Energy, in dwarvish definition, includes anything nonmaterial which acts at a distance. Most energy magic is concerned with light and heat, but there is also the magic of sound, and forms of distant force which push and pull. Most energy magic except the very simplest movements of light and heat requires the use of crystals of various kinds.
The commonest form of energy magic involves moving energy to or from another, parallel space or dimension. Even minimally trained humans can summon a weak light and enough heat to start a fire, but advanced practitioners can create devices which draw in enough energy to heat water for steam (as a working fluid for vehicles and to power factories) or to smelt metals. Other applications include cooling (by moving heat away to a cooler space) and, of course, magical lights which are reliable, bright and cool. All of these devices require crystals to stabilise the gate, so they are expensive to buy (and have to be maintained regularly), but cost nothing to fuel.
An application of energy magic to sound is the privacy rug, which prevents words spoken within its bounds from being heard outside it.
Personal shields can be made which protect the wearer from projectile weapons by creating an interdiction field around his or her body. They are very expensive (they require diamonds as a base), not especially powerful, and uncomfortable to wear because of the loud humming noise.
A university-trained human practitioner of energy magic has a red stone (garnet or ruby, usually) set in his or her metal bracelet.
Hope at Merrybourne is a prominent energy mage.