Future provision of control reserve from offshore wind farms: An analysis of benefits and barriers

The rapidly growing share of renewable energy sources in the power market causes new challenges on system security. With conventional power plants exiting the market, the provision of ancillary services (AS) by renewable power plants is gaining in importance. Offshore wind farms (OWFs), having a relatively stable feed-in, seem particular suitable for the provision of negative control reserve (down regulation of power). This paper quantitatively assesses potentials for additional OWF revenues and system cost savings coming with the participation of OWFs in the German negative tertiary control reserve (TCR) market. The analysis is conducted with a market model which uses the historical situation in 2013 as a basis and forecasts market conditions at higher penetration levels of offshore wind. The paper shows that OWFs can generate revenues and save system costs on the market for negative TCR, which is true at low, but also at high penetration levels of wind. The quality of wind speed forecasts is pointed out as strong determinant of OWF revenues and system cost saving potentials. We investigate the key market barriers in distinct case studies and we show which market design changes could substantially increase the attractiveness of the negative TCR market for OWFs by adding flexibility to the market and reducing market barriers for fluctuating energy sources.