The 393MW Uskmouth coal-fired power station at Newport, Wales, UK is undergoing an innovative conversion project to repurpose two of its ageing coal-fired units to operate on waste-derived fuel pellets for a net capacity of 220MW.

SIMEC Atlantis Energy, the current owner of the non-operational Uskmouth power plant, is  executing the conversion project in two phases with each phase involving 110MW of waste-to-energy generating capacity. The third unit of the plant is also planned for similar conversion in the future.

The large-scale combustion testing for the conversion project was completed in June 2020 and the pre-construction works for the phase one conversion project are currently underway.

Although the financial close for the project was previously scheduled for the third quarter of 2020, it has been delayed due to the COVID-19 pandemic.

The engineering, procurement, and construction (EPC) contract negotiations for the project are expected to be completed in early 2021, while the phase one commissioning is expected to take place after 18 months from the commencement of EPC works.

Utilising fuel pellets made up of waste biomass materials (50%) and non-recyclable plastic wastes (50%), the repurposed facility is intended to generate sustainable energy over an estimated operational life of 20 years.

Project background

The Uskmouth coal-fired facility, which was commissioned with three generating units in 1959, was closed by previous owner Scottish and Southern Energy (SSE) in 2014.

SIMEC Energy, a member of the GFG Alliance, acquired the facility from SSE in December 2014, and entered into a strategic partnership agreement with tidal power developer Atlantis Resources for the conversion of Uskmouth power station, as well as for the development of the Meygen tidal power project in Scotland in December 2017.

Fuel supply for the Uskmouth waste-to-energy facility

The Uskmouth coal-fired power station will be repurposed to operate using a new type of waste derived fuel pellet, called Subcoal®, which is a high quality alternative fuel to be developed using Dutch recycling company N+P’s proprietary technology.

Two new full scale production facilities are being set up in the UK by SIMEC Subcoal Fuels (SSF), a 50:50 joint venture between SIMEC Energy and N+P Group, to produce the required fuel volumes for the conversion plant.

Half of the Subcoal® fuel pellet content will be derived from waste biomass materials such as paper and cardboard, while the remaining half will comprise non-recyclable plastic wastes.

The power station is expected to consume approximately 900, 000 tonnes (t) of waste derived fuel pellets a year. The pellets will have an average calorific value of 20 mega joules per kg and produce 50% less CO2 and will be significantly cheaper than fossil fuels and normal biomass.

Waste-to-energy generation at the Uskmouth power station

The existing combustion chamber, boilers, burners, turbine generators, and the related gas cleaning equipment will be upgraded as part of the conversion project to allow the combustion of the new alternative waste-derived fuel.

The fuel pellets received from a pelleting facility will be conveyed to the mills for pulverising and the crushed fuel material will be fed into the combustion chamber to heat water in the boilers to generate steam that will drive the turbines for power generation. The resulting waste gases will be cleaned before they are emitted.

Power off-take

The power generated from the converted facility was initially planned to be sold to GFG Alliance companies under two power purchase agreements for a period of 20 years.

Atlantis has also engaged data centre development specialist TechRE to explore options to locate edge and hyperscale data centres near the Uskmouth power station site.

The electricity output of the facility is proposed to be delivered to the onsite data centre through a private wire network under a long-term power purchase agreement.


SIMEC Atlantis Energy signed a debt financing agreement with the South Korean financial institution Hana Financial Investment (HFI) to secure £170m for the Uskmouth power station conversion project phase one in August 2020.

Key players involved

Mitsubishi Hitachi Power Systems Europe (MHPS Europe) was awarded a contract for the design, development and testing of the combustion system for the power station conversion project in October 2019.

The scope of contract included industrial scale milling tests on the fuel pellets, industrial scale combustion tests on the fuel, and furnace burner system design.

SIMEC Energy and N+P Group agreed to form the joint venture company SIMEC Subcoal Fuels (SSF) for setting up new Subcoal® production facilities in the UK in May 2018. SSF will also supply 900,000t of Subcoal® to the Uskmouth power station under a 20-year fuel supply agreement.

RPS, an international consultancy firm, was appointed as environmental planning and permitting (EPP) consultant for the power station conversion as well as for an adjacent fuel pellet production facility in November 2018.

The front-end engineering and design (FEED) contract for the project was awarded to WSP, an engineering and professional services consultancy, while TechRE has been engaged to explore options to locate edge and hyperscale data centres near the power station site.