After analysing the way some new technologies work a global expert in road transport has concluded there is no future for hydrogen fuel cell trucks, if the goal is sustainability. Recent years have seen an explosion of interest in alternatives to diesel engines to power trucks with a number of well hyped projects using electric or fuel cell power hitting the headlines.
“Although generating and storing hydrogen seems like an attractive way to manage excess electricity production, the fundamental thermodynamics of the various processes makes it a very wasteful solution,” said David Cebon in a recent article on the subject. “Use of Hydrogen as a fuel only makes sense if sustainable energy is so abundant that we are willing to throw away most of it.
“A more realistic view of the future is that it will be a significant challenge to generate enough sustainable electricity to replace fossil fuels for electricity generation and heat supply, worldwide.”
Originally fromAustralia, David Cebon is a Professor of Mechanical Engineering in Cambridge University and a Fellow of the Royal Academy of Engineering. He is Director of the Cambridge Vehicle Dynamics Consortium and the Centre for Sustainable Road Freight and he leads Cambridge University Engineering Department’s Transport Research Group and the Department’s research theme ‘Energy, Transport and Urban Infrastructure’.
According to Cebon, if you take the same 100kWh of electricity, use it to generate hydrogen (by electrolysis of water), compress, store and transport the hydrogen in a vehicle, then run it through a fuel cell to create electricity and use that to drive an efficient electric vehicle, you will end up with about 23kWh at the wheels.
“The route via hydrogen is extremely wasteful, because converting electricity into hydrogen (by electrolysis) is only about 75 per cent efficient and converting hydrogen into electricity (in a fuel cell) is only about 50 per cent efficient, at best,” said Cebon.
“The best strategy to reduce greenhouse gas emissions and energy cost is simply to use electricity to charge the batteries of electric vehicles. Forget the hydrogen! Even better is to power the vehicles directly without going through batteries at all: for example, using overhead powerlines with conductive power transfer. This is about 80 per cent efficient (well-to-wheel).”
“Does it make sense to use 23 per cent of sustainable electricity (and waste 77 per cent) with a hydrogen solution for road freight, or is it more sensible to use 80 per cent via direct electrification?The answer is clearly a no-brainer. Hydrogen is far too inefficient and far too costly on a well-to-wheel basis. Direct electrification is the way to go.”