Tesla’s grid-scale battery in South Australia has, according to reports, utterly savaged the Frequency Control and Ancillary Services (FCAS) market, taking 55% of the work and driving the price down by 90%. This is a big shock for gas plants, which have traditionally performed this role, and if these figures are true, a death knell for such operations. FCAS generation is used when parts of a grid need to be repaired or taken offline, standing in for the downtime. According to the new McKinsey report, the FCAS pricing hit as much as $14,000 AUD per MW, which is orders of magnitude above the typical costs. Figures from 2012 list Australian prices at $150-200 for coal and $111-122 for wind, meaning…