As a more productive process

themophilic digestion has not been popularized in China for the possibility of negative net biogas yield. A heat demand model based on the biogas plant at Alviksgården

Sweden was established to calculate the heating load so as to investigate energy consumption and net biogas yield. By comparing to the mesophilic biogas plant with the same scale in Jintan

Jiangsu

the results showed that despite the energy consumption of the thermophilic biogas plant at Alviksgården 2.1 times of the mesophilic one in Jintan

with a much higher biogas volumetric productivity as 2.3 m3·m-3·d-1

the biogas yield increment from increasing the digestion temperature from mesophilic to thermophilic was considerably larger than the energy consumption increment used for heating. Based on the current biogas productivity of the biogas plant at Alviksgården

if waste heat recovery was introduced to further decrease energy demand in substrate heating

net biogas yield could be increased from 82% to 90%. While without waste heat recovery

biogas productivity should be increased to 4.2 m3·m-3·d-1 to reach the same net biogas yield

suggesting that waste heat recovery was more efficient and economical than increasing biogas productivity via improvement of digestion technology to further increase net biogas yield.