These bacteria can be very sensitive to changes in their environment. Temperature is a prime example. As the temperature falls, bacteria activity decreases and biogas production decreases. As the temperature increases some bacteria begin to die, once again biogas production decreases. Insulation, heat exchangers, heating elements, water baths, and steam injection are all means which have been used to control digester temperature.
Temperature control is an important consideration when designing digesters.
The materials list includes two potential heat sources. Anaerobic digestion will occur even at room temperature. However, any method of maintaining digester temperature constant near 35 degrees centigrade will improve digester performance. Any novel means of maintaining temperature are encouraged. After all, practicing engineering design is the primary purpose of this project.