Thermal generation providers look to storage to boost efficiency and cut emissions.
by Jason Deign
Drax, the U.K.’s largest power plant, this month applied to build a 200-megawatt battery system as part of a wider move away from coal.
Plans for the battery — which would be the largest in the U.K. and more than double the country’s current level of electrical storage — followed a June proposal to convert two of Drax’s six coal generation units into 3.6 gigawatts of gas-fired capacity.
Three units in the plant, located in Yorkshire, northeast England, are already burning biomass, mostly imported from the U.S. and Canada.
The plans “are subject to a positive investment decision and would need to be underpinned by a 15-year capacity market contract,” said Drax in a press statement.
“The upgrade would enhance Drax Power Station’s flexible and responsive capability, and make Yorkshire the home of large-scale battery technology,” according to the statement. “At this early stage in the planning process, these figures represent the maximum parameters of the project.”
It remains to be seen how Drax’s plans might be affected by U.K. government moves to adjust the way battery storage is treated within capacity markets. Until now, battery systems have been assumed to be able to deliver up 96 percent of nameplate capacity at any point in time.
But in July the U.K. Department for Business, Energy and Industrial Strategy announced a review of this derating value, related to the fact that many fast-discharge storage assets in the country’s enhanced frequency response market would be exhausted within an hour.
The exercise is expected to downgrade the derating value of short-term storage assets, because they can only provide limited support when the grid is stressed. Assets that can deliver energy for 4 hours or more are not likely to be affected.
Assuming Drax does eventually go ahead with its battery plan, it will be following in the footsteps of another European plant owner, Endesa. In February, Endesa unveiled proposals to add an unspecified amount of lithium-ion battery capacity to one of its biggest coal plants.
The Spanish subsidiary of the Italian energy giant Enel was said to be pondering the installation of 30 minutes of storage in a bid to improve efficiency and flexibility at its 1,158-megawatt Carboneras coal plant, the third-largest source of pollution in the country.
Like Carboneras, Drax’s coal-fired generation activities are a major source of atmospheric pollution. This has led plant owner Drax Group to attempt various reboots since the power station was built in the early 1970s.
In 2006, for example, Drax studied adding carbon capture and storage technology to the plant. The work was dropped in 2015 after it was deemed too financially risky.
In the meantime, the company started switching half its generating units to biomass, taking advantage of green energy subsidies that the Financial Times says were worth £450 million ($607 million at today’s prices) in 2015 alone.
Today, the plant faces continued pressure to evolve because of faltering coal market dynamics. When it was built, with a maximum capacity of 36,000 tons of fuel per day, coal mining was a national industry that supported mass employment across Yorkshire.
Now, most of Drax’s fuel is imported from abroad, and support for coal is waning across Europe. In April, the U.K.’s electricity system made headlines after running for an entire day without any coal-fired generation, something that had not happened since the 1800s.
The trend appears to be forcing operators such as Drax and Endesa to consider storage as a way of cutting emissions and remaining competitive in a low-carbon generation world.
This is also happening with gas, where, for instance, Southern California Edison and General Electric have developed hybrid electric turbines.
“Adding battery storage to a conventional plant can turn a slow-responding resource into a fast-responding resource — using the battery to meet immediate needs while ramping up fossil-fuel generation for longer-term operations,” said GTM Research analyst Daniel Finn-Foley.
“By sizing the project correctly and using the battery to simulate conventional operation, a plant can provide some form of spinning reserve without the traditional downside of burning fuel,” he said.