|Moisture content of most woods as kiln dried, dried at 70% relative humidity and 90% relative humidity|
Freshly cut soft maple, aspen and willow are about 50% water, by weight.
How bad is that? That means you need to add about equal amounts kiln dried wood to get the green wood to burn...and all the heat goes up the chimney as water vapor.
Things go around the bend at about 30% moisture. You need to burn twice as much wood, by weight, to net the same amount of heat as air dried wood.