Here's a refreshing lemony energy drink recipe to give you a caffeine energy boost when you don't want coffee. It's a double-strength brew of green tea plus yerba maté and delivers about 135 mg caffeine plus antioxidants. Compared with store-bought energy drinks, this homemade energy drink recipe saves about 150 calories and has less than half the sugar. Add an extra-fresh taste by garnishing the rim with chopped mint. Yerba maté is a tea made from the leaves of a South American tree. Look for it with other tea in the natural-foods section of large supermarkets or natural-foods stores.