Renewables could be more reliable than we think

As society works to transition to a low-carbon future, it might be possible to balance the amounts of energy coming from variable, renewable sources like wind and solar more than we’ve thought.

Intermittency — the fact that the sun doesn’t always shine and the wind doesn’t always blow — has long been viewed as a serious problem in moving toward more clean energy.

“Those who assert that large shares of variable supply represent an insurmountable, additional challenge to power-system operation may be looking with too narrow a gaze,” states a new book from the International Energy Agency (IEA). “Variability and uncertainty are not new challenges; power systems have long taken them into account. Fluctuating demand — from hour to hour, day to day, season to season — has been a fundamental characteristic of all power systems since the first consumer was connected to the first power plant. All power systems include a range of flexible resources to manage this fluctuation: dispatchable power plants for the most part, but some systems may also incorporate electricity storage, demand-side management, and/or interconnections to neighbouring power markets. The question is: can the use of these resources be enhanced efficiently to balance increasing variability
resulting from VRE deployment?”

Furthermore, how much flexibility renewables can offer will vary considerably from one part of the world to another, the IEA finds.

The bad news, especially in light of the post-Fukushima concerns about nuclear energy, is that Japan has the least flexibility in its renewable resources. And it might come as no surprise that Denmark, already a clean-energy leader, has the most flexibility.

In “Harnessing Variable Renewables,” a new book detailing the results of its Grid Integration of Variable Renewables (GIVAR) project, the IEA assesses eight regions around the globe in their ability to balance renewable energy sources to provide reliable power.

Japan proves to be the least flexible, with the potential to accommodate a variable renewable energy base of 19 per cent. Factors contributing to that limit include the weak interconnections among Japan’s 10 power utilities, which makes it hard to balance supplies from one region to another.

Denmark, on the other hand, could accommodate up to 63 per cent of variable renewables in its energy mix. Its greater capacity is due in part to its energy grid’s strong connection to others across the Nordic region. That linkage makes it possible to share renewable resources across a large area, even if the wind isn’t blowing or the sun isn’t shining in one part or another.

Other regions’ capacities included 48 per cent for the Nordic Power Market (Denmark, Finland, Norway and Sweden); 45 per cent for the Western Interconnection of the US; 37 per cent for the region in eastern Canada operated by the New Brunswick System; 31 per cent for the British Isles (Great Britain and Ireland); 29 per cent for Mexico; and 27 per cent for the Iberian Peninsula (Spain and Portugal).

These capacities, though, reflect only what each region could accommodate given its current energy infrastructure.

“These estimates do not in any way represent a technical ceiling on deployment potential,” the IEA states. “(A)dditional flexible resources can still be deployed as and when required.”