Arizona Republic: Arizona Public Service Co. plans to partially close one of the nation’s dirtiest coal-fired power generators, the Four Corners Power Plant in New Mexico, company officials said Monday. If state and federal regulators approve, APS will spend $294 million buying a larger stake in two of the plant’s newer, larger, cleaner-burning generators to replace what power it loses in closing the oldest three units. The massive, 47-year-old plant supplies power to customers in four states, and the move could…