Baking powder is already bicarbonate of soda and an acid, so it functions much the same way. Baking powder is the combination of bicarbonate of soda and cream of tarter, so you'll substitute it in the same 1:1 ratio as the bicarbonate of soda and acid. This means if your recipe calls for 2 teaspoons of yeast, you'd substitute 2 teaspoons of baking powder. This method also doesn't require resting and rising like a yeast dough.