n which ci is the unitary cost of s

n which ci is the unitary cost of secondary energy, either for the landfill gas-to-energy (LGTE), waste-to-energy (WTE) option, or landfill gas upgrade (LGU) alternative. The parameter α is the capital recovery factor, calculated with an interest rate of 10% and a fifteen-year lifetime for all cases. The annual operation and maintenance cost, Co&m, was estimated as a fraction of the investment, a methodology based on mathematical regressions of economic data published elsewhere and an approach used in pre-feasibility studies and economic analysis [35] and [36]. A location factor of 1.08 was included as the investment for the country; this factor mainly addresses the additional cost for freight, taxes and insurance [36]. The value of Re corresponds to revenues, which eventually may be incorporated as heat generated for sale or re-use of any by-product. Because Chile does not have a district heating market, revenues were not incorporated [37].