"Steel is very strong per volume, so steel is a good choice when strength per volume is one of the main constraints. However, wind turbine towers are essentially empty inside so there is room to increase the volume by making the walls thicker. The Laminated Veneer Lumber (LVL) material in a Modvion tower has higher strength per weight and higher strength per cost than steel alternatives."

Strength per volume versus strength per weight is an interesting trade-off. They're arguing this could let towers get taller.