Search

• The state of São Paulo offers ten potential scenarios for the establishment of biorefineries. • Eucalyptus residues are a promising feedstock that produces 71,000 tons of bio-oil/year. • The minimum selling price of bio-oil varies according to plant capacities between from $11.6 to 19.3/GJ. • The minimum selling price of bio-oil is particularly sensitive to plant capacity and yield. • Co-processing bio-oil with vacuum gasoil can contribute 3.4 % of total "green fuel" in Brazil. Forestry residue is potentially useful for obtaining bio-oil and its by-products (biochar, syngas, and acid-rich aqueous extract) via fast pyrolysis. As such, we carried out a techno-economic analysis of both the production of bio-oil from Eucalyptus grandis residues (ER) and their availability in the state of São Paulo, Brazil. Discounted cash flow was used to calculate the minimum selling price (MSP) of bio-oil. Georeferencing identified the location of 20 Eucalyptus plantations, ten of which were selected due to their better economic performance. These ten plantations were potentially able to produce 59 million L/year of bio-oil. The economic analysis of the future biorefineries showed that an MSP of 11.6–19.3 $ (US)/GJ could support the processing of 60,000–5,000 tons/year of ER. A simulation of a large biorefinery revealed a capital investment (CAPEX) of around 6 M$ (US), reaching an operating expenditure peak of approximately 3 M$/year. The sensitivity analysis identified that plant capacity had the most significant impact on MSP, while the by-products (acid extract and biochar) lowered this by 22 %. The large biorefinery simulated using the Monte Carlo method had an 80 % chance of reaching a net present value (NPV) > 0, and an 80 % probability of reaching an internal rate of return (IRR) > 10 %. This study demonstrated that the production of bio-oils by the ten simulated centralized biorefineries is economically viable based on the NPV and IRR indicators. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) systems transform solar irradiation into electricity, thereby substituting for traditional energy sources and reducing environmental pollution. The present work evaluates a developed market (Italy) in which subsidies have been re-introduced for PV plants with a nominal capacity above 20 kW through the FER1 (renewable energy sources) Decree. The discounted cash flow (DCF) methodology is applied to several cases of PV plants in public buildings, in order to determine the value of several critical variables (i.e. level of insolation, plant size, share of self-consumption, investment cost, electricity purchase price). In particular, differences in net present value (NPV) and discounted payback time (DPBT) between subsidy and no-subsidy scenarios are quantified. Break-even point (BEP) analysis is used to define the share of self-consumed energy for which NPV is positive. This share is found to range from 9 to 28% in 105 kW plants and from 10 to 35% in 25 kW plants. In addition, the results verify profitability in almost all of the baseline case studies and only half of the alternative scenarios (involving no subsidies). The estimated profits are consistent with investments aimed at increasing the share of self-consumed energy. • The proposed economic model supports public decision makers. • The economic model is based on both baseline and alternative scenarios. • PV systems realized on public buildings can be economically viable. • PV plant profitability is not verified in half of the cases without subsidies. • Share of self-consumed energy is the key variable in the economic assessment. [ABSTRACT FROM AUTHOR]

The mining industry produces large volumes of mine tailings – a mix of crushed rocks and process effluents from the processing of mineral ores. Mine tailings are a major environmental issue due to implications related to their handling and storage. Depending on the mined ore and the process used, it may be possible to recover valuable elements from mine tailings, among them critical raw materials (CRMs) like rare earths, vanadium, and antimony. The aim of this study was to investigate the techno-economic feasibility of producing critical raw materials from mine tailings. Data from 477 Chilean tailings facilities were analyzed and used in the techno-economic assessment of the valorization of mine tailings in the form of CRMs recovery. A review of applicable technologies was performed to identify suitable technologies for mine tailings processing. To assess the economic feasibility of CRMs production, net present value (NPV) was calculated using the discounted cash flow (DCF) method. Sensitivity analysis and design of experiments were performed to analyze the influence of independent variables on NPV. Two options were assessed, rare earth oxides (REOs) production and vanadium pentoxide (V 2 O 5) production. The results show that it is possible to produce V 2 O 5 with an NPV of 76 million US$. In the case of REOs, NPV is positive but rather low, which indicates that the investment is risky. Sensitivity analysis and the ANOVA run using the design of experiments indicated that the NPV of REOs is highly sensitive to the price of REOs and to the discount rate. [ABSTRACT FROM AUTHOR]