Just like, pretty much every, android device it uses a USB charger. Many advertisement related images don't include cords and the like for prettier pictures. Using HDMI to power things is a tricky thing, many monitors and TVs din't supply power over HDMI and among those that do (especially Sony TV iirc) they provide less-than ideal amounts of power.
On recent HD TVs that's true, but if you go back more than 2-3 years (or didn't buy a giant 55" set) then it's quite likely you'll have to resort to the AC adapter.