Influence of the chip format on the development of mass loss, moisture content and chemical composition of poplar chips during storage and drying in open-air piles

After seven months, medium wood chips displayed with a moisture content of 26w-%, dry matter losses of only 17% and a fines fraction of <5w-% the best results for energy-related use. Small chips with dry matter losses of 19%, moisture contents of 34w-% and a fines fraction of 12.6w-% displayed very unfavourable conditions for energy-related use. However, small chips showed the highest reduction of the C:N ratio (from 145:1 to 57:1) due to the storage process.