We established the minimum number of cattle for commercializing electricity from the cattle waste-to-energy technology. By optimizing the cattle waste-to-energy technology for the various number of cattle, the minimum number of cattle was discovered. The number of cattle for commercializing electricity from cattle waste-to-energy technology is 60 dairy cows subject to co-digestion of manure and food waste, and the inclusion of a screw press. When digesting manure only, the minimum number of cattle is 130 cows.