traditional kerosene jet fuel can help to reduce some of these health concerns.

Progress in Alternative Aviation Fuels

ICAO reports that as of July, more than 2,500 flights have been powered by bio-based jet fuels. While this is an impressive start, the aviation industry will need to make much greater progress to combat rapidly rising emissions. Several recent news stories have highlighted the advancements that are being made to increase the use of alternative fuels, including biofuels, in aviation.

The U.S. Navy, which has been working to increase biofuels use across the board, this week ran test flights using 100 percent biofuel. Already, Navy ships and aircraft have used up to 50 percent biofuels. Increasing biofuels is part of the Navy’s efforts to use at least 50 percent renewable energy by 2020. Dennis McGinn, assistant secretary for energy, installations and environment, said of the improvements, “This will be part of the new normal. We’ll be putting biofuel blends into our ships in the form of marine diesel. We’ll be putting it into our helicopters and our jet aircraft.”

Additionally, nonprofit Advanced Biofuels USA received a grant of nearly $17,000 from USDA to study the feasibility of creating sustainable jet fuel from energy beets. The group will also analyze the possibility of using the phosphate uptake of energy beets as a method to address nutrient loading in the Chesapeake Bay.

Two European airlines, KLM and Lufthansa, have recently signed contracts with U.S. biofuel companies. KLM CEO Pieter Elbers said, “Sustainable biofuel is currently one of the most effective ways to reduce CO2 emissions in the airline industry… we have been able to take this step, giving a further impulse to the consistent production of biofuel.” 

Virgin Atlantic was also in the news this week for creating a sustainable waste-to-energy fuel from steel mill waste. The airline reports that the fuel, which is made from ethanol, reduces emissions by as much as 65 percent compared with traditional jet fuel. Lanzatech, the firm working with Virgin Atlantic, estimates that scaling up this technology could allow them to meet 19 percent of global demand.

Standards and Initiatives at the National and International Level

During its 2010 meeting, the International Civil Aviation Organization Assembly set an organizational goal of achieving carbon-neutral growth after 2020. The market-based measure, which will be discussed and potentially finalized at their meeting beginning September 27, can go a long way toward reaching that goal. As the ICAO Assembly meets once every three years, this upcoming meeting is a big opportunity to get international aviation on the right track towards reducing emissions.

The market-based measure (MBM) proposed by ICAO would begin with the voluntary participation of countries from 2021 to 2026. Approximately 50 countries have already committed to participate, including the United States and China. In the second phase, beginning in 2027, participation would be mandatory for all countries except those exempted, which would include least developed countries.

ICAO’s market-based measure includes sustainable bio-based jet fuel. This will help to incentivize the further use of these fuels, allowing them to be more economically competitive. Additionally, there are several national initiatives underway to promote alternative fuels. In the United States, this includes the Commercial Aviation Alternative Fuels Initiative (CAAFI), Northwest Advanced Renewables Alliance (NARA), Sustainable Aviation Fuels Northwest (SAFN), Midwest Aviation Sustainable Biofuels Initiative (MASBI), and Farm-to-Fly.

Author: Rebecca Chillrud

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