Hydrogen is the faster answer

31 Jul 2017
The Norwegian fast ferries have an issue with battery installation

The Norwegian fast ferries have an issue with battery installation

While Norway’s standard ferry routes have come under scrutiny, cleaning up the fast ferries has been thought of as an ‘intractable’ problem. At least so far.

While many feel progress on emissions has been ‘slow’, Erik Lanssen of Selfa Arctic said the Norwegian government has been nothing short of “inspiring” in the way that it has taken the lead: this year it committed to building 50 electric ferries.

Of course, it’s not only helping the environment, developing clean technology has also been a useful diversification for Norway’s ailing shipbuilding industry which went into a tail spin following the collapse of the oil price. “It’s saved the yards,” said Mr Lanssen.

Despite this, there are some areas that have done better than others, and some that haven’t done well at all. The total CO2 output of just five fast ferries equates to that of 600 of Norway’s buses. Together the segment consumes around 86,400,000 litres of diesel a year.

But this is tricky: fast ferry design “is all about the weight” explained Erik Lanssen.

His daughter, Christine, has chipped in with the research – fast ferries consume a huge amount of power, especially on the acceleration, which puts even the ‘big’ ferries in the shade.

And unfortunately, batteries just don’t have the energy density of diesel, kilo for kilo, to make it work over a 10 nautical mile route. "You spend too much energy pushing the battery's weight up to speed," he explained.

But this is where the hydrogen alternative comes into its own.

Per litre it doesn’t have the energy density, but change that to ‘per kilo’ and it gives you a completely different scenario.

While the Norwegian authorities are also making room for 10 hydrogen ferries via the HYBRIDShips project, these are not, it needs to be noted, fast ferries. These will have a design speed of around 12 knots and though they are interesting in their own right, they avoid the inherent issues of their faster cousins, and don’t have quite the same need to watch the scales.

So the ‘per kilo’ measurement falls rather shorter for fast ferries than their slower relatives – speedier vessels need to pay more attention to the total weight of the tanks when loaded.

The SF Breeze – a fast ferry concept for San Francisco Bay headed up by Sandia National Laboratory in the US - looked at two different types of container, one being 6,000psi pressure composite tanks, another being liquefied hydrogen. Interestingly, instead of the high pressure alternative this has plumped for a liquid hydrogen, cryogenic system despite the drop in temperature: 252.87°C. Joe Pratt of Sandia explained it’s an extension of the work being carried out on liquefied natural gas which is a mere -163°C – so hydrogen may be LNG’s natural successor.

And it’s not a fossil fuel. Unlike LNG.

By Stevie Knight