Hydrogen Vs Battery Electric: it's not a (Net) Zero-Sum Game

It is broadly accepted that hydrogen has an important part to play in our net zero future -the shape and the extent of that role, however, is widely debated.

Low carbon mobility is one of those areas. Most analysis has focussed on the commanding position held by battery electric vehicles (BEVs) in personal mobility, and some of the advantages which hydrogen fuel cells have in heavy duty or return-to-base applications like buses[1], waste vehicles[2] and heavy haulage.[3]

Implicit in many of these discussions is the idea that hydrogen and BEVs are in competition for their own slice of the (enormous) net zero mobility pie, and the opening of doors for one technology would close that same door to the other.

So it was of great interest recently to read about Plug Power's recent unveiling of a hydrogen-powered BEV charger.[4] The charger comprises a liquid hydrogen tank supplying a fuel cell to generate the electricity needed to charge plug-in BEVs. Other organisations are using similar solutions to charge BEVs from hydrogen, including Extreme E (who use a fuel cell system to charge the race fleet)[5] and Geopura, who themselves offer hydrogen power units for a range of industrial purposes, including BEV charging.[6]

Unlocking BEV

One of the things that make the climate crisis and the pursuit of net zero goals so complex and challenging is the intricate web of variables, each of which affects (and is affected by) the others. 

More electric vehicles on the road means more electricity required to charge them up. To fulfil their net zero potential, those vehicles need to be charged with green energy. The same is true of making green hydrogen in electrolysers. Without enough renewable energy to draw upon, we end up just shuffling the cards and moving the carbon emissions out of sight, rather than actual real-terms reductions. 

On the face of it, a hydrogen-powered BEV charger might seem like it incorporates the worst of both worlds. Charging a BEV is a slower process than hydrogen refuelling, so why use hydrogen to power a charger, removing one of the key advantages of using hydrogen in the first place? On the other hand, one of the recurring criticisms levelled at green hydrogen is the inherent inefficiency of the process of using electricity to generate hydrogen (which then generates electricity again through a fuel cell). Electrolysers are expensive equipment, so there is little incentive to run one only when the grid has surplus power. Given the finite renewable resources we have, why not cut to the chase and charge directly from grid? 

Gridlock

When Shoosmiths went to All-Energy this May, one of the recurring messages that cut through from across the sector were the challenges facing generators who want to connect to grid. Recently, waits of more than a decade to connect to the grid have been reported for many GB renewables projects.[7] Those projects which are already connected have limited options for energy storage, and a great deal of potential renewable power is lost through curtailment when demand is low,[8] or when the transmission network lacks the capacity to match generation to demand.[9]

When it comes to EV charging, grid-connected energy storage helps reduce curtailment, but it doesn't tackle the issue of demand-side grid constraints.

Demand-side batteries can also be used as a way of storing up enough energy to power the chargers (and this is something that National Highways is actively exploring and supporting).[10] This is a different way of approaching the same problem, but one which requires both a grid connection and the room to install an on-site battery. For sites with an existing but insufficient grid connection, this can be the perfect solution. Without both, it is not a viable option. 

Hydrogen-powered BEV chargers, on the other hand, supply their own electricity at the point of need – no external grid connection required. When paired with an electrolyser to generate green hydrogen (which need not be on-site), they can also take advantage of the second challenge, by generating green hydrogen when overall electricity demand is low or local curtailment is high, to enable the renewable resources we already have to operate at maximum efficiency (after all, round-trip efficiency doesn't matter as much when the alternative is not generating any energy at all). 

For sites where there is no grid connection, or where there isn't the footprint for a high-capacity energy storage system, using a low carbon fuel to generate electricity through a fuel cell is a viable option for bypassing some of the bottlenecks facing the roll-out of EV infrastructure, and to reach areas where EV infrastructure is currently lacking (remote areas without robust grid connections). It may not be the most efficient use of energy on paper, but it tackles a real-world problem and can help move the needle on BEVs by tackling one of the key blockers for EV uptake in the UK – the availability of charging infrastructure.[11]

All the tools in the toolbox

The Climate Change Committee's report in March this year[12] backs up the idea that a robust, decarbonised electricity system is possible, but relies upon a wide range of reforms beyond simply deploying more renewables.[13]

The hydrogen-powered BEV charger is, in microcosm, a great example of the challenges facing the energy transition. Addressing those challenges needs a multi-pronged approach and there is no silver bullet. Just to tackle issues in grid capacity, great strides have been (and continue to be) made towards solutions like virtual power plants, energy storage, demand-matched peer-to-peer energy trading, bidirectional BEV charging, independent microgrids and energy efficiency measures (to name just a few). 

And of course, the urgent need for more renewables will only increase with the move to rapidly electrify and decarbonise more sectors.

The road to net zero is paved with hundreds of these challenges, dependencies, bottlenecks, and (ultimately) trade-offs. The one resource which still feels truly limitless is the creativity and ingenuity of those working in the green energy and tech spaces to come up with solutions to the challenges.