Effect of population age structure on capacity for biomass cogeneration: A case study of a rural area in China

To improve the overall efficiency of biomass cogeneration, a case study was conducted in a rural area to investigate the effect of the age structure of the local population on the total capacity of the biomass cogeneration system. The age-structure-based energy consumption data of 150 households were obtained through a questionnaire survey. The data treatment and function fitting yielded functional relationships between the average family age and the annual household electricity, heat, total energy consumptions and the heat–electricity ratio of biomass cogeneration. Conclusions can be summarized as follows: (1) The annual household electricity, heat and total energy consumptions peak at average family ages of approximately 40, 60 and 55, respectively. The heat–electricity ratio of biomass cogeneration peaks at an average family age of approximately 68. (2) During the heating period, the heat–electricity ratio of biomass cogeneration is positively related to the difference between indoor and outdoor temperatures, while during the non-heating period, the ratio is stable. (3) The total capacity of biomass cogeneration estimated based on the age structure of the local population (Method A) may not be consistent with that estimated based on the per-capita energy consumption (Method B). As the total energy consumption varies in a parabolic pattern with the average family age, the estimate yielded by Method A is smaller than that yielded by Method B if the average family age is smaller than 35 or larger than 73; the two methods yield similar estimates if the average family age falls in the range of 35–73.