Biome Reactors adds a sole block: The Biome Reactor. This block allows the exchange of Redstone Flux(commonly referred to as RF) in order to change the biome in a 7 block radius. Different blocks have to be put inside the reactor for each different biome. It usually uses around 400,000 RF to change the biome.
We have a page on the Minecraft Forums! http://www.minecraftforum.net/forums/mapping-and-modding/minecraft-mods/2655049-biome-reactors-1-0-0-change-biomes-using-redstone
An API for modders who want the machine to be able to convert their own custom biomes is available here: https://github.com/Alex-the-666/BiomeReactorsApi