Reusing existing ship structures for large capacity wave energy conversion (RESWEC)

Lead Research Organisation: Cranfield University
Department Name: School of Water, Energy and Environment


The aim of the project is to assess the feasibility of the structural modifications of a range of existing oil tankers to support an array of oscillating water columns for large capacity wave energy conversion.
As with any complex project facing a number of engineering uncertainties, a methodology to de-risk each of the project sub-tasks has been developed. The technical approach will build upon known technologies and measurable quantities to produce realistic and pragmatic solutions to the challenges encountered. By starting with an existing ship, there is an opportunity to reuse the engineering expertise, and financial outlay, required to design and build a large seagoing vessel. Proposed modifications must ensure that the original strength will be maintained, with the primary loading carried by alternative members where the original continuity must be disrupted for installation of the OWC chambers. Several configurations will be developed leading to a selection of the most suitable. The new arrangement and particulars will then be used to calculate and assess the intact stability characteristics of the modified configuration. Several alternative research and development plans have been considered, but then rejected, due to the exponential nature of compounding risk. By focusing on the concept in its entirety, i.e. attempting to solve all of the challenges relating to OWC operation, PTO, electrical generation and naval architectural questions in a single proposal, the risk to project success would be inherently increased. That risk cannot be mitigated in the same fashion as tackling each major subgroup in a methodical manner, with a further technical and economic risk that the inadequate attention may generate unreliable solutions. One of the key technical issues, which is the core of this project, lies with the prediction of the structural loads in the case of a ship hull having not only multiple openings at the bottom, but also when wave energy is converted into pneumatic energy through an air turbine represented, at model scale, by an orifice plate. A purely analytical/numerical approach to predict such loads would be very risky in the case of this particularly challenging fluid-structure interaction problem presenting an air and water interface. Only a carefully thought-out experimental approach can provide an initial set of data required by the naval architect to assess the feasibility of the proposed concept.
The project will be industry-led by Protean Wave Technology Ltd (PWT), with detailed work packages delegated to the parties with greatest expertise in each area. PWT will manage the project, communicate with Innovate UK on financial matters and report the project deliverables. PWT will coordinate and deliver the structural and stability analyses, whilst liaising and working closely with the team in Cranfield University on the test program.

Planned Impact

This research will be very much relevant to the shipbuilding industry and particularly Naval Architects/Design Offices specialized in ship retrofitting.
Description Maximisation of wave energy conversion on a large existing ship (suezmax Tanker) in the field of marine renewable energy. Existing sea going structures can provide a suitable platform to house wave energy conversion systems such as Oscillating Water Columns (OWCs). This project enabled to optimise the number, position and layout of the OWCs in the ship hull for maximum energy recovery. There is currently a large number of unused oil tankers worldwide which could be retro-fitted for wave energy conversion instead of building from scratch entirely new wave emery converters.
Exploitation Route Researchers will explore further the multiplication of power conversion systems on a given platform. Other developers in wave energy can pursue the option of re-using existing sea going structures.
Sectors Energy

Description Due diligence for investors to invest in a demonstrator project with Protean Wave Technology Ltd
First Year Of Impact 2017
Sector Energy
Impact Types Economic