Editing IPCC:AR6/WGIII/Chapter-10 (section)

== Appendix 10.3: Line of Sight for Feasibility Assessment ==

<div id="h1-14-siblings" class="h1-siblings"></div>

{| class="wikitable"
|-
! rowspan="2"|
! colspan="3"| '''Geophysical'''

|-
! '''Physical potential'''

! '''Geophysical recourses'''

! '''Land use'''

|-
| '''Demand reduction and mode shift'''

| +

| +

| +

|-
| ''Role of contexts''

| Adoption of Avoid Shift Improve approach along with improving fuel efficiency will have negligible physical constraints; they can be implemented across the countries.

| Reduction in demand, fuel efficiency and demand management measures such as Clean Air Zones and parking policies will reduce negative impact on land use and resource consumption – without any constraints in terms of available resources.

| Reduction in demand, increase in fuel efficiency and demand management measures will have a positive impact on land use as compared to ‘without’ them – no likely adverse constraints in terms of limited land use (such as decline in biofuel).

|-
| ''Line of sight''

| colspan="3"| Holguín-Veras, J. and I. Sánchez-Díaz, 2016: Freight Demand Management and the Potential of Receiver-Led Consolidation programs. ''Transp. Res. Part A Policy Pract.'' , '''84''' , 109–130, doi:10.1016/j.tra.2015.06.013.

Creutzig, F. et al., 2018: Towards demand-side solutions for mitigating climate change. ''Nat. Clim. Change'' , '''8(4)''' , 260–263, doi:10.1038/s41558-018-0121-1.

Rajé, F., 2017: ''Transport, Demand Management and Social Inclusion: The need for ethnic perspectives'' . Routledge, London, UK, 184 pp.

Dumortier, J., M. Carriquiry, and A. Elobeid, 2021: Where does all the biofuel go? Fuel efficiency gains and its effects on global agricultural production. ''Energy Policy'' , '''148''' , 111909, doi:10.1016/j.enpol.2020.111909.

|-
| '''Biofuels for land transport, aviation, and shipping'''

| +

| ±

| –

|-
| ''Role of contexts''

| Climate conditions are an important factor for bioenergy viability. Land availability constraints might be expected for bioenergy deployment.

| Land and synthetic fertilisers are examples of limited resources to deploy large-scale biofuels, however the extent of these restrictions will depend on local and context specific conditions.

| Implementing biofuels may require additional land use. However, it will depend on context and local specific conditions.

|-
| ''Line of sight''

| colspan="3"| Daioglou, V., J.C. Doelman, B. Wicke, A. Faaij, and D.P. van Vuuren, 2019: Integrated assessment of biomass supply and demand in climate change mitigation scenarios. ''Glob. Environ. Change'' , '''54''' , 88–101, doi:10.1016/j.gloenvcha.2018.11.012.

Roe, S. et al., 2021: Land‐based measures to mitigate climate change: Potential and feasibility by country. ''Glob. Change Biol.'' , '''27(23)''' , 6025–6058, doi:10.1111/gcb.15873.

|-
| '''Ammonia for shipping'''

| +

| +

| ±

|-
| ''Role of contexts''

| A global ammonia supply chain is already established; the primary requirement for delivering greater carbon emissions reductions will be through the production of ammonia using green hydrogen or CCS.

| The use of ammonia would reduce reliance on fossil fuels for shipping and is expected to reduce reliance on natural resources when produced using green hydrogen. The primary resource requirements will be the supply of renewable electricity and clean water to produce green hydrogen, from which ammonia can be produced.

| No major changes in land use for the vehicle. Increases may occur if the hydrogen is produced through electrolysis and renewable energy sources or hydrogen production with CCS.

|-
| ''Line of sight''

| colspan="3"| Bicer, Y. and I. Dincer, 2018: Clean fuel options with hydrogen for sea transportation: A life cycle approach. ''Int. J. Hydrogen Energy'' , '''43(2)''' , 1179–1193, doi:10.1016/j.ijhydene.2017.10.157.

Gilbert, P. et al., 2018: Assessment of full life-cycle air emissions of alternative shipping fuels. ''J. Clean. Prod.'' , '''172''' , 855–866, doi:10.1016/j.jclepro.2017.10.165.

|-
| '''Synthetic fuels for heavy-duty land transport, aviation, and shipping (e.g., DAC-FT)'''

| ±

| ±

| ±

|-
| ''Role of contexts''

| Fischer Tropsch chemistry is well established; pilot scale direct air capture (DAC) plants are already in operation;

– Does not qualify as a mitigation option except in regions with very low-carbon electricity.

| + Gasification can use a wide range of feedstocks; DAC can be applied in a wide range of locations – Limited information available on potential limits related to large input energy requirements, or water use and required sorbents for DAC.

| No major changes in land use for the vehicle. Potential increases in land use for electricity generation (especially solar, wind or hydropower) for CO 2 capture and fuel production; likely lower land use than crop-based biofuels.

|-
| ''Line of sight''

| Realmonte, G. et al., 2019: An inter-model assessment of the role of direct air capture in deep mitigation pathways. ''Nat. Commun.'' , '''10(1)''' , 3277, doi:10.1038/s41467-019-10842-5.

Liu, C.M., N.K. Sandhu, S.T. McCoy, and J.A. Bergerson, 2020: A life cycle assessment of greenhouse gas emissions from direct air capture and Fischer-Tropsch fuel production. ''Sustain. Energy Fuels'' , '''4(6)''' , 3129–3142, doi:10.1039/C9SE00479C.

Ueckerdt, F. et al., 2021: Potential and risks of hydrogen-based e-fuels in climate change mitigation. ''Nat. Clim. Change'' , '''11(5)''' , 384–393, doi:10.1038/s41558-021-01032-7.

| Realmonte, G. et al., 2019: An inter-model assessment of the role of direct air capture in deep mitigation pathways. ''Nat. Commun.'' , '''10(1)''' , 3277, doi:10.1038/s41467-019-10842-5.

|
|-
| '''Electric vehicles for land transport'''

| +

| ±

| ±

|-
| ''Role of contexts''

| Electromobility is being adopted across a range of land transport options including light-duty vehicles, trains and some heavy-duty vehicles, suggesting no physical constraints.

| Current dominant battery chemistry relies on minerals that may face supply constraints, including lithium, cobalt, and nickel. Regional supply/availability varies. Alternative chemistries exist; recycling may likewise alleviate critical material concerns. Similar supply constraints may exist for some renewable electricity sources (e.g., solar) required to support EVs. May reduce critical materials required for catalytic converters in ICEVs (e.g., platinum, palladium, rhodium).

| No major changes in land use for the vehicle. Potential increases in land use for electricity generation (especially solar, wind or hydropower) and mineral extraction, but may be partially offset by a decrease in land use for fossil fuel production; likely lower land use than crop-based biofuels, or technologies with higher electricity use (e.g., those based on electrolytic hydrogen).

|-
| ''Line of sight''

| IEA, 2021: ''Global EV Outlook 2021'' . International Energy Agency, Paris, France, 101 pp.

| Jones, B., R.J.R. Elliott, and V. Nguyen-Tien, 2020: The EV revolution: The road ahead for critical raw materials demand. ''Appl. Energy'' , '''280''' , 115072, doi:10.1016/J.APENERGY.2020.115072.

Xu, C. et al., 2020: Future material demand for automotive lithium-based batteries. ''Commun. Mater. 2020 11'' , '''1(1)''' , 1–10, doi:10.1038/s43246-020-00095-x.

IEA, 2021: ''The Role of Critical Minerals in Clean Energy Transitions'' . International Energy Agency, Paris, France, 287 pp.

Zhang, J. et al., 2016: Assessing Economic Modulation of Future Critical Materials Use: The Case of Automotive-Related Platinum Group Metals. ''Environ. Sci. Technol.'' , '''50(14)''' , 7687–7695, doi:10.1021/ACS.EST.5B04654.

Milovanoff, A., I.D. Posen, and H.L. MacLean, 2020: Electrification of light-duty vehicle fleet al.ne will not meet mitigation targets. ''Nat. Clim. Change'' , '''10(12)''' , 1102–1107, doi:10.1038/s41558-020-00921-7.

| Arent, D. et al., 2014: Implications of high renewable electricity penetration in the U.S. for water use, greenhouse gas emissions, land-use, and materials supply. ''Appl. Energy'' , '''123''' , 368–377, doi:10.1016/j.apenergy.2013.12.022.

Orsi, F., 2021: On the sustainability of electric vehicles: What about their impacts on land use? ''Sustain. Cities Soc.'' , '''66''' , 102680, doi:10.1016/J.SCS.2020.102680.

|-
| '''Hydrogen FCV for land transport'''

| +

| ±

| ±

|-
| ''Role of contexts''

| The use of fuel cells in the transport sector is growing, and will potentially be important in heavy-duty land transport applications.

| FCVs are reliant on critical minerals for manufacturing fuel cells, electric motors and supporting batteries. Platinum is the primary potential resource constraint for fuel cells; however, its use may decrease as the technology develops, and platinum is highly recyclable.

|
|-
| ''Line of sight''

| IEA, 2020: ''Global EV Outlook 2020'' . Paris, France, 276 pp.

| Hao, H. et al., 2019: Securing Platinum-Group Metals for Transport Low-Carbon Transition. ''One Earth'' , '''1(1)''' , 117–125, doi:10.1016/j.oneear.2019.08.012.

Rasmussen, K.D., H. Wenzel, C. Bangs, E. Petavratzi, and G. Liu, 2019: Platinum Demand and Potential Bottlenecks in the Global Green Transition: A Dynamic Material Flow Analysis. ''Environ. Sci. Technol.'' , '''53(19)''' , 11541–11551, doi:10.1021/acs.est.9b01912.

| Orsi, F., 2021: On the sustainability of electric vehicles: What about their impacts on land use? ''Sustain. Cities Soc.'' , '''66''' , 102680, doi:10.1016/J.SCS.2020.102680.

|}

{| class="wikitable"
|-
! rowspan="2"|
! colspan="4"| '''Environmental-ecological'''

|-
! Air pollution

! Toxic waste, ecotoxicity eutrophication

! Water quantity and quality

! Biodiversity

|-
| '''Demand reduction and mode shift'''

| +

| 0

| 0

| 0

|-
| ''Role of contexts''

| Reduction in demand, increase in fuel efficiency and demand management measures will improve air quality.

|
| Reduction in demand, fuel efficiency and demand management measures such as Clean Air Zones and parking Policies will reduce need for roads and protect biodiversity.

|-
| ''Line of sight''

| colspan="4"| Creutzig, F. et al., 2018: Towards demand-side solutions for mitigating climate change. ''Nat. Clim. Change'' , '''8(4)''' , 260–263, doi:10.1038/s41558-018-0121-1.

Dumortier, J., M. Carriquiry, and A. Elobeid, 2021: Where does all the biofuel go? Fuel efficiency gains and its effects on global agricultural production. ''Energy Policy'' , '''148''' , 111909, doi:10.1016/j.enpol.2020.111909.

Ambarwati, L., R. Verhaeghe, B. van Arem, and A.J. Pel, 2016: The influence of integrated space–transport development strategies on air pollution in urban areas. ''Transp. Res. Part D Transp. Environ.'' , '''44''' , 134–146, doi:10.1016/j.trd.2016.02.015.

DEFRA and DoT, 2020: ''Clean Air Zone Framework: Principles for setting up Clean Air Zones in England'' ., Department of Environment Food &amp; Rural Affairs/Department of Transport, Government of UK, London, UK, 35 pp.

|-
| '''Biofuels for land transport, aviation, and shipping'''

| ±

| ±

| –

| –

|-
| ''Role of contexts''

| Biofuels may improve air quality due to reduction in the emission of some pollutants, such as SOx and particulate matter, in relation to fossil fuels. Evidence is mixed for other pollutants such as NOx. The biofuels supply chain (e.g., due to increased fertiliser use) may negatively impact air quality.

| Increased use of fertilisers and agrochemicals due to biofuel production may increase impacts in ecotoxicity and eutrophication; some biofuels may be less toxic than fossil fuel counterparts.

| Increasing production of biofuels may increase pressure on water resources due to the need for irrigation. However, some biofuel options may also improve these aspects in respect to conventional agriculture. These impacts will depend on specific local conditions.

| Additional land use for biofuels may increase pressure on biodiversity. However, biofuel can also increase biodiversity depending on the previous land use. These impacts will depend on specific local conditions and previous land uses.

|-
| ''Line of sight''

| colspan="4"| Robertson, G.P. et al., 2017: Cellulosic biofuel contributions to a sustainable energy future: Choices and outcomes. ''Science'' , '''356(6345)''' , doi:10.1126/science.aal2324.

Humpenöder, F. et al., 2018: Large-scale bioenergy production: how to resolve sustainability trade-offs? ''Environ. Res. Lett.'' , '''13(2)''' , 024011, doi:10.1088/1748-9326/aa9e3b.

Ai, Z., N. Hanasaki, V. Heck, T. Hasegawa, and S. Fujimori, 2021: Global bioenergy with carbon capture and storage potential is largely constrained by sustainable irrigation. ''Nat. Sustain.'' , '''4(10)''' , 884–891, doi:10.1038/s41893-021-00740-4.

|-
| '''Ammonia for shipping'''

| ±

| –

| ±

| Limited Evidence (LE)

|-
| ''Role of contexts''

| If produced from green hydrogen or coupled with CCS, ammonia could reduce short-lived climate forcers and particulate matter precursors including black carbon and SO 2 . However, the combustion of ammonia could lead to elevated levels of nitrogen oxides and ammonia emissions.

| Ammonia is highly toxic, and therefore requires special handling procedures to avoid potentially catastrophic leaks into the environment. That said, large volumes of ammonia are already safely transported internationally due to a high level of understanding of safe handling procedures. Additionally, the use of ammonia in shipping presents a risk of eutrophication and ecotoxicity from the release of ammonia into the water system – either via a fuel leak or via unburnt ammonia emissions.

| May increase or decrease water footprint depending on the upstream energy source.

| Lack of studies assessing the potential impacts of the technology on biodiversity.

|-
| ''Line of sight''

| colspan="4"| Bicer, Y. and I. Dincer, 2018: Clean fuel options with hydrogen for sea transportation: A life cycle approach. ''Int. J. Hydrogen Energy'' , '''43''' (2), 1179–1193, doi:10.1016/j.ijhydene.2017.10.157.

Gilbert, P. et al., 2018: Assessment of full life-cycle air emissions of alternative shipping fuels. ''J. Clean. Prod.'' , '''172''' (2018), 855–866, doi:10.1016/j.jclepro.2017.10.165.

ABS, 2020: ''Ammonia as a Marine Fuel'' . American Bureau of Shipping, Spring, 28 pp.

|-
| '''Synthetic fuels for heavy-duty land transport, aviation, and shipping (e.g., DAC-FT)'''

| +

| NE

| ±

| LE

|-
| ''Role of contexts''

| Potential reductions in air pollutants related to reduced presence of sulphur, metals, and other contaminants; improvements likely smaller than for electric vehicles or hydrogen fuel cell vehicles.

|
| DAC requires significant amounts of water, which may be a limitation in water stressed areas; typically uses less water than crop-based biofuels.

| Potential biodiversity issues related to electricity generation; however fossil fuel supply chains also adversely impact biodiversity; net effect is unknown.

|-
| ''Line of sight''

| Beyersdorf, A.J. et al., 2014: Reductions in aircraft particulate emissions due to the use of Fischer –Tropsch fuels. ''Atmos. Chem. Phys.'' , '''14(1)''' , 11–23, doi:10.5194/acp-14-11-2014.

Lobo, P., D.E. Hagen, and P.D. Whitefield, 2011: Comparison of PM Emissions from a Commercial Jet Engine Burning Conventional, Biomass, and Fischer –Tropsch Fuels. ''Environ. Sci. Technol.'' , '''45(24)''' , 10744–10749, doi:10.1021/es201902e.

Gill, S.S., A. Tsolakis, K.D. Dearn, and J. Rodríguez-Fernández, 2011: Combustion characteristics and emissions of Fischer –Tropsch diesel fuels in IC engines. ''Prog. Energy Combust. Sci.'' , '''37(4)''' , 503–523, doi:10.1016/j.pecs.2010.09.001.

|
| Realmonte, G. et al., 2019: An inter-model assessment of the role of direct air capture in deep mitigation pathways. ''Nat. Commun.'' , '''10(1)''' , 3277, doi:10.1038/s41467-019-10842-5.

Byers, E.A., J.W. Hall, J.M. Amezaga, G.M. O’Donnell, and A. Leathard, 2016: Water and climate risks to power generation with carbon capture and storage. ''Environ. Res. Lett.'' , '''11(2)''' , 024011, doi:10.1088/1748-9326/11/2/024011.

|
|-
| '''Electric vehicles for land transport'''

| +

| –

| ±

| LE

|-
| ''Role of contexts''

| Elimination of tailpipe emissions. If powered by nuclear or renewables, large overall improvements in air pollution. Even if powered partially by fossil fuel electricity, tailpipe emissions tend to occur closer to population and thus typically have larger impact on human health than powerplant emissions; negative air quality impacts may occur, but only in fossil fuel-heavy grids.

| Some toxic waste associated with mining and processing of metals for batteries and some renewable electricity supply chains (production and disposal).

| May increase or decrease water footprint depending on the upstream electricity source.

| Potential biodiversity issues related to electricity generation; however fossil fuel supply chains also adversely impact biodiversity; net effect is unknown.

|-
| ''Line of sight''

| Requia, W.J., M. Mohamed, C.D. Higgins, A. Arain, and M. Ferguson, 2018: How clean are electric vehicles? Evidence-based review of the effects of electric mobility on air pollutants, greenhouse gas emissions and human health. ''Atmos. Environ.'' , '''185''' , 64–77, doi:10.1016/J.ATMOSENV.2018.04.040.

Horton, D.E. et al., 2021: Effect of adoption of electric vehicles on public health and air pollution in China: a modelling study. ''Lancet Planet. Heal.'' , doi:10.1016/s2542-5196(21)00092-9.

Gai, Y. et al., 2020: Health and climate benefits of Electric Vehicle Deployment in the Greater Toronto and Hamilton Area. ''Environ. Pollut.'' , '''265''' , 114983, doi:10.1016/j.envpol.2020.114983.

Choma, E.F., J.S. Evans, J.K. Hammitt, J.A. Gómez-Ibáñez, and J.D. Spengler, 2020: Assessing the health impacts of electric vehicles through air pollution in the United States. ''Environ. Int.'' , '''144''' , 106015, doi:10.1016/j.envint.2020.106015.

Schnell, J.L. et al., 2019: Air quality impacts from the electrification of light-duty passenger vehicles in the United States. ''Atmos. Environ.'' , '''208''' , 95–102, doi:10.1016/j.atmosenv.2019.04.003.

Tessum, C.W., J.D. Hill, and J.D. Marshall, 2014: Life cycle air quality impacts of conventional and alternative light-duty transportation in the United States. ''Proc. Natl. Acad. Sci.'' , '''111(52)''' , 18490–18495, doi:10.1073/pnas.1406853111.

| Lattanzio, R.K. and C.E. Clark, 2020: ''Environmental Effects of Battery Electric and Internal Combustion Engine Vehicles'' ., Congressional Research Service, Washington, DC, USA, 41 pp.

Puig-Samper Naranjo, G., D. Bolonio, M.F. Ortega, and M.-J. García-Martínez, 2021: Comparative life cycle assessment of conventional, electric and hybrid passenger vehicles in Spain. ''J. Clean. Prod.'' , '''291''' , 125883, doi:10.1016/j.jclepro.2021.125883.

Bicer, Y. and I. Dincer, 2017: Comparative life cycle assessment of hydrogen, methanol and electric vehicles from well to wheel. ''Int. J. Hydrogen Energy'' , '''42(6)''' , 3767–3777, doi:10.1016/j.ijhydene.2016.07.252.

Hawkins, T.R., B. Singh, G. Majeau‐Bettez, and A.H. Strømman, 2013: Comparative Environmental Life Cycle Assessment of Conventional and Electric Vehicles. ''J. Ind. Ecol.'' , '''17(1)''' , doi:10.1111/j.1530-9290.2012.00532.x.

| Onat, N.C., M. Kucukvar, and O. Tatari, 2018: Well-to-wheel water footprints of conventional versus electric vehicles in the United States: A state-based comparative analysis. ''J. Clean. Prod.'' , '''204''' , 788–802, doi:10.1016/j.jclepro.2018.09.010.

Kim, H.C. et al., 2016: Life Cycle Water Use of Ford Focus Gasoline and Ford Focus Electric Vehicles. ''J. Ind. Ecol.'' , '''20(5)''' , 1122–1133, doi:10.1111/jiec.12329.

Wang, L. et al., 2020: Life cycle water use of gasoline and electric light-duty vehicles in China. ''Resour. Conserv. Recycl.'' , '''154''' , 104628, doi:10.1016/j.resconrec.2019.104628.

|
|-
| '''Hydrogen FCV for land transport'''

| +

| ±

| ±

| LE

|-
| ''Role of contexts''

| Fuel cells’ only tailpipe emission is water vapour. However, blue hydrogen production pathways may generate air pollutants near the production sites. Overall, FCV would reduce emissions of criteria air pollutants.

| Mining of platinum group metals may generate additional stress on the environment, compared to conventional technologies. Furthermore, the recycling of fuel cell stacks can generate additional impacts.

| May increase or decrease water footprint depending on the upstream energy source.

| Lack of studies assessing the potential impacts of the technology on biodiversity.

|-
| ''Line of sight''

| Wang, Q., M. Xue, B. Le Lin, Z. Lei, and Z. Zhang, 2020: Well-to-wheel analysis of energy consumption, greenhouse gas and air pollutants emissions of hydrogen fuel cell vehicle in China. ''J. Clean. Prod.'' , '''275''' , doi:10.1016/j.jclepro.2020.123061.

| colspan="2"| Velandia Vargas, J.E. and J.E.A. Seabra, 2021: Fuel-cell technologies for private vehicles in Brazil: Environmental mirage or prospective romance? A comparative life cycle assessment of PEMFC and SOFC light-duty vehicles. ''Sci. Total Environ.'' , '''798''' , 149265, doi:10.1016/j.scitotenv.2021.149265.

Bohnes, F.A., J.S. Gregg, and A. Laurent, 2017: Environmental Impacts of Future Urban Deployment of Electric Vehicles: Assessment Framework and Case Study of Copenhagen for 2016–2030. ''Environ. Sci. Technol.'' , '''51(23)''' , 13995–14005, doi:10.1021/acs.est.7b01780.

|
|}

{| class="wikitable"
|-
! rowspan="2"|
! colspan="3"| '''Technological'''

|-
! Simplicity

! Technological scalability

! Maturity and technology readiness

|-
| '''Demand reduction and mode shift'''

| +

| +

| +

|-
| ''Role of contexts''

| Application of demand reduction and fuel efficiency measures can be scaled and developing countries can leapfrog to most advanced technology. India skipped Euro V, and implemented Euro VI from IV, but this shift will require investment in the short term.

| Technology to deliver demand reduction and fuel efficiency is readily available.

| Significant economic benefit in short and long term.

|-
| ''Line of sight''

| colspan="3"| Vashist, D., N. Kumar, and M. Bindra, 2017: Technical Challenges in Shifting from BS IV to BS-VI Automotive Emissions Norms by 2020 in India: A Review. ''Arch. Curr. Res. Int.'' , '''8(1)''' , 1–8, doi:10.9734/ACRI/2017/33781.

DEFRA and DoT, 2020: ''Clean Air Zone Framework: Principles for setting up Clean Air Zones in England'' ., Department of Environment Food &amp; Rural Affairs/Department of Transport, Government of UK, London, UK, 35 pp.

|-
| '''Biofuels for land transport, aviation, and shipping'''

| ±

| ±

| +

|-
| ''Role of contexts''

| Typically based on internal combustion engines, similar to fossil fuels, however, may require engine recalibration.

| Biofuels are scalable and may benefit from economies of scale; potential for scale up of sustainable crop production may be limited.

| There are many biofuels technologies that are already at commercial scale, while some technologies for advanced biofuels are still under development.

|-
| ''Line of sight''

| colspan="3"| Mawhood, R., E. Gazis, S. de Jong, R. Hoefnagels, and R. Slade, 2016: Production pathways for renewable jet fuel: a review of commercialization status and future prospects. ''Biofuels, Bioprod. Biorefining'' , '''10''' , 462–484, doi:10.1002/bbb.1644.

Puricelli, S. et al., 2021: A review on biofuels for light-duty vehicles in Europe. ''Renew. Sustain. Energy Rev.'' , '''137''' , 110398, doi:10.1016/J.RSER.2020.110398.

|-
| '''Ammonia for shipping'''

| –

| ±

| ±

|-
| ''Role of contexts''

| Requires either new engines or retrofits for existing engines. It is likely some ammonia will need to be mixed with a secondary fuel due its relatively low burning velocity and high ignition temperature. This would likely require existing powertrains to be modified to accept dual fuel mixes, including ammonia. Exhaust treatment systems are also required to deal with the release of unburnt ammonia emissions.

| Ammonia supply chains are well established; transport and storage more feasible than hydrogen; scalability of electrolytic production routes remains a challenge for producing low-GHG ammonia.

| The production, transport and storage of ammonia is mature based on existing international supply chains. The use of ammonia in ships is still at the early stages of research and development. Further research and development will be required for ammonia to be widely used in shipping, including improving the efficiency of combustion, and treatment of exhaust emissions. Ammonia could also potentially be used in fuel cell powertrains in the future, but the development of this technology is even less mature at present.

|-
| ''Line of sight''

| colspan="3"| Frigo, S., R. Gentili, and F. De Angelis, 2014: Further Insight into the Possibility to Fuel a SI Engine with Ammonia plus Hydrogen. SAE Technical Paper 2014-32-008, doi:10.4271/2014-32-0082.

Dimitriou, P. and R. Javaid, 2020: A review of ammonia as a compression ignition engine fuel. ''Int. J. Hydrogen Energy'' , '''45(11)''' , 7098–7118, doi:10.1016/J.IJHYDENE.2019.12.209.

MAN Energy Solutions, 2019: ''Engineering the future two-stroke green-ammonia engine'' . MAN Energy Solutions, Copenhagen, Denmark, 20 pp.

|-
| '''Synthetic fuels for he''' '''avy-du''' '''ty land transport, aviation, and shipping (e.g., DAC-FT)'''

| +

| –

| –

|-
| ''Role of contexts''

| Can produce drop-in fuels, which use existing engine technologies.

| Rate at which DAC or other carbon capture can be scaled up is likely a limiting factor; large energy inputs (requiring substantial new low-carbon energy resources), and sorbent requirements likely to be a challenge.

| Some processes (e.g., Fischer Tropsch) are well established, but DAC and BECCS are still at demonstration stage.

|-
| ''Line of sight''

| Sutter, D., M. van der Spek, and M. Mazzotti, 2019: 110th Anniversary: Evaluation of CO 2 -Based and CO 2 -Free Synthetic Fuel Systems Using a Net-Zero-CO 2 -Emission Framework. ''Ind. Eng. Chem. Res.'' , '''58(43)''' , 19958–19972, doi:10.1021/acs.iecr.9b00880.

The Royal Society, 2019: ''Sustainable synthetic carbon based fuels for transport: Policy Brief'' . The Royal Society, London, UK, 46 pp.

| The Royal Society, 2019: ''Sustainable synthetic carbon based fuels for transport: Policy Brief'' . The Royal Society, London, UK, 46 pp.

Realmonte, G. et al., 2019: An inter-model assessment of the role of direct air capture in deep mitigation pathways. ''Nat. Commun.'' , '''10(1)''' , 3277, doi:10.1038/s41467-019-10842-5.

| Liu, C.M., N.K. Sandhu, S.T. McCoy, and J.A. Bergerson, 2020: A life cycle assessment of greenhouse gas emissions from direct air capture and Fischer-Tropsch fuel production. ''Sustain. Energy Fuels'' , '''4(6)''' , 3129–3142, doi:10.1039/C9SE00479C.

|-
| '''Electric vehicles for land transport'''

| ±

| ±

| ±

|-
| ''Role of contexts''

| Fewer engine components; lower maintenance requirements than conventional vehicles; potential concerns surrounding battery size/weight, charging time, and battery life.

| Widespread application already feasible; some limits to adoption in remote communities or long-haul freight; at large scale, may positively or negatively impact electric grid functioning depending on charging behaviour and grid integration strategy.

| + Technology is mature for light-duty vehicles; – Improvements in battery capacity and density as well as charging speed required for heavy-duty applications.

|-
| ''Line of sight''

| Burnham, A. et al., 2021: ''Comprehensive total cost of ownership quantification for vehicles with different size classes and powertrains'' . Argonne National Laboratory, US Department of Energy, Lemont, IL, USA, 227 pp.

| IEA, 2021: ''Global EV Outlook 2021'' . International Energy Agency, Paris, France,101 pp.

Milovanoff, A., I.D. Posen, and H.L. MacLean, 2020: Electrification of light-duty vehicle fleet al.ne will not meet mitigation targets. ''Nat. Clim. Change'' , '''10(12)''' , 1102–1107, doi:10.1038/s41558-020-00921-7.

Crozier, C., T. Morstyn, and M. McCulloch, 2020: The opportunity for smart charging to mitigate the impact of electric vehicles on transmission and distribution systems. ''Appl. Energy'' , '''268''' , 114973, doi:10.1016/j.apenergy.2020.114973.

Kapustin, N O. and D.A. Grushevenko, 2020: Long-term electric vehicles outlook and their potential impact on electric grid. ''Energy Policy'' , '''137''' , 111103, doi:10.1016/j.enpol.2019.111103.

Das, H.S., M.M. Rahman, S. Li, and C.W. Tan, 2020: Electric vehicles standards, charging infrastructure, and impact on grid integration: A technological review. ''Renew. Sustain. Energy Rev.'' , '''120''' , 109618, doi:10.1016/j.rser.2019.109618.

Liimatainen, H., O. van Vliet, and D. Aplyn, 2019: The potential of electric trucks – An international commodity-level analysis. ''Appl. Energy'' , '''236''' , 804–814, doi:10.1016/j.apenergy.2018.12.017.

Forrest, K., M. Mac Kinnon, B. Tarroja, and S. Samuelsen, 2020: Estimating the technical feasibility of fuel cell and battery electric vehicles for the medium and heavy duty sectors in California. ''Appl. Energy'' , '''276''' , 115439, doi:10.1016/j.apenergy.2020.115439.

| IEA, 2021: ''Global EV Outlook 2021'' . International Energy Agency, Paris, France, 101 pp.

Smith, D. et al., 2020: ''Medium- and Heavy-Duty Vehicle Electrification: An Assessment of Technology and Knowledge Gaps'' . Oak Ridge National Laboratory, Oak Ridge, TN, USA, 85 pp.

Forrest, K., M. Mac Kinnon, B. Tarroja, and S. Samuelsen, 2020: Estimating the technical feasibility of fuel cell and battery electric vehicles for the medium and heavy duty sectors in California. ''Appl. Energy'' , '''276''' , 115439, doi:10.1016/j.apenergy.2020.115439.

|-
| '''Hydrogen FCV for land transport'''

| ±

| –

| –

|-
| ''Role of contexts''

| Lower maintenance requirements compared to conventional technologies; potential issues with on-vehicle hydrogen storage, fuel cell degradation and lifetime; fewer weight and refuelling time barriers compared to electric vehicles.

| Currently the refuelling infrastructure is limited, but it is growing at the pace of the technology deployment. Challenges exist with transport and distribution of hydrogen. Electrolytic hydrogen not currently produced at scale.

| The technology is already available to users for light-duty vehicle applications and buses, but further improvements in fuel cell technology are needed. Use in heavy-duty applications is currently constrained. Maturity and technology readiness level can vary for different parts of the supply chain, and is lower than for EVs.

|-
| ''Line of sight''

| Trencher, G., A. Taeihagh, and M. Yarime, 2020: Overcoming barriers to developing and diffusing fuel-cell vehicles: Governance strategies and experiences in Japan. ''Energy Policy'' , '''142''' , 111533, doi:10.1016/j.enpol.2020.111533.

| Pollet, B.G., S.S. Kocha, and I. Staffell, 2019: Current status of automotive fuel cells for sustainable transport. ''Curr. Opin. Electrochem.'' , '''16''' (May), 1–6, doi:10.1016/j.coelec.2019.04.021.

| Wang, J., H. Wang, and Y. Fan, 2018: Techno-Economic Challenges of Fuel Cell Commercialization. ''Engineering'' , '''4(3)''' , 352–360, doi:10.1016/j.eng.2018.05.007.

Kampker, A. et al., 2020: Challenges towards large-scale fuel cell production: Results of an expert assessment study. ''Int. J. Hydrogen Energy'' , '''45(53)''' , 29288–29296, doi:10.1016/J.IJHYDENE.2020.07.180.

|}

{| class="wikitable"
|-
! rowspan="2"|
! colspan="2"| '''4. Economic'''

|-
! Costs in 2030 and long term

! Employment effects and economic growth

|-
| '''Demand reduction and mode shift'''

| +

| LE

|-
| ''Role of contexts''

| Significant economic benefit in short and long term.

|
|-
| ''Line of sight''

| colspan="2"| Creutzig, F. et al., 2018: Towards demand-side solutions for mitigating climate change. ''Nat. Clim. Change'' , '''8(4)''' , 260–263, doi:10.1038/s41558-018-0121-1.

The UK, 2020: ''The Green Book.'' HM Treasury, London, UK, https://www.gov.uk/government/publications/the-green-book-appraisal-and-evaluation-in-central-governent/the-green-book-2020 .

|-
| '''Biofuels for land transport, aviation, and shipping'''

| ±

| LE

|-
| ''Role of contexts''

| Some biofuels are already cost competitive with fossil fuels. In the future, reduction of costs for advanced biofuels may be a challenge.

| Biofuels are expected to increase job creation in comparison to fossil fuel alternatives. This is still to be further demonstrated.

|-
| ''Line of sight''

| colspan="2"| Daioglou, V. et al., 2020: Bioenergy technologies in long-run climate change mitigation: results from the EMF-33 study. ''Clim. Change'' , '''163(3)''' , 1603–1620, doi:10.1007/s10584-020-02799-y.

Brown, A., et al., 2020. ''Advanced Biofuels – Potential for Cost Reduction'' . IEA Bioenergy, Paris, France, 88.

|-
| '''Ammonia for shipping'''

| –

| NE

|-
| ''Role of contexts''

| Green ammonia is likely to be significantly more expensive than conventional fuels for the coming decades.

|
|-
| ''Line of sight''

| colspan="2"| Energy Transitions Commission, 2021. ''Making the hydrogen economy possible'' . Energy Transitions Commission, 92 pp. https://energy-transitions.org/wp-content/uploads/2021/04/ETC-Global-Hydrogen-Report.pdf .

[[#Energy%20Transitions%20Commission--2020|Energy Transitions Commission, 2020]] . ''The First Wave: A blueprint for commercial-scale zero-emission shipping pilots'' . Energy Transitions Commission, 102 pp. https://www.energy-transitions.org/wp-content/uploads/2020/11/The-first-wave.pdf .

|-
| '''Synthetic fuels for heavy-duty land transport, aviation, and shipping (e.g., DAC-FT)'''

| –

| NE

|-
| ''Role of contexts''

| Large uncertainty on future costs but expected to remain higher than conventional fuels for the coming decades.

|
|-
| ''Line of sight''

| Ueckerdt, F. et al., 2021: Potential and risks of hydrogen-based e-fuels in climate change mitigation. ''Nat. Clim. Change'' , '''11(5)''' , 384–393, doi:10.1038/s41558-021-01032-7.

Zang, G. et al., 2021: Synthetic Methanol/Fischer –Tropsch Fuel Production Capacity, Cost, and Carbon Intensity Utilizing CO 2 from Industrial and Power Plants in the United States. ''Environ. Sci. Technol.'' , '''55(11)''' , 7595–7604, doi:10.1021/acs.est.0c08674.

Scheelhaase, J., S. Maertens, and W. Grimme, 2019: Synthetic fuels in aviation – Current barriers and potential political measures. ''Transp. Res. Procedia'' , '''43''' , 21–30, doi:10.1016/j.trpro.2019.12.015.

|
|-
| '''Electric vehicles for land transport'''

| +

| LE

|-
| ''Role of contexts''

| Lifecycle costs for electric vehicles are anticipated to be lower than for conventional vehicles by 2030; ''high confidence'' for light-duty vehicles; ''lower confidence'' for heavy-duty applications.

| Some grey studies exist on employment effects of electric vehicles; however, the peer-reviewed literature is not well developed.

|-
| ''Line of sight''

| [[#IEA--2021a|IEA, 2021a]] : ''Global EV Outlook 2021'' . International Energy Agency, Paris, France, 101 pp.

Liimatainen, H., O. van Vliet, and D. Aplyn, 2019: The potential of electric trucks – An international commodity-level analysis. ''Appl. Energy'' , '''236''' , 804–814, doi:10.1016/j.apenergy.2018.12.017.

Kapustin, N.O. and D.A. Grushevenko, 2020: Long-term electric vehicles outlook and their potential impact on electric grid. ''Energy Policy'' , '''137''' , 111103, doi:10.1016/j.enpol.2019.111103.

Forrest, K., M. Mac Kinnon, B. Tarroja, and S. Samuelsen, 2020: Estimating the technical feasibility of fuel cell and battery electric vehicles for the medium and heavy duty sectors in California. A ''ppl. Energy,'' 2 '''76,''' 115439, doi:10.1016/j.apenergy.2020.115439.

|
|-
| '''Hydrogen FCV for land transport'''

| +

| LE

|-
| ''Role of contexts''

| Lifecycle costs for hydrogen fuel cell vehicles projected to be competitive with conventional vehicles in future, however high uncertainty remains.

| Some studies exist on employment effects of hydrogen economy; however, the literature is not well developed and does not apply directly to FCVs.

|-
| ''Line of sight''

| Miotti, M., J. Hofer, and C. Bauer, 2017: Integrated environmental and economic assessment of current and future fuel cell vehicles. ''Int. J. Life Cycle Assess.'' , '''22(1)''' , 94–110, doi:10.1007/s11367-015-0986-4.

Ruffini, E. and M. Wei, 2018: Future costs of fuel cell electric vehicles in California using a learning rate approach. ''Energy'' , '''150''' , 329–341, doi:10.1016/j.energy.2018.02.071.

Olabi, A.G., T. Wilberforce, and M.A. Abdelkareem, 2021: Fuel cell application in the automotive industry and future perspective. ''Energy'' , '''214''' , 118955, doi:10.1016/j.energy.2020.118955.

|
|}

{| class="wikitable"
|-
! rowspan="2"|
! colspan="3"| '''Socio-cultural'''

|-
! Public acceptance

! Effects on health &amp; well-being

! Distributional effects

|-
| '''Demand reduction and mode shift'''

| ±

| +

| ±

|-
| ''Role of contexts''

| Public support for some measures, such as emissions charging schemes, can be mixed initially, they are likely to gain acceptance as benefits are realised and/or focused. Such as recent COVID-19 road network changes in London.

| Significant economic health and well-being benefits.

| Some measures, such as travel restrictions, emission charging schemes and others, can have mixed distributional effects initially (e.g., on accessibility).

|-
| ''Line of sight''

| colspan="3"| Winter, A.K. and H. Le, 2020: Mediating an invisible policy problem: Nottingham’s rejection of congestion charging. ''Local Environ.'' , '''25(6)''' , 463–471, doi:10.1080/13549839.2020.1753668.

Creutzig, F. et al., 2018: Towards demand-side solutions for mitigating climate change. ''Nat. Clim. Change'' , '''8(4)''' , 260–263, doi:10.1038/s41558-018-0121-1.

DEFRA and DoT, 2020: ''Clean Air Zone Framework: Principles for setting up Clean Air Zones in England'' ., Department of Environment Food &amp; Rural Affairs/Department of Transport, Government of UK, London, UK, 35 pp.

Adhikari, M., L.P. Ghimire, Y. Kim, P. Aryal, and S.B. Khadka, 2020: Identification and Analysis of Barriers against Electric Vehicle Use. ''Sustainability'' , '''12(12)''' , 4850, doi:10.3390/su12124850.

TfL (2020) London Streetspace changes. https://www.pgweb.uk/planning-all-subjects/quieter-neighbourhoods/2847-120-doctors-and-nurses-urge-continuation-of-low-traffic-neighbourhoods-and-cycle-lanes-schemes .

|-
| '''Biofuels for land transport, aviation, and shipping'''

| ±

| LE

| ±

|-
| ''Role of contexts''

| Varied public acceptance of biofuel options is observed in different regions of the world.

| No known impacts.

| Food security but agricultural economies.

|-
| ''Line of sight''

| colspan="3"| Løkke, S., E. Aramendia, and J. Malskær, 2021: A review of public opinion on liquid biofuels in the EU: Current knowledge and future challenges. ''Biomass and Bioenergy'' , '''150''' , 106094, doi:10.1016/j.biombioe.2021.106094.

Taufik, D. and H. Dagevos, 2021: Driving public acceptance (instead of skepticism) of technologies enabling bioenergy production: A corporate social responsibility perspective. ''J. Clean. Prod.'' , '''324''' , 129273, doi:10.1016/j.jclepro.2021.129273.

|-
| '''Ammonia for shipping'''

| LE

| LE

| LE

|-
| ''Role of contexts''

| Some concerns in industry regarding handling of hazardous fuel; limited evidence overall.

|
|-
| ''Line of sight''

| colspan="3"| N/A

|-
| '''Synthetic fuels for heavy-duty land transport, aviation, and shipping (e.g., DAC-FT)'''

| LE

| LE

| NE

|-
| ''Role of contexts''

| Currently low public awareness of the technology and little evidence regarding associated perceptions.

| No known impacts.

|
|-
| ''Line of sight''

| N/A

|
|-
| '''Electric vehicles for land transport'''

| ±

| ±

| ±

|-
| ''Role of contexts''

| Growing public acceptance, especially in some jurisdictions (e.g., majority of light-duty vehicle sales in Norway are electric), but wide differences across regions; range anxiety remains a barrier among some groups.

| No major impacts; some potential for reduced noise, which can improve well-being of city residents but may adversely affect pedestrian safety.

| Higher vehicle purchase price and access to off-road parking limits access for some disadvantaged groups; potentially insufficient infrastructure for adoption in rural communities (initially); air quality improvements may disproportionately benefit disadvantaged groups, but may also shift some impacts onto communities in close proximity to electricity generators.

|-
| ''Line of sight''

| Coffman, M., P. Bernstein, and S. Wee, 2017: Electric vehicles revisited: a review of factors that affect adoption. ''Transp. Rev.'' , '''37(1)''' , 79–93, doi:10.1080/01441647.2016.1217282.

Burkert, A., H. Fechtner, and B. Schmuelling, 2021: Interdisciplinary Analysis of Social Acceptance Regarding Electric Vehicles with a Focus on Charging Infrastructure and Driving Range in Germany. ''World Electr. Veh. J.'' , '''12(1)''' , 25, doi:10.3390/wevj12010025.

Wang, N., L. Tang, and H. Pan, 2018b: Analysis of public acceptance of electric vehicles: An empirical study in Shanghai. ''Technol. Forecast. Soc. Change'' , '''126''' , 284–291, doi:10.1016/j.techfore.2017.09.011.

| Campello-Vicente, H., R. Peral-Orts, N. Campillo-Davo, and E. Velasco-Sanchez, 2017: The effect of electric vehicles on urban noise maps. ''Appl. Acoust.'' , '''116''' , 59–64, doi:10.1016/j.apacoust.2016.09.018.

| Canepa, K., S. Hardman, and G. Tal, 2019: An early look at plug-in electric vehicle adoption in disadvantaged communities in California. ''Transp. Policy'' , '''78''' , 19–30, doi:10.1016/j.tranpol.2019.03.009.

Brown, M.A., A. Soni, M.V Lapsa, K. Southworth, and M. Cox, 2020: High energy burden and low-income energy affordability: conclusions from a literature review. ''Prog. Energy'' , '''2(4)''' , 42003, doi:10.1088/2516-1083/abb954.

|-
| '''Hydrogen FCV for land transport'''

| ±

| ±

| ±

|-
| ''Role of contexts''

| Public acceptance is growing in countries where the technology is being promoted and subsidised. However, sparse infrastructure, high costs and perceived safety concerns are currently barriers to a widespread deployment of the technology.

| No major impacts: some potential for reduced noise, which can improve well-being of city residents but may adversely affect pedestrian safety.

| Higher vehicle purchase price limits access for some disadvantaged groups; potentially insufficient infrastructure for adoption in rural communities (initially); air quality improvements may disproportionately benefit disadvantaged groups.

|-
| ''Line of sight''

| colspan="3"| Itaoka, K., A. Saito, and K. Sasaki, 2017: Public perception on hydrogen infrastructure in Japan: Influence of rollout of commercial fuel cell vehicles. ''Int. J. Hydrogen Energy'' , '''42(11)''' , 7290–7296, doi:10.1016/j.ijhydene.2016.10.123.

Canepa, K., S. Hardman, and G. Tal, 2019: An early look at plug-in electric vehicle adoption in disadvantaged communities in California. ''Transp. Policy'' , '''78''' , 19–30, doi:10.1016/j.tranpol.2019.03.009.

Brown, M.A., A. Soni, M. V Lapsa, K. Southworth, and M. Cox, 2020: High energy burden and low-income energy affordability: conclusions from a literature review. ''Prog. Energy'' , '''2(4)''' , 42003, doi:10.1088/2516-1083/abb954.

Trencher, G., 2020: Strategies to accelerate the production and diffusion of fuel cell electric vehicles: Experiences from California. ''Energy Reports'' , doi:10.1016/j.egyr.2020.09.008.

|}

{| class="wikitable"
|-
! rowspan="2"|
! colspan="3"| '''Institutional'''

|-
! Political acceptance

! Institutional capacity and governance, cross-sectoral coordination

! Legal and administrative feasibility

|-
| '''Demand reduction and mode shift'''

| ±

| ±

| ±

|-
| ''Role of contexts''

| Public support for some measures, such as emissions charging schemes, can be mixed initially, it is likely to gain acceptance as benefits are realised and/or focused. Such as recent COVID-19 road network changes in London.

| Some local authorities have limited capacity to deliver demand management measures as compared to other developed authorities. However, this can be mitigated to optioneering processes to select the preferred measures in the local context.

| Legal air quality limits are forcing cities and countries to implement travel demand reduction and fuel efficiency measures, such as in the UK and Europe. However, there may be legal and administrative changes in delivery of measures.

|-
| ''Line of sight''

| colspan="3"| Winter, A.K. and H. Le, 2020: Mediating an invisible policy problem: Nottingham’s rejection of congestion charging. ''Local Environ.'' , '''25(6)''' , 463–471, doi:10.1080/13549839.2020.1753668.

Creutzig, F. et al., 2018: Towards demand-side solutions for mitigating climate change. ''Nat. Clim. Change'' , '''8(4)''' , 260–263, doi:10.1038/s41558-018-0121-1.

DEFRA and DoT, 2020: ''Clean Air Zone Framework: Principles for setting up Clean Air Zones in England'' ., Department of Environment Food &amp; Rural Affairs/Department of Transport, Government of UK, London, U35 pp.

TfL (2020) London Streetspace changes. https://www.pgweb.uk/planning-all-subjects/quieter-neighbourhoods/2847-120-doctors-and-nurses-urge-continuation-of-low-traffic-neighbourhoods-and-cycle-lanes-schemes .

|-
| '''Biofuels for land transport, aviation, and shipping'''

| ±

| ±

| ±

|-
| ''Role of contexts''

| Varied political support for biofuels deployment in different regions of the world.

| There is varied institutional capacity to coordinate biofuels deployment in different regions of the world.

| There are different legal contexts and barriers for biofuels implementation on different regions of the world.

|-
| ''Line of sight''

| colspan="3"| Lynd, L.R., 2017: The grand challenge of cellulosic biofuels. ''Nat. Biotechnol.'' , '''35(10)''' , 912–915, doi:10.1038/nbt.3976.

Markel, E., C. Sims, and B.C. English, 2018: Policy uncertainty and the optimal investment decisions of second-generation biofuel producers. ''Energy Econ.'' , '''76''' , 89–100, doi:10.1016/j.eneco.2018.09.017.

|-
| '''Ammonia for shipping'''

| ±

| -

| -

|-
| ''Role of contexts''

| Varied political support for deployment in different regions of the world.

| The major contributor to marine emissions is international shipping, which falls under the jurisdiction of the International Maritime Organization. Coordination with international governments will be required.

| Potential challenges related to emissions regulations.

|-
| ''Line of sight''

| colspan="3"| Hoegh-Guldberg, O. et al., 2019: ''The Ocean as a Solution to Climate Change: Five Opportunities for Action'' . World Resources Institute, Washington D. C., 116 pp.

Energy Transitions Commission, 2021. ''Making the hydrogen economy possible'' . Energy Transitions Commission, https://energy-transitions.org/wp-content/uploads/2021/04/ETC-Global-Hydrogen-Report.pdf .

[[#Energy%20Transitions%20Commission--2020|Energy Transitions Commission, 2020]] . ''The First Wave: A blueprint for commercial-scale zero-emission shipping pilots'' . Energy Transitions Commission, https://www.energy-transitions.org/wp-content/uploads/2020/11/The-first-wave.pdf .

|-
| '''Synthetic fuels for heavy-duty land transport, aviation, and shipping (e.g., DAC-FT)'''

| LE

| –

| ±

|-
| ''Role of contexts''

| Plans for adoption of technology remain at early stage; political acceptance not known.

| Synthetic fuel use in aviation and marine shipping requires international coordination; challenges exist related to carbon accounting frameworks for utilisation of CO 2 ; likely fewer barriers for use of fuel in land transport applications.

| Legal barriers exist for synthetic fuel use in aviation; need for development of CO 2 capture markets; drop-in fuels are compatible with existing fuel standards in many jurisdictions.

|-
| ''Line of sight''

| colspan="3"| Scheelhaase, J., S. Maertens, and W. Grimme, 2019: Synthetic fuels in aviation – Current barriers and potential political measures. ''Transp. Res. Procedia'' , '''43''' , 21–30, doi:10.1016/j.trpro.2019.12.015.

|-
| '''Electric vehicles for land transport'''

| ±

| ±

| ±

|-
| ''Role of contexts''

| Varied political support for deployment in different regions of the world.

| Coordination needed between transport sector (including vehicle manufacturers; charging infrastructure) and power sector (including increased generation and transmission; capacity to handle demand peaks). Institutional capacity is variable.

| Compatible with urban low emission zones; grid integration may require market and regulatory changes.

|-
| ''Line of sight''

| colspan="3"| Milovanoff, A., I.D. Posen, and H.L. MacLean, 2020: Electrification of light-duty vehicle fleet al.ne will not meet mitigation targets. ''Nat. Clim. Change'' , '''10(12)''' , 1102–1107, doi:10.1038/s41558-020-00921-7.

IEA, 2021: ''Global EV Outlook 2021'' . International Energy Agency, Paris, France, 101 pp.

|-
| '''Hydrogen FCV for land transport'''

| ±

| ±

| ±

|-
| ''Role of contexts''

| Varied political support for deployment in different regions of the world.

| Coordination needed across sector (including vehicle manufacturers, hydrogen producers and refuelling infrastructure). Institutional capacity is variable.

| Compatible with urban low emission zones; fuel distribution network may require market and regulatory changes.

|-
| ''Line of sight''

| colspan="3"| Itaoka, K., A. Saito, and K. Sasaki, 2017: Public perception on hydrogen infrastructure in Japan: Influence of rollout of commercial fuel cell vehicles. ''Int. J. Hydrogen Energy'' , '''42(11)''' , 7290–7296, doi:10.1016/j.ijhydene.2016.10.123.

|}

<div id="footnote-001" class="_idFootnote"></div>

[[#footnote-001-backlink|1]] Active travel is travel that requires physical effort, for example journeys made by walking or cycling.

<div id="footnote-000" class="_idFootnote"></div>

[[#footnote-000-backlink|2]] See Annex II Table 1 for details of regional groupings used in this report.