Road warriors are always concerned about remaining battery life when out and about. Sure, you can always carry a second battery for your laptop, Tablet PC or UPC but there is another option for extended trips that provides 4 – 10 hours of additional battery life for your computer. A company from my home state of Texas, Batterygeek, offers an entire product line of high capacity external batteries that can be charged separately from your device through an included power adapter. The batteries plug directly into the AC jack on your computer through an assortment of tips that are included that fit many brands of laptops. The external battery can be carried for use in emergencies and are small and highly portable. There are several capacities and amperages available depending on how much power you want and the requirements of your device. The batteries are in the $150 range and Batterygeek ships to many countries. You can determine if a particular batter will work in your device through a form on their site. Yes, there is a model that fits the Sony U series.
UPDATE: Due to a personal vendetta trashing the comments they are now closed for this thread. Sorry for that.