This report provides a review of the use of the ‘Rochdale Envelope’ approach to defining a flexible design envelope when consenting tidal energy projects.
The ‘Rochdale Envelope’ arises from two legal cases in the UK: R. v Rochdale MBC ex parte Milne and R. v Rochdale MBC ex parte Tew  and R. v Rochdale MBC ex parte Milne .
The Rochdale Envelope approach has been adopted in the consenting of a number of offshore wind farm projects in the UK, with the Environmental Impact Assessment (EIA) based on assessing the realistic worst-case scenario where flexibility or a range of options are sought as part of the consent application. The Infrastructure Planning Commission (IPC) (2011) provides guidance on the use of the Rochdale Envelope for Nationally Significant Infrastructure Projects, particularly offshore wind.
The same principle has been used successfully in the tidal industry to support project requirements for flexibility of design and technology of varying degrees and extent. The approach taken to consenting and the amount of flexibility required in the design envelope will depend on the objectives and circumstances of the development with each project often facing unique challenges. This report provides a review of the approaches taken by the tidal industry to date, including an outline of the wide range ofpossible tidal technology designs which can be deployed to harness tidal energy.
This report also provides case studies of key consented tidal projects and outlines the advantages and disadvantages of the approaches to design envelope taken, in terms of project details and flexibility.