Selby, North Yorkshire-based power company Drax Group said it has switched on its fourth biomass generating unit — taking its giant power station a step closer to achieving its coal-free ambitions.

About 65% of the electricity Drax produced in 2017 was renewable – enough to power four million households.

Having upgraded three of its coal units to use biomass, Drax said it is already “the biggest decarbonisation project in Europe.”

Drax has already invested around £700 million in upgrading the first three units and associated supply chain infrastructure to use sustainable biomass instead of coal.

The conversion of a fourth unit means it is on course to be off coal before the UK Government’s 2025 deadline.

To convert the unit the project team has re-used some redundant infrastructure left from when the company was first co-firing biomass with coal on a large scale, around eight years ago.

A trial last year confirmed that by modifying the old co-firing fuel transportation system, compressed wood pellets can be delivered in the quantities required to fully convert the fourth generating unit.

Drax Power CEO Andy Koss said: “This is another major milestone in the transformation of the power station.

“It will extend the life of the plant, protecting jobs, whilst delivering cleaner, reliable power for millions of homes and businesses.

“It is testament to the engineering expertise, skill and ingenuity we have at Drax.

“The team has developed some very innovative solutions for this upgrade, using all the knowledge we’ve gained throughout the work we have done so far to transform the business using sustainable biomass.”

The cost of conversion of the fourth generating unit — at around £30 million — is significantly below the level of previous conversions.

In 2016 Drax supported more than 6,000 jobs in the Northern Powerhouse region while generating £577 million for the local economy.