Years Of Payback Period Research Articles

Optimal design for an ethanol plant combining first and second-generation technologies

The synthesis and optimal design of batch plants is addressed in this study. It was applied to the technology of conventional ethanol production in a Cuban distillery using the product of enzymatic hydrolysis of pretreated bagasse as another sugared substrate, starting from laboratory results. The optimal configuration of stages, the number of units in each stage, the unit sizes and minimum total production cost are obtained from the global optimization model and the proposed superstructure. This global model is a mixed integer nonlinear programming (MINLP) formulation, which is represented and resolved by the Professional Software, General Algebraic Modeling System (GAMS) version 23.5 applying DICOPT Solver. Different scenarios are analyzed: attaching pretreatment and enzymatic hydrolysis of bagasse to a conventional distillery plant, selling ethanol, or selling the furfural as by-product if there is a guaranteed market. With this, an actual net present value (VNA) of USD 44´893 358.7 and 1.51 years of Payback Period (PP) are obtained.

Cost analysis of plug-in hybrid electric vehicles using GPS-based longitudinal travel data

Using spatial, longitudinal travel data of 415 vehicles over 3–18 months in the Seattle metropolitan area, this paper estimates the operating costs of plug-in hybrid electric vehicles (PHEVs) of various electric ranges (10, 20, 30, and 40 miles) for 3, 5, and 10 years of payback period, considering different charging infrastructure deployment levels and gasoline prices. Some key findings were made. (1) PHEVs could help save around 60% or 40% in energy costs, compared with conventional gasoline vehicles (CGVs) or hybrid electric vehicles (HEVs), respectively. However, for motorists whose daily vehicle miles traveled (DVMT) is significant, HEVs may be even a better choice than PHEV40s, particularly in areas that lack a public charging infrastructure. (2) The incremental battery cost of large-battery PHEVs is difficult to justify based on the incremental savings of PHEVs' operating costs unless a subsidy is offered for large-battery PHEVs. (3) When the price of gasoline increases from $4/gallon to $5/gallon, the number of drivers who benefit from a larger battery increases significantly. (4) Although quick chargers can reduce charging time, they contribute little to energy cost savings for PHEVs, as opposed to Level-II chargers.

Economic analysis of biogas and compost projects in a palm oil mill with clean development mechanism in Malaysia

This article is a case study to compare the economic viabilities of biogas generation and compost projects in a palm oil mill in Malaysia with and without clean development mechanism (CDM). Biogas is captured from anaerobic ponds or digester tanks treating palm oil mill effluent (POME) and converted to green renewable electricity for grid connection, while compost is produced from the shredded empty fruit bunch and raw untreated POME. The both technologies were compared by considering the changes of the materials flow and energy balances. A palm oil mill with a capacity of 54 t fresh fruit bunch per hour has the potential to produce either 6.9 GWh of electricity from biogas or fertilizer equivalent to 488 t of nitrogen, 76 t of phosphorus and 1,065 t of potassium per year. The economic analysis for 10 years project term analysis indicated that CDM gave a significant impact and ensured economic viability for both projects with 25 % of internal rate of return (IRR), RM 12.39 million of net present value (NPV) and 3.5 years of payback period (PBP) for biogas project, whereas 31 % of IRR, RM 10.87 million of NPV and 2.9 years of PBP for compost project, respectively. In addition, sensitivity analysis indicated that the profitability of both projects will vary depending on the economic situation, such as electricity price which is based on the government policy, whereas compost price that depend on fertilizer market price with 43 % NPV change in 20 % range of fertilizer value.

Electricity Generation from Leachate Treatment Plant

Tehran has a population of over 12 million and produces more than 7500 tons of waste every day. Tehran’s municipal solid waste is processed and landfilled at Kahrizak disposal center. Due to inappropriate waste management, a lake with a leachate volume of 180,000m3 has been formed. To solve this problem a leachate treatment plant is currently under construction. A byproduct of leachate treatment is biogas. In this study, the feasibility of electricity generation using biogas has been investigated. Considering that 68.81% of the waste is degradable, the produced leachate has a high organic load (COD = 53900 mg/L and BOD = 34400mg/L). The results showed that a power plant with a capacity of 1.8 MW could be constructed in the site. This electricity can be utilized in Kahrizak Disposal Site and also sold to the network (10 US cents/ kilowatt). Financial analysis using ProForm software shows 1.3 years of payback period and emission reduction of carbon dioxide equal to 5752 tones/year in comparison with the natural gas power plant. Therefore this project is financially feasible for private investors with internal rate of return equal to 77% or mo