Abstract: A heater element for generating heat via Joule heating, the heater element having a layer of aligned carbon nanotubes and electrical terminals located to allow, in use, an electrical current to be passed along the layer of aligned carbon nanotubes. The direction of the electrical current in use is substantially perpendicular to the alignment direction of the aligned carbon nanotubes. Also disclosed is a method of manufacturing a heater element, the method including growing carbon nanotubes in a CVD reactor and forming the layer of aligned carbon nanotubes by pulling a carbon nanotube yarn from the CVD reactor, the alignment direction being the direction of pulling from the CVD reactor.