In this talk we will discuss a construction of scalar-flat Kähler toric metrics on non-compact 4-manifolds. The construction actually gives a new perspective on Gibbons-Hawking’s so called gravitational instantons. Perhaps more interestingly, it allows us to write down some new examples of complete scalar-flat Kähler metrics on some important non-compact manifolds (namely non-compact toric surfaces). We will discuss the energy of such metrics and point to some open directions regarding the construction. Some of this is joint work with Miguel Abreu.