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- Dahal, Karna, 1984, et al.
(author)
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Reviewing the development of alternative aviation fuels and aircraft propulsion systems
- 2020
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Conference paper (other academic/artistic)abstract
- Alternative aviation fuels such as bio-jet fuels, liquid natural gas (LCH4), hydrogen (H2), electro-jet fuels and direct electricity use play an important role in decarbonizing the aviation sector. New aircraft propulsion systems are being developed but low-blending of fuels is possible for some options. It is imperative to understand the technical, environmental and economic performance of the different alternative aviation fuels and the new engine and propulsion technologies for the utilization of these fuels. We have reviewed various literature to map the current status of development on alternative aviation fuels and related aircraft propulsion systems in relation to different perspective such as their cost and technical maturity. There are several challenges related to the design and implementation of the fuels and new propulsion systems. For instance, the volumetric energy content of alternative fuels is lower than the conventional aviation fuels which requires larger fuel storage tanks. Despite the advantageous environmental performance, both the bio-jet and electro-jet fuels are currently not economically competitive. Yet, studies forecast that increased use of alternative aviation fuels is possible after modifications of engines, fuel storage tanks and improvements of the aerodynamics of aircraft and by introducing subsidies and/or carbon taxes on conventional jet fuels.
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| 2. |
- Dahal, Karna, 1984, et al.
(author)
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Techno-economic review of alternative fuels and propulsion systems for the aviation sector
- 2021
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In: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1879-0690 .- 1364-0321. ; 151
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Research review (peer-reviewed)abstract
- Substitution of conventional jet fuel with low-to zero-carbon-emitting alternative aviation fuels is vital for meeting the climate targets for aviation. It is important to understand the technical, environmental, and economic performance of alternative aviation fuels and prospective engine and propulsion technologies for future aircraft. This study reviews alternative fuels and propulsion systems, focusing on costs and technical maturity, and presents conceptual aircraft designs for different aviation fuels. The cost review includes minimum jet fuel selling price (MJFSP) for alternative aviation fuels. Direct operating cost (DOC) is estimated based on the conceptual aircraft designs and the reviewed MJFSP. The DOCs for bio-jet fuel (5.0–9.2 US cent per passenger-kilometer (¢/PAX/km)), fossil and renewable liquefied hydrogen (5.9–10.1 and 8.1–23.9 ¢/PAX/km, respectively), and electro-methane and electro-jet fuel (5.6–16.7 and 9.2–23.7 ¢/PAX/km, respectively) are higher than for conventional jet fuel (3.9–4.8 ¢/PAX/km) and liquefied natural gas (4.2–5.2 ¢/PAX/km). Overall, DOC of renewable aviation fuels is 15–500 % higher than conventional jet fuels. Among the bio-jet fuels, hydroprocessed esters and fatty acids (23–310 $/GJ) and alcohol-to-jet (4–215 $/GJ) pathways offer the lowest MJFSPs. The implementation of alternative fuels in existing aircraft engines and the design and development of appropriate propulsion systems and aircraft are challenging. The overall cost is a key factor for future implementation. Bio-jet fuel is most promising in the near term while hydrogen and electrofuels in the long term. The level of carbon tax on fossil jet fuels needed for the latter options to be competitive depend on the hydrogen production cost.
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| 3. |
- Wikner, Anna, et al.
(author)
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Lower bone strength in young patients with Fontan circulation compared to controls
- 2024
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In: Cardiology in the Young. - : Cambridge University Press. - 1047-9511 .- 1467-1107.
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Journal article (peer-reviewed)abstract
- Objectives: Previous reports indicate bone deficits in patients with Fontan circulation. However, the consequences of these deficits on bone strength and when these changes occur are unclear.Aim: To compare the tibial bone strength-strain index between young patients (6-19 years) with Fontan circulation and age- and sex-matched controls, and to determine strength-strain-index in subgroups of children (6-12 years) and adolescents (13-19 years) versus controls.Method: The tibia was examined with peripheral quantitative CT. Based on the assessed data, bone strength-strain index was calculated in the lateral and anterior-posterior directions.Results: Twenty patients with Fontan and twenty controls (mean age 13.0 ± 4.4 years; 50% females) were examined. Patients had a lower strength-strain index in the lateral direction compared to controls (808.4 ± 416.8mm3 versus 1162.5 ± 552.1mm3, p = 0.043). Subgroup analyses showed no differences regarding strength-strain index in children (6-12 years) with Fontan circulation compared to controls. However, the adolescents (13-19 years) with Fontan circulation had lower strength-strain indexes in both the lateral and anterior-posterior directions compared to controls (1041.4 ± 299.8mm3 versus 1596.4 ± 239.6mm3, p < 0.001, and 771.7 ± 192.4mm3 versus 1084.9 ± 215.0mm3, p = 0.004). When adjusted for height, there were differences between patients (6-19 years) and controls in strength-strain indexes in both the lateral and anterior-posterior directions. In subgroup analyses, the results remained robust.Conclusion: Young patients (6-19 years) with Fontan circulation have a lower strength-strain index in the tibia compared to controls. Subgroup analyses show that this deficit is mainly driven by the differences in adolescents (13-19 years), which might suggest that bone strength decreases with age.
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