What is LP Power?
LP means liquid propane. On RVs, typically the stove, water heater, and furnace run on propane. The refrigerator usually runs on propane while driving, and AC elecctrical while the RV is connected to shore power (some of the more advanced models also have the option of running on DC/battery power). Then, like Krazeehorse said, LP powered electrical generators on diesel-powered units--as compared to the gasoline-powered electrical generators usually available on gasoline-powered motorhomes.