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Offshore wind’s reactive power

K2 Management’s Gary Bills explains why National Grid’s decision to award a 10-year contract to Dogger Bank C to keep voltage levels in the power network stable is a game changer for the sector.

We might one day reflect on early 2022 and the significance it had in advancing the role wind plays in the UK’s energy mix.

Gary Bills

Indeed, with the mammoth Scotwind seabed lease announcement in January – which will see floating offshore technology brought, at scale, to the seas off Scotland for the first time, as well as vast commitments to bolster the country’s wind supply chains – 2022 is already shaping up to be a noteworthy year for an industry moving through the gears.

Challenges lie ahead, of course; the sector finds itself in the mire of ‘greenflation’, which is causing development costs to soar. Turbine manufacturers are seemingly, and publicly, bearing the brunt of that at the moment.

But following the Scotwind news, February has brought two further announcements that show the wind industry is well and truly heading in the right direction.

Wind can be a power network stabiliser

In early February, the National Grid announced that it had for the first time awarded a contract to an offshore wind farm to help keep voltage levels in the power network stable. Dogger Bank C will provide 200 megavolt amperes of reactive power (MVAr), which is used to maintain network stability, for a 10-year period from 2024. That means the 1.2GW, third phase of what is destined to be the world’s largest offshore wind farm, will help stabilise voltage on the grid in the northeast of England, after the expected closure of Hartlepool nuclear power station in March 2024.

For almost a decade, there has been an ambition for renewables to contribute to the grid’s balancing mechanism in this way.

As Julian Leslie, head of networks at National Grid ESO, said in his statement: “We’re excited to see that an offshore wind farm’s transmission asset will deliver reactive power to support the wider network for the first time in Britain.”

“For an energy system to be truly carbon-zero, it’s vital that renewable energy assets can provide this sort of reactive power that stabilises the grid when it is experiencing bumps in delivery”

But given the oft-cited intermittency challenges of wind and solar, how is this possible?Subsequently, National Grid ESO has announced that a “game changing” modification to the GB Grid Code will enable it to procure grid stability services from all renewable generators – making such a contract award possible. National Grid ESO described this change as a “breakthrough moment”, and “a key piece in the energy transition jigsaw”.
And it is exciting. For an energy system to be truly carbon zero, it’s vital that renewable energy assets can provide this sort of reactive power to stabilise the grid when it is experiencing bumps in delivery.

Wider access to the balancing mechanism allows power generators with as small as 1MW capacity to be registered as balancing mechanism units, and typically most wind turbines commissioned from 2014 onwards have the technology needed to provide reactive power without additional site equipment.

In essence, the converters within wind turbines are always energised and able to import or export reactive power. The turbine doesn’t need to be turning to export reactive power to the grid. This enables fast injections of power into the grid when there are dips in the system. This means that larger wind farms, comprising hundreds of turbines, have the basic potential to supply enough reactive power in times of need.

Critically, though, the right infrastructure needs to be in place for real-time exchange of information between power producers and the grid. This means that wind farms need to be able tell the grid when they are able to export ‘spare’ energy to stabilise the network. And vice-versa, the grid needs to be able to tell wind farm operators that it is in need of power.

This step change, plus evolving economies of scale – such as larger turbines, and wind farms constituting greater numbers of turbines – means wind power capable of fulfilling this hugely important role to the UK’s broader energy needs.

When it comes to the long-term, genuine viability of wind as a key pillar in the energy transition, the significance of this sort of step forward shouldn’t be underplayed.

It should be noted, though, that it doesn’t solve problems around storing energy produced by turbines over the longer term. That is where the continued development and integration of batteries and other energy storage solutions remain a priority. In this regard, a separate announcement that Harmony Energy is planning to construct what will be one of Europe’s largest battery storage facilities in Cottingham near Hull is yet more welcome news. It has agreed a 40-year lease on a site that will have the capacity to store up to 200MWh of power to feed directly back into the network.

More regular CfDs brings developer comfort

The second announcement that has put a February smile upon the faces of UK wind stakeholders is the government unveiling that Contracts for Difference (CfD) auctions are going to be held annually from 2023. This mechanism supports new low-carbon electricity projects by awarding contracts through a competitive auction process, backing domestic energy production.

“We are hitting the accelerator on domestic electricity production to boost energy security, attract private investment and create jobs in our industrial heartlands,” said the UK’s business and energy secretary Kwasi Kwarteng.

And he’s not wrong; this will bring more gigawatts of clean energy to the UK system, faster. But it actually does more than just that. It brings greater comfort to developers, who can bid for these contracts knowing that if they miss out one year, they can bid again in just a year’s time – as opposed to having to wait longer and without certainty of when the next auction will be.

In the intervening periods between CfD rounds, technology, incentives, regulation and supply chains move on. This has typically meant that the expensive work a developer has undertaken for one could be out of date by the time the next auction round arrives.

More regular CfD rounds mean that during those shorter intervening periods where less is likely to change, developers need only tweak and refine applications, without having to reinvent the wheel at great cost to stave off competitors that will be coming to the table with newer technologies or plans built around updated regulation.

Greater investor confidence

There is a great deal of liquidity in renewables at the moment, and more capital to deploy than there are projects to invest in. It means investors are participating in an environment that is forcing moves of higher risk, like becoming involved in projects much earlier.

But these two announcements mean several things for investors: more projects to invest in, the opportunity to show greater confidence in developers, and – with offshore wind making its first foray into network stabilisation – more avenues for return on investment.

Gary Bills is regional director EMEA at K2 Management, a renewable energy consultancy headquartered in Munich