Alternative Fuels for Brick Ovens

Walnut shells used in French oven

It is generally assumed in our forested country (U.S.) that dry hardwood is what you need to get a wood-fired brick oven to baking temperatures. However, there is a long tradition internationally of employing combustible fuels other than wood.
In France, even though the forests could supply oak, chestnut, and other hardwoods, I found the local baker using walnut shells, a by-product of the region's walnut crop.

Olive and grape vine trimmings

All over Italy, pruned branches from olives and other crop trees were bundled next to brick ovens for use a a primary fuel .  These thin and dry fuels burn quickly and hot and the bakers have developed methods of heating even a two meter wide interior oven with the minimum of fuel.
An apple orchard near my home sells pruned limbs for less than the going price for common firewood even though apple wood has one of the highest BTU to weight ratios. Apple wood also leaves the option of smoking foods at low smouldering temperatures.

A recent TBO oven fired with oak scraps

Many furniture shops throw out board ends of maple, oak, beech, and cherry. These non-varnished kiln-dried chunks of wood are perfect for the urban brick oven.

firewood drying for next bake

I recall entire multi-ton firings of clay roof tiles in Mexico fueled entirely on corncobs.
Whatever the fuel, it is best if bone dry. One method that assures this is to place the fuel for the next firing in the oven following a past firing (as long as the temp is down below 300F).