According to their directions, electric.
I believe the underlying motivation for electric -vs- gas is the possibility of an explosion, since there is are some fumes that come off. They also recommend not using an oven that is used for food. My uneducated guess is those are CYA type statements.
On the other hand, powder is basically expanding the surface are to infinity which in itself could explode when exposed to flames. Anyone ever make household flour explode? I have (I am a deviate).