Wednesday, January 29, 2020

"Study: LNG as Marine Fuel not Such a Cool Choice?"

We disagree with the conclusions but are posting for future reference.

From World Maritime News:

Although liquefied natural gas (LNG) contains 25 pct less carbon per unit of energy than conventional marine fuels, its use might not reduce greenhouse gas (GHG) emissions on a life-cycle basis, according to a study published by the International Council on Clean Transportation (ICCT).
The study explained that LNG being mostly methane, is a potent greenhouse gas (GHG) that traps 86 times more heat in the atmosphere than the same amount of CO2 over a 20-year time period.
“If even a small amount of methane escapes anywhere along the process of extracting it from the earth and burning it in an engine, using LNG could emit more life-cycle GHGs than conventional fuels,” the paper said.
The study compares the life-cycle GHG emissions from LNG, including upstream emissions from leakage during extraction, processing, and transport and downstream emissions from combustion and unburned methane, to those of heavy fuel oil, very low sulfur fuel oil, and marine gas oil (MGO).
It evaluated the climate impacts using 100-year and 20-year global warming potentials (GWPs).
“Over a 100-year time frame, the maximum life-cycle GHG benefit of LNG is a 15% reduction compared with MGO, and this is only if ships use a high-pressure injection dual fuel (HPDF) engine and upstream methane emissions are well-controlled. However, the latter might prove difficult as more LNG production shifts to shale gas, and given recent evidence that upstream methane leakage could be higher than previously expected. Additionally, only 90 of the more than 750 LNG-fueled ships in service or on order use HPDF engines.

“Using a 20-year GWP, which better reflects the urgency of reducing GHGs to meet the climate goals of the International Maritime Organization (IMO), and factoring in higher upstream emissions for all systems and crankcase emissions for low-pressure systems, there is no climate benefit from using LNG, regardless of the engine technology. HPDF engines using LNG emitted 4% more life-cycle GHG emissions than if they used MGO.”
The authors of the study also claims that the most popular LNG marine engine—low-pressure dual fuel (LPDF), medium-speed, four-stroke—was also the leakiest....MUCH MORE, including critiques.