The Loadstar explains: onboard carbon capture and storage

Fizzier Fanta, anyone? Photo: © Olga Krutova

So, what’s new in fuels, then?

Amid the battleground of future fuels, a new technology is quietly making its way into the discussion. Shipping lines may soon be able to offer low- or near-zero carbon shipping through the expedient of onboard carbon capture and storage (CCS) – but there are a number or prerequisites.

Go on, what is CCS?

A new technology which is being used to filter out the carbon dioxide emitted from powerplant flue gas. It relies on underground storage facilities, generally disused oil wells, and the ability to transport carbon to a well and pump it back into the ground, from whence it came.

How does CCS work?

The specifics of these systems are proprietary and well-guarded, but generally they rely on amines – monoethanolamine (MEA), diethanolamine (DEA) and piperazine (PZ) – to scrub CO₂ from flue gas by causing it to bind to them chemically and become a liquid. You can then apply heat to this liquid to crack the CO₂ from the amines, leaving you with a reusable amine and pure CO₂, which can be stored instead of being emitted to the atmosphere.

We shouldn’t be relying on complicated technology when we already have nature’s carbon capture device – the humble tree.

Yes, yes, no doubt. We’d only need to plant three times as many hectares of forest as already exist on Earth to cover one year’s CO₂ emissions – good luck with that.

So, how is this technology for power plants applicable on a ship?

A ship’s engine room is like a power station in many respects. While there is usually a vast multi-storey low-speed two-stroke engine powering the propeller, there are also auxiliary gensets, whose sole purpose is burning fuel to provide electricity to run the ship’s systems, which use some of the same four-stroke diesel engines you find in power plants.

Onboard CCS (OCCS) works much like it does in a powerplant, storing the CO₂ in a tank somewhere on board as a gas, a liquid, or even as a solid in the form of biochar, and offloading it at a port.

It exists already? What are shipping lines waiting for?

There’s a catch. A recent study of OCCS found that to capture just 19.7% of the CO₂ from ship exhaust would require some 9.2% of additional fuel to be burned just to provide the power needed; meaning that more CO₂ must be generated and dealt with within the system.

Land-based research has found the same thing: it is possible to capture 95% of CO₂ from power plants, if they only burn 40% more fuel to power the CCS. Ships are unlikely to get a better deal than this. The study found that retrofitting an OCCS system capable of nearly 20% CO₂ capture would cost $13.6m on a Stena tanker, and the running cost, including the additional fuel, would be $830,000 a year. The study’s participants expect more research and development would bring down these costs.

Another problem is that the success of OCCS in shipping is rather reliant on ports having a connection to suitable burial sites, and providing an offloading service for vessels. There is, unfortunately, scant evidence of this actually happening yet.

Where are these CO₂ burial sites, then?

Various sites are planned for under North America, the Norwegian North Sea, Denmark, the UK  and elsewhere. They’ll be ready soon, we’re told.

The plan, in many cases, is to pump CO₂ into existing oil and gas wells, something the fossil fuel industry has been doing for decades, called “well stimulation” – effectively, extracting more oil using the pressure of the pumped CO₂ gas. In fact, CCS will probably enable further oil extraction from dormant wells, so that’s… great.

The market loves a commodity, though. What else can you do with pure CO₂?

You can use it to make carbonated drinks; it’s also used in fire extinguishers, and some greenhouse farms use it for supra-normal CO₂ concentrations to boost plant growth.

But there are only a certain number of use cases, and we are not going to avert global warming by making Fanta even fizzier.

But won’t more atmospheric CO₂ lead to taller trees, healthier crops and a massive surge in biodiversity, the likes of which the world has never seen (a real argument tendered by the fossil fuel industry)?

No.

But what about China, eh?

China supports the second-largest population in the world, manufactures most things, emits less CO₂ per capita than 24 other countries (including Luxembourg, Canada and the US) and currently every six months or so, builds enough new renewable energy to power the whole of Britain.

But if there’s CO₂ in the air, couldn’t we just set up CCS anywhere?

Technically, yes. It’s called direct air capture (DAC). According to International Energy Agency (IEA) projections, once DAC is scaled up and commercialised, it could remove one tonne of CO₂, the equivalent of a flight from New York to Los Angeles, for a mere $630.

Today’s DAC systems expend 2000–3000 kWh, the hourly output of a mid-size solar farm, per tonne of CO₂ captured. This means we should probably put DAC on the back-burner until every last home, office, factory, car, truck, aircraft and ship is running on emission-free energy.