Abstract: A compressor that compresses a working fluid through the direct use of thermal energy. The thermal compressor includes at least two sealed heating containers connected to one another. Compression can take place by periodically isolating and heating the working fluid contained within each heating container to different pressures, such that upon connecting the heating containers, pressure, density, and/or altitude differences between the heating containers induces a flow of the working fluid from one heating container to the other. Thermal energy may be transferred to the working fluid through heat exchangers, electrical heaters/resistors, and/or other devices. The amount of heat provided to each container, as well as the duration of the heating process, may be controlled by a central controlling system.