Can Renewables Restart the Grid? The UK Investigates

 

If successful, the U.K. National Grid’s Distributed ReStart project should prove that assets such as wind, solar and battery plants can work alongside synchronous generators to restore power following a countrywide blackout. 

 

“The project is exploring how distributed energy resources can be used to restore power in the highly unlikely event of a total or partial shutdown of the national electricity transmission system,” said National Grid in a report published last month.

 

“Past and current approaches rely on large power stations, but as the U.K. moves to cleaner, greener and more decentralized energy, new options must be developed. The enormous growth in DER presents an opportunity to develop a radically different approach to system restoration.”

 

Distributed ReStart was launched in January 2019 and is set to run to March 2022, with £10.3 million ($13.5 million) in backing from the U.K.’s Electricity Network Innovation Competition, an annual funding scheme, secured in 2018. 

 

National Grid is carrying out the project in partnership with the Iberdrola-owned electricity distributor SP Energy Networks and TNEI, an independent energy consultancy. 

 

The project partners are planning to carry out DER-based black starts on the two distribution networks that SP Energy Networks runs in the U.K. 

 

As well as demonstrating how the grid might be restarted using distributed assets, the project will look into issues such as maintaining cybersecurity while adding black-start-capable systems to the network.

 

National Grid expects the initiative to deliver £115 million ($149 million) in net present value by 2050, through reduced costs associated with large generator readiness. If the project is a success, the grid operator will start procuring DER-based black-start services from mid-2022 onward. 

 

“It’s envisaged that the Distributed ReStart project will demonstrate a world first,” says National Grid on its website. 

 

The need to rely on large synchronous generators for black-start capacity is one argument for keeping carbon-fueled assets on the grid, since black starts usually require gas turbines if no hydropower is available. 

 

At the same time, though, a black start of the kind being tested by National Grid isn’t just rare — it’s so rare that it’s never happened. 

 

“Distributed ReStart is the restoration process after a total shutdown of the entire electricity system, caused by a physical event such as an earthquake which causes widespread destruction of infrastructure,” said Ben Davis, National Grid’s external affairs manager.

 

Using wind and solar to help revive grids after a blackout would be a welcome change of role for inherently intermittent renewable energy sources, which are usually viewed as contributing to grid instability. 

 

In 2017, wind farm shutdowns were implicated in a statewide blackout across South Australia. 

 

And in August 2019, the U.K.’s Hornsea One offshore wind farm was partly to blame for a power outage that affected around a million British customers, more than at any point in the last 10 years. 

 

Because of this, the Distributed ReStart project is “one of the most important initiatives” that National Grid has ever undertaken, according to Jeremy Harrison, a principal analyst in the local energy systems unit at Delta Energy & Environment, a Scottish consulting firm. 

 

“There is a lot of criticism about the vulnerability of systems to intermittent generation,” he said. “Building an evidence base is key to being able to move toward an energy system dominated by renewables. We’re starting to demonstrate [that] you don’t need physical and mechanical inertia.”

 

Although Distributed ReStart may be unique in its size and scope, similar projects are underway in other countries, Harrison said. 

 

In Europe, for example, an initiative called Interflex, led by the French firm Enedis, is looking at high-renewable-energy-penetration smart grid applications including islanding and black starts. And microgrids are routinely developed with self-starting capabilities. 

 

More generally, there is growing interest worldwide in using distributed energy resources to carry out grid functions that have previously been the domain of large thermal plants. 

 

This month, for example, Austria’s transmission system operator, Austrian Power Grid, and the Energy Web Foundation, a blockchain platform developer, are expected to announce the launch of a proof of concept using small-scale generation sources to help regulate and balance the grid. 

 

The proof of concept will use an open-source software suite known as the Energy Web Decentralized Operating System to streamline asset qualification, registration, offer management and settlement functions for distributed assets in Austrian Power Grid’s balancing reserves.