In its current Market Power Report - Energy the Bundeskartellamt acknowledges the Return on Withholding Capacity (RWC) Index, which Marc Bataille, Olivia Bodnar, Alexander Steinmetz and Susanne Thorwarth have developed as an alternative or supplementary indicator for measuring market power in the electricity generation market. The RWC Index enables an assessment of the risk of abusive capacity restraint and, accordingly, the establishment of antitrust market dominance.
The BKartA comes to the conclusion that "the RWC can therefore, if properly implemented as a screening instrument, complement the RSI in a meaningful way in the future.
Related Literature:
Bataille, Marc, Olivia Bodnar, Alexander Steinmetz, Susanne Thorwarth (2019), Screening Instruments for Monitoring Market Power - The Return on Withholding Capacity Index (RWC), Energy Economics, Volume 81, S. 227 - 237, Juni 2019, download: https://ideas.repec.org/a/eee/eneeco/v81y2019icp227-237.html