Minecraft wiki entry for Dried_Kelp_Block, associated text: Crafting a dried kelp block first requires smelting 9 pieces of kelp, so its net fuel value is only 11 items. However, using a different fuel source to smelt pieces of kelp that are then crafted into dried kelp blocks, the number of operations per fuel is effectively increased. If a lava bucket were used to smelt 100 pieces of kelp that were then crafted into 11 dried kelp blocks, which can then smelt a total of 220 items, the lava bucket's initial number of operations per fuel would be more than doubled from 100 to 220.