Gemini Sustain Plus

On this page, we’re sharing information, useful material and regular updates on the Gemini Sustain Plus programme.

Page contents

    What is Gemini Sustain Plus?

    National Gas Transmission, in partnership with Xoserve and Correla, is undertaking a programme of work to significantly modernise and enhance the Gemini Platform under XRN 5564

    The Gemini Sustain Plus programme will be delivered over a two-year period.

    The target delivery is currently planned for September 2024.

    Gemini will continue to provide Capacity and Balancing services, while also delivering system compliance against new Uniform Network Code (UNC) modifications. This will enable change more efficiently, while also driving an improved customer experience.

    These activities will include: 

    • Converting all current Gemini functionality and code into modern (Java microservices) code
    • Delivering new and existing functional requirements, and new non-functional requirements
    • Consolidating and redesigning the Gemini user interface screens
    • Implementing Azure cloud infrastructure components (including replacing the current Oracle database)
    • Improvements to the support service arrangement to respond better to incidents and change (in-line with new service levels and KPIs)

    Connectivity and Onboarding - 1 April to 31 May 2024

    During the Connectivity and Onboarding phases, we helped customers test their connections and set up their individual accounts in the updated Gemini System.

    If you haven’t completed any of these steps, please email us as soon as possible.

    When the updated Gemini System is delivered, there will be no dual-running alongside the legacy system.


    Market trials for APIs - 17 June to 12 July 2024

    Market trials for business processes/screens - 5 to 30 August 2024

    There are two market trials periods which will allow participants to trial a set of key processes (supported by historic data) to familiarise themselves with the new look and feel of the upgraded Gemini application.

    It will also provide an opportunity to view any changes that may be introduced, as well as to navigate any other screens that have been fully developed but are not supported by data. 


    We’re now starting market trials for APIs

    Monday 17 June – Friday 12 July

    During this time, we’re issuing your technical leads from the Gemini Audit with your end point URL list, and a copy of the draft API specifications. We’ve shared these below, alongside other documents that you might find useful during this stage.

    If you haven’t yet received your credentials, please email us at


    Need support during our API market trials phase?

    We’re hosting technical surgeries to support you throughout the project. You can book your place below.

    Register for a surgery

    We're also hosting weekly calls with all market trials API participants, where you’ll be able to discuss and share queries in an open forum. If you haven’t received an invite for this, please email us at

    Email us

    Please also use the above email address if you need to report an issue with Market Trials.


    Common queries: market trials for APIs

    We are looking at how this process will change going forwards - the authentication method is moving from Basic to oAuth2 so there will be additional factors to consider in handling this process - but the credential change interval is moving to 12 months, so this will be a less frequent requirement than the current solution.

    You will need to change the way that you connect to Gemini APIs, connectivity will be internet based, RESTful and will use a new method of authentication (oAuth2 and JWT).

    Once you connect and authenticate to the new APIs – the actual API structure and functionality remain the same – so you can continue to use XML based queries or you can move to JSON based queries as both methods will be supported.

    Yes - API credentials will consist of Client ID, Client Secret, Subscription ID, and resource - these will be used to get a JWT needed to access each of the new APIs.

    The credentials that were demonstrated previously, were for the online screens rather than API access (online screens use individuals email address and password).

    Yes, there will be new credentials, new URL and you will need to use JWT for authentication - however once connected and authenticated the actual API schema will be the same and you can choose between using XML or JSON based schema.

    The test environment will contain historic (not current) production data.

    Have you completed the connectivity and onboarding steps?

    We're ensuring all Gemini users are able to connect to the new Gemini Sustain Plus environments and activate their individual account profiles. 

    Without taking part in these steps, you won’t be able to carry out any Gemini processes when the new system launches.

    Step one – Confirm you can connect to the new Gemini Sustain Plus production site

    We need all Gemini users to confirm that you're able to connect to the new Gemini Sustain Plus production environment. 

    Please use the following link to connect to the 'to be' production environment. 

    Once you've successfully connected, please complete this short confirmation form.

    Connectivity confirmation form.


    Step 2 - Check you can connect to the market trials environment

    If you're registered for market trials, we also need you to ensure you can connect to our market trials environment.

    Please use the following link to connect to the market trials environment.


    Step 3 - Onboard and check individual accounts

    All Gemini users will have received an email from Microsoft on behalf of National Gas Gemini, inviting you to access the Gemini application.

    This is not a phishing email and will be in the language that your system is set up in.

    Please accept the invitation and follow the instructions to activate the account.

    Read or download an example of this email below.

    Example invitation email

    Once you accept the invite, you'll need to follow some short instructions to set up your account.

    When you've successfully completed these steps (having previously connected to the market trials environment), you'll see:

    • a landing page displaying a 404 error - this is normal and shown while the site is still in development 
    • your new account ID, which will be visible on the top right of your screen

    We have created a short demo video where you can see the above steps being undertaken.


    Need help with any of these steps?

    Issues accessing the new environments

    These new environments are published using the Azure Front Door network. 

    If you can't connect to the new environments, you may need to whitelist the IP addresses for Microsoft Azure services. 

    Visit the Microsoft website to view the set of IPs for whitelisting.

    Join our technical surgeries

    We're also hosting technical surgeries to support you during the Gemini Sustain Plus project.

    Register for a surgery

    Customer focus groups schedule

    View the dates, times and access material for our customer focus groups below:

    Date Time More information
    22 July 2024 1pm - 2:30pm See calendar entry



    Common queries: Gemini Sustain Plus

    We’re sharing the common questions we’ve received throughout the Gemini Sustain Plus project.

    For common queries on the API market trials phase, please read the dedicated ones we’ve shared further up the page.


    Opportunity for training will be provided in 2024 (dates to TBC). It is essential for all companies that use Gemini to participate.

    There will be some functional changes which are in response to pain points raised by customers. i.e. the look and feel of the system, as well as bringing together Entry and Exit Capacity.

    No, after implementation of the Sustain Plus programme Citrix will no longer be required to access Gemini. Portal access will be available using a web browser over an internet connection.

    The existing Gemini API functionality will continue, but there will be changes to the connectivity and user credentials. Any changes to the technical specifications will be published to the industry.

    Get in touch

    If you have any questions or queries about Gemini Sustain Plus, please email us at

    Our support teams are available during business days from 9am - 5pm Monday to Friday.

    Email us

    Need help?

    We're hosting technical surgeries to support you during the Gemini Sustain Plus project. 

    Register for a surgery

    Focus groups

    National Gas have launched a series of Gemini Sustain Plus focus groups.

    The next session will be on Microsoft Teams on 22 July 2024.

    If you wish to attend and haven’t received the Teams invite please email us.

    Email us