How to tap beer without CO2, like the germans do? I know how to tap beer from a keg with CO2. The CO2 provides the pressure and you will get the beer.

But how can germans tap their beer without using CO2?
I've never seen any evidence that Germans use anything but CO2, so if you have a source that'd be cool.  That said, for getting beer out of the cask/keg/barrel you generally have 3 options:


Pressurized gas.  As mentioned by the other answer this is most commonly CO2 since CO2 is produced by yeast, so if you sealed the container while yeast were still processing sugars and producing CO2, they would pressurize the container.  Some brewers, especially home brewers, will pressurize their kegs through natural carbonation but most just push CO2 from a canister.  BUT there's also "beer gas" which is a mix of Nitrogen and CO2, think Guinness or Boddingtons.  This came into use to emulate the soft carbonation of cask/real ale/kellerbier, which leads to:
Siphoning.  A hand pump, or beer engine, uses a siphon to "pull" the beer out of the cask and up to the tap.  The physics needs atmospheric pressure to be maintained inside the cask, so it's usually open to the air at the top.  This required a fast turnaround on casks to prevent the beer from spoiling, which is one of the reasons cask/"real" ale fell out favor.  Kegs simply kept longer and were more economical.  I think CAMRA still isn't a fan of them, but some bars use "breathers" which basically add very low pressures of CO2 to replace the volume lost by the beer, but not enough to pressurize the cask.  This just lets the beer last longer in the cask.
Gravity pouring.  This tends to happen most often at festivals or if a bar has a "guest cask".  A spout is installed in the side and beer pours out.  All the caveats about air spoilage from cask ale still exist here.


So if the bartender pulls a handle and leaves it there until the glass is full of beer, that's a pressurized gas system.  If the bartender has to keep pulling the handle to fill the glass and the beer has that cool "cascading" look, it was pulled by siphoning.  If the cask is on the bar and the bartender just opens a spigot...that's a gravity pour.

I don't know that there are any other options...maybe an open barrel and ladling the beer out like soup?