A study by Dutch environmental research organisation CE Delft has found that both bio and synthetic LNG can be “viable” as a ship fuel, providing a pathway to decarbonisation.
The study was commissioned by SEA-LNG, a shipping industry coalition with a purpose of accelerating adoption of LNG as a marine fuel.
The main constituent of LNG is methane, and so bio LNG would be made from liquefying bio methane. Similarly, synthetic LNG is made by liquefying synthetic methane.
Liquefied bio methane (LBM) means gas formed from biological methods (such as rotting vegetation or rubbish), which is then liquefied. The source material is known as “biomass”.
Liquefied synthetic methane (LSM) means gas formed by reacting hydrogen with CO2 and then liquefying it. The hydrogen could be formed from electrolysing water with renewable energy, and the CO2 could be captured from a CO2 flue gas elsewhere.
Although LNG has lower CO2 emissions than liquid fossil fuel (oil), it still involves CO2 emissions – it is 90 per cent methane (CH4) with smaller amounts of ethane (C2H6), propane (C3H8) and butane (C4H10), and all the carbon atoms end up as carbon dioxide.
But if the methane is made synthetically with CO2 which would otherwise have been emitted elsewhere, such as from the flue gas of a coal power station, burning it in a ship engine makes no net additional CO2 emission.
If the methane is made from biomass, the CO2 emitted when the methane is burned originally came out of the atmosphere, being absorbed when the biomass was growing, so there is no net CO2 addition to the atmosphere.
The study concluded that both LBM and LSM could be “made available in sufficient quantities to make a contribution towards future decarbonisation for the shipping industry, and that the costs need not be significantly higher than those of other low- and zero-carbon fuels.”
“Estimated sustainable global supplies potentially exceed the demands of shipping in the future, and are likely to be commercially competitive relative to other low- and zero-carbon fuels,” the study found.
An advantage of using these fuels over other low carbon fuels is that they could power existing LNG vessels without any major modifications, and use an existing fuel supply infrastructure for LNG.
Research
The study looked through around 150 academic and industry publications.
It looked at the global availability of biomass, including from energy crops, agricultural residue, forestry products and residues, and concluded that there is enough to “exceed the global total energy demand of the maritime sector.”
It did not include aquatic biomass, such as algae grown in the ocean, in the study, although this could “play a dominant role in the long term”.
The study acknowledged that other industry sectors might also want the methane, and there would need to be “significant investments in production capacity”.
The study estimates that the production costs of LBM and LSM will be “broadly comparable to other renewable fuels like green hydrogen and ammonia” – but LBM / LSM will have an advantage in that they can be handled using the existing infrastructure.
It said that the availability of LSM will be dependent on how much renewable energy gets built. An alternative pathway is that hydrogen from renewable energy could also power ships directly, or be used to make ammonia for ship fuels.
Future of LNG
SEA-LNG estimates that the greenhouse gas benefits of LNG fuelled compared to liquid fuels are 21 per cent on a “well to wake” basis, covering all emissions from the oil and gas well to the vessel’s propulsion.
“If we are to make effective, meaningful progress with emissions reductions, waiting for the ‘perfect’ solution is not an option. We must act today, and LNG is the only option that both provides considerable GHG emissions reductions now, while charting a clear pathway towards a sustainable future for the shipping industry.”
“Confusing and countering claims abound for different zero-emissions technologies – all of which require decades of research and development before they are proven safe for marine operations, globally available, and commercially viable,” says Peter Keller, chairman of SEA LNG.
The full report is available at https://sea-lng-updates.com/