Tim Stallard of the University of Manchester (which has developed the ‘Manchester Bobber’ wave device) reviews emerging industry standards

First published in Infocus: Wave Energy, July 2008. Copyright Cleantech Investor Ltd. 2008.Note: Much of the information in this article is an abbreviated form of the project description given on the EquiMar website (www.wiki.ed.ac.uk/display/EquiMarwiki) from which further details and recent developments may be obtained.

A recent AEA/SEI/International Energy Agency - Ocean Energy Systems (IEA-OES) report identifies that “the comparison of different technologies is made difficult by the absence of internationally recognised standards for development, testing and measurement” and that there is “a lack of understanding regarding impacts on the environment”. To address these issues a range of protocols is required that allows evaluation of the different types of technology, and ensures that standard reporting methods are employed and that appropriate methods are used to test and deploy early stage devices.

The EU Framework 7, EquiMar project has been designed to address these issues and will deliver a suite of protocols for the equitable evaluation of marine energy converters (based on either tidal or wave energy). These protocols will harmonise testing and evaluation procedures across the wide variety of devices presently available, with the aim of accelerating adoption through technology matching and improved understanding of the environmental and economic impacts associated with the deployment of arrays of devices. The twenty-two partners contributing to this project include seven EU university groups, four internationally renowned research groups and several industrial partners: together they hold a long track-record in marine energy research and development. This project represents a mechanism for collating the existing knowledge base into robust appraisal methods, and will build on the disparate protocols that presently exist. The methods proposed will provide confidence that diverse technologies have been proven to comparable standards and will provide guidance on the wider economic and environmental implications of marine energy device deployment.

The EquiMar project will progress the development of protocols on the following topics.

Knowledge Base

Current explicit and implicit knowledge for marine energy systems in terms of monitoring performance, cost and environmental impact will be collated. Findings will feed into the rest of the technical activities outlined below. Additionally, this activity will help to raise awareness among stakeholders on the project and produce useful material for dissemination. Preliminary findings from the first stage of this data collation activity will be presented at the 2nd International Ocean Energy Conference, October 2008.

Environmental Specification

In the marine environment, characterising the performance of wave and tidal stream devices is a difficult task and it is important to understand how devices interact with ocean waves and marine currents. Wave and current conditions vary between locations due to changes in water depth, bathymetry profile, geometry and exposure of the area, proximity to land and other meteorological factors, including the presence of other devices if the location is a ‘wave farm’. An extensive review of existing wave and current data collated from representative deployment sites is in progress.

Concept Appraisal and Tank Testing Practices

At present no common practices are adopted to assess the performance and operational characteristics of conceptual and small prototype wave and tidal energy devices. Information acquired from this early stage assessment or small scale testing in tanks is typically used to secure development funding or promote a specific wave or tidal energy device. Since there are no standards this test data is, in many cases, either being misinterpreted or inaccurately presented, which in turn leads to a failure in performance expectations as device designs are scaled up in size.

This package of work sets out to assess and develop: common practices to be adopted for numerically and computationally assessing conceptual device performance; and procedures for undertaking tank testing of small prototype wave and tidal energy devices. This will be undertaken by assessing the procedures and methods adopted by the industry partners in the initial development of their wave and tidal energy converters. Failings in these methods will be identified and used to inform new Best Practices. Robustness testing of these new practices will be undertaken by retrospective analysis of concepts using these techniques to verify that the outputs are representative of the results monitored from the wave and tidal devices developed.

Sea-trial testing procedures

When ocean energy extraction device development leaves the laboratory for the open sea an element of control on the testing and evaluation procedures is inevitably lost. Designers must accept the environmental conditions that occur naturally, rather than having the luxury of generating them as and when required. Sea-trial schedules and analysis methodologies must therefore be very carefully planned and rigorously followed if the performance and behaviour of the machines, particularly at different settings, are to be verified and improved under real operating conditions.

The move from housed, indoor test tanks to exposed, outdoor sites is usually associated with the increase in the size, or scale, of the ocean energy converter (typically from around quarter to full scale machines). The scaling of different generator types will therefore be considered. Verification of the smaller scale results will be an important feedback as this will vindicate the design decisions taken on these test results. Development of standardised offshore test methodologies will be achieved through close consultation with device developers.

Deployment Assessment for Multi-MW Device Arrays

The deployment and performance of the first generation of wave farms and tidal stream arrays represent a significant stage in ocean energy development. This topic of work is aimed at delivering a Best Practice to (a) provide guidance for developers - prior to deployment - on how to integrate their device designs into farms or arrays on a multi-megawatt scale, and (b) to standardise methods for assessing the performance of arrays, or farms, as a whole. Variations in wave and tidal device designs will have a strong influence on the first of these aims, possibly leading to device-specific sites or array layout configurations. Performance of arrays can be broken down into specific areas such as installation, ease (and requirement) of maintenance as well as the unit cost of electricity generated.

Environmental Impact Assessment

The environmental impacts of ocean energy projects are not yet fully understood. Only a few Environmental Impact Assessments (EIAs) have been carried out and then only for small pilot plants. The assessment of such impacts is a highly complex process, not only because of the medium where these projects are developed, but also due to the variety of devices and the different ways in which they interact with the surrounding environment. A further conflict exists with the fact that most EIAs are designed to gain development consent rather than aid environmental protection. On one hand, EIA is a legislative requirement, and on the other hand, its findings could be used as proof of sustainability. This will increase public acceptance, where lack of knowledge has been shown to play a negative role in this growing sector. It will also benefit the industry by making it more attractive to investors and governments, who traditionally might have seen environmental concerns as a barrier. The objective of this work package is to develop a common framework regarding environmental impact assessment issues in order to produce a Best Practice Protocol.

Economic Assessment of Large Scale Deployment

This package of work will develop methods for assessing how the economic viability of the main types of wave energy technology may change with increasing scale of deployment. To distinguish between technologies, the focus will be on evaluating the essential infrastructure costs associated with different types of marine energy device and the scope for reducing cost of electricity by optimisation of device performance. This will provide a framework for assessing the long term viability of designs that are at differing stages of development. These tools will be of considerable use to policy makers and marine energy investors.

EquiMar will assess devices through a suite of protocols covering site selection, device engineering design, the scaling up of designs, the deployment of arrays of devices, the environmental impact, in terms of both biological and coastal processes, and the economic issues associated with large scale deployment. Guidelines for appraising a given combination of technology and site will also be developed. The outcomes from the EquiMar project will be a series of protocols developed through a robust, auditable process and disseminated to the wider community. It is expected that these protocols will establish a sound base for future standards (e.g. IEC).

Existing Marine Energy Protocols & Standards

Marine Renewables Deployment Fund (MRDF) Monitoring Protocol (2006, Draft), UK DTI.

The “Wave and Tidal Energy Demonstration Scheme” provides funding for developers to deploy a small array of devices at an offshore location. To provide a return on this investment, successful applicants are required to follow a defined set of assessment protocols. Separate Wave Energy (Smith G.H. and Taylor, J.) and Tidal Energy (Couch, S. and Jeffrey, H.) protocols were developed.

Galway Bay Test Site Protocols

In 2006 the Irish Government launched an Ocean Energy Strategy. As part of this activity Sustainable Energy Ireland (SEI) and the Marine Institute established a 1:4 scale open sea test site in Galway Bay. Access to this test site is subject to compliance with a number of safety and operational criteria. All device designs, including mooring and installation procedures, are subject to a mandatory independent structural sea worthiness evaluation process before site access is offered. SEI’s 4-phase programme is based on a scaling protocol for wave energy devices written for SEI by University College Cork (UCC).

Det Norske Veritas (DNV) Guidelines

DNV started work on guidelines for the design and operation of wave energy converters, under the Carbon Trust’s Marine Energy Challenge (www.carbontrust.co.uk). The guidelines are based on those developed for other areas of marine operation, but with some adaptation to meet the specific needs of the marine renewable sector. The certification framework is based on safety aspects and functional requirements.

Danish Device Evaluation Procedure

In Denmark a four-stage evaluation process for ocean energy devices has been developed which requires independent scrutiny at each stage. Proof of concept tests must be performed in an independent laboratory; power output must be estimated at laboratory scale against standard sea conditions before the deployment of a scale device in the field and ultimately the deployment of a prototype device. At each stage of results a standardised reporting format is required.

Energy Policy Research Institute

In June 2004 EPRI published a report describing a means for assessing a range of devices in terms of their readiness for full-scale testing or further R&D requirements. In that survey only one was believed to be ready for the development of pilot plant.

European Marine Energy Centre (EMEC) wave device assessment protocol (2004, Draft)