The next breakthrough in battery-hybrid power, according to Corvus Energy vice president Halvard Hauso is set to be the North Sea Giant.
“It’s a ground-breaking project," Mr Hauso told delegates at the Annual Offshore Support Journal Conference & Awards in London. "It’s the first battery-hybrid DP3 vessel, and when it was built, it was the largest vessel [of its kind].”
The retrofit project started in 2015 and the total cost for the project was NOK74M (US$8.5M).
Part of a collaboration between Wärtsilä and their partners from Maritime CleanTech, the aim is for the vessel to operate on 80% of its DP3 mode with only one genset and the battery. The set up could eliminate the need for operating an additional genset as a spinning reserve and save on fuel, maintenance reduction and emissions, Mr Hauso says.
However, the North Sea Giant has been too busy to take the final steps in the conversion and to prove it can achieve the results its hybridisers are hoping for.
“The battery has been onboard for a year, but because the vessel has been so busy in subsea work, they have not been able to take it out and [finish] the conversion. So they will do it in March and they expect savings of … 5,500 tonnes of CO2 and 30 tonnes NOx, annually,” Mr Hauso said.
Mr Hauso clarified that the vessel only needs to be available for final equipment tests to approve its ability to run on one genset in DP3 mode.
“With a battery lifetime of 10 years, then there is a lot of savings over the full lifetime of the battery,” he said. “If you only remember two things about batteries: they save fuel and they save the environment.”
Batteries are undergoing a period of rapid development, according to Mr Hauso, and Corvus Energy has 190 projects under its belt, with more than two million operating hours for its battery systems. And the company continues to push ahead with development. On the same day Corvus Energy won the Offshore Support Journal's 2019 environmental award, it announced its acquisition of lithim-ion battery specialists Grenland Energy.
The ‘typical’ savings he quotes for the offshore vessel market are, he says, ‘big figures’.
“We are not talking about a percent or two, we are talking big figures. So, for a DP vessel, we save something like 35-50% on the maintenance. And that is because we don’t run that many engines without the battery. And the engine that is running runs at an optimal load,” says Mr Hauso.
“Then, of course, when you don’t run the engine, you save a lot of fuel. We are talking 20-25% fuel savings for a subsea vessel. And, of course, when you don’t use fuel, you save CO2 ... And for the NOx, you even save more because the engine that is running is running at optimum.”
Optimum engine performance is achieved largely through peak shaving, where batteries curb the heavy loads engines would otherwise handle on their own in certain operating scenarios. It sits around 85% of the engine’s full capacity.