Understanding intermittency and grid stability impacts

Some renewable energy sources, particularly wind and solar, are intermittent – meaning that they are not fully predictable and there can be sudden and significant changes in the resource and the output of any grid-connected power plant.  Intermittent renewables can reliably provide 10 to 30 percent of total electricity supplies, without creating grid stability issues, depending upon the strength of the regional transmission grid and if the renewables are operated in conjunction with hydropower or fuel-based power generation.  Denmark currently generates more that 20% of its electricity from wind power.  Capacity credit is the other aspect of intermittency, and its proper assessment requires a location-specific study of the coincidence between the renewable energy resource and the peak periods of the major load center that is being served.

Emerging storage possibilities (like Compressed Air Energy Storage) and new grid-operating strategies offer promise that the role of intermittent technologies can be extended much further. Alternatively, hydrogen may become the medium for storing intermittently available renewable energy production.