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Optimal Design Tools for Ocean Energy Arrays

Final Report Summary - DTOCEAN (Optimal Design Tools for Ocean Energy Arrays)

Executive Summary:
DTOcean (Optimal Design Tools for Ocean Energy Arrays) was a collaborative research and development project funded by the European Commission. It gathered 18 partner organisations from 11 countries and was co-ordinated by the University of Edinburgh. DTOcean aimed to accelerate the industrial development of marine energy by creating software tools for the optimised design of first generation wave and tidal energy converter arrays.

The complete DTOcean software package includes the following computational modules:
- Hydrodynamic Array Layout
- Electrical System Architecture
- Moorings & Foundations
- Array Installation
- Operations & Maintenance

Given a set of user inputs regarding the chosen wave or tidal energy converter and array location, DTOcean software will identify optimal layouts, components and procedures in each of the above modules. Optimality will be established at array lifecycle level, taking into account dependencies between each module, and will be defined in terms of three key metrics: Levelised Cost of Energy (LCoE); Reliability; and Environmental Impact.

Development of the DTOcean suite of tools has now been completed and, following thorough validation based on real-world array development scenarios, the complete software package is freely available to the public via the Joint Research Centre. It is anticipated that a wide variety of stakeholders (including device developers, project developers, researchers, financiers and government organisations) will implement DTOcean and a supportive community of users will develop.

Project Context and Objectives:
The DTOcean project was established to provide software optimisation tools for the design of first generation wave and tidal energy arrays. In doing so, the intention has been to accelerate the development and deployment of ocean energy technologies on the path to commercialisation of the sector.

The ocean energy sector can be considered nascent, whereby wave and tidal energy conversion technologies show great promise but are not yet sufficiently developed to attract significant private investment and become truly commercialised. Ocean energy developments must become cost competitive with other renewable (e.g. offshore wind) and conventional (e.g. gas) energy conversion technologies. A number of prominent roadmap studies have outlined the challenges that must be overcome and the needs that must be satisfied in pursuit of commercialisation. An often-cited need is for design optimisation tools for array scale developments and the DTOcean project has endeavoured to fulfil this need.

The DTOcean suite of tools has been designed to be of use to a wide variety of stakeholders in the ocean energy sector including: device developers; arrays developers; researchers; financiers; and governments. From a technical perspective, the tool can be used to provide optimal arrays designs in terms of: hydrodynamic layouts; electrical architectures; moorings and foundations; installation procedures; and operations & maintenance procedures. Optimality is established according to the key metrics of Levelised Cost of Energy (LCoE), reliability and environmental impact. From a policy and funding perspective, the same tools can be used to compare and contrast a number of potential array developments, again in terms of the three key metrics of LCoE, reliability and environmental impact.

As previously stated, the overall objective of the DTOcean project has been to accelerate the commercialisation of the ocean energy sector. This is achieved by providing a means of optimising array designs, thus further optimising LCoE, reliability and environmental impact and making array developments more attractive to private investors. Furthermore, the DTOcean suite of tools allows policy makers and funders to select the most competitive proposed developments and back the projects most likely to accelerate development of the sector.

Project Results:
The DTOcean project has now concluded. All deliverables have been supplied to the European Commission and the final suite of software tools, along with documentation, has been made available to the public via the Joint Research Centre. DTOcean was divided into nine distinct work packages, details of which follow below.

The overarching goal of Work Package 1 (Scenarios) was to define and populate a number of scenarios based on real-world marine energy array developments. The purpose of these scenarios was to define a scope for tool development and to provide a means of validating the final software, ensuring that it meets the needs of the user. A database structured to contain all technical and environmental parameters required by the software was developed and has been supplied with the full suite of tools. For internal use only, this database was populated with data gathered to represent the chosen validation scenarios.

DTOcean WP2 (Array layout) was tasked with developing software capable of defining hydro-dynamically optimal array layouts for both wave and tidal devices. In fulfilment of this requirement, the DTOcean project has delivered software that incorporates accurate and computationally efficient hydrodynamic sub-models. These models are state of the art for the sector, particularly when considering computational cost.

The main achievement of WP 3 (Electrical System Architecture) has been to define and implement in software a methodology that proposes technically and economically optimal configurations for offshore electrical networks within ocean energy arrays. This requires electrical component selection, cable route planning, calculation of electrical efficiency, and comparison in terms of cost, reliability and environmental impact.

Given details of a device, a layout and the bathymetry and geo-technics of an array site, WP4 (Moorings & Foundations) has developed a software module which selects and positions appropriate mooring and foundation solutions. Based on a large database of commercially available components, which is supplied with the DTOcean package, moorings and foundations are selected to provide suitable support for devices at optimal cost, reliability and environmental impact.

WP5 (Lifecycle Logistics) has produced and implemented in software two separate models, one for logistics and one for installation procedures. The logistics module provides the basis for the installation module and is also used in the operations & maintenance module as described under Work Package 6. The modules produced under Work Package 5 define optimal procedures based on consideration of available maritime infrastructure, ship routing, port selection, equipment selection, logistic phase identification and weather window analysis.

Identification of optimal operations & maintenance (O&M) procedures for ocean energy arrays is achieved by the module coded under WP6 (System Control & operation). Implementing the logistics module provided by WP5, the O&M module provides methods and schedules of O&M for the predicted lifetime of an array, giving particular consideration to optimising capital and operational expenditure.

The modules produced by all preceding Work Packages have been forwarded to Work Package 7, where they have been integrated into a single suite of tools capable of offering optimal solutions at an array lifecycle level. WP7 (Design Tool Development & Operation) was also responsible for the thorough verification and validation of the tools to ensure that DTOcean is fit for purpose.

All activities related to knowledge management, dissemination and exploitation (including a project website, manuals, workshops and planning for future exploitation) were carried out under WP8 (Knowledge, Management, Dissemination & Exploitation) while project management and coordination was led by the University of Edinburgh to form the core of Work Package 9.

Potential Impact:
The DTOcean suite of tools has now been released to the public and is in the early days of being put into use. Over the coming years, it is anticipated that DTOcean will contribute significantly to the accelerated development of the ocean energy sector in pursuit of commercialisation. DTOcean has been designed particularly with the first generation of array scale developments in mind. At the outset of the project it was thought that arrays of this scale may be entering the water by now although it has since become clear that the first arrays are likely to go live following the completion of DTOcean. The suite of tools provided by DTOcean is ready and waiting for first generation of array developers and it is once these projects come to fruition that the real impact of DTOcean will be appreciable.

The DTOcean project has been impact focussed since being initiated three years ago and the following ongoing impacts were apparent as the project progressed:
- Increased cooperation and collaboration between sector stakeholders. The DTOcean consortium and advisory board includes key stakeholders from academia, industry, government, finance and civil society. This arrangement has encouraged greater cross-sector agreement on priority goals and has focussed funding and effort. Knowledge sharing has been facilitated and a number of new collaborative projects have formed as a result of engagement within DTOcean.
- Refined sector goals. The research conducted under DTOcean, while targeted at defining tool requirements, has helped refine knowledge regarding the critical barriers and challenges which must be overcome as the marine energy sector moves towards commercialisation. Such knowledge is the basis of roadmap studies and the guidance that DTOcean research results provide is being actively and effectively disseminated throughout the sector by consortium and advisory board members.
- Increased research activity and talent retention. The DTOcean project provided employment for a significant number of academic and industrial staff. Indeed, some of the most promising young researchers in the sector are directly involved with DTOcean. Retention of talent such as this is critical for the ongoing development of the marine energy sector. Likewise, active promotion and dissemination has generated significant interest from current students and it is hoped that many will go on to form careers in the sector.

The ongoing impacts of DTOcean following release are expected to include:
- A contribution to the definition and fulfilment of national and European energy policies and targets. This impact will be particularly relevant to governmental stakeholders.
- A contribution to the definition and fulfilment of strategic research goals. This impact will be particularly relevant to academic stakeholders.
- Accelerated development and deployment of large-scale, commercial marine energy arrays. This impact will be particularly to industrial stakeholders.
- A significant contribution to publicly available marine energy research. Active dissemination activities ensure that civil society is aware of the benefits of DTOcean and the wider marine energy sector.

List of Websites:
Henry Jeffrey
Institute for Energy Systems, School of Engineering,
Faraday Building, The University of Edinburgh,
King's Buildings, Mayfield Rd,
Edinburgh, EH9 3JL