Decarbonizing the aviation system using bio-jet fuel
Figure 1: A comparison of life-GHG emissions in jet fuel for fossil fuel and bio-jet fuel produced using various conversion technology pathways. Utrecht University
Feb. 16, 2018 - Unlike automobiles and other light transport vehicles, airplanes face technical, safety and infrastructure challenges for being powered by electricity derived from renewable sources such as wind and power, hydrogen or fuel cell technology and will need a more energy-dense renewable fuel (i.e. bio-jet fuel). Electric aircraft are, currently, very small and are powered by batteries or photovoltaic solar panels. However, the weight and duration of power are obstacles. Electric hybrid planes will likely be utilized before full electric airplanes. Decarbonizing the aviation sector via switching to more energy-dense biofuel could, however, play an important role in reducing atmospheric CO2 concentration across the country while transitioning to a future energy system.
Three common pillars identified by signatories of Paris Agreement, are energy efficiency, decarbonizing electricity generation and fuel switching. Aviation sector is one of the decentralized emitter of greenhouse gases (GHG) in the world. Decarbonizing transportation system can be achieved via fuel switching. Given this sector’s growing contribution to global CO2, aviation could play a key role in meeting the global climate targets. While major airlines continue to demand the use of narrow range of hydrocarbon jet fuel for the foreseeable future, some European airlines and aircraft manufacturers have committed to voluntary CO2 reduction targets.
According to a 2015 report from the Canadian Airport Council, Canadian passenger traffic forecast is estimated a market growth to about 216 million passengers by 2033, a 50 per cent increase compared to 122 million in 2013.
Life cycle carbon emissions
Emissions of passenger aircraft per passenger kilometre (km) vary, on average, from 114 g CO2 equivalent per km for long distance flights to about 260 g CO2 equivalent per km for short distance flights. In our view, GHG emissions can be reduced by one to two per cent annually through improved engines’ fuel efficiency, aircraft redesign, airport modifications, new and efficient navigational system, etc. However, significant reduction in GHG emissions requires airlines to use more sustainable alternative jet fuel such as bio-jet in the long-term.
According to a report from Utrecht University, the use of bio-jet reduces net life-cycle carbon emissions as it enables reusing and recycling carbon that is already in the biosphere to create the fuel. Figure 1 compares life-GHG emissions in jet fuel for fossil fuel and bio-jet fuel produced using various conversion technology pathways. As shown, most pathways yield greenhouse gas emissions reductions exceeding 60 per cent compared to fossil jet fuel. However, some fail to reach a 50 per cent reduction threshold due to high greenhouse gas emissions associated with feedstock cultivation (e.g. fertilizer) or hydrogen consumption. As shown, on a well-to-wheel basis the bio-jet can significantly reduce GHG emissions compared to conventional jet fuel (if emissions from land use change can be avoided) and achieving such a target requires increase in bio-jet production and consumption by the aviation sector.
Bio-jet fuel in Canada
Although bio-Jet has been produced on a limited scale, the transportation fuel industry is very competitive, making it very difficult for producers of bio-jet to be economically competitive with fossil fuel, particularly due to low oil prices. Besides the capital cost of building large-scale production facilities, the difficulty of establishing new supply chains, the projected operating costs associated with proven feedstock and the technical difficulties with conversion processes are all posing challenges to market access. In addition, the oil industry has been conservative in its engagement and support of alternative jet fuel development. As fossil-derived jet fuel is likely to be much cheaper to produce for quite some time into the future, effective policies will be required for all aspects of bio-jet fuel development, from encouraging production of feedstocks through to the production and use of the bio-jet fuel itself. In the short term, most commercial bio-jet fuels will likely come from oleo chemical feedstocks, such as tallow, used cooking and palm oils. However, in the mid-to-long term, cellulosic feedstocks will likely supersede these lipids/fats as the main source of bio-jet fuel because they are not in direct competition with food, are in large supply, and will likely be less expensive.
With the support from companies such as Boeing, Bombardier, Air Canada, West Jet and NORAM and from the funding agencies Green Aviation Research and Development Network, NSERC, International Energy Agency (IEA) and BiofuelNet, The Forest Products Biotechnology/Bioenergy group at University of British Columbia have been assessing the potential of producing bio-jet fuel from forest residues. According to IEA Bioenergy – Task 39, the group is co-ordinating the efforts to determine whether a bio-jet production facility could be commercialized in British Columbia using local forest residues. Utilizing vast biomass resource as well as the existing energy and crude oil infrastructure in Alberta, can provide the opportunity to cost-effectively decarbonize the aviation sector via producing and blending a more energy dense biofuel in conventional jet fuel.
Benefits, barriers and challenges
Commercialization of bio-jet offers potential societal benefits by expanding energy sources, reducing GHG and other emissions that impact air quality and economic development. Many of these benefits are the result of agricultural opportunities that are not accessible to food crops. For significant reduction in GHG emissions from flights, second generation feedstock should be utilized, i.e. oils from nonfood crops or waste products – such as animal fat, used cooking oil, forestry and agricultural waste, and household trash. Having a variety of feedstocks makes it easier to produce renewable jet fuel around the world because refineries can use the feedstock most available in their region. The majority of the bio-jet could be distributed, i.e. located close to feedstock supplies, to keep costs and emissions minimum.
According to a presentation by MIT at the 2016 IEA Bioenergy workshop, the need for annual growth in alternative jet fuel production out to 2050 is estimated to be on the order of 5-15 Mt/yr (100-300 kbpd) in global biofuel production capacity to achieve between 10 to 20 per cent emission reduction by 2050. This would require an estimated $6-$50 billion capital investment per year. The main economic challenges are feedstock availability and price, lack of multi-stakeholder collaboration, techno-economic factors, accelerated technology development and demonstration projects funding for both small and large start-ups. The technical challenges are not limited to feedstock development, novel conversion technology with lower energy use, fuel testing and certification process by ASTM but also policies like renewable fuel standard, sustainability assessment tools and models. Certification of a bio-jet technology through ASTM standard specification can take years and includes rigorous testing and evaluation. For now, fuel producers lack the funds, policy support, and renewable fuel incentives to build more factories and increase production volumes, though there are signs that the industry is ready to grow.
As aviation is international in nature, Canada should take the lead the global policies specific to bio-Jet as it is crucial to encourage larger-scale commercialization and use of the same. Technological development of advanced bio-fuels should be done through multi-stakeholder alliance including equipment manufacturers, airlines, fuel producers and airports. Carbon offsets continue to contribute to global emission reductions and it not clear whether it will accelerate the bio-jet development.
By 2050, the global aviation industry aims to combat climate change by reducing net carbon emissions by 50 per cent compared with 2005 levels. That’s a commitment to cut one-tenth the emissions projected for 2050. Improved engine efficiency and aircraft aerodynamics will provide some reductions. But transitioning to fully renewable jet fuel is key to meeting the targets suggested by the International Air Transport Association (IATA). The international nature of aviation will require global coordination of policy makers and also involvement of organization like ICAO. According to a research in Penn States’ College of Agricultural Science, in North America, several policy initiatives are pushing bio-jet fuel use in the states. One of them is EPA's Renewable Fuel Standard that, through a rather complex system, ultimately provides credits for cellulosic biofuels, up to $2 a gallon. The second is, in certain markets like California and Oregon, a low-carbon fuel standard that provides credit for low-carbon-emitting fuels such as bio-jet fuel.
Policy makers should play an active role to help bio-jet in the same evolutionary pathway like bio-ethanol and bio-diesel. Key policy areas to focus are mandated bio-jet blend like ethanol in gasoline, support commercialization of bio-jet through incentives and tax credits, enhance production and use through the entire supply chain from feedstock supply to distribution with initiatives like European Union Initiative Towards sustainable Kerosene for Aviation (ITAKA) project and industry and consumers play a part in expand the production and use e.g., Fly Green Fund and other corporate programs that encourage customers to cover the price of using premium bio-jet.
For more details, technical discussions and reference, please visit www.enscitech.ca/decarbonizing-aviation-sector/
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