Simple Payback Time Research Articles

Energy efficiency in small and medium enterprises: Lessons learned from 280 energy audits across Europe

The European Energy Efficiency Directive requests the application of high quality and cost effective energy audits across Europe. The potential of up to 20% of energy savings shall be realized to follow the strategy of smart, sustainable, and inclusive growth. A number of barriers must be tackled to implement the Directive, especially among small and medium sized enterprises (SMEs). A large number of cost effective energy efficiency measures remains unimplemented because of financial reasons, a lack of information, and limited in-house skills. Information measures, audits, capacity buildings are suggested as potentially effective measures to support implementation of energy efficiency measures. Within the work described in this paper, an auditing approach was developed, focusing on modelling the energy consumption of an SME. The model of the energy consumption is built using simple MS Excel tools, dividing the process into unit operations and attributing annual consumption to these units, from measurements or by calculation. Consumption is linked to drivers of consumption and corresponding losses, thus developing an understanding of the origin of energy consumption, priorities, and the potential for reduction. The approach simultaneously addresses the needs for the identification of measures, capacity building, information and awareness raising. The auditing approach was tested with 280 companies in Austria, Bulgaria, Cyprus, Italy, Romania, Slovakia and Spain. A wide range of energy efficiency measures was identified and implemented, partly consisting of no-cost options, but partly also innovative technical solutions. Over EUR 10 million investments with a simple payback time of less than three years were triggered. 6500 toe per year of primary energy savings were realized, as well as greenhouse gas emission reductions of 13,500 tonnes per year.

Energy performance of an existing office building in the northern part of Italy: Retrofitting actions and economic assessment

In recent years, the interest of the scientific community towards building energy performance has become more evident in order to meet the National and European Directives. In this context, retrofits that result in improved building energy performance are widely investigated. The paper presents a comparative analysis of two different and complementary strategies to enhance the energy performance of an existing tertiary building located in Bologna, Italy. The first retrofit action is to reduce the heat transfer by transmission (i.e. use of low-emissivity glass) and the second one is to decrease the ventilation losses (i.e. installation of a heat recovery system). Then a third case has been investigated: it contemplates simultaneously both the solutions of windows replacement and installing a ventilation recovery system. Potential energy savings were calculated by means of dynamic simulation assisted by Trnsys energy simulation tool. Finally, an evaluation of the simple payback time and the net present value was performed in order to investigate global cost assessment. The window replacement option in the analyzed building office proved to be absolutely unprofitable, even if it would appear as the first and simplest action to be performed. On the contrary, the installation of a total energy recovery system resulted in sensible reduction of energy consumption and at the same time generated good values of NPV with reference to all the three different analyzed variation of the cost of energy.

Economic evaluation of different scenarios for gas turbine waste heat recovery to produce water and power

ABSTRACTIn this study, economic analysis of different configurations of combined power and water systems is performed using DEEP software. Three different desalination systems including reverse osmosis (RO), multi-effect desalination (MED) and multi-stage flash (MSF) coupled to a gas turbine power plant with 2 × 165.1 MW capacity are considered and analysed. A specific capacity of 50,000 m3/day is assumed for all desalination systems. The results indicate that the RO system has the lowest simple payback time, while MED has the highest thermal utilisation. In terms of levelised cost of water, the RO system has the lowest amount with 1.03 $/(m3/day), while levelised cost of water for MED and MSF are equal to 1.47 and 1.93 $/(m3/day), respectively. Also sensitivity analysis showed that the fuel cost is the most effective parameter on the levelised cost of water. In general, it can be concluded that the RO system is the best choice in terms of economics.

Triple-finned tubes – Increasing efficiency, decreasing CO2 pollution of a steam boiler

This paper presents the results of techno-economical analysis of a proposal of the utilization of TFT (triple-finned tubes) in a boiler's tube banks. The following three tube bank arrangements were compared: (A) the base – staggered plain tube bank; (B) the combination of triple-finned and plain tubes – two rows of triple-finned tubes every 10 rows; (C) the alternating tube bank, where half of the plain tubes were replaced by triple-finned tubes in an in-line arrangement.The results of CFD calculations of heat load q let to obtain relative values of the Nu number on the tube bank in (B) and (C) arrangements and the base arrangement (A) were carried out in a 2D model using the CFD (computational fluid dynamics) code Fluent.Heat transfer values of an ECO (economizer) with triple-finned tubes were obtained for the calculation of outlet flue gas temperature and outlet loss. Calculations of the Nu number of the tube were performed for all arrangements. Next, boiler efficiency and fuel consumption were calculated by 0D modelling. Received results were used to make economical analysis. In the case of modernization in the (C) arrangement, efficiency would be 90.67%, which is an increase of 1.1%. This is related to the reduction of flue gas temperature to 138 °C from 158.8 °C.Economically, the most advantageous solutions, are the variants of modernization (B) and (C) for the newly formed boiler. In both cases, SPBT (simple payback time) capital payback period is very short - close to half of a year.It is worth noting that the proposed modernizations of the arrangement (B) and (C), will respectively reduce CO2 emissions by 550 t/a and 826 t/a.The results show that triple-finned tubes can be used to increase the performance of cross-flow tube banks.

Assessment of Thermo Modernization Using the Global Cost Method

The article uses the global costs method to choose the best thermo modernization solutions for the buildings. Global costs were calculated according to the cost-optimal draft regulation as summing up the initial investment costs and the discounted annual operating costs.Requirements of thermo modernization work assumed to comply with the new requirements of the building's thermal protection entered in Poland on January 1, 2014.The case study was carried out for multi-family building located in Poznan.Global cost method was compared with the more common indicators of economic evaluation Simple Pay Back Time (SPBT), and Net Present Value (NPV).

Analysis of the Model Application of Mechanical Equipment for Hydrothermal Treatment at Biogas Plant

The goal of the paper was to analyse model applications of mechanical equipment for hydrothermal treatment. Alternative 1 was an alternative with a treatment output of 14 500 Mg of processed material, the annual electricity and heat total production of 4000 MWh respectively 3800 MWh, total capital expenditure of 40 000 000 CZK, unit capital expenditure of 2759 CZK per 1 Mg of processed biodegradable material and annual operating expenses of 19 371 000 CZK. The net present value (NPV) is 1 061 000 CZK, the internal rate or return (IRR) totals 4.9%, the simple payback time (Ts) is 12.6 years and the discounted payback time (Tsd) is 19.2 years. Alternative 2 employing the mechanical equipment proved a potential increase in the treatment output to 18 125 Mg, and an increase in the electricity and heat total production to 5000 MWh respectively 4800 MWh, thanks to the shortened intensification of the anaerobic fermentation process. At the same time, the total capital expenditure rose to 43 000 000 CZK, the operating expenses rose to CZK 24 213 000. The unit capital expenditure of alternative 2 amounts to 2372 CZK per 1 Mg of the of processed biodegradable material. The NPV totals 8 329 000 CZK, IRR is at 6.7%, the simple payback time (Ts) is 10.8 years and Tsd totals 15.3 years.

Ultrasonic Treatment of Algae in a New Jersey Reservoir

A system of ultrasonic buoys was installed in the Canoe Brook Reservoir 1 in Short Hills, N.J., to assess the impact of the system on controlling algae and cyanobacteria in the reservoir. The four buoys operated for five months in spring/summer 2014. The results of the study indicated that the ultrasonic system was effective for controlling algae when the correct ultrasonic program was used. During the testing period, geosmin and methyl isoborneol concentrations were well controlled. Additionally, the average alum dose used by the plant was reduced by 22% compared with the same period in 2013, with improved dissolved air flotation effluent turbidity and combined filter effluent turbidity and an 83% increase in unit filter run volumes. An economic assessment showed the buoys saved approximately $87,800 in operational costs, with a projected simple payback time of 1.8 years for the system.

Thermal treatment of medical waste in a rotary kiln

This paper presents the results of a study of an experimental system with thermal treatment (incineration) of medical waste conducted at a large complex of hospital facilities. The studies were conducted for a period of one month. The processing system was analysed in terms of the energy, environmental and economic aspects. A rotary combustion chamber was designed and built with the strictly assumed length to inner diameter ratio of 4:1. In terms of energy, the temperature distribution was tested in the rotary kiln, secondary combustion (afterburner) chamber and heat recovery system. Calorific value of medical waste was 25.0 MJ/kg and the thermal efficiency of the entire system equalled 66.8%. Next, measurements of the pollutant emissions into the atmosphere were performed. Due to the nature of the disposed waste, particular attention was paid to the one-minute average values of carbon oxide and volatile organic compounds as well as hydrochloride, hydrogen fluoride, sulphur dioxide and total dust. Maximum content of non-oxidized organic compounds in slag and bottom ash were also verified during the analyses. The best rotary speed for the combustion chamber was selected to obtain proper afterburning of the bottom slag. Total organic carbon content was 2.9%. The test results were used to determine the basic economic indicators of the test system for evaluating the profitability of its construction. Simple payback time (SPB) for capital expenditures on the implementation of the project was 4 years.

A Comparative Study for Optimum Design of Grid Connected PV System based on Actual System Specifications

This paper presents a comparative study using new approach for optimum design of rooftop grid connected PV system installation on an institutional building at Minia University, Egypt. The new approach demonstrated in this paper based on optimal configuration of PV modules along with inverters according to not only MPP voltage range but also maximum DC input currents of the inverter. Five different brands of commercially available PV modules and inverters have been conducted in this study. Many different configurations of rooftop grid connected PV systems have been investigated and a comparative study among these configurations has been carried out taking into account PV modules and inverters specifications. Energy production aptitudes, cost of energy, simple payback time and GHG emissions have been appraised for each configuration using proposed MATLAB computer approach. Simulation results show that, annual energy production of about 258.8 MWh, COE of about 0.5482 $/kWh, payback period equal 6.95 years and total annual GHG emissions reduction of about 180.9 tons. General Terms Design, Programming, Solar Energy.

Exergy–economic evaluation of heat recovery device in mechanical ventilation system

The paper presents new approach in evaluation of heat recovery devices in mechanical ventilation system. The evaluation is based on exergy balance equation and economic analysis, what requires application of one of multicriteria decision aid methods—weighted sum method. The proposed set of evaluation criteria consists of: driving exergy, simple payback time and investment cost. The proposed method is applied to compare the four variants of heat recovery device in inlet-exhaust mechanical ventilation system of the capacity of 10,000m3/h installed in residential part of hotel. The analysis is performed for four preference models. The results of the multicriteria evaluation indicate that counter flow plate heat exchanger and the rotating heat/mass regenerator are better solutions comparing with water loop heat exchanger and heat pipe heat exchanger. Counter flow plate heat exchanger is the most compromise solution for the two preference models PREF_00 (based on statistic approach) and PREF_03 (investment cost priority preference model). Rotating heat/mass regenerator is the most compromise solution for the preference model 01 (driving exergy priority preference model). The proposed method can be helpful in the choice of the most compromise solution of the heat recovery device in pre-design phase.

AN EMPIRICAL ANALYSIS OF CORRELATION BETWEEN THE THICKNESS OF A THERMAL INSULATION LAYER OF THE FLOOR AND THE PAYBACK PERIOD

The article provides the correlation analysis between the thickness of a thermo-insulation layer of the typical floor-on-soil sample and its simple payback time in a traditional new construction single-apartment residential and net-zero energy building. The calculations were carried out on the energy efficiency class of the building and the geographic area of the construction. On the basis of the results, a simple payback time was calculated. The main aim – thermal transmittance coefficients of soil touching partitions must satisfy the normative value of technical construction regulation and European standards. The research object of the study is relationships between the thickness of a thermoinsulation layer of the typical floor-on-soil sample and its simple payback time. Lithuania was chosen as the geographic area of the research. Calculations were carried out for seven towns: Vilnius, Kaunas, Klaipeda, Siauliai, Panevezys, Utena, and Dukstas. The test result – developed correlation functions. Correlation analysis results are important not only for designers making decisions during the pre-design stage, but also for energy consumption auditors and experts.

Solar-LED alternatives to fuel-based Lighting for night fishing

Many of the 12 to 33million artisanal (“small scale”) fishers in the developing world work at night using energy-intensive kerosene lanterns to attract fish to their nets. In Tanzania—where 100,000 such fishers operate, spending US$70million per year on lighting—we identified current practices and conducted user-centered field tests of LED-based system usability, performance and energy savings potential, and estimated the market size for today's fuel-based lighting. Fishers in the areas we studied spend 35% to 50% of their take-home pay on lighting equipment and fuel. Due to the combination of higher intensity pressurized lanterns, and longer operating hours, Tanzanian fishers use as much lighting fuel as would about 1million ordinary household lanterns. We found that similar catches could be obtained with battery-powered LED lighting systems, with a simple payback time for the LED system investment of three to four months. The fishers we interviewed were almost universally pleased with the concept behind the lights used in the field tests, and eager to purchase them provided the right price and performance. However none of the LED systems we tested were adequate for this use. Essential product modifications include improved durability and performance in harsh fishing environments. Independent testing and certification would encourage product quality and support consumer confidence as they adopt these highly beneficial new technologies. Our results provide a roadmap for product manufacturers and others interested in deployment, with an overnight-conversion market size of US$17 to US$21million in Tanzania alone, plus US$6 to US$7million per year in ongoing replacement expenditures. This potential could well justify retooling and marketing investment on the part of lighting manufacturers.

Energetic and economic assessment of cogeneration plants: A comparative design and experimental condition study

In the present paper, the nominal design data and the experimental data of eleven industrial cogeneration power plants, based on different prime mover technologies and actually in operation in Italy, have been compared. The aim of the study is to compare the expected energetic and economic results with the real performance and economic profitability of the plants in operation: the analyses have highlighted that, in the design phase, the simple payback time is usually underestimated. An assessment of the European incentives policy on cogeneration has also been undertaken, focusing on Italian legislation, which foresees a tax reduction for fuel and Tradable White Certificate support mechanisms: these incentives allow an average SPB (Simple PayBack) reduction of about 15–20%. A sensitivity analysis on the SPB has also been performed, changing the fuel and maintenance costs, and the thermal and electrical energy prices, and the particular features of the different CHP (Combined Heat and Power) technologies have been pointed out.

Energy Audit of an Industrial Site: A Case Study

In order to reduce energy consumptions for sustainable and energy-efficient manufacturing, continuous energy audit and process tracking of industrial machines are essential. Compared to other non-residential buildings that have been widely researched, industrial buildings are generally characterized by larger thermal loads, ventilation losses and pollution control requirements. This paper presents the results of a preliminary energy audit carried out on 8 large industrial buildings of a famous car manufacturing holding in Italy. Energy demand for heating varied from 6 to just over 74 kWh/m3year among the buildings of the site. The energy audit enabled to build a specific factory energy model which has been used in order to analyze the impact of various energy saving actions on the primary energy consumptions of the site. It has been demonstrated that in this specific case the improvement of the building envelopes and the optimization of the performances of the existing HVAC systems can determine a reduction of gas consumption up to 15% per year with a predicted annual economic saving of the order of 100000 €; the total simple pay-back time of the proposed thermal retrofitting is evaluated to be less than 6 years

BUILDING THERMOMODERNIZATION AND REDUCING AIR POLLUTION

Abstract The present paper describes a technical-economic analysis of thermomodernization works in multifamily buildings and public utility facilities constructed with the use of both traditional and industrialized technologies (prefabricated large-panel concrete, Zeranska brick), built before 1990. 1441 buildings located in 7 towns were analysed. The energy consumption indicator of the buildings undergoing the analysis was the indicator of heat load demand per cubic capacity, which was established on the basis of site inspections and technical documentation. The obtained results were used in analysing the cost-effectiveness of the suggested thermomodernization works. The following were adopted as criteria of the investment effectiveness: the ‘Simple Pay Back Time’ (SPBT), reducing the amounts of particulate matter and sulphur dioxide polluting the air, and heat load saving (amounting to a few or even several megawatts, which, in the case of a small town, is often sufficient to cover a prospective increase in heat load demand).

Determination of annual heat losses from heat and steam pipeline networks and economic analysis of their thermomodernisation

The paper presents a method of evaluation and selective thermomodernisation of overhead thermal pipeline networks. The expression “thermomodernisation” is used for determination of all those activities that deal with improvement of heat insulation features of the pipelines under consideration. The method is particularly useful for extensive and complex heat or steam pipelines. A novel method for the determination of annual heat losses from overhead pipelines into the environment has been developed in the work. The heat losses from the pipelines are generated during the whole year. The proposed method is based on the concept of one-off examination of the pipeline under consideration by means of a thermovision camera, performed in existing weather conditions. An example of an analysis has been carried out and results are presented for an existing industrial pipeline network. In this analysis the whole pipeline network was divided into segments characterised by identical technical features. To determine the annual heat loss, the operation of the considered pipeline during the whole year in different meteorological conditions was simulated numerically. Next, economic factors were calculated for each pipeline segment. Generally, the selection of line segments recommended for thermomodernisation was done on the basis of heat losses and SPBT (simple pay-back time) calculations.

Energy performance assessment and a retrofit strategies in public school buildings in Rome

The aim of this paper is to assess the quality of public schools in Rome in order to create a good database as a first-step in defining possible intervention strategies to reduce energy consumption in this sector. The urgency is not only determined by the criticality of the current situation but also by the observation of how a very important voice of losses is related to inefficiencies in the management of buildings and plants that can be easily overcome with simple and low cost actions.The measures adopted to reduce consumption in school building sector were defined according to the dimensional, technological and architectural features of the schools. The analysis was performed by comparing the costs parameterized for standard retrofit interventions for the existing envelopes and plants to the benefits achievable by the interventions in terms of energy and money saving through a simple payback time analysis (PBT) useful to identify priorities for action. Finally, it has been estimated the environmental benefit achievable in 20 years through a spread action of refurbishment on plants and on envelopes.

Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers

The recent development of open-source 3-D printers makes scaling of distributed additive-based manufacturing of high-value objects technically feasible and offers the potential for widespread proliferation of mechatronics education and participation. These self-replicating rapid prototypers (RepRaps) can manufacture approximately half of their own parts from sequential fused deposition of polymer feedstocks. RepRaps have been demonstrated for conventional prototyping and engineering, customizing scientific equipment, and appropriate technology-related manufacturing for sustainable development. However, in order for this technology to proliferate like 2-D electronic printers have, it must be economically viable for a typical household. This study reports on the life-cycle economic analysis (LCEA) of RepRap technology for an average US household. A new low-cost RepRap is described and the costs of materials and time to construct it are quantified. The economic costs of a selection of 20 open-source printable designs (representing less than 0.02% of those available), are typical of products that a household might purchase, are quantified for print time, energy, and filament consumption and compared to low and high Internet market prices for similar products without shipping costs. The results show that even making the extremely conservative assumption that the household would only use the printer to make the selected 20 products a year the avoided purchase cost savings would range from about $300 to $2000/year. Assuming the 25h of necessary printing for the selected products is evenly distributed throughout the year these savings provide a simple payback time for the RepRap in 4months to 2years and provide an ROI between >200% and >40%. As both upgrades and the components that are most likely to wear out in the RepRap can be printed and thus the lifetime of the distributing manufacturing can be substantially increased the unavoidable conclusion from this study is that the RepRap is an economically attractive investment for the average US household already. It appears clear that as RepRaps improve in reliability, continue to decline in cost and both the number and assumed utility of open-source designs continues growing exponentially, open-source 3-D printers will become a mass-market mechatronic device.

Evolution of the U.S. energy service company industry: Market size and project performance from 1990–2008

The U.S. energy service company (ESCO) industry is an example of a private sector business model where energy savings are delivered to customers primarily through the use of performance-based contracts. This study was conceived as a snapshot of the ESCO industry prior to the economic slowdown and the introduction of federal stimulus funding mandated by enactment of the American Recovery and Reinvestment Act of 2009 (ARRA). This study utilizes two parallel analytic approaches to characterize ESCO industry and market trends in the U.S.: (1) a “top-down” approach involving a survey of individual ESCOs to estimate aggregate industry activity and (2) a “bottom-up” analysis of a database of ∼3250 projects (representing over $8B in project investment) that reports market trends including installed EE retrofit strategies, project installation costs and savings, project payback times, and benefit-cost ratios over time. Despite the onset of a severe economic recession, the U.S. ESCO industry managed to grow at about 7% per year between 2006 and 2008. ESCO industry revenues were about $4.1 billion in 2008 and ESCOs anticipate accelerated growth through 2011 (25% per year). We found that 2484 ESCO projects in our database generated ∼$4.0 billion ($2009) in net, direct economic benefits to their customers. We estimate that the ESCO project database includes about 20% of all U.S. ESCO market activity from 1990–2008. Assuming the net benefits per project are comparable for ESCO projects that are not included in the LBNL database, this would suggest that the ESCO industry has generated ∼$23 billion in net direct economic benefits for customers at projects installed between 1990 and 2008. There is empirical evidence confirming that the industry is evolving by installing more comprehensive and complex measures—including onsite generation and measures to address deferred maintenance—but this evolution has significant implications for customer project economics, especially at K-12 schools. We found that the median simple payback time has increased from 1.9 to 3.2 years in private sector projects since the early-to-mid 1990s and from 5.2 to 10.5 years in public sector projects for the same time period.

An aquifer thermal storage system in a Belgian hospital: Long-term experimental evaluation of energy and cost savings

Over a three years period, an aquifer thermal energy storage system was monitored in combination with a heat pump for heating and cooling of the ventilation air in a Belgian hospital. The installation was one of the first and largest ground source heat pump systems in Belgium. Groundwater flows and temperatures were monitored as well as the energy flows of the heat pumps and the energy demand of the building. The resulting energy balance of the building showed that the primary energy consumption of the heat pump system is 71% lower in comparison with a reference installation based on common gas-fired boilers and water cooling machines. This corresponds to a CO 2-reduction of 1280 ton over the whole measuring period. The overall seasonal performance factor (SPF) for heating was 5.9 while the ATES system delivered cooling at an efficiency factor of 26.1. Furthermore, the economic analysis showed an annual cost reduction of k€ 54 as compared to the reference installation, resulting in a simple payback time of 8.4 years, excluding subsidies.