  In this paper, we describe an extremely efficient method for computing the
renormalized stress-energy tensor of a quantum scalar field in
spherically-symmetric black hole spacetimes. The method applies to a scalar
field with arbitrary field parameters. We demonstrate the utility of the method
by computing the renormalized stress-energy tensor for a scalar field in the
Schwarzschild black hole spacetime, applying our results to discuss the null
energy condition and the semi-classical backreaction.
