As of Buildcraft 2.0.1 there is the option to use pneumatic engines to power the various machines in BuildCraft. Engines may be picked up by breaking them with any type of pick above stone.
Each has various strengths and requirements to function.
Engines can be daisy-chained. That is, one engine can send its energy to another, which can then send the combined energy to another engine or to the mechanism to be powered. This is useful for driving a mechanism faster, but incurs a danger of overheating. If the energy is not being removed from the system at about the same rate the system is producing it, the engine at the machine end of the chain may explode. A more efficent way to do this is to use Conductive Pipe. This can be used over longer distances with no chance of exploding for redstone or steam engines . Although this more efficient, it is also more expensive, as energy losses are rampant over long distances while using stone conductive pipes, the cheapest conductive pipe that will transport energy.
You can monitor the temperature of the engine by the color of its core. Blue represents a cold engine, green represents an engine that is warming up, yellow represents an engine that is running at the optimum efficiency, red represents an engine that is in danger of overheating and an engine that is bright red has overheated and will explode if not turned off or cooled down very quickly.
In SMP for beta 2.2.1 of buildcraft, the energy folder should be installed last or the engines won't work properly.
Redstone engines only need a redstone current for power, and will never overheat or explode; in fact, they gain power as they heat up, with them being most efficient in the blinking-red stage. However, they produce the least power out of all the machines.
Power: It will pump one item (at a time) from a chest each time it pumps (per engine).
Steam Engines require coal, charcoal or any kind of wood as a fuel source. As with all the engines, these must have a direct redstone current, such as a redstone torch or a lever. These engines can explode if left running too long, but it takes a lot less time for them to overheat that it does for a combustion engine. You will know they are about to explode when they are alternating between orange and red, just as you will with combustion engines.
Power: It will pump half a stack of items from a chest each time it pumps (per engine).
Configuration of Power Source
In the directory .minecraft/buildcraft/config the config file "buildcraft.cfg" contains a line starting "power.framework=".
It defaults to "power.framework=buildcraft.core.RedstonePowerFramework" - This allows Buildcraft devices to be run directly from redstone pulses. To use engines, you must use the setting "power.framework=buildcraft.energy.PneumaticPowerFramework".