UK Oil & Gas PLC announced that DEEP.KBB GmbH, one of Europe's leading salt cavern design and underground energy storage engineering groups, has completed preliminary project design for the company's proposed new underground H₂ storage facility located west of Weymouth in Dorset (South Dorset). The design, prepared for the company's wholly owned UK Energy Storage subsidiary (UKEn), confirms the suitability of the site for a material scale H₂ storage project, comprising 24 salt caverns at a depth of ~1,330 m below surface. The project is fully in keeping with the Government's clean power 2030 ambitions.

The following metrics summarize the Design and its advantages versus UKEn's original Portland site, see Table 1 and also RNS of 27/06  and 21/08/2024:

• The design comprises 24 caverns providing up to 1.01 billion standard m³ (bcm) working H₂ volume, 12% greater than Portland's 0.9 bcm
• Calculated H₂ withdrawal and injection rates could provide up to 2.9 times the annual cycling capacity of Portland, creating a technical maximum annual storage capacity of 30.2 TWh¹/yr vs Portland's 10.4 TWh¹/yr, a substantive increase
• If delivered and operated at full capacity, the Site's technical maximum 30.2 TWh¹/yr annual storage capacity could represent a material proportion of the currently predicted UK 2050 annual H₂ storage demand of 50-100 TWh¹/yr²
• The design's adoption of a conventional "cushion gas" operating scheme would significantly reduce project development costs (CAPEX) by around 36% compared to Portland, reducing costs by around £450 MM
• The design's resultant increased cycling capacity, lower CAPEX and operating costs create potential for a significantly increased future annual revenue base versus Portland and a more competitive submission for government revenue support
• The site also lies closer to the planned H₂ Connect H₂ trunk pipeline, designed to connect South Dorset to the UK H₂ transmission pipeline system (Project Union) and the main H₂ clusters in the South, East Coast and Northwest.

The design's significantly greater injection and withdrawal rates and consequent increased annual energy storage capacity compared to Portland, are a direct consequence of the underlying geology at the location. The Triassic salt is thicker, permitting larger caverns, and lies 1,070 m closer to surface at 1,330 m versus 2400m at Portland. The associated lower hydrostatic pressure and temperatures within the salt underlying the Site enable a simple, conventional "cushion gas" scheme to be utilized to provide the minimum necessary cavern working pressure required to maintain cavern integrity.

The cushion gas scheme, as proposed by DEEP.KBB, is a proven technology used in numerous salt caverns in the UK, Europe and USA, offering a much simpler development and operation than the required brine compensation scheme (see glossary) at Portland. The Design's scheme requires no additional brine wells, brine facility or brine pipelines, plus there is only one well per storage cavern versus two for brine compensation.

Therefore, applying Xodus supplied cost data to the proposed cushion gas scheme, South Dorset CAPEX is now estimated to be around £800 MM in today's money, around £450 MM lower than the Portland project.

As the company intends to apply for government revenue support only for its strongest H₂ storage projects (see RNS of 29th May 27th June 2nd August 2024), it is the Company view that South Dorset's potentially significantly increased revenue potential, plus the simpler, substantially lower CAPEX renders it more economically competitive than Portland and versus other potential applicants' projects on a cost/TWh basis.

Consequently, the company has made a strategic decision that it will pursue revenue support only for its more competitive South Dorset and East Yorkshire projects and will no longer pursue the Portland project. The new South Dorset H₂ storage project will therefore play a flagship role in the company's activities to help the decarbonization of the UK energy system, the Portland Energy Hub, the pan-Dorset economic framework and regional Solent Cluster. Similarly, as clean power and H₂ storage is now the Company's primary focus, the Company has also ceased its activities in Turkey.

Given our positive relationship with Portland Port and the role of H₂ in decarbonizing the marine sector, the company believes that there remain synergies between our South Dorset project and the port. With this in mind, the company is considering the opportunity of a green H₂ pilot plant at the port that could be linked directly to the South Dorset site's storage, offering the potential for local clean H₂ to power generation both for the port and Weymouth.

The company's aim of delivering these key strategic energy infrastructure elements is fully in step with the Government's ambitious target to decarbonize the UK power system by 2030. The currently envisaged project time scale, subject to necessary regulatory consents and financing, would see construction well under way by 2030, with first operational caverns in the 2030-32 window.

Stephen Sanderson, the company's Chief Executive, commented, "DEEP.KBB's Design work demonstrates that the South Dorset Site has the potential for far greater future revenues and profitability versus the Company's original and otherwise robust Portland H₂ storage project. It is, therefore, also likely to be a more compelling case for government revenue support in the forthcoming H₂ storage procurement process, now scheduled for later this year. Consequently, our efforts will now be focused upon this material project and its northern sister in East Yorkshire, both of which plan to utilize simple and proven cushion gas operating technology."