12 Inventories 31.12.2009 31.12.2010
  CHF thousands    
  Green electricity certificates 11,609 5,704
  Emissions certificates 5,139 4,786
  Emissions certificates held – for – trading 931 4,520
  Material inventories 16,614 15,144
  Total 34,293 30,154

Inventories consist of material inventories and certificates and are valued at the lower of acquisition costs and net realisable value. Certificates that are not necessary for own generation needs and which are held for trading purposes are valued at fair value less selling costs. In the year under review a value adjustment of TCHF 600 (previous year TCHF 1,950) was recognised. This adjustment was made to the net selling price.