LNG dual-fuel is fast becoming the transition fuel of choice for tanker newbuildings and there have been retrofits in other sectors, but is it an option for large tankers?
LNG retrofits are an increasingly popular option. According to DNV GL’s Alternative Fuel Insight Platform (AFI) database, 23 vessels have now been retrofitted with LNG fuel engines. A key influencer in the retrofit process is the size of the LNG tank. The largest LNG tank fitted so far in a retrofit is the 6,500 m3 unit installed on the UASC containership Sajir. Many regard the LNG retrofit on the 2014-built 15,000 teu vessel as a pilot study for the whole of the shipping industry.
Sajir had been built in 2014 with the possibility of introducing LNG, but even so, the retrofit was not a straightforward process. Owner Hapag-Lloyd said without the pre-retrofit work, its investment for the conversion would have been a lot higher, as it can cost US$1M for just one auxiliary to be modified to a dual-fuel engine.
Furthermore, MAN head of sales, retrofit projects Klaus Rasmussen noted Hapag-Lloyd paid a higher cost for the retrofit work on Sajir because it was first of its kind. He said any further retrofits would be cheaper as a result of experience gained to date. The vessel’s 54.9-MW MAN B&W 9S90MEC10 engine was converted to MAN Energy Solutions’ dual-fuel ME-GI engine concept.
Currently, nine vessels have had engines converted to WinGD’s dual-fuel LNG burning DF engines and 10 vessels have been fitted with MAN Energy Solutions’ LNG burning energy unit. The methodology is in place to convert vessels to LNG power and DNV GL already has rules in place.
Will we see larger vessels such as VLCC tankers being converted to dual-fuel LNG power? Independent shipbroking house Affinity’s founder and managing partner Richard Fulford-Smith has long been a cheerleader of seaborne LNG, but he has his doubts regarding retrofits: “LNG retrofits on VLCCs will not happen,” he noted bluntly, citing the LNG tank arrangements and the financing involved in such conversions.
Still, this has not put off French LNG tanker designer Gaztransport & Technigaz (GTT), which has a solution in place for retrofitting LNG fuel tanks to VLCCs. Presenting at the Tanker Shipping & Trade conference, GTT’s product line manager Pascal Ta explained how one of the cargo tanks could be sacrificed to create the LNG tank. The LNG tank is constructed between two longitudinal bulkheads and is surrounded internally with GTT’s Mark III propriety insulation. The primary barrier prevents the steel hull from contact with the LNG and carries the structural loads. On the internal tank side of the insulation is the GTT waffle structure, which reduces sloping of the cargo and carries the stresses from the cargo during the voyage.
The converted tank is midway of the hull of the converted tanker to reduce hull stresses. For a tank of 14,000 m3, the tank will be around 27-m long. The converted tanker would also require piping and other ancillary equipment associated with LNG dual-fuel.
It has been noted that funding such retrofits might not be as problematic as first impressions suggest. Several years ago, when the IMO 2020 marine fuel sulphur cap was first proposed, many banks were doubtful that financing scrubber retrofits was possible. But since then, hundreds of scrubbers have been retrofitted – many financed by banks. It seems that if the business case makes sense, then the finance will be made available, which is good news for LNG retrofits.