Abstract: We discuss the generalization of gravitational energy-momentum
pseudo-tensor to Extended Theories of Gravity, in particular to
higher-order theories in curvature invariants. This result is achieved by
imposing that the local variation of gravitational action of any order n
vanishes under rigid translations. We also prove that this tensor, in
general, is not covariant but only affine, that is, it is a pseudo-tensor.
The pseudo-tensor is calculated in the weak-field limit up to a first
non-vanishing term of order h^2, where h is the metric perturbation. The
average value of the pseudo-tensor, over a suitable spacetime domain, is
obtained. Finally, we calculate the emitted power, per unit solid angle,
carried by a gravitational wave in a direction x for a fixed wave number k
under a suitable gauge.