Using the Rochdale Envelope

30th September 2016

Related Topics

Related tags

  • Business & Industry ,
  • Built environment ,
  • Planning ,
  • Energy ,
  • Management


Iheomadinihu Ezeocha

Gemma Keenan, senior environmental consultant in the renewables and marine development team at Royal HaskoningDHV, considers how tidal stream energy developments can benefit from using the Rochdale Envelope approach.

The Rochdale Envelope approach was developed during onshore planning applications to provide flexibility in design options where details of the whole project are not available when the application is submitted, while ensuring the impacts of the final development are fully assessed during the Environmental Impact Assessment (EIA).

Consents granted on the basis of the Rochdale Envelope are conditional on providing the final details for agreement prior to construction.

The Rochdale Envelope approach has been successfully adopted in the consenting of a number of offshore wind farm projects in the UK and is now being used in the consenting of tidal stream energy developments.

Tidal stream energy consenting

The tidal energy industry is at an early stage of development and there is a wide range of possible technology designs available.

When the project description is highly defined in the Environmental Statement (ES), this can lead to requirements for an addendum to the consent if changes are required. Two examples of developments that have required such an addendum include:

  • the original consent for the SeaGen tidal turbine in Strangford Lough, Northern Ireland, required changes to the device foundation from a monopile to pinpiles; and
  • an array of Andritz Hammerfest devices in the Sound of Islay by Scottish Power Renewables required adjustments to the device locations within the original boundary.

Importance of flexibility

Addendums are likely to result in delays to the project programme and additional costs to the developer. Lessons learned during consenting show that tidal stream energy sites which have a single technology option require flexibility in the project design envelope, in order to:

  • allow variation in device layout pending detailed site investigation surveys to optimise generation efficiency or micro-site around constraints;
  • allow for some device and technique advances between submission of the EIA and construction; and
  • provide flexibility in some areas of supply chain options which may avoid developers becoming vulnerable to price volatility of a limited supply source, enabling cost reductions for the development.

In addition, some site developers have limited or no affiliation to one technology developer and are therefore keen to maintain flexibility in the device types until further site investigation and technology procurement works are undertaken. Due to the financial constraints on the majority of tidal developments, these works are usually undertaken post-consent when there is greater confidence in the project and financing can be secured.

The Perpetuus Tidal Energy Centre gained consent in April 2016 to demonstrate arrays of a range of tidal technologies. The EIA considers tidal device types that might be installed at the site and undertakes an impact assessment based on realistic worst case scenarios for each receptor impact.

A similar approach has since been proposed by the third sector company Menter Môn, for the development of their proposed Morlais Marine Energy site in north Wales.

Maintaining a high quality EIA

It is important that an ES clearly outlines if the EIA has been undertaken using the Rochdale Envelope principle, including signposting where areas of flexibility are required. Sufficient detail must be provided to allow the impacts to be fully assessed and the parameters used should be transparent. Where there are a range of potential options or parameters the assessment of each impact should outline the relevant realistic worst case scenarios.

It is good practice to discuss and agree the planned approach with the relevant planning authority prior to proceeding with the EIA. Based on experience of using the Rochdale Envelope in offshore renewables, it is clear that stakeholders and regulators are concerned, not only with ensuring that the actual impacts of the development will be equal to or less than those assessed in the EIA, but also that the EIA does not excessively exaggerate the impact by combining multiple worst case scenarios into a development scenario which is highly unrealistic.

Such an exaggerated approach can make it difficult for stakeholders to provide meaningful advice and judgement during the consent determination process.

The Crown Estate report of the Rochdale Envelope workshop for wave and tidal energy developments in the Pentland Firth and Orkney Waters confirms that it is unlikely that developers will be in a position to determine all design parameters prior to submitting an application for consent.

It is therefore important that consent is granted on the basis of conditions which provide the flexibility for detailed design to be finalised post-consent while also protecting the environment.


Subscribe to IEMA's newsletters to receive timely articles, expert opinions, event announcements, and much more, directly in your inbox.

Transform articles

Renewables account for almost half of Britain’s power generation

Solar power generation hit a new high in the last quarter as renewables accounted for almost half of Britain’s energy production, according to a report from Montel Analytics.

18th July 2024

Read more

Only a third of the emission reductions required for the UK to achieve net zero by 2030 are covered by credible plans, the Climate Change Committee (CCC) has warned today.

18th July 2024

Read more

Almost three-fifths of UK environmental professionals feel there is a green skills gap across the country’s workforce, or that there will be, a new survey has uncovered.

4th July 2024

Read more

Three in five British adults want more public involvement in the planning system, which could be at odds with Labour’s plans to boost economic growth, IEMA research has found.

3rd July 2024

Read more

Ahead of the UK general election next month, IEMA has analysed the Labour, Conservative, Liberal Democrat, and Green Party manifestos in relation to the sustainability agenda.

19th June 2024

Read more

Nine in 10 UK adults do not fully trust brands to accurately portray their climate commitments or follow the science all the time, a new survey has uncovered.

19th June 2024

Read more

Just one in 20 workers aged 27 and under have the skills needed to help drive the net-zero transition, compared with one in eight of the workforce as a whole, new LinkedIn data suggests.

18th June 2024

Read more

Consumers are flexing their purchasing power in support of more sustainable products and services. Dr Andrew Coburn, CEO of sustainability intelligence and analytics firm, Risilience, considers the risk of greenwashing and sets out three key steps businesses can take to avoid the pitfalls and meet the opportunities of changing consumer demand.

18th June 2024

Read more

Media enquires

Looking for an expert to speak at an event or comment on an item in the news?

Find an expert

IEMA Cookie Notice

Clicking the ‘Accept all’ button means you are accepting analytics and third-party cookies. Our website uses necessary cookies which are required in order to make our website work. In addition to these, we use analytics and third-party cookies to optimise site functionality and give you the best possible experience. To control which cookies are set, click ‘Settings’. To learn more about cookies, how we use them on our website and how to change your cookie settings please view our cookie policy.

Manage cookie settings

Our use of cookies

You can learn more detailed information in our cookie policy.

Some cookies are essential, but non-essential cookies help us to improve the experience on our site by providing insights into how the site is being used. To maintain privacy management, this relies on cookie identifiers. Resetting or deleting your browser cookies will reset these preferences.

Essential cookies

These are cookies that are required for the operation of our website. They include, for example, cookies that enable you to log into secure areas of our website.

Analytics cookies

These cookies allow us to recognise and count the number of visitors to our website and to see how visitors move around our website when they are using it. This helps us to improve the way our website works.

Advertising cookies

These cookies allow us to tailor advertising to you based on your interests. If you do not accept these cookies, you will still see adverts, but these will be more generic.

Save and close