LNG Power for OSVs

Rolls Royce and DNV engaged in a joint study of different fuel and engine configurations. The vessel selected for this study was the Rolls Royce designed UT 776 PSV. In the study, four alternative power system arrangements were considered, with two gas tank versions. The four power system arrangements were:

• Diesel

• Hybrid Diesel/LNG

• Lean burn gas

• Dual Fuel

The gen-sets were powered by various sizes of Bergen C-series diesel and gas engines and the dual fuel engine was a commercially available unit. For diesel and hybrids the assumption was that the exausts would have a SCR system giving a constant value of NOx reduction of 75%. In terms of cost, the diesel was the winner in the study as there is the added expense for other solutions of insulated LNG tanks. Lean burn gas scored marginally on total energy consumption, yet scored heavily on reduction of equivalent CO2 release and NOx reduction.

There was really no clear winner when analyzing CAPEX, OPEX and financial costs. LNG tankage increased the costs of a vessel compared with a straight diesel version. However, technical solutions for LNG installations are becoming more competitive. OPEX costs vary depending on emission taxes applied and on fuel prices. Depending on where in the world you are several limiting factors may come into play when accessing the desirability of introducing Hybrid Diesel/LNG power systems. The price levels for LNG fluctuate widely in different continents, as do diesel prices. Yet refueling availability may be more likely to influence the adoption of an LNG system than CAPEX differences.

Infrastructure for LNG bunkering in significant quantities is in place in northern Europe in countries such as Norway, Sweden and Germany, along with other Baltic and North Sea countries. In a few years Rolls Royce forecasts that LNG bunker will be available at key locations around the world. In Brazil there is still a long way to go in terms of LNG bunkering infrastructure, and there is still not much government control over emissions.

Hybrid Diesel/LNG systems may be an option for OSV operators in Brazil in the long run, as it will take time to implement adequate LNG bunkering infrastructure along the lengthy Brazilian coast but with a structure for LNG bunkering set up in key locations on the coast HD/LNG systems would be viable and could bring a significant economy for OSV operators as the cost of LNG in Brazil is hardly prohibitive. At least for now, without convenient LNG bunkering stations, the diesel fuel solution still reigns but it is conceivable that in five years time we may be seeing HD/LNG OSVs operating in Brazil in considerable numbers. Claudio Paschoa Information courtesy of Rolls Royce