Discounted Payback Period Research Articles

Investment Project Analysis of Mud Handling Using Slurry Pump Method: A Case Study of Pit C2 PT. Berau Coal

Disposal is important in mining activity for allocation of waste material that need to be dispose to obtain the coal ores. The disposal allocation in Pit C2 currently has a long distance and there is an additional cost incurred due to the distance rate adjustment from distance contract reference. To overcome this problem, there is an option of short distance disposal scenario, namely in pit dump scenario. With this scenario, there is cost efficiency from the distance rate adjustment due to the reduction in disposal distance. Sump H as a planned area for in pit dump is currently fulfilled with sedimentation material, with a volume around 1,2 million cubic meters (BCM). Therefore, it is necessary for mud handling in Sump H area for it to become in pit dump location area. One of the proposed scenarios is the use of slurry pump, this scenario is more suitable for current condition due to it can finished earlier. However, it is necessary to study and evaluate further the financial analysis of the proposed scenario in comprehensive manner. To obtain the financial feasibility of this project, this research use capital budgeting analysis in which the parameters used are studied further using sensitivity analysis and probability analysis. From the results of the financial feasibility analysis of this slurry pump scenario, it shows that this project is financially feasible with an NPV value of IDR 16.227.951.215,26, with an IRR of 43,08%, a Payback Period of 1,6 years, a Discounted Payback Period of 1,77 years and a Profitability value Index 1,7. In addition, based on the Monte Carlo Simulation for probability analysis, it is found that the probability of this project failing is 0%. Therefore, it can be concluded from the results of the financial feasibility analysis, this project is recommended to be implemented.

Sensitivity study of the economics of a floating offshore wind farm. The case study of the SATH® concrete platform in the Atlantic waters of Europe

The objective of the present work is to develop a sensitivity analysis to determine the most essential parameters that affects to the economic feasibility of a marine wind farm composed by platforms built in concrete material. The main purpose is to analyze how the input variables such as number of offshore wind turbines, the energy produced by one wind turbine, the interest rate, the capital cost, the electric tariff, etc. affect to the economic output variables: the Levelized Cost Of Energy (LCOE), the Internal Rate of Return (IRR), the Net Present Value (NPV) and the Discounted Pay-Back Period (DPBP) of the considered offshore wind farm. This paper studies the concrete floating offshore wind platform SATH®, developed by the SAITEC enterprise. Results indicate what are the most relevant variables in economic terms to take them into consideration for their installation in the future.

Designing, sizing and economic feasibility of a green hydrogen supply chain for maritime transportation

Green hydrogen plays a strategic role in the decarbonization of the maritime transportation. A step useful to favor the use and the exploitation of the hydrogen is the development of hydrogen supply chains that, by including both the infrastructures and the end users, can simplify the economic issues and the authorization processes. This paper is focused on the designing, sizing and economic feasibility of a sustainable supply chain that consists of a solar-driven electrolysis system that generates hydrogen for powering a fuel cell-based propulsion system installed on board a small passenger ferry boat travelling on a short route. The sizing procedure is based on a numerical procedure that aims to find the optimal supply chain configuration, in terms of components’ sizes, able to satisfy the hydrogen demand and to sustain the electrical energy requirements by only using the renewable source. Results of this study highlight that a hydrogen production of 128.7 tons/year is produced by using an alkaline electrolysis unit of 1780 kW integrated with a 8.15 MWp photovoltaic power plant. The produced hydrogen allows to satisfy the specific requirements of the ferry boat with a total number of 314 roundtrips per year. From the economic point of view, by valorizing the electricity surplus and the by-product oxygen from the electrolysis process, the estimated profitability index and the discounted payback period are 2.03 and 9 years, respectively, making the investment attractive. The calculated levelized cost of the produced green hydrogen is equal to 5.61 €/kg. These results demonstrate the techno-economic feasibility of the proposed supply chain based on hydrogen technologies that, being already available on the market, can be effectively implemented to support the decarbonization of the maritime sector.

Techno-economic analysis of a microgrid design for a commercial health facility in Ghana- Case study of Zipline Sefwi-Wiawso

Most commercial entities depend on the availability, and reliability of electricity supply for their business ventures. Poor energy security, unreliability, and high cost of electricity characterize the utility grid of Ghana, forcing most of these facilities to resort to using diesel generators to supplement their energy needs. This study, therefore, proposes the development of a Microgrid (MG) to provide electricity to the Zipline facility in Sefwi-Wiawso, Ghana. The optimally designed MG is achieved using the HOMER software and consists of 94.8 kW Sunpower solar panels, 231 kWh Samsung M8068 Li-ion batteries, 56.31 kW ABB MGS inverter, 158 kW CAT-C7 diesel generator, and an infinite distribution grid. The proposed design with a lifespan of 25 years has an initial capital cost of US$ 45,929.17 and a nominal discounted payback period of 2.11yrs making a total savings of US$ 322,563.21.

Restoration of the red deer population as a factor in the ecological and economic development of the region

The article discusses the issues of restoration of biological resources in forestry in the Samara region. The proposed creation of farms for the reproduction of large animals that were subjected to barbaric extermination in the nineties will solve not only the environmental problem, but will provide the opportunity to create a base for providing hunting services to the population, reducing pressure from poachers, and increasing the profitability of forests as economic objects. One of the species subject to population restoration is red deer (Cervus elaphus L.). Its number decreased to 310 heads (1997). Currently it is 1190 heads (2022). In the Samara region, red deer are found annually in the territory of 6-7 municipal districts out of 27. The number and spatial distribution of deer, like other ungulates, have annual fluctuations and are a vector indicator of the relationship between natural and anthropogenic factors. Creation of a farm for 210 heads. It will allow you to annually raise up to 60 animals, which can be released into the wild. To provide feed, about 500 hectares of agricultural land will be required. Project efficiency indicators: - the payback period of the project was 77 months; - discounted payback period – 101 months; - net present value – 2419.0 thousand rubles; - internal rate of return – 13.06%.

Experimental Investigation on the Effect of Flow Rate and Load on the Hydrodynamic Behavior and Performance of an Archimedes Screw Turbine

One of the best solutions to overcome problems caused by fossil fuel consumption is using renewable energy. In this research, effect of flow rate and load on the performance of an Archimedes turbine was experimentally studied. At first, Archimedes turbine with optimal size was made using 3D printer technology. Then it was placed in the river simulation setup. After the calibration and uncertainty analysis, tests were performed for three flow rates and five electrical resistances. The results showed that increasing the flow rate leads to a rise in power, torque, and angular velocity of the turbine, but it leads to a non-linear behavior in efficiency. On the other hand, an increase in electrical load has also led to a decrease in converter performance for all conditions. In addition, by implementing π-Buckingham theory, the converter's hydrodynamic behavior was studied by using Reynolds numbers, dimensionless flow, and power coefficiency. The results showed that an increase in Reynolds number leads to a decrease in power coefficiency. However, an increase in dimensionless flow increases the power coefficiency first and then decreases (nonlinear behavior). In addition, the Archimedes screw turbine was also studied from an economic point of view, and the results showed that increasing discount rate leads to an increase in discounted payback period, and in the worst case, the payback period is 3.09 years, and in the best case, it is 1.6 years. Also, the construction of the Archimedean screw turbine in Iran can save currency for $1439.5.

Development potential for rooftop solar photovoltaic: case studies in commercial and industrial sectors of Hue City

A growing interest in solar energy development to ensure national power security and slow the onset of the current climate crisis has spurred the deployment of rooftop solar photovoltaic (PV) in cities in Vietnam. This paper aims to examine the technical and financial potential for rooftop solar PV development of two enterprises in Hue City, namely Truong Tien Plaza Commercial Center and Huetronics Joint Stock Company. The Google Earth Pro, the Roof Pitch Factor, and the on-site survey were employed to determine the rooftop characteristics of the two facilities. The technical potentials of Huetronics Company and Truong Tien Plaza were estimated at 1,256 kWh/day and 1,437 kWh/day, respectively. The financial analysis with Cost-Benefit Analysis reveals that both reference cases proved to be financially viable: the Discounted Payback Period is 5.8 years in the case of Huetronics and five years for Truong Tien Plaza; the Net Present Values are greater than zero, and the Internal Rate of Return is higher than the Cost of Capital. Such results are expected to assist in making informed policy decisions on the commercial and industrial rooftop solar PV development in Hue City.

PROPERTY LIFE CYCLE COST ANALYSIS METODS

The minimization of the property life cycle cost as a criterion for making a decision regarding the economic feasibility of purchasing or building a certain real estate object compared to other objects with functional utility today has become a mandatory requirement of most regulatory and legal acts in Ukraine.
 At the same time, the practical implementation of this requirement faces the problem of methodical provision of life cycle cost analysis from the standpoint of the uncertainty of these costs in the future and the need to take into account the time value of money.
 The application of valuation procedures based on cash flow discounting, proposed in this article, can contribute to the solution of this problem.
 Discounting cash flows will require the classification of life cycle costs not only by content load, but also by the time of their occurrence into initial and future costs, which in turn are divided into once-only, periodic and regular costs.
 Acceptable units of measurement of discounted cash flows can be net present costs, equivalent annual cost, net savings; savings to investments ratio, internal rate of return, discounted payback period, each of which corresponds to its own model and valuation criterion.
 To solve the problem of the uncertainty of future costs and to take into account the risk inherent in their forecasting, the methods of analyzing the sensitivity of the results to changes in the market situation are proposed and the justified feasibility of using stochastic discounted cash flows models is justified.

Techno-economic feasibility analysis of grid-connected residential PV systems in Algeria

Small-scale photovoltaic (PV) power systems have been proven to be successful in generating electricity, conserving fossil fuels, and reducing greenhouse gas emissions in the residential sector, which is one of the largest consumers of energy. In Algeria, to reduce energy consumption in this sector, the authorities are considering implementing a policy that would encourage grid-connected residential PV systems. This paper presents a techno-economic assessment of grid-connected residential PV systems in four climate zones in Algeria. This work was performed using HOMER software for two different PV system configurations, grid/PV and grid/PV/battery. The technical performances of the considered systems were evaluated through the assessment of the self-consumption and self-sufficiency, while the net present value (NPV), internal rate of return (IRR), profitability index (PI), and discounted payback period (DPBP) were used to determine their feasibility. A sensitivity analysis was carried out to evaluate the effects of feed-in tariff (FiT), battery costs, and PV array capacity on the profitability of the systems. The results revealed that the grid/PV systems are technically and economically feasible in all of the four climate zones. For the grid/PV/battery systems, the grant of battery costs and the development of a regional FiT system are recommended. This article provides a tool for policymakers to assess the technical and financial performance of residential solar PV systems to develop adequate policy supports and tariff structures for Algeria.

An Economical Boil-Off Gas Management System for LNG Refueling Stations: Evaluation Using Scenario Analysis

The use of liquefied natural gas (LNG) in the transportation sector is increasing, and boil-off gas (BOG) management systems are considered viable options to increase economic efficiency and reduce greenhouse gas emissions at LNG refueling stations. The present study proposed an economically optimized method by investigating four refueling station scenarios, including different BOG management systems. Among the four scenarios, the scenario in which compressed natural gas was produced from BOG had the lowest minimum selling price (MSP) and was the most economical. Sensitivity and uncertainty analyses were conducted for the economically optimal scenario, which identified the factors with the most influential impact and their uncertainties on the MSP. Finally, to determine the feasibility of the business through profitability analysis, the net present value, discounted payback period, and present value ratio due to changes in the discount rate were presented, and the discounted cash flow rate of return was found to be 13.22%. As a result of this study, a BOG management system can contribute to improving the economic feasibility for LNG refueling stations by reliquefying BOG and re-selling it (the most efficient way is scenario 4) and will provide an economical guide for countries with much demand for LNG in the transport sector.

Assessment of the energy and overall efficiency of the closed irrigation network of irrigation systems on the basis of the complex of resource-saving measures

The presence of water, food and energy crises, both at the global and regional levels, as well as their deterioration under conditions of climate change, with an insufficient level of technical condition of existing irrigation systems, increase the strategic importance of irrigation as the guarantor of the agricultural sector sustainable development. This makes it necessary to increase, foremost, energy and overall (technical, technological, economic, and environmental) efficiency of the closed irrigation network of irrigation systems. In this regard, the complex that includes organisational-technological, technical, and resource-saving groups of measures was developed. Estimation of energy and overall efficiency of the closed irrigation network of irrigation systems at the implementation of developed complex were executed on the example of the agricultural enterprise located in the Petropavlovsk district of the Dnipropetrovsk region of Ukraine. For this purpose, machine experiment based on a use of the set of optimisation, forecasting and simulation models was implemented, including the model of climatic conditions, the model of water regime and water regulation technologies, as well as the model of crop yields on reclaimed lands. According to the obtained results, established that implementation of the complex reduces the consumption of irrigation water by 2.2–30.7% and electricity consumption by 12.9–38.2%. The rate of specific costs decreases from 1.6 to 1.32–1.47, and the coefficient of environmental reliability increases by 5.6–16.7%. At the same time, the profitability index increases from 1.07 to 1.75–2.57, and the discounted payback period decreases from 18 to 8–5 years.

Performance assessment of a solar-assisted absorption-compression system for both heating and cooling

Combining renewable energy with building energy supply is an effective way to pivot the building sector to carbon–neutral. This paper proposes a novel solar-assisted energy supply system which is applied in residential buildings for heating, cooling and domestic hot water. The heating/cooling output of the proposed system is mainly contributed by a vapor compression system to address the supply–demand mismatch of solar energy supply system, and the other part is assumed by a solar driven absorption system that is operating with lower generation temperature and higher evaporation temperature to assist the vapor compression system. Therefore, a solar-assisted absorption-compression system (SAACS) exploits the full potential of solar heat for annual energy supply by improving the contribution of per unit solar collection area, with considerable electricity-saving compared to air-source heat pumps. A thermodynamic model is established and validated by the results of the built experimental prototype which is testing. Solar-assisted heating mode and solar-assisted cooling mode are compared in comprehensive evaluation criteria to illustrate the performance differences caused by the assisted solar energy. The results indicate that solar heat at 60 °C is feasible for heating and cooling, revealing the great potential for efficient conversion from solar energy for heating and cooling. Due to the introduction of solar energy, the cooling and heating COPele increases by 10.3 % ∼ 17.6 % and 32.3 % ∼ 56.3 %, respectively. Despite the lower increase in COPele, electricity-saving ratio shows greater value at low hot water temperatures, varying from 24.3 % to 19.6 % for cooling and from 44.1 % to 39.7 % for heating as hot water temperature increases from 60 °C to 85 °C. The maximum SCOP is 0.63 for cooling, and 1.14 for heating. Yearly investigation shows that the SAACS combined with 20 m2 CPC collector has an annual average solar fraction of domestic hot water of 0.85 and a discounted payback period of 3.12 years. These results demonstrate the feasibility and flexibility of the SAACS applied to residential buildings toward decarbonization.

Determination of Rational Values of the Parameters of an Unventilated Trombe Wall Using the Method of Multicriteria Optimization for the Climatic Conditions of Uzbekistan

The energy demands of the construction sector are expected to multiply over the next decade, driven by population growth, rising incomes, accelerating urbanization and changes in consumption patterns. This process is also dramatically affected by the depletion of fossil resources and high specific energy consumption for heating buildings. Under these conditions, it is necessary to develop comprehensive energy efficiency measures in these areas to meet the energy demands of residential, commercial and administrative buildings. In this work, using the methods of degree-day, multicriteria optimization and regression analysis, the optimal combinations of factors for an unventilated Trombe wall are determined: the orientation of the building, the thermal support of the translucent enclosure of the unventilated Trombe wall and the ratio of the surface of the unventilated Trombe wall to the surface of the building facade. The calculations were performed for three levels of thermal protection for buildings in the climatic conditions of the city of Tashkent (Uzbekistan). A typical one-storey three-room house was chosen as the object. As the calculation results show, within the considered range of values, the relative dominances of the factors are as follows: orientation - 5.37%; thermal support of translucent barriers - 72.95%; and area ratio - 21.68%. Using the optimal values, the specific energy consumption of buildings for heating can be reduced from an average of 12.9-14.8% to 52.6-65.3%. Additionally, the CO2 emissions are reduced from 5621.8 kg to 12435.5 kg per year. The discounted payback period, depending on the investment, ranges from 18.7 to 40.9 years. Regression equations are proposed for three levels of thermal protection of the considered object, making it possible to determine the specific energy consumption for heating.

A Model for Finding a Suitable Location for a Micro Biogas Plant Using Gis Tools

The article presents a model for finding the most suitable locations for setting up micro-biogas plants (<50 kW), which represent an efficient way of processing organic waste in small local communities. The input parameters of the model, which was made with GIS tools, were the number of farms and heads of large livestock with their locations, the number of food establishments and their collected food waste and waste fat. We tested the case study model in the Gorenjska region in Slovenia. The result of processing the input data in the model are four locations in three municipalities Naklo 1, Naklo 2, Kranj and Cerklje. We evaluated the locations with economic indicators net present value (NPV), internal rate of return (IRR) and discounted payback period (DPP). With sensitivity analysis, we investigated the impact of increasing investment costs, decreasing energy prices and different scenarios with adding corn silage to the anaerobic process. Location Naklo 1 has NPV 31,410.26 €, IRR 10.53% and DPP 22 years, Naklo 2 has NPV −58,808.91 € and DPP of more than 25 years, location Kranj has NPV 140,313.00 €, IRR 13.07% and DPP 16 years, location Cerklje has NPV −43,026.82 € and DPP of more than 25 years.

Financial feasibility study and innovation in robotic milking

The study aimed to analyze the financial feasibility of implementing robotic milking on a dairy farm in western Santa Catarina/Brazil. This is a descriptive case study with a qualitative basis using semi-structured interviews. Based on cost measurement for implementation of robotic milking in the period of activity of 2022, a comparative analysis was made of the incremental cash flow relative to a transition from conventional to robotic milking. One of the major findings is that the simple payback time is approximately 4.9 years while the discounted payback period is approximately 5.11 years, considering a MARR of 10% as the expected profit per year. The implementation of robotic milking yields an IRR of 28.79%. It was also found that accounting is an important instrument for planning resources and investments for activities developed in rural settings, thus enabling short and long-term planning.

Study of Technological Process of Fermentation of Molasses Vinasse in Biogas Plants

The volume of ethanol production waste—molasses waste in Ukraine—reaches up to 4 million m3 per year. It is not easy to dispose of and is polluting the environment. Currently, the development of an effective technology for using molasses in biogas plants to obtain energy gas—biogas—is an urgent problem. The purpose of our work is to determine the rational volume of loading molasses bard into the methane tank in a quasi-continuous mode to obtain the maximum volume of biogas. To achieve this goal, the following experimental studies were carried out: mono-fermentation of molasses and combined fermentation of cattle manure and molasses on a laboratory biogas plant in a periodic mode; on the basis of the obtained laboratory studies, a special simulation model of biogas output during the quasi-continuous fermentation of substrates was established and the amount of molasses added to obtain the maximum biogas output was determined. The maximum output of biogas under the periodic system of loading the methane tank when adding 10.5% molasses to cattle manure is 1.462 l/(h kg DOM); when adding 26.1% molasses to cattle manure, it is 3.594 l/(h kg DOM). In order to increase the yield of biogas, it is advisable to add molasses in the amount of 30% of the volume of the substrate to the substrate based on cattle manure, which allows the discounted payback period of the biogas plant to be reduced to 1.2 years.

Investment Risk Analysis of Jakarta - Cikampek II Selatan Toll Road

The availability of infrastructure is important in supporting economic activities. The toll road is one of the infrastructures that have undergone extensive development over the past five years. It benefits the Indonesian community by shortening travel time and increasing economic growth. Toll road development is a long-term investment that requires very large costs and a long payback period. Potential risks could hinder the development of toll roads and would delay the payback period further. Due to the delay in the construction schedule, there is an estimation difference between the beginning financial feasibility in 2017 and the adjustment in 2022, when the toll road is currently under construction. Financial feasibility analysis is not complete without risk analysis. Thus, investment risk analysis has to be done. The results showed a payback period of 9.65 years, a discounted payback period of 19.41 years, an NPV of IDR 4,759,916 Trillion, and an IRR of 11.63% is greater than 10.65%, the cost of capital. Since all the results exceed the acceptance criteria, this toll road project is feasible, although it is calculated using the latest adjustment assumptions. However, from the comparison result, the adjusted has a lower IRR and discounted payback period compared to the beginning (12.32% and 18 years). Using sensitivity analysis, 3 sensitive variables are identified to impact NPV results greatly. According to the scenario analysis result, each of the scenario’s payback period, discounted payback period, NPV, and IRR is considered to be accepted. It showed that the toll road project is feasible in pessimistic, most likely, and optimistic scenarios. Based on the risk management result, there are 1 extreme risk, 2 high risks, 5 moderate risks, and 1 low risk. A risk mitigation plan helps reduce each potential risk's probability or impact.

Accelerating electric vehicle adoption: techno-economic assessment to modify existing fuel stations with fast charging infrastructure

With the increasing electric vehicle (EV) penetration, there arises an immediate need for charging infrastructure. In the future, the electrification of transportation will reduce the requirement of existing fuel stations, thereby rendering them obsolete. However, they are best suited to cater to the charging demand of EVs as the drivers are accustomed to the locations and the incremental cost of providing this service will be lower. In this paper, we propose a novel methodology to assess the techno-economic feasibility of retrofitting an existing fuel station with EV charging infrastructure also known as Electric Vehicle Supply Equipment (EVSE). To further enhance the value proposition, the potential of integrating Battery Energy Storage System (BESS) with EV charging infrastructure, which results in the reduction of grid connection costs, is studied. The sustainability of the proposed system is improved with additional onsite Photovoltaic (PV) generation. The proposed methodology is implemented for the UK as a case study. The configurations in this study are designed based on the technical considerations involved in retrofitting a typical fuel station as a fast charging facility for EVs. From the results, it is observed that the configurations with 4 EVSE, 1 BESS, and 8 h of operation and the configuration with 4 EVSE, 1 BESS, and 1 PV system for 8 h of operation are economically viable. The abovementioned configurations are the most economically feasible configurations in terms of the Net Present Value (NPV), Internal Rate of Return (IRR) and the Discounted Payback Period (DPP) amongst the other configurations considered in this study. The proposed methodology indicates that though the connection cost is the dominant factor affecting the feasibility, the use of BESS with or without PV can reduce the connection cost by almost 90% depending on the capacity of BESS. The methodology acts as a decision support tool to select a techno-economically feasible configuration of EVSE, BESS, and PV.Graphical abstract

Approximate climate analysis for assessing the suitability of Indian climate zones for hydroponic fodder applications

Hydroponic fodder has been proposed as a novel low-tech solution to India’s fodder scarcity. Hydroponic fodder can reduce water requirements by up to 95% and use up to 70% less land due to their vertically scalable nature. The short crop cycles of approximately 7 days yields a seed to feed ratio of 1:8. This study analyses the external environmental weather conditions in Indian climate zones, assessing their suitability for the application of hydroponic fodder solutions. The weather of each climate zone was approximated by a representative city through parameter selection and optimisation by three-dimensional Euclidean distance minimisation. Simulation and analysis were carried out on the Rhinoceros software platform with the Grasshopper and LadyBug plug-ins. Hourly temperature plots, sun-path diagrams and psychrometric charts with modified predicted mean vote polygons superimposed were generated for each climate zone. The ambient weather suitability of the following representative cities was simulated to be as follows: Ahmedabad (86.70%), Kolkata (81.86%), Bengaluru (94.07%), Lucknow (73.23%) and Srinagar (30.85%). A cost benefit analysis was buttressed by a sensitivity analysis with respect to the selling price of green fodder. A preliminary cash flow analysis yielded a discounted payback period of 4 months for direct fodder sales and 20 months for sale of livestock products as a co-benefit of green fodder production.

Design and economic analysis of a hydrokinetic turbine for household applications

Social and political concerns on climate change have made renewable energy an essential component of government’s work plans. Grid-connected horizontal-axis hydrokinetic turbines are promising eco-friendly power sources for electrical energy supply to households near middle-to-high discharge rivers, while providing an opportunity to sell the energy surplus. In this work, a rotor design analysis of a hydrokinetic turbine with a 1 m nominal radius is performed based on blade element momentum theory. Then, an economic analysis is presented in terms of the discounted payback period and the internal rate of return. The numerical results show that three-bladed hydrokinetic turbines with a nominal tip speed ratio of 5 and state-of-the art high lift-to-drag ratio hydrofoils (∼100) lead to maximum performance with a power coefficient around 0.45. Performance can be further improved in an affordable manner using diffuser-augmented hydrokinetic turbines. The use of hydrokinetic energy in household applications can be profitable in leading economic countries with a discounted payback period of 4–6 years. In energy developing countries, this technological solution can be cost effective accompanied by economic subsides and implementation of a local industry, resulting in similar payback periods.