Scotland has already begun the process of building multiple tens of gigawatts of new floating and offshore wind. What it has not yet done satisfactorily is to invest in ways of harvesting that energy at midnight, for example, when demand is at rock bottom.

One solution that already has formal approval is Drax’s pumped storage hydro facility at the iconic ‘Hollow Mountain’ Cruachan Power Station in Argyll and Bute.

Drax is poised to begin work on a £500 million project to build a second pumping station at Ben Cruachan. 

This would double the plant’s capacity but is dependent on Drax getting the right backing from UK ministers. 

Ian Kinnaird, Scottish Assets & Generation Engineering Director at Drax says that with the right support from Government, the new plant could be operational as early as 2030.

The Herald:

During the construction phase, the expansion project is projected to support over 150 jobs in Argyll and Bute and over 500 jobs across the wider Scottish supply chain. Across the UK, the total jobs supported is over 1,000.

The Scottish Government has already given development consent so what is outstanding to date is agreement on the formula that would recompense Drax for operating the plant and allow it to recoup its outgoings. 

“What we are in favour of as a Long Duration Energy Storage industry is a ‘cap and floor’ type scheme, such as that which was used to fund the development of the electrical interconnectors between Europe and the UK,” Kinnaird says.  

It was clear when those projects were being considered that the private companies involved needed to be assured of a minimum revenue from the assets they were constructing to cover the cost of equity. That created the ‘floor’ part of the deal. 

At the same time, with power prices sometimes fluctuating wildly through the day, government needed to be fair to consumers, so the return to the companies were capped at a certain level above the floor price. The balance was returned to consumers (hence ‘cap and floor’).

According to Kinnaird, discussions are well-advanced with ministers, but the final decisions remain to be made. Part of the problem in devising a suitable cap and floor formula for Cruachan is that the problem is a lot more complex than with the electricity interconnectors. 

The Herald:

“When you have laid a subsea cable, the job is largely done. The cable continues to operate and electrons go back and forth and do not create wear and tear on the cable. A pumping station is a very different beast. There you do get wear and tear, and the more you use it, the more wear you get,” he points out. 

The great thing about pumped storage hydro as a ‘battery’ for containing electrical power that would otherwise be wasted, is that it can be turned on at a moment’s notice, almost literally. This ability to react fast to the changing demands of the national grid is what gives it an advantage over traditional thermal power stations such as coal-fired plants.

These plants can take many hours to be ready to generate power, leaving them unable to meet short-term spikes in demand for electricity.

However, pumped storage hydro plants, can generate electricity in a matter of seconds. “The dilemma with electricity is that it is use it or lose it,” Kinnaird notes. “When the wind blows out at sea in the small hours and all those floating wind turbines that are going to be built are generating power, where is it going to go if the demand isn’t there?”

It makes sense to use that electricity to pump the water from Cruchan’s lower reservoir to its upper reservoir. That water is then released, as needed to generate electricity. With the current power station, Drax can supply power to the National Grid for up to 16 hours. This is far more steady power than grid storage batteries can provide. 

“The UK government has promised to introduce a new policy framework by the end of 2024 that aims to unlock private investment in new pumped storage hydro plants.  We urgently need both UK and Scottish governments to honour these commitments,” Kinnaird says.

The Herald:

To date, although there are numerous examples of successful pumped storage facilities around the world, 95 percent of these have been built by state backing rather than by private enterprises. 

“No new pumped storage facilities have been built in the UK in over 40 years because we have not had the right policies or investment frameworks in place from Government to support new private projects. These are projects with high upfront capital costs and a lot of uncertainty around future revenues. This is what makes a cap and floor scheme approach key,” Kinnaird argues.

With the right regulatory framework from government, Drax is ready to invest the £500 million that would be required for a new pumping station at Cruachan. The group has just given the green light to a £80 million upgrade to the existing installation. 

“It is important to emphasise that we see a very bright future for hydropower in Scotland. All that is waiting for is the right policy framework,” he concludes. n     
www.drax.com