Eventually as the difficulty gets higher only the most efficient farm will survive. Not sure about China but I think there are also other places where you can find cheap electricity for example Iceland where electricity cost is also comparatively cheap. What's best is that you get can free natural cooling for the hardware as well.
Not sure if it is the biggest, but it may be one of the biggest in the world. And it is placed in a strategic location which lowers the cost for electricity, as it lowers the power for cooling needed given it is placed on a high-altitude location.
See this thread:
https://bitcointalk.org/index.php?topic=969823.0