In a small bowl, combine flour, baking powder, baking soda and salt; set aside. Using an electric mixer, beat butter and agave until light. Beat in egg, orange juice concentrate and orange peel. Gradually add flour mixture, mixing until just blended; stir in almonds. Spoon into 8 greased or paper-lined 2 1/2-inch muffin cups. Bake at 350°F for 25 to 30 minutes, or until toothpick inserted in center comes out clean. Remove muffins from pan to wire rack. Serve warm or at room temperature.