at least on the small scale, combine the two...use the waste steam to heat the mash (like we did in chemistry classes lo those many years ago...)...which helps save on the condensation and re cycle costs.
if you are not using a high grade grain for your mash (in which case, it's recycled as animal food) then the spent mash might be sun dried for fuel use...
ck country doc in louisiana (no fancy sayings right now)