A Carbon Neutral World: Aviation and Shipping

Of all the areas that need to be de-carbonised for a net-zero future, Aviation and Shipping is the trickiest. There are no clear paths towards net-zero or even dramatic reductions short of these 2 methods of transport being banned worldwide, which, I'm sure you'll agree is highly unlikely. However, I'll go through the possibilities.

Before I go on, why have I separated aviation and shipping from other forms of transport? Basically, because it's handled outside the normal UN climate change agreement process, as it's difficult to apportion the carbon produced to individual countries.

Aviation: It's unlikely that anything other than short hop flights can be fully de-carbonised in the foreseeable future. Planes can be made more efficient, traffic control can be used to shorten flights, and biofuels can be mixed with aviation fuel to reduce the carbon emissions but, fundamentally, it's difficult to make flights net-zero.

This is because there aren't any obvious replacements for aviation fuel. It may be possible to make short-haul flights all electric in time (Norway wants to do this by 2040), but the aircraft to do so are still in development (e.g. By Boeing and Airbus). Hydrogen has been looked at as a potential replacement but has it's problems. It would basically mean a re-think of the shape of aircraft (because the fuel would have to be held in the body of the plane rather than the wings, as now), making them look more like Thunderbird 2, and this would interfere with the aerodynamics.

Anyway you cut it, medium- to long-haul flights are likely to be a big greenhouse gas (GHG) producer for decades to come.

So what else can be done? Well, for start, airlines need to stop the practise of 'fuel-tankering' (where planes fly around with more fuel than they need to reduce costs)…..See here for details.

Also, in the UK, 70% of all flights are taken by just 15% of adults, which suggests that, if people became more responsible, or were dissuaded from flying so much by carbon or 'frequent-flyer' taxes, it could make a sizeable reduction in overall airmiles and therefore GHGs. I realise it's nice to have the freedom to have, say, a few weekends away in Barcelona or Prague, in addition to a couple of holidays every year, but not at the expense of future generations, surely.

Shipping  It has become fundamental to how our modern, interconnected world works, with vast quantities of goods (80% of the total) being moved around the planet all year round e.g. In 2013 there 120 million shipping containers, carrying $4 trillion in goods. The numbers will have only got bigger since then.

The ships can carry hundreds of containers at a time for thousands of kilometres, and often taking weeks to do so (Speed of delivery is not generally an issue).

Unfortunately, these ships usually run on heavy fuel oil which, though cheap, creates a lot sulphur, black carbon, and nitrogen oxide pollution. It also produces 3% of global GHGs (about the equivalent of Germany as a whole). 

Electrically powered ships are a reality and are evolving rapidly, but they are only likely to be practical for river, coastal, and ferry journeys. Container ships need something else.

There is currently pressure for shipping companies to make their vessels more efficient (See Carbon War Room for an example). You'd think it would be in these companies' interests to have more efficient ships as it saves costs on fuel, but those costs are small enough that there's little incentive to replace or retrofit inefficient ships. Some are making the effort along those lines though, and even trying stuff like adding sails!

Next year, there is likely to be a push to use less polluting diesel as a fuel but I'm not sure this will do much for the GHG side of things.

However, next week the International Maritime Organisation (IMO) will meet to decide if container ships should reduce their speed by 20%. This could cut fuel consumption and carbon emissions by around a third, reduce underwater noise by two thirds, whale collisions by 78%, sulphur and nitrogen oxide by 24%, and mean a significant cut in black carbon. 

Apart from saving on fuel costs, the measure would have no extra costs involved (e.g. from retrofits). So it makes sense if the shipping companies want to be seen to be doing their bit. See here for more.

The medium- to long-term prospect is that oil-based fuels will be replaced by alternative fuels like hydrogen. In fact, the OECD believes it's possible to have net-zero shipping by 2035 with current technology. Maersk, the largest shipping company in the world, plans to be carbon neutral by 2050 which implies it will be rolling out net-zero ships by 2030.

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