New IEA Report Addresses Grid Integration Of Variable Renewable Energies

The growing level of variable renewable energy technologies such as wind and solar will present challenges for grid operators as they seek to integrate variable electricity generation into traditional grids, requiring that certain changes be made now in an effort to avoid overspending and delays, while simultaneously protecting the security of energy supply.

These are the findings from a new report published by the International Energy Agency, entitled Getting Wind and Sun onto the Grid, which seeks to not only identify the expected challenges being faced and soon to be faced by grid operators in integrating variable renewable energies (VRE) such as wind and solar into the grid, but also provide solutions to these same challenges.

According to the report, variable renewable energy such as solar and wind had reached double-digit shares of annual electricity generation in ten countries in 2015 — including at least 50% in Denmark, and around 20% in Ireland, Spain, and Germany. This has recently been confirmed by new figures from the European Union’s own Eurostat which highlighted the region’s progress towards ensuring at least 20% of the Union’s energy consumption comes from renewable energy sources.

The new IEA report notes, however, that despite the growing reality of VRE, “discussion of VRE integration is often still marred by misconceptions, myths, and in cases even misinformation.”

“Commonly heard claims include that electricity storage is prerequisite to integrate VRE, and that conventional generators are exposed to very high additional cost as VRE share grows. Such claims can distract decision-makers from the real, though ultimately manageable issues; if unchecked they can bring VRE deployment to a juddering halt.”

The report identifies four stages of VRE deployment and integration, each with its own specific characteristics and operational priorities. In the first phase VRE integration has no noticeable impact on the grid, where the output of wind and solar plants is simply subsumed in the daily variations in power demand. Countries currently in this phase include Indonesia, South Africa, and Mexico, where annual VRE shares only reach up to around 3% in annual electricity generation.

The second phase begins to see VRE creating a noticeable impact, but this can be dealt with simply by upgrading some operational practices, such as intelligent forecasting of VRE output. Countries in this phase include Chile, China, Brazil, India, New Zealand, Australia, the Netherlands, Sweden, Austria, and Belgium, with VRE shares ranging from 3% to almost 15%.

The third phase is where real significant integration challenges begin to occur, as the impact of the variability is felt both in terms of overall system operation and by other power plants. This is where power system flexibility must be paramount — the ability for a power system to respond to uncertainty and variability in its supply-demand balance. The two main flexible resources are dispatchable power plants and the transmission grid, but demand-side options and new energy storage technologies are likely to grow in importance. Countries in this phase include Italy, the United Kingdom, Greece, Spain, Portugal, and Germany, with VRE shares ranging from 15% to 25% in annual generation.

The fourth and final phase sees “highly technical” and “less intuitive” challenges occur, and require resilience in the face of events that might disturb normal operations on very short time scales. Only Denmark and Ireland can be considered to be facing these challenges, with VRE share ranging from 25% to 50% in annual generation.

The overall report attempts to specifically identify the challenges throughout each of the four phases, and provide solutions. The continued growth and penetration of wind and solar will only increase the likelihood these challenges will increase in frequency, and require timely and effective solutions.