Mast Energy Developments PLC

(Incorporated in England and Wales)

(Registration Number: 12886458)

LEI :213800HFVHGJ9YGO9F71

Share code on the LSE: MAST

ISIN: GB00BNG90H86

('MED' or 'the Company')

Dated: 7 October 2025

MAST Energy Developments PLC

("MAST" or "MED" or the "Company")

MAST's Hindlip 7.5 MW Flexible Generation Power Project Significant Construction Progress

With Arrival of Rolls-Royce Engines

Application For Block Listing

London, UK - Mast Energy Developments PLC (LSE: MAST) is pleased to announce, further to its RNS announcement dated 20 August 2025, significant progress on its 7.5 MW Hindlip flexible generation power project, which is fully funded in partnership with Powertree, the highlights and details of which are outlined below.

Key Highlights:

·    Engineering, Construction, and Procurement ("EPC") progress at Hindlip 7.5 MW flexible generation power project takes significant step forward with arrival of the Rolls-Royce mtu low-carbon reciprocating gas turbine engines, which is typically the longest order lead-time capex item and the critical path to commercial operations date ("COD");

·    Rolls-Royce mtu 20V4000 GS low-carbon reciprocating gas turbine engines secured through Yellow Power, a leading UK EPC company focused on Rolls-Royce mtu power solutions;

·    See photos below of Hindlip's engines being assembled;

·    The Rolls-Royce mtu 20V4000 series offers world-class efficiency, reliability, and lower emissions, making it one of the most competitive engines for decentralised flexible power generation;

·    Stamford HV804X alternators paired with the engines deliver clean, stable output with industry leading >96% efficiency and low harmonic distortion, supporting electricity grid resilience; and

·    Site full construction works (including inter alia civils, LV and HV electricals, and grid- and gas connection) progressing, keeping the project on track to complete construction and reach COD in Q2 2026.

Technical Prowess of the Rolls-Royce mtu 20V4000 GS Engines:

·    20-cylinder V-configuration, lean-burn low-carbon reciprocating natural gas turbine engine with turbocharging;

·    World class electrical efficiency ~42% with high total efficiency when combined with heat recovery options;

·    Robust design proven across global power applications, with low maintenance overheads;

·    Engines are certified for hydrogen and green-gas readiness, ensuring long-term sustainability and use of engines; and

·    Excellent local operations and maintenance support via Yellow Power and Rolls-Royce.

About Rolls-Royce mtu:

Rolls-Royce's Power Systems division, through its mtu brand, is a world leading supplier of high-speed gas engines for power generation and marine applications. The mtu Series 2000 and Series 4000 engine families have been developed over more than two decades, with over 100,000 units delivered worldwide. The business has established a strong position in clean, efficient gas-based power, with engines offering low emissions performance in line with stringent global standards. Recent advancements include hydrogen-ready certification and compatibility with sustainable fuels, positioning the mtu portfolio at the forefront of the energy transition. mtu gas engines are deployed globally in stationary generation, combined heat and power, and marine propulsion, with ongoing development in hybrid and hydrogen solutions to support decarbonisation.

Ivan Wentzel, Head of Operations at MAST Energy, said: "We are delighted to confirm the securing and assembly of Rolls-Royce mtu 20V4000 GS engines for our Hindlip site in partnership with Powertree through Yellow Power, a trusted supplier with deep expertise in Rolls-Royce mtu technology. These engines set the benchmark for efficiency, reliability, and compliance in the flexible generation sector. Hindlip is firmly on track for COD in Q2 2026 as planned, further strengthening MED's portfolio of flexible generation assets and contributing to the UK's energy security."

Photos:

1:         Rolls-Royce engine arrival at Yellow Power factory

2:         Cooling Skin Manufacturing and Assembly

3:         Rolls-Royce engine assembled and destined for Hindlip site

4:         Fully assembled Rolls-Royce engine and cooling skid destined for Hindlip site

Stay up to date with MED's latest news and updates by joining our emailing list and social media channels, as follows:

MED general enquiries - https://www.med.energy/contact

MED email alerts - https://www.med.energy/rnsannoucements-1

MED LinkedIn page - https://uk.linkedin.com/company/mast-energy-developments-plc

MED X (formerly Twitter) handle - @mastplc

About MAST Energy Developments PLC:

MAST Energy Developments PLC (LSE: MAST) is a UK-based developer, operator and owner of flexible generation power assets. The Company has deep expertise in infrastructure planning, grid access, gas access, and efficient power supply. Its new AI power supply strategy is intended to position MAST as a leading AI infrastructure platform on the London Stock Exchange (read more here).

Application for Block Listing

Capitalised terms used in this part of this announcement have the same meaning as those given to them in the Company's RNS announcement dated 23 May 2025 unless otherwise defined.

The Company announces that it has made an application to the Financial Conduct Authority ("FCA") and the London Stock Exchange for the block listing (the "Block Listing") of a total of 245,200,000 ordinary shares at par value of £0.001 each (the 'Ordinary Shares').

The Block Listing application relates to Ordinary Shares to be issued from time to time pursuant to the exercise of Cash Warrants issued pursuant to the Equity Fundraise announced on 11 July 2025.

When issued, these Ordinary Shares will be credited as fully paid and will rank pari passu in all respects with the existing issued Ordinary Shares of the Company. It is expected that admission will become effective for the Ordinary Shares on 8 October 2025.

ENDS

This announcement contains inside information for the purposes of the UK version of the Market Abuse Regulation (EU No. 596/2014) as it forms part of United Kingdom domestic law by virtue of the European Union (Withdrawal) Act 2018 ('UK MAR'). Upon the publication of this announcement, this inside information is now considered to be in the public domain.