Install Electric Energy Storage Batteries (EES) on board Aegir and Sleipnir
The overall objective of this project is to safely and economically install Electric Energy Storage (EES) or batteries on board the Aegir and Sleipnir to serve as ‘spinning reserve’ or back-up power, allowing less engines to run during operations and thereby reducing emissions. Basically, a vessel is transformed into a ‘Toyota Prius’, which has shown to reduce power consumption by as much as 15% in some cases. In the last four years, Heerema has conducted significant research into the ‘Hybrid Thialf’, with the goal to install a battery on-board Thialf. This has not yet been performed as changes to the power management system proved more economically beneficial. Hybridization still remains an important aspect for prevent carbon emissions however, especially considering the synergy that can be achieved with other carbon reduction projects such as Shore Power. Currently, concept design studies for the Aegir and Sleipnir are being performed. Preliminary results for the Aegir show approximately 20% reduced engine hours and almost 5% reduced fuel consumption.
The Transocean Spitsbergen is a hybrid semi-submersible drilling unit operating of the coast of Norway. In October 2019, AKA Group announced the completion of the conversion of the vessel to DP3 closed-bus operation and the addition of 5.6 MW of Hybrid Power. The hybrid system targets a 14% reduction in fuel use during normal operations, leading to a significant reduction in CO2 and NOX emissions.
Why install batteries?
Heerema’s vessels are ‘diesel-electric’ (or LNG-electric). That means that diesel (or LNG) engines power generators, which in term provide electricity for all the equipment and processes on board. Power is mainly needed to operate the cranes, maintain ‘hotel-load’ and operate thrusters while on DP (dynamic position). The cranes and thrusters require intermittent and very large power loads. In order to accommodate these loads, and for redundancy reasons, additional generators are running as back-up. A battery system can absorb the intermittent loads, removing the need for an additional generator. This reduces fuel consumption and thus carbon emissions.
Below is an excerpt of the model to simulate the power management system of the Aegir. It is based on real-life KIM-S data from November 2019-2020. Preliminary results of the feasibility study for the Aegir, performed by Michiel Bots, show a reduction of engine hours up to 21% and average engine load increased from 42% to 57%.