This system does not require any pluging in. it becomes part of the heating system, and runs using a small amount of diesel and battery power
I've included there link if your interested. there very big in europe as most european conteries it is illegal to run your vehicle with out you being in it. it also stops you cold starting as the engine is heated up. and can also suppliment the cab heating. which in this weather can be a bonus
http://www.webasto.us/home/en/homepage.html
regards Ground Hwg