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

=== 10.3.3 Fuel Cell Technologies ===

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In harder-to-electrify transport segments, such as heavy-duty vehicles, shipping, and aviation, hydrogen holds significant promise for delivering emissions reductions if it is produced using low-carbon energy sources. In particular, hydrogen fuel cells are seen as an emerging option to power larger vehicles for land-based transport ( [[#Tokimatsu--2016|Tokimatsu et al. 2016]] ; [[#IPCC--2018|IPCC 2018]] ; [[#IEA--2019b|IEA 2019b]] ). Despite this potential, further advancements in technological and economic maturity will be required in order for hydrogen fuel cells to play a greater role. While this section focuses primarily on hydrogen fuel cells, ammonia and methanol fuel cells may also emerge as options for low power applications.

During the last decade, hydrogen fuel cell vehicles (HFCVs) have attracted growing attention, with fuel cell technology improving through research and development. Fuel cell systems cost 80% to 95% less than they did in the early 2000s, at approximately USD50 per kW for light-duty (80 kW) and $100 per kW for medium-heavy-duty (160 kW). These costs are approaching the US Department of Energy’s (US DOE) goal of USD40 per kW in 2025 at a production target of 500,000 systems per year ( [[#IEA--2019c|IEA 2019c]] ). In addition to cost reductions, the power density of fuel cell stacks has now reached around 3.0 kilowatt per litre (kW/l) and average durability has improved to approximately 2000 to 3000 hours ( [[#Jouin--2016|Jouin et al. 2016]] ; [[#Kurtz--2019|Kurtz et al. 2019]] ). Despite these improvements, fuel cell systems are not yet mature for many commercial applications. For example, the US DOE has outlined that for hydrogen fuel cell articulated trucks (semi-trailers) to compete with diesel vehicles, fuel cell durability will need to reach 30,000 hours (US DOE 2019). While some fuel cell buses have demonstrated durability close to these targets ( [[#Eudy--2018a|Eudy and Post 2018a]] ), another review of light fuel cell vehicles found maximum durability of 4000 hours ( [[#Kurtz--2019|Kurtz et al. 2019]] ). As more fuel cell vehicles are trialled, it is expected that further real-world data will become available to track ongoing fuel cell durability improvements.

Ammonia and methanol fuel cells are considered to be less mature than hydrogen fuel cells. However, they offer the benefit of using a more easily transported fuel that can be directly used without converting to hydrogen ( [[#Zhao--2019|Zhao et al. 2019]] ). Conversely, both methanol and ammonia are toxic, and in the case of methanol fuel cells, carbon dioxide is released as a by-product of generating electricity with the fuel cell ( [[#Zhao--2019|Zhao et al. 2019]] ). Due to the lower power output, methanol and ammonia fuel cells are also not well suited to heavy-duty vehicles ( [[#Jeerh--2021|Jeerh et al. 2021]] ). They are therefore unlikely to compete with hydrogen fuel cells. However, ammonia and methanol could be converted to hydrogen at refuelling stations as an alternative to being directly used in fuel cells ( [[#Zhao--2019|Zhao et al. 2019]] ).

Several FCV-related technologies are fully ready for demonstration and early market deployment, however, further research and development will be required to achieve full-scale commercialisation, likely from 2030 onwards ( [[#Staffell--2019|Staffell et al. 2019]] ; [[#Energy%20Transitions%20Commission--2020|Energy Transitions Commission 2020]] ; [[#IEA--2021b|IEA 2021b]] ). Some reports argue that it may be possible to achieve serial production of fuel cell heavy-duty trucks in the late 2020s, with comparable costs to diesel vehicles achieved after 2030 ( [[#Jordbakker--2018|Jordbakker et al. 2018]] ). Over the next decade or so, hydrogen FCVs could become cost-competitive for various transport applications, potentially including long-haul trucks, marine ships, and aviation ( [[#Hydrogen%20Council--2017|Hydrogen Council 2017]] ; [[#FCHEA--2019|FCHEA 2019]] ; [[#FCHJU--2019|FCHJU 2019]] ; BloombergNEF 2020; [[#Hydrogen%20Council--2020|Hydrogen Council 2020]] ). The speed of fuel cell system cost reduction is a key factor for achieving widespread uptake. Yet, experts disagree on the relationship between the scale of fuel cell demand, cost, and performance improvements ( [[#Cano--2018|Cano et al. 2018]] ). Costs of light-, medium-, and heavy-duty fuel cell powertrains have decreased by orders of magnitude with further reductions of a factor of two expected with continued technological progress ( [[#Whiston--2019|Whiston et al. 2019]] ). For example, the costs of platinum for fuel cell stacks have decreased by an order of magnitude ( [[#Staffell--2019|Staffell et al. 2019]] ); current generation FCVs use approximately 0.25 g/kW platinum and a further reduction of 50–80% is expected by 2030 ( [[#Hao--2019|Hao et al. 2019]] ).

Hydrogen is likely to take diverse roles in the future energy system: as a fuel in industry and buildings, as well as transport, and as energy storage for variable renewable electricity. Further research is required to understand better how a hydrogen transport fuel supply system fits within the larger hydrogen energy system, especially in terms of integration within existing infrastructure, such as the electricity grid and the natural gas pipeline system ( [[#IEA--2015|IEA 2015]] ).

Strong and durable policies would be needed to enable widespread use of hydrogen as a transport fuel and to sustain momentum during a multi-decade transition period for hydrogen FCVs to become cost-competitive with electric vehicles ( [[#Hydrogen%20Council--2017|Hydrogen Council 2017]] ; [[#FCHEA--2019|FCHEA 2019]] ; [[#FCHJU--2019|FCHJU 2019]] ; [[#IEA--2019c|IEA 2019c]] ; [[#BNEF--2020|BNEF 2020]] ; [[#Hydrogen%20Council--2020|Hydrogen Council 2020]] ). The analysis suggests that hydrogen is likely to have strategic and niche roles in transport, particularly in long-haul shipping and aviation. With continuing improvements, hydrogen and electrification will likely play a role in decarbonising heavy-duty road and rail vehicles.

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