In a large bowl, using the high speed of an electric mixer or mixing by hand, beat the sugar with the butter, until smooth, about 1 minute.
Beat in the egg yolks, at medium speed, until the ingredients are fluffy and pale yellow, about 2 to 3 minutes.
Pour in the beer, mixing to blend, then add the flour and the baking powder, mix thoroughly 1 minute.
In a separate bowl, using clean beaters, beat the egg whites until stiff, then gently fold the beaten whites into the batter.
Pour into a lightly greased and floured 10-inch tube pan and bake in a 350 degree oven for 50 minutes, until a wooden skewer comes out clean and the cake springs back when lightly pressed with your finger.