Measuring the Dunkelflaute: How (not) to analyze variable renewable energy shortage

TL;DR

This paper reviews and critically assesses various methods for quantifying renewable energy shortages, aiming to unify methodologies and improve accuracy in analyzing variable renewable energy shortfalls across regions and technologies.

Contribution

It provides a comprehensive overview of existing approaches, discusses their merits and challenges, and proposes methodological improvements for better comparison and analysis.

Findings

Different methods have varying strengths and limitations.

Harmonization of terminology and methodology is needed.

Proposed improvements can enhance accuracy of shortage detection.

Abstract

As variable renewable energy sources increasingly gain importance in global energy systems, there is a growing interest in understanding periods of variable renewable energy shortage ("Dunkelflauten"). Defining, quantifying, and comparing such shortage events across different renewable generation technologies and locations presents a surprisingly intricate challenge. Various methodological approaches exist in different bodies of literature, which have been applied to single technologies in specific locations or technology portfolios across multiple regions. We provide an overview of various methods for quantifying variable renewable energy shortage, focusing either on supply from variable renewables or its mismatch with electricity demand. We explain and critically discuss the merits and challenges of different approaches for defining and identifying shortage events and propose further methodological improvements for more accurate shortage determination. Additionally, we elaborate on comparability requirements for multi-technological and multi-regional energy shortage analysis. In doing so, we aim to contribute to unifying disparate methodologies, harmonizing terminologies, and providing guidance for future research.