Abstract
Purpose The goal of this study is to analyze the economic
performance of an alternative system for waste management
proposed by the European Integral-b project. Its aim is to treat
both used cooking oil (UCO) and solid organic waste (SOW)
from the hospitality sector by biodiesel production and anaerobic
digestion, respectively. A cogeneration engine adapted to
use glycerol as a fuel is implemented. These results complement
others from a previous life cycle assessment (LCA).
Methods The system proposed (scenario A) is compared to a
system consisting of average waste management options (scenario
B) by means of life cycle costing (LCC). The functional
unit (FU) is the amount of UCO and SOW from hospitality
produced per person and year in Spain. The profits generated
by the FU under the two scenarios are calculated from a financial
point of view. It is assumed that co-products from both
scenarios translate into revenues for waste managers. Scenario
analysis assesses different rates for the electricity output, subject
to market regulations, and different levels of UCO availability.
Monte Carlo simulations are carried out to analyze
parameter and price uncertainty.
Results and discussion The profits in all the scenarios are
negative, and those of scenario A are lower than those of
scenario B under all the scenario formulations. Scenario A
generates greater income than scenario B but also higher expenses,
mainly due to SOW collection. The new electricity
rates are detrimental for the financial performance of the
Integral-b since the overall profits mostly depend on the sale
of electricity. Readier UCO availability benefits both scenarios
to a similar extent. The uncertainty analysis reinforces the
comparative results, although there is some likelihood scenario
A will generate greater profits. The sensitivity analysis allows
for the key parameters to be identified in order to optimize
the process further. Possible trade-offs between the LCC
and LCA results have been evaluated.
Conclusions Results from the financial analysis show that the
Integral-b process delivers greater losses as compared to a
reference scenario. Both generate net costs, meaning that
stakeholders have to finance the functions provided.
Uncertainty in the electricity regulations constitutes an obstacle
for such projects as these to be implemented. As in LCA,
the definition of the system boundaries and FU is critical in
LCC.
