The various components of an anaerobic digester may be subject to malfunctions, and in all cases, they will be subject to repair. Therefore, maintenance is periodically required. The CHP unit is serviced every 2000 and 20,000 operational hours and needs an overhaul every 60,000 operational hours. The pumps need to be overhauled every 3e5 years. Under normal circumstances, the other components of the installation are not likely to wear out before the end of the technical lifetime (10e20 years), but some repairs may be necessary.