The problem with wood as a fuel is that any densifying human culture can burn it faster than it grows. Industrial uses compete with household uses for cooking f

The problem with wood as a fuel is that any densifying human culture can burn it faster than it grows. Industrial uses compete with household uses for cooking fuel and heating. Europe in the 14th to 16th centuries saw massive deforestation in England, Germany, and elsewhere, and the state had to reserve stands of large timber as a military resource for shipbuilding. This was a significant concern in the early Tudor and Elizabethan era, for example, and the Black Forest reached its smallest extent during this time also, IIRC. Wood for fuel came from intensive coppice stands, and significant wood was imported as well. As the article says: "Wartime gasifier cars could achieve about 1.5 miles per kilogram [of wood]." Comparing the time it takes to grow a kg of wood versus the value of moving a car only 1.5 miles illustrates the problem pretty nicely. Wood is not a sustainable fuel for an industrial civilization, at anything like current rates of consumption.