Energy efficiency and marine renewable energy

Technical Bulletin 2015

This section concerns two energy topics of major importance in the marine and offshore sector: the exploitation of marine renewable energy (MRE) and the energy efficiency of ships.

Regarding MRE, the first paper addresses the development and enhancement of a BV guideline dedicated to Current and Tidal Turbines (NI603). Tidal turbines feasibility has already been demonstrated at sea by several technology developers over recent years in different countries. However, exploitation at sea still comes with significant design, installation, grid connection, and maintenance challenges. Based on experience with tidal turbine technology developers, BV provides a new guideline to support this emerging sector. The paper presents recommendations from the existing experience at sea of tidal devices; best practices from related sectors, such as shipping, wind energy or offshore oil & gas; and a risk-based approach to consider for the particular requirements of each tidal turbine installation.

As operation and maintenance activities and associated costs are crucial in the viability of a MRE device, the two following papers address the development of a lifecycle cost analysis combined with a Reliability, Availability, Maintainability (RAM) assessment. The RAM assessment models the impact of operation, failures and associated maintenance activities on power production availability and costs. This cost/reliability assessment is used in the second paper to assess the concept of MRE combined platforms (e.g. wind and wave), providing synergies in terms of reducing risk and cost through sharing components, infrastructure and maintenance activities. In the third paper, the combined cost/reliability assessment is used to identify optimal power aggregation methods for multiple MRE devices at sea. Gathering electrical production from multiple devices at sea into a single transmission line to shore is indeed a significant challenge for the MRE sector. The benefits from sharing components such as DC link, inverter and transformer is discussed, based on initial equipment investment; costs induced by failures and maintenance activities over the platform lifespan; and resulting loss of income due to power production interruptions.

The second main topic of this section is energy efficiency, a crucial aspect of ships today, both from regulation, with the reduction of emissions, and exploitation, with the reduction of fuel consumption, points of view. The last paper focus on this subject, presenting the design of a new generation of 180 000 m3 LNG carrier with high energy efficiency considering future LNG trading patterns, new trading route and compliance with future environmental regulations. For this purpose, a full hull form, propulsion and power generation optimisation has been performed for a pre-defined complete operational profile of the ship (i.e. full voyage including loading and unloading operations, manoeuvring, channelling, etc.). Various dual fuel propulsion and power generation architectures have been defined and their performances have been assessed using a holistic energy modelling of the ship. Bureau Veritas has been developing and applying its Ship Energy Efficiency Calculation and Analysis Tool (SEECAT) for this purpose for several years. Moreover a fine Boil-Off gas model, predicting the evolution in time of the Boil-Off gas rate and Lower Heating Value has been developed and integrated in the simulations. The study is completed by a cost analysis that enables us to compare the designs and select the optimal one.

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