21 December 2007
Urban areas have a vast potential of unused energy in sewage. An existing sewer pipe was used in experiments
to try to extract and deliver heat from and to the sewage. Pipes were laid along the sewer pipe to form
a water jacket heat exchanger which was used to extract and dissipate heat from and to the sewage. This heat
was then used as a heat source for the heat pump. Three types of water jackets were constructed and laid along
the sewer pipe. Experiments were carried out using sewage heat as the heat source to measure heat which could
be extracted for heating during winter or for melting snow on the roads. Experiments were also performed to
measure heat that could be used for cooling during the summer.
Results showed that heat could be extracted from sewage without any effects on the sewage treatment plant.
Compared to underground heat extraction, heat extraction from sewage using water-jacket heat exchangers
provides far better heat extraction performance per unit length, and is much more economical.