With once-through cooled fossil power plants being retired, in a high electricity-consumption scenario, California Independent System Operator staff data show it may take another 4,600 MW of fossil power to support a 33 percent renewables portfolio standard, Mark Rothleder, CAISO director, market analysis and development, said Aug. 25. While CAISO does not advocate for that much new fossil power, ignoring its potential is \u201ca risk we can\u2019t afford to muck up,\u201d said chief executive officer Steve Berberich. \u201cIf we miss it, we risk rolling blackouts,\u201d he added. Staff continues to pin down data. \u201cWe need to resolve\u201d demand-response and conservation levels \u201cin the next couple years,\u201d Berberich said. Earlier data showed that when including high conservation and low consumption, no new fossil fuel generation would be required for renewables\u2019 support. The fossil requirement\u2019s expected to be folded into the California Public Utilities Commission long-term power procurement proceeding which is set for a decision late next year.