Piezoelectric energy harvesters (EHs) are designed to operate at resonance in order to have the most electric power harvested. Three challenges have been confronted by these EHs: (1) low output power scavenged from low frequency vibrations, (2) limited effectiveness of harvesting mechanism in a narrow band, and (3) being unidirectional. To overcome these challenges, in this thesis a novel space frame EH is proposed. A formulation is derived to calculate the responses of such a harvester to base accelerations based on the finite element method. The natural frequencies of the space frame harvester and its corresponding cantilevered one are calculated according to the novel formulation. The correspondence is based on their lengths, total masses, and fundamental frequencies. The results are in good agreement with the values obtained from the ABAQUS software. It is demonstrated that this novel multimodal EH has 11 natural frequencies less than 500Hz whereas the cantilevered beam has only 3 natural frequencies in that range. Furthermore, the space frame EH can be designed to be suitable for excitations with low frequencies as well as excitations in different directions. Finally, the electric responses of both harvesters such as output voltages, currents, RMS powers, open and short circuit natural frequencies, and optimal resistive loads are obtained. The internal volume of the novel harvester and the surfaces of the tip mass can be utilized for the interface electrical circuit and other electronic components. Other advantage of such a harvester is offering a larger area to attach piezoelectric layers. Furthermore, both free and clamped ends of the space frame undergo large amounts of strain in contrast with the conventional cantilevered beam which has large strains only in the clamped end. The dimensions of substructure, piezoelectric layers, and end mass, the total volume of the space frame and the position of piezoelectric layers can be used as design parameters for a desirable EH. Keywords: Energy harvesting, Piezoelectric, Wideband, Multimodal, low frequency, multidirectional, The finite element method, Space frame, Unsymmetrical cross section, Surface to volume ratio