A review of Europe’s top wind-powered countries seems to refute the idea that gas peaking capacity is required to balance out intermittent generation. But partly it’s because these high-wind nations have unique balancing acts, and partly because gas is not the answer after all.
As of 2015, Denmark, Ireland, Portugal and Spain were all covering more than 20 percent of their electricity demand with wind, according to figures released last month by WindEurope, the European industry body.
Natural-gas consumption, meanwhile, appears to have increased in only one of these four nations, based on data from ReportLinker.
In Denmark, where wind penetration was already above 40 percent in 2015 and is set to exceed 70 percent in 2030, as per WindEurope forecasts, gas demand has remained essentially static in recent years.
Admittedly, Denmark is hardly a good example of what might happen to a nation faced with high renewables penetration, though.
A small country sandwiched between the Nordics and Western Europe, with robust transmission links on either side, it can export or import electricity freely to make up with domestic production excesses or shortfalls.
An analysis by Danish energy system development consultant Paul-Frederik Bach claimed that most grids without demand flexibility would be unable to provide balancing capacity for intermittent renewable shares above a range of between 23 and 40 percent.
He concluded: “It is obvious that exchanges with other countries provide an essential part of the regulating work for the Danish power system.”
For that reason, it might be more instructive to look to Spain and Portugal. Both countries have had close to 20 percent wind power penetration on the grid since 2010.
A market moratorium in Spain allowed Portugal to pull ahead in terms of wind’s share of the generation market in 2015, although Spanish auctions this year could see that trend reversing.
As of two years ago, though, and despite having a largely isolated grid, Spain seemed to be coping well with the need to balance wind, with gas demand still comparable to historic levels.
There were two reasons for this, though. The first is that in 2015 Spain was still suffering from a protracted economic crisis that dampened energy demand overall.
The second was that the bulk of Spain’s wind balancing capacity has never come from gas but from hydro reserves, which this winter peaked at more than 8,300 gigawatt-hours of capacity.
While Portugal has access to this via up to 2.95 gigawatts of interconnection capacity, by 2015 the country was also beyond the 23 percent wind share boundary that Bach said might start to cause balancing challenges.
Perhaps coincidentally, gas consumption seems to have been rising since. This might offer some proof that peaker plants are being fired up to compensate for swings in wind production, but the situation in Ireland muddies the issue.
Between 2010 and 2015, Ireland went from fourth to second in Europe in terms of wind's contribution to the electricity system. And like Spain, Ireland’s grid is relatively isolated.
However, its hydro capacity is negligible, with 60 gigawatt-hours of production meeting only 0.1 percent of the grid’s annual generation needs, EirGrid figures show. Balancing capacity might therefore be expected to come from gas.
But figures show no appreciable increase in gas consumption.
This apparently contradictory finding can be explained on the basis that increasing wind generation, at least at the levels seen in Ireland, does not lead to a significant increase in how much gas is used, but instead in when it is used.
An Irish energy market study by the consultancy firm Incoteco noted that while Ireland’s fleet of eight combined-cycle gas turbines (CCGTs), including one in Northern Ireland, were designed for baseload power generation, now they are now being used for ramping and load following.
The switch in operation has led to a drastic drop in the fleet’s capacity factor, from 80 percent to 40 percent, Incoteco claimed. At the same time, Ireland is forecast to curtail up to 8 percent of its wind generation by 2020.
Thus, while increasing wind penetration in Europe may not be directly increasing gas consumption, it does appear to be putting a strain on CCGTs, which could lead to higher operating costs.
For load factors of less than 25 percent, open-cycle gas turbines are a better bet, said Andy Boston of Red Vector, an energy modeling company. “But diesels are cheaper for very low load factors,” he said.
How industrialized nations will square this with a desire to eliminate carbon through renewables remains to be seen.