Furnace
A Furnace is a Building in FarmVille 2. The player can get 
10 Power from this building each 
23 hours.
After placing the Furnace, some building materials are needed to finish the Building.
8 Wood Planks- 8 Fire Bricks
- 8 Metal Grate Bar
After that 4 Neighbors are needed to hire for constructing the Furnace.
Pictures of the furnace build process[]
Once you reached level 6, you can start building the Furnace (notice, it says collect every 4 hours here, later updates increased that time to 8 and later 23 hours)
Building phase 1 of the furnace requires some materials. Most of that is already provided.
Building phase 2 of the furnace requires you to have some neighbors to help you. Some of them are already provided.
Once completed, you can collect power from the furnace.