Repowering Drax

Drax has come a long way since its days as a single-site 100%-coal generator. Four of its six 660 MW coal units have been converted to 100% biomass, while a repowering project that will see the steam turbines of the remaining two used in gas fuelled 2-on-1 combined cycle plants – and the end of coal generation at the Drax site – has recently received planning permission.

Consent has been given for two 1800 MW combined cycle plants (each consisting of two 600 MW gas turbines with HRSGs supplying steam to a 600 MW reused steam turbine) to be constructed at the Drax site, with the first entering operation in 2023, provided a capacity market agreement (15 years duration) can be secured to underpin the investment. The UK capacity market is currently suspended, following a legal challenge initiated by Tempus Energy (provider of demand side response and flexibility optimisation software), but Drax is hoping for resumption of auctions in early 2020.

The Drax repowering project envisages use of the existing cooling systems for the new facilities, which will be designed for open cycle operation (with bypass stacks) as well as combined cycle. The project also includes installation of two 100 MW energy storage facilities, one per combined cycle plant.

The two-person planning inspectorate panel recommended that consent should be withheld – on the grounds, among others, that additional combined cycle capacity is not needed in the UK and the project was not in line with national decarbonisation objectives. But this assessment was overturned by the Secretary of State for Business, Energy and Industrial Strategy (Andrea Leadsom), who (apart from the possibility of a judicial review) has the final say, noting, for example, that the new plants will be carbon capture ready, are complementary to renewables and include energy storage.

Drax entered the gas generation business with its acquisition (completed 31 December 2018) from Iberdrola of a 2.6 GW portfolio of UK power plant assets that included four combined cycle plants, Damhead Creek (805 MW), Rye House (715 MW), Shoreham (420 MW) and Blackburn Mill (60 MW) (together with the Cruachan pumped storage plant (440 MW), run-of-river hydro at Galloway and Lanark (126 MW) and the Daldowie power- from-waste facility).

The company is also developing four 299 MW open cycle gas turbine peaking projects (Hirwaun, Progress, Millbrook and Abergelli), all of which have panning permission.

Upgrading Shoreham

Drax has placed an order with GE for a GT26 HE (high efficiency) gas turbine upgrade to be carried out at Shoreham. This is GE’s second order for the GT26 HE upgrade, the first was placed earlier this year by Uniper, for its Enfield plant in the UK.

GE says it will also will also “provide digital solutions and plant improvement services to help Drax increase the plant’s flexibility and ultimately increase its competitiveness in the United Kingdom.”

Andy Koss, CEO, generation, at Drax said: “GE’s GT26 HE gas turbine upgrade could provide a significant efficiency increase, more flexibility and greater power output from Shoreham power station. These are critical attributes, which complement the roll out of renewables in the UK and can help to ensure a stable power supply whatever the weather. In addition, our fleet would reap the benefits of GE’s digital solutions to help us react more quickly to marketplace conditions while reducing our operating costs and improving the plant’s carbon footprint.”

GE will perform an “enablement inspection” in 2019 to allow operation until 2021, which is when the new HE package will be implemented on the gas turbine. The upgrade would increase combined-cycle efficiency by about 2.5% and add more than 40 MW of power at baseload.

“Our new HE product is the most advanced solution we’ve ever introduced on a GT26 gas turbine, and it provides significant performance improvements for an F-class combined-cycle gas turbine upgrade,” said Amit Kulkarni, general manager, H/F- class turbines within GE’s Power Services business. “Not only will this upgrade help Drax improve its efficiency and output, but it will also improve its competitive position in the UK energy marketplace. The power increase will be rewarded in the event of a successful bid in the UK’s capacity auction, and the lifetime improvement will reduce maintenance costs.”

The GT26 HE upgrade constitutes “a leap forward in efficiency, output and maintenance interval extensions”, says GE. It takes advanced technology from GE’s HA gas turbine, with additive manufactured parts and innovations in aerodynamics, material science and combustion dynamics and “embeds technology breakthroughs across every major component of the GT26 frame— turbine, compressor and combustor—to take turbine performance to a new level, significantly decreasing fuel costs while increasing full-load output and extending maintenance intervals.

The digital elements of the project will “help Drax take its first step toward a digital industrial transformation and reinvent how the utility operates its assets”, says GE.