We usually think of this water, which drains from our
dishwaters, showers, and, yes, toilets, as carrying just filth —
but it also flushes a great deal of heat from homes and
businesses. In cold months, sewage is about 60 degrees, and in
summer it can exceed 75 degrees, reports Andrew Maykuth of the
Philadelphia Inquirer. And why let that heat go to waste? To
avoid doing so, Philadelphia-based NovaThermal Energy launched
its first US pilot project in Philadelphia on April 12 that will
harvest heat from still-warm sewage to heat buildings. The
technology is essentially a geothermal heat pump that extracts
and concentrates heat as the sewage travels through the pump. In
the winter, pipes carry this heat through the walls of
buildings; in the summer, another set of pipes carries the heat
away. The critical piece of NovaThermal’s tech is primarily
scatological: the company holds a patent on a filtering device
that removes — ahem — “larger debris” that could damage the pump
from entering the system. NovaThermal En