Pollution is just a resource in the wrong place: Denver is building a sewer heat-recovery program, as Sam Brasch of Colorado Public Radio reports.

[Shanti] Pless said the biggest barrier isn’t technology — it’s helping developers rethink the size of their heating and cooling systems. Sewer heat recovery often works best as the heart of a district-size energy system, where a central plant provides energy to a whole neighborhood or office complex.