SEPTEMBER
2016
LNG
INDUSTRY
25
C
lean-burning natural gas has emerged as an important fuel for ships as the marine industry
seeks ways of complying with increasingly stringent environmental regulations. These
restrictions limit emissions of SO
X
, NO
X
and particulates. In order to comply with such
restrictions, operators can either employ after-treatment systems when using conventional marine
fuels, or use cleaner fuel, such as natural gas, which has fewer harmful emissions.
One drawback of natural gas is that it has low energy density compared to traditional fuels. In
order to serve as a convenient energy source, the density needs to be increased. This is done by
cooling the gas to cryogenic temperatures, creating LNG. This can be stored in insulated tanks,
keeping it in a liquid state for longer periods. However, heat flux from the surroundings will increase
the temperature inside of the tank, causing the liquid to evaporate. The generated gas from this is
known as boil-off gas (BOG).
The notorious
Björn Nygård, Wärtsilä Corp., Finland,
looks at
methods for handling boil-off gas on board
LNG-fuelled ships.
