A regional optimization model for waste-to-energy generation using agricultural vegetative residuals
. Waste Management 2018
, 546 - 555. Abstract
The spatial distribution of vegetative agricultural residuals (VAR) implies that any waste treatment system (WTS) designed to manage VAR is particularly sensitive to transportation costs. Additionally, a wide range of treatment technologies is potentially available for VAR treatment, but some of them lack a well-developed market for their output products. This study develops a method to design an economically feasible VAR treatment system, analyzing the profitability of the system as a function of logistics and uncertain market prices of the available treatment technologies' products. The design method includes an economic optimization model followed by a sensitivity analysis of the potential changes in the system’s profitability. The results show that the market price of the treatment technologies' products has a larger impact on the system’s profitability than transportation costs. Specifically, if biochar prices reach the level forecasted by experts, pyrolysis will become the dominant technology of the WTS. The research highlights the importance of the treatment technology selection and the location of treatment facilities in the design of an optimal WTS for VAR.
Designing an agricultural vegetative waste-management system under uncertain prices of treatment-technology output products
. Waste Management 2018
, 37 - 43. Abstract
Setting up a sustainable agricultural vegetative waste-management system is a challenging investment task, particularly when markets for output products of waste-treatment technologies are not well established. We conduct an economic analysis of possible investments in treatment technologies of agricultural vegetative waste, while accounting for fluctuating output prices. Under a risk-neutral approach, we find the range of output-product prices within which each considered technology becomes most profitable, using average final prices as the exclusive factor. Under a risk-averse perspective, we rank the treatment technologies based on their computed certainty-equivalent profits as functions of the coefficient of variation of the technologies’ output prices. We find the ranking of treatment technologies based on average prices to be robust to output-price fluctuations provided that the coefficient of variation of the output prices is below about 0.4, that is, approximately twice as high as that of well-established recycled-material markets such as glass, paper and plastic. We discuss some policy implications that arise from our analysis regarding vegetative waste management and its associated risks.