Line 16 2 1/2 inch muffin cups with paper bake cups; set aside. In a medium mixing bowl, stir together flour, baking powder, ginger, cinnamon, soda, and salt. In a small mixing bowl, stir together the egg white, molasses, water, and oil. Stir molasses mixture into flour mixture just till blended. Spoon into prepared muffin cups. Bake in a 350ºF.  oven for 15-20 minutes or till cupcakes spring back when pressed lightly in center. If desired, sprinkle with powdered sugar. Serve warm or cool.