This was on an artists blog. Derwent does make a battery operated sharpener for their pencils but according to the posts I've read, it doesn't work. It chews them up.
Use the wide hole of a two-hole sharpener or a General's All-Art sharpener to sharpen them, or try the Derwent Helix sharpener that has multi-width capacity. Many grinder type sharpeners, electric or crank, have multi-hole capacity.