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Bio-LNG: waste, and potential

The alchemy of turning waste into ship fuel

What if shipping could not only eliminate its carbon emissions and reliance on fossil fuels by 2050, but actually make a positive contribution to the climate – and all without retrofitting a thing? Bio-LNG might be worth a look.

Given the 70% IMO is demanding, LNG’s modest 20% GHG saving is no game-changer, even when it is not being partially offset by methane slip. Yet while orders for ammonia, methanol and hydrogen-powered ships dither, LNG propulsion goes from strength to strength. Euronav’s new fleet of tankers might use ammonia – or, they might fall back on LNG as a substitute. K-Line has just ordered a 210,000dwt LNG-powered bulker for delivery in 2024. With the help of a kite sail, it may achieve a 30% CO2 emissions reduction.

Using LNG with fuel cells might help as well. Samsung is trying out LNG carriers with solid oxide fuel cells (SOFCs), which can reach 60% efficiency in some cases – 25% more than some ship engines.

Unfortunately, LNG is hardly changing the world. But thanks to investments made by shipowners in good faith, it is now pervasive in ship propulsion. To leave these vessels by the wayside as “stranded assets”, in the search for exotic carbon-neutral electro-fuels, would be wasteful. Fortunately there might be one way for them to do more good than their owners remotely imagined.

Brown gold

There are vast reserves of methane (natural gas) under the seabed, but fossil fuels in general only become more difficult, environmentally damaging, and costly, to get to. The fortune spent on doing so gives the impression that methane is rare and hard to procure. But is it emitted to the atmosphere every day, in huge quantities, by bacteriological breakdown of organic matter.

Much of these emissions would exist But whether man-made or not, for the 20 years after fresh methane is emitted, it traps 86 times as much of the sun’s heat as the equivalent amount of CO2, before gradually degrading to become CO2. Over the course of 100 years, this process averages out to around 30 times as much global warming potential (GWP). But engines, while not particularly efficient propulsion-wise, are good at turning hydrocarbons into CO2 exhaust.

This means that by trapping ambient methane emissions, purifying, condensing, cooling and liquefying them to create bio-LNG, and burning them for propulsion, ships could not only be made carbon-neutral immediately – but reduce the harm from a given quantity of methane by 3000%. Under any remotely sensible carbon-credit regime, this ought to buy quite a lot of them.

One man’s trash…

In May, Wärtsilä announced that it is supplying a bio-LNG liquefaction plant for Norway’s Biokraft, due to be delivered in 2022. The new equipment will double an existing facility’s capacity to 50 tonnes per day – though modest, Biokraft anticipates that demand for bio-LNG could increase to the extent that 50 such plants will need to be constructed across Norway.

“Wärtsilä’s latest mixed refrigerant – MR – technology used in our liquefaction plants is extremely reliable and offers the lowest operating costs for liquefying biogas,” said Maria Ortiz, Sales Manager, Biogas Solutions at Wärtsilä Gas Solutions. “We are proud to have once again been selected by Biokraft since it represents a clear endorsement of customer satisfaction.”

Meanwhile, CMA CGM wants to use bio-LNG to power its ships. Together with EveRé, a wastewater treatment company, TotalEnergies, and gas firm Elengy, it is conducting a feasibility study into using bio-LNG from a plant in Marseille, using human sewage and agricultural waste as feedstocks.

“The project fits perfectly into the local ecosystem, benefiting from the particularly well-suited and already-existing infrastructure at the Grand Port Maritime, including EveRés waste methanization unit, Elengy’s LNG terminals, which will be used for the storage of the bio-LNG, TotalEnergies’ bunker vessel, which will be located at the port as of January 2022, and CMA CGM’s fleet of LNG-powered vessels,” said a CMA CGM statement.

Huge potential

Shipping demands around 5 million barrels of oil equivalent per day (boe/d) in bunker fuel, and consultancy Wood Mackenzie expects this to rise to 5.9 million by 2040. Meanwhile, according to by the International Energy Agency, some 730 million tonnes of oil equivalent (mtoe) of bio-methane could be produced annually, using today’s available feedstocks – equivalent to 16.3 million boe/d. This means that if properly scaled up, biomethane could wipe out shipping’s carbon emissions, without accounting for new technologies like fuel cells and sails – and never mind the measly 50% the IMO is demanding. Bio-methane could also serve as a feedstock for steam-reforming methanol and hydrogen, as well.

In fact, given the outrageous environmental benefit of turning anthropogenic and non-anthropogenic methane emissions into CO2 – with carbon sequestration still in the pipeline as well – LNG-powered ships, potentially, are a ready-built fleet of enormous, industrial-scale planet-saving machines in-waiting. Presumably, they will also carry some cargo, as well.