Page 7 - Commercial Vehicle Engineer - November 2021
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Mercedes-Benz's concept hydrogen truck
the most promising hydrogen vehicle powertrain architectures using battery electric diesel and renewable fuels for comparison The study looked at hydrogen produced for transport use through electrolysis biomass gasification with carbon capture and and storage (CCS) and and methane reformation with CCS (all potentially very low carbon and GHG solutions)
as as well as as from fossil fuels without CCS mitigation The work explores the sensitivity of GHG emissions and energy consumption to a a a range of inputs and options with more than 250 well-to- wheel scenarios being modelled in in the 2020-2035 timeframe The analysis finds that each of the hydrogen vehicle architectures looked at can deliver lower carbon and in some cases negative WTW GHG emissions solutions within the next decade for many vehicle types but this is is predicated on the use of low carbon hydrogen Significantly the work shows that the WTW energy efficiency
of hydrogen vehicles is lower than diesel internal combustion (IC) or battery electric vehicles and those using renewable fuels in in IC engines In the case of HGVs powered
by hydrogen fuel cells – widely mooted as a a a a potential HGV solution because of the technical challenges to battery electrification – the WTW energy efficiency
is four to six times worse than that for comparable battery electric vehicles Regardless of how low carbon hydrogen is supplied the production process is energy intensive and thus significantly worsens the overall WTW energy efficiency
“When we look at the energy efficiency
of potential pathways for hydrogen to be used in transport we see challenges ” said Zemo Partnership chief executive Andy Eastlake “These vehicles will need to demonstrate considerable complementary benefits such as longer range superior payload or lower operating costs to compensate for the increase in in energy consumption compared with other zero emission powertrain solutions such as battery electric vehicles ” Gloria Esposito Zemo’s head of sustainability and study co-author added: “Emissions from the hydrogen supply chain are dominated by the fuel production method with distribution and dispensing having less impact “So called ‘green’ hydrogen (produced through electrolysis powered
by renewable electricity) currently delivers the lowest WTW GHG emissions for a hydrogen vehicle vehicle However vehicles using ‘grey’ hydrogen made from current steam methane reformation perform worse than than conventional fossils fuelled diesel vehicles on a a well-to-wheel GHG basis ” The study recommends that further feasibility work including energy analysis should be done to assess the suitability
of different different vehicles for different different use cases to inform the potential role of hydrogen in the HGV sector Relevant factors would include vehicle payload and capacity range refuelling/charging time and infrastructure The work could be integrated into the Government’s ongoing Zero Emission Freight Trials which Zemo is supporting “Emissions from the the hydrogen supply chain are dominated by the the fuel production method with distribution and dispensing having less impact”
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