text: However , in the analysis responding to the Jeffords / Lieberman request that had NOx , SO2 , mercury and CO2 reduction levels similar to S. 556 , we found significant approximately a 20-30 percent decline of coal generation and a 30-50 percent increase in electricity prices compared to the reference case ( depending on assumptions of energy technology penetration ) .
  
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  The analysis of NOx , SO2 , mercury and CO2 showed that prices had gone down .