Challenges to gas acceptance are critical, but manageable, says DNV GL

By 

Carly Fields,

When it comes to choosing the best fuel on the near horizon to help the international shipping industry shrink its carbon intensity by 2050, DNV GL is not shy in coming forward in its support of liquefied natural gas (LNG).

Speaking to Baltic Briefing, Knut Ørbeck-Nilssen, chief executive of DNV GL’s Maritime unit, explains why he’s “bold” on gas as a shipping fuel: “The pathway to carbon neutral goals starts with gas. Gas is readily available today and can deliver measurable GHG reductions of 15%-20%.”

DNV GL sees LNG as a fuel that is both proven and available, offering advantages for ships in the light of ever-tightening emission regulations. LNG, it adds, can be competitive pricewise with distillate fuels and, unlike other solutions, in many cases does not require the installation of additional process technology.

LNG is a fuel that DNV GL understands. It certifies and classes both LNG-fuelled ships and LNG tankers in service today and has conducted a number of terminal feasibility and safety studies as well as certification and survey work related to LNG.

Responding to a common criticism of LNG as a future fuel, Mr Ørbeck-Nilssen agrees that LNG is a ‘bridging’ fuel.

However, it’s a “pretty long bridge, maybe for one or two vessel generations,” he says.

Take-up of LNG fuel has been slower than expected. In 2012, DNV GL predicted that by 2020, the LNG-fuelled fleet would comprise around 1,000 vessels. Three years later, that figure was revised downwards to between 400 and 600 vessels, with the low oil price and slower than expected development of bunkering infrastructure cited as key reasons.

But Mr Ørbeck-Nilssen believes the industry is now reaching a tipping point for acceptance of LNG as a viable bridging fuel. The class society confirmed it is currently working with a number of owners that are planning to order LNG-fuelled ships.

Supporting DNV GL’s stance, a recent study from international multi-sector industry coalition SEA-LNG found commercial benefits of LNG as a marine fuel for a newbuild 210,000 dwt ore carrier sailing from Australia to China. Through an investment evaluation undertaken by simulation and analytics company Opsiana, the study reported strong returns on investment for LNG as a marine fuel on a Net Present Value (NPV) basis over a 10-year horizon. Key findings of the study were that LNG delivers a superior return on investment on an NPV basis of several million dollars in comparison with conventional compliant fuels across all fuel scenarios investigated and that LNG engine and fuel systems investment is paid back within two to four years.
 

Methane quandary

However, there is one important hurdle to overcome before LNG can be universally accepted as the bridging fuel of choice, that of methane slip – emissions of unburnt methane. This slippage, if is not limited by ships burning LNG, can significantly reduce the environmental benefits of using natural gas over diesel. The International Council on Clean Transportation brought this topic into the public eye with its paper on ‘The climate implications of using LNG as a marine fuel’. The report concluded that using a 20-year global warming potential (GWP) and factoring in higher upstream and downstream emissions, there is “no life-cycle GHG emissions benefit to using LNG for any engine technology”.

Mr Ørbeck-Nilssen challenges the paper’s findings: “The ICCT report takes a rather short-term look with an emphasis on the 20-year GWP.” He criticises its focus on 4-stroke engines and older models and points out that the number of vessels is irrelevant; “it’s the overall energy consumption and engines types used that matters”.

“Until 2010, GHG emissions from gas engines were equal or higher than for diesel engines. Since 2010, gas engines produce overall lower GHG emissions than engines running on MGO.”

Further, methane slip is significantly reduced in modern engines with further reductions expected, and two-thirds of LNG fuel consumption in the near future is expected to come from 2-stroke engines, which have a higher GHG emissions saving potential (14%-21%) than 4-stroke engines (6%-15%, he added.

Methane slip is a critical, but manageable, challenge,” Mr Ørbeck-Nilssen said.

While synthetic gas production will solve the upstream methane slip problem, the higher expense of producing this type of gas might well preclude its use in shipping.

But while the debate on the fuel of the future is monopolising discussions, Mr Ørbeck-Nilssen points out that it’s not just about existing fuels and new fuels. “It’s also about efficiency and incentives and optimised hydrodynamics.” DNV GL calculates an energy savings potential of 15%-35% on average per vessel through optimised hydrodynamics and machinery.

Data can also help to optimise the maritime supply chain, with up to 20% GHG reduction potential, while the application of the Energy Efficiency Design Index to all existing ships and tightening of the Ship Energy Efficiency Management Plan could generate further savings.

“To meet the IMO 2050 targets is a challenging one,” he concludes. “Therefore, it’s important that we have an open mind and a broad perspective on the fuel of the future. There is no single one apart from LNG, a bridging fuel that can facilitate the transition from traditional fuels to carbon-neutral fuels.”