19. Inventories

 31.12.201631.12.2015
Materials 262 506 407 378
Semi-finished products and work in progress 245 336
Finished products 22 374 42 511
Certificates of energy origin 163 801 195 885
Merchandise 9 042 11 582
Cost 457 968 657 692 
Impairment loss on inventories (9 027) (8 183)
Net carrying amount 448 941 649 509 

The Group extracts coal. A portion of the coal is used during production, the remaining coal is sold to the entities that do not belong do the Group. It is not possible to reliably determine what portion of the coal shall be sold, therefore the entire supply was assigned in this table as “Materials”.

Inventories expensed during the current year amounted to PLN 1 210 608 thousand and were presented as “Consumption of materials and supplies and costs of goods sold”. In 2015, PLN 1 597 024 thousand were recognized as an expense.

No collateral has been established on inventories.