After knocking down the gate in the landing zone, then go northeast with the Dwarf Bulborbs. They will be guarding the part, just kill them and tell at least forty Pikmin to carry the item back to base. It is in the wide open, there should be no problem finding it.
"Why, it's the Eternal Fuel Dynamo! It was a unlimited energy supply! I won't have to worry about saving electricity anymore! This will make my fight fir survival a little bit easier... This should light things up. No more candlesfor me!"