Fossil fuels have both created modern civilisation and risk destroying it.  What to do?

Decarbonising the power we use to drive our societies is a critical part of the response to climate change and the requirement to reduce our collective carbon footprint.  The most visible aspect of this is in transport and what fuels it.  Removing the carbon from our power can be done (amongst other technologies) with electric batteries, hydrogen as a fuel, hydrogen fuel cells, and plug-in hybrid electric vehicles. 

Hydrogen poses a host of research challenges

Hydrogen is a key choice for decarbonising large vehicles (the IET’s ‘Destination Net Zero’ report has  more detail on this), offering as it does advantages across land- based and maritime transport, with a longer-term potential for aviation. It could also serve as a medium for storing renewable energy generated when consumer demand is low, which would help address the impact of decarbonising the grid.

There are two methods of employing hydrogen to power a vehicle.  One involves putting the gas into an engine and burning it, as with fossil fuels.  The other is to use it in a fuel cell. Other technologies with research and development potential for decarbonising transport to use with hydrogen include hydrogen internal combustion engines, hydrogen storage, hydrogen transmission, and steam methane reforming with carbon capture.

Hydrogen retrofit trial

Newcastle University has been involved in a demonstration project at RAF Leeming in Yorkshire to convert an airside tug from diesel to hydrogen with industrial partner ULEMCo.  This proved the concept of 100% hydrogen combustion with zero emissions.

The University is putting sensors on the tailpipe to check for any emissions. If this can be perfected, it could enable millions of diesel-engined vehicles to be converted to work on hydrogen.  This is a real prize that would mean not having to build new vehicles, simply being retrofitted to extend their lives, while saving on new embedded carbon.

Short Turn-Around

For consumers, hydrogen vehicles have the advantage of a short refuelling time (comparing well with petrol station dwell time). Their similar range and equivalent payloads can be achieved without adding to vehicle weight.  

The range of a hydrogen powered vehicle is broadly equal to its petrol or diesel counterpart, with fuel-cell vehicles having an advantage because they can carry more hydrogen.  In turn this will produce a greater range.  Hydrogen cars currently have a range of between 300 – 400 miles.

But, as the UK’s EV roll-out has demonstrated, having readily available refuelling points in the right locations (and in sufficient quantities) is necessary to give consumers the confidence to adopt alternative fuelled vehicles.

This can applied not only to road freight transport but to less ‘glamourous’ sectors such as local services vehicles involved in refuse collection, gritting and street cleaning in residential areas. Such vehicles have significant on-board energy demands requiring high energy density solutions. Service schedules along predictable routes include downtime between shifts to refuel. Hydrogen refuelling systems can be installed in central depots to supply multiple types of vehicles on their return to base or to common destinations (such as waste to energy plants).

For more on hydrogen as a future fuel, check out these IET reports:

‘The role of hydrogen in a net zero energy system.’

‘Hydrogen’s potential as a fuel for road transport’

Challenges

There are challenges, however.  One is to create a viable, interoperable electric vehicle (EV) infrastructure, while delivering a steady supply of renewable electricity. Extending electrification is only one solution for rail transport, but cost is an important barrier.  Battery electric trains and hydrogen power are both being trialled.

In aerospace and maritime transport, fundamental research questions are still to be answered. Hydrogen is the front runner to power aviation.  For maritime transport, ammonia could be useful in the long term.  This could be supplemented by batteries and wind assisted technologies.

The long R&D cycle in finding solutions where obvious ones don’t exist is another barrier. 

A note of caution

Where does all the hydrogen come from?  How will it be produced and where?  Will it be green and sustainable?  A recent comment piece in The Guardian raises some interesting questions.

Tunisia, it notes, has been suggested by the EU as a future green hydrogen production hub for Europe. To do this, the country will need to split water into its component water and hydrogen atoms, a process powered by green (solar) electricity.  While Tunisia has no shortage of sunshine, it is one of the driest countries on the planet, suffering extensive drought in recent years.  Where will the water come from?  One answer could involve drawing water from the Mediterranean Sea and putting it through a desalination plant.

A report last year for the Heinrich Böll Foundation, suggests this could be a dirty, energy-intensive, water-guzzling process. Raoudha Gafrej, a Tunisian water expert, says in the report that the degradation of marine ecosystems from toxic sludge produced by desalination plants would be irreversible.

A single kilogram of hydrogen produces three times the energy of a kilogram of petrol, small wonder the gas looks so seductive as a fuel source.  However, producing it in Europe is far more expensive than in North Africa, and whether European consumers will willingly foot the bill is open to question.

Meanwhile, there is pressure not to transfer the costs and burden of Europe’s necessary drive for green hydrogen over to societies less able to take up the slack. Especially when Africa itself could benefit from using locally produced green hydrogen.

What do you think about this topic?  It’s always worth engaging with colleagues and fellow engineers, so why not throw in your thoughts right now?  If you’re not a member, you can register for EngX here.  If you are, you can jump straight in!

What do you think we can overcome the hurdles to creating net zero, carbon free fuel sources?  Surely, the idea of a ‘net-zero fuel is an oxymoron, why do we even try?

How far is it possible to have a ‘net-zero fuel’?