Leading Danish owner and operator Uni-Tankers has gone the extra mile so that two of its most reliable servants are fully equipped to meet expectations for energy efficiency for the years ahead. The tanker specialist, which operates a fleet of 44 ships, recently sanctioned an overhaul of the chemical carriers Anhout Swan and Lessow Swan to ensure that both would be equipped to sail on into shipping’s lower carbon future.
International Maritime Organization targets envisage a 40% reduction in greenhouse gasses from ships by 2030. Next year, owners face a new IMO regime on ship efficiency, demanding they adhere to an Energy Efficiency for Existing ships Index (EEXI) and provide their Carbon Intensity Indicator (CII). Each ship’s EEXI rating is generated with reference to an Energy Efficiency Design Index (EEDI) baseline.
“We have an ambition to be first in class in every aspect of our operations, and that applies to minimizing our environmental impact and reducing our emissions,” said Peter Stokbro, Technical Director, Uni-Tankers. “After 14 years of proven performance, we went out to the market to seek solutions to future-proof Anhout Swan and Lessow Swan for efficiency and GHG compliance.”
Goals for greenhouse gasses
While ships built today may be designed for optimal fuel efficiency at lower speeds, those delivered 7-15 years ago were optimized for higher engine loads. With fuel prices at unprecedented levels, suboptimal performance by propulsion systems running at ‘part load’ is a cost inefficiency that can eat into competitiveness, as well as a negative for sustainability.
Uni-Tankers consulted Berg Propulsion and Zeppelin on its options to enhance the efficiency of the 2008-built ships when operating at speeds of 14kn. Berg simulations demonstrated that, in combination, the precise control available to the MPC800 system and a modification of the ships’ four-stroke MaK 8M32C main engines to run in variable rpm mode would deliver significant efficiency gains for controllable pitch (CP) propellers and thrusters.
“When we learned that Berg had a retrofit solution ready, the decision to go ahead became easy,” Stokbro says. He confirmed that installing the new Berg Propulsion control system had been pivotal in achieving a remarkable 15-17% efficiency gain on board two existing ships.
“The MPC800 control system upgrade also assists Uni-Tankers in complying with the EEXI and CII,” said Kristian Larsen, Fleet Manager for Uni-Tankers. “It lets us operate the vessels as fuel efficiently as possible, meeting our ambition of providing highly competitive sustainable shipping solutions.”
Lower fuel consumption
Jonas Nyberg, Managing Director West for Berg Propulsion, explained that the ability to control power more effectively using variable speeds cuts energy use overall, reducing both fuel consumption and emissions.
“This is an excellent example of the way vessels already in operation can be optimized to anticipate the transition to the EEXI and CII regimes,” he said. “The aim is to stay ahead of the curve and help customers move towards greener operations with lower CO2 emissions by offering solutions which also enhance competitiveness.”
Installing the MPC800 control system upgrade is one of several class-approved options devised by Berg Propulsion to help ships rise to efficiency challenges. In close cooperation with owners and operators, Berg analyses a ship’s current and future operational needs, evaluates its EEXI rating, and uses 3D scanning and modelling tools to develop retrofit options that offer cost-based efficiency gains, also factoring in any necessary drydocking work.