We study the energy harvesting from the galloping oscillations of rigid prisms flexibly mounted in a wind tunnel. A square section and a 2/3 rectangular section are tested and the inclination angle of the prisms referred to the flow direction is optimally adapted. The energy harvester is based on magnets moving with the prism in the front of a coil-core at rest. Energy is dissipated in a load resistance for which an optimal value is found. Efficiency of the "prism wind turbine" is weak compared to usual wind turbine due to the physics of the galloping mechanism. However such systems remain interesting for their potential of adaptation to various situations.