The Orkney International Science Festival

An Autonomous Hydrogen Ship for the Aberdeen Run

By Mike Robertson

The seaman prepared to start his watch at 4 am.  This was quite normal.  What wasn’t normal was that he had driven from home to do it.  This seaman is one of the new mariners operating autonomous vessels which have no crew on board. 

Science fiction? 

Not necessarily as Mike Tinmouth, the chief operating Officer  of Acua Ocean explained in a recent Orkney International Science Festival (OISF) and Orkney Renewable Energy Forum (OREF) talk.

They are currently working on a fully autonomous vessel to take cargo from Aberdeen to Orkney.  But, that’s not all it can do.   The innovative design of this new vessel can be used in many different ways as you will see later.

Around sixty people packed into the lecture theatre of the Robert Rendall building in Stromness and another nine joined online to hear Mike take us through some of the challenges of developing a hydrogen powered self-driving vessel.

With 74% of the earth’s surface water the idea of a needle in a haystack does begin to cover the task of managing it.   The UK, for example, only has one frigate to patrol  around 4.5 million square kilometres of ocean.  That’s the equivalent to having one police car for the whole of Britain.  At the same time there is a greater need to monitor the sea especially with the introduction of offshore wind farms and their associated undersea cables.  We also want to replace some of the dull, dangerous, dirty and “distant” seafaring jobs of the past.  Autonomous vessels could be the solution by enabling new ways of solving complex problems – but it’s not without its challenges.

There have been many previous attempts at autonomous vessels but these often mirror manned solutions when a completely different design would be more effective.  Often, too, the public perception of an the evil robot taking over the world doesn’t help.  Add hydrogen to that, people immediately think of the Hindenburg disaster.  All this gives the public a very negative view adding to the technological challenges.

Although these vessels operate on their own they are not without human control.   You don’t just set the boat off and go home for your tea.  The maritime agency still require a master in charge and a permanent watch but these functions are now handled remotely from a permanently manned control centre. 

Hydrogen was chosen as the primary fuel because of its net-zero properties and Orkney with its surplus energy is well placed to provide fully green hydrogen.  Further afield it’s not so easy because road haulage regulations require that hydrogen is shipped by diesel lorries and ships, typically from Europe.  Even so it is still better than using diesel or some other fossil fuel.

The power train of  these boats is electric with a hydrogen fuel-cell charging a Lithium-Ion battery which powers electric motors.  Using electric power makes it relatively easy to switch to different net-zero fuels like ammonia if they become more advantageous.  Lithium-Ion batteries bring their own problems since protecting them from damage and fire requires some pretty unpleasant chemicals.  

To meet the challenges of operating in the real world these vessels need to scale to meet demand.  This is made easier by not having to include cabins, toilets, corridors and more which would be essential if a crew had to be accommodated so giving more space for cargo.   For many jobs an autonomous vessel can operate in sea states much higher than is safe for a crew.  This extends the operational window, reducing the idle time of expensive resources.    Also, without having to cope with crew changes autonomous vessels can remain at sea far longer.

So, what does this boat look like?

You might think this is a catamaran, but you’d be wrong. It’s a SWATH which stands for Small-Waterplane-Area-Twin-Hull.  Because the two hulls are below the waterline and below most of the wave action, the vessel is stable in much heavier seas than a normal monohull.  The two hulls contain cryogenic tanks which hold 3,000 litres of liquid hydrogen.  Hydrogen is far more energy dense than other fossil fuels.  The hydrogen in each tank only weighs 120Kg.  This means the change in weight as the fuel is used doesn’t change significantly.   This amount of hydrogen can power the vessel for up to 40 days.

In addition to carrying around 4 tonnes of cargo, this configuration of the vessel has a vast array of sensors capturing data about the environment which is fed to scientists around the world for analysis.

One big advantage of this vessel is its cost.  At around £2 million you could employ hundreds of them around the world for less than the a single frigate at £1.2 billion.

A full risk analysis of the vessel shows that even if another large vessel collided with it, rupturing the tanks and causing an explosion, you would have to be within a 100m of it to risk serious injury or death.  In fact the nature of hydrogen means that in the unlikely event of a leak it would disperse very quickly without any adverse effect to the environment.

Where do we go from here.  The next stage, starting next year, is to carry cargo between Aberdeen, Orkney and Shetland.  

Every now and again a disruptive technology comes along which radically changes the way of the world.  Looking back in history we can see this happening with the steam engine, computers and the Internet.  Autonomous vehicles could be the next one and while we are all aware of road vehicles we perhaps haven’t thought of it in a marine environment.  The possibilities are intriguing and I look forward to see how this develops.

A video of the talk can be seen on the OREF website,  https://www.oref.co.uk/category/presentations/.

More information about the company and their technology here, https://www.acua-ocean.com/.