A new study by Zemo Partnership recommends that Government policy should increase its focus on the well-to-wheel emissions of new fuels for transport.
While hydrogen, electric and renewable fuels (produced from waste-based feedstocks) can all cut emissions compared with their diesel-powered counterparts, Zemo Partnerships says there are major variations in their effectiveness and efficiency in terms of cutting emissions depending on choices made over the full well-to-wheel life cycle.
The Hydrogen Vehicle Well-to-Wheel GHG and Energy study warns that a focus solely on mitigating tailpipe emissions can risk neglecting the full impacts and the overall energy consumption of the system.
The new study looks specifically at hydrogen, extending analysis provided in Zemo's recently published Low Carbon Hydrogen Well-to-Tank Pathways study.
The work is timely as it comes shortly after the publication of the Government’s hydrogen strategy, a potentially important component of the overall decarbonisation plan for transport.
Key building blocks of the hydrogen strategy are currently under consultation and the Zemo Partnership work is intended to help inform these.
The Zemo analysis combines GHG and energy consumption data for a variety of hydrogen vehicles - trucks, buses, vans and cars. It presents well-to-wheel results for the most promising hydrogen vehicle powertrain architectures using battery electric, diesel and renewable fuels for comparison.
The study looks at hydrogen produced for transport use through electrolysis, biomass gasification with carbon capture and storage (CCS) and methane reformation with CCS (all potentially low carbon and GHG solutions) as well as from fossil fuels without CCS mitigation.
The work explores the sensitivity of GHG emissions and energy consumption to a range of inputs and options, with more than 250 well-to-wheel scenarios being modelled 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, well-to-wheel GHG emissions solutions within the next decade for many vehicle types, but this is predicated on the use of low carbon hydrogen.
Significantly, the work determines that the well-to-wheel energy efficiency of hydrogen vehicles is lower than diesel internal combustion (IC) or battery electric vehicles and those using renewable fuels in IC engines.
In the case of HGVs powered by hydrogen fuel cells – widely mooted as a potential HGV solution because of the technical challenges to battery electrification – the well-to-wheel 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.
Andy Eastlake, Zemo Partnership chief executive, said: “When we look at the energy efficiency of potential pathways for hydrogen to be used in transport we see challenges.
"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 energy consumption compared with other zero emission powertrain solutions such as battery electric vehicles.”
The study recommends that further feasibility work including energy analysis, should be done to assess the suitability of different vehicles for 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 potentially be integrated into the Government’s ongoing Zero Emission Freight Trials (ZERFT) which Zemo is also supporting.