CCGT

Summary

The requester asked for the estimated fuel cost per MWh for the Pulrose power station in both combined-cycle and open-cycle modes. The Manx Utilities Authority responded by providing broad brush estimates based on assumed thermal efficiencies and gas transport costs, noting that actual costs vary with load and volatile gas prices.

Key Facts

• The response was issued by the Manx Utilities Authority on 7 August 2025.
• Fuel costs are described as a function of natural gas price and thermal efficiency, which varies by load.
• The provided figures are marginal costs covering fuel only, excluding operating and maintenance costs.
• The authority clarified that the estimates are illustrative and unlikely to match actual marginal costs at any given time.
• Gas pricing is volatile and purchased through various structures including daily, weekly, monthly, and seasonal contracts.

Data Disclosed

• 4822489
• 2025-07-23
• 2025-08-07
• April 2021
• MWh
• CCGT
• OCGT
• NBP
• IM99 1PS

Original Request

What is the estimated fuel cost per MWh generated at Pulrose: When operating in full combined-cycle mode? When operating in open-cycle (gas turbines only) mode?

Data Tables (1)

Full Response Text

Manx Utilities PO Box 177, Douglas Isle of Man, IM99 1PS

e: enquiries@manxutilities.im t: 01624 687687 www.manxutilities.im

Our ref: 4822489 7 August 2025

Dear ###

We write further to your request, received 23 July 2025, which states:

"What is the estimated fuel cost per MWh generated at Pulrose:

When operating in full combined-cycle mode?

When operating in open-cycle (gas turbines only) mode?"

Our response to your request is as follows:

The cost per/MWh of the Gas Turbine sets at Pulrose is a function of both the price paid for natural gas, as delivered at Pulrose, and the thermal efficiency of the sets themselves, which will vary over time due to various technical parameters, the principal one of which will be load.

In order to provide you with an estimate of the approximate marginal costs (i.e. fuel only, excluding any variable and fixed operating and maintenance costs and other overheads) of generating in both combined and open cycle we attach the following table, which makes an assumption of a reasonable average thermal efficiency in both modes of operation as well as a reasonable estimate of the cost of transporting gas from the GB trading point (the National Balancing Point or NBP) and the Isle of Man. These are broad brush estimates and in reality, these examples are unlikely to match the actual marginal cost at any given time.

CCGT = Combined Cycle Gas Turbine OCGT = Open Cycle Gas Turbine

Further Information

To assist further, the following table provides a graph of the average monthly NBP gas price back to April 2021, and overlays our estimated marginal costs based on these prices at the example thermal efficiencies.

Please note that NBP Natural Gas is priced on a daily basis but is also traded on a working day/weekend/ monthly, quarterly (3 month) and seasonal (6 month) basis and as part of our purchasing strategy our daily gas usage may consist of a number of elements of these different pricing structures, bought at different times sometimes many months in advance. This graph therefore in no way reflects the actual marginal generation costs incurred by us over the period but is provided by way of illustration to demonstrate the volatile nature of gas pricing and the order of magnitude of effect that this can have on generating costs.

CCGT = Combined Cycle Gas Turbine OCGT = Open Cycle Gas Turbine

Please quote the reference number 4822489 in any future communications.

Your right to request a review

If you are unhappy with this response to your freedom of information request, you may ask us to carry out an internal review of the response, by completing a complaint form and submitting it electronically or by delivery/post.

An electronic version of our complaint form can be found by going to our website at https://services.gov.im/freedom-of-information/Review . If you would like a paper version of our complaint form to be sent to you by post, please contact me and I will be happy to arrange for this. Your review request should explain why you are dissatisfied with this response and should be made as soon as practicable. We will respond as soon as the review has been concluded.

If you are not satisfied with the result of the review, you then have the right to appeal to the Information Commissioner for a decision on; 1. Whether we have responded to your request for information in accordance with Part 2 of the Freedom of Information Act 2015; or 2. Whether we are justified in refusing to give you the information requested.
In response to an application for review, the Information Commissioner may, at any time, attempt to resolve a matter by negotiation, conciliation, mediation or another form of alternative dispute resolution and will have regard to any outcome of this in making any subsequent decision.

More detailed information on your right to a review can be found on the Information Commissioner’s website at www.inforights.im. Should you have any queries concerning this letter, please do not hesitate to contact me. Further information about freedom of information requests can be found at www.gov.im/foi.

I will now close your request as of this date.