A model for improving energy efficiency in industrial motor system using multicriteria analysis

In the last years, several policies have been proposed by governments and global institutions in order to improve the efficient use of energy in industries worldwide. However, projects in industrial motor systems require new approach, mainly in decision making area, considering the organizational barriers for energy efficiency. Despite the wide application, multicriteria methods remain unexplored in industrial motor systems until now. This paper proposes a multicriteria model using the PROMETHEE II method, with the aim of ranking alternatives for induction motors replacement. A comparative analysis of the model, applied to a Brazilian industry, has shown that multicriteria analysis presents better performance on energy saving as well as return on investments than single criterion. The paper strongly recommends the dissemination of multicriteria decision aiding as a policy to support the decision makers in industries and to improve energy efficiency in electric motor systems.     

Integrated procurement of pulpwood and energy wood from early thinnings using whole-tree bundling

To increase the volume of energy wood and pulpwood harvested from early thinnings, their procurement costs will have to be significantly reduced. This can be done through the integration of pulpwood and energy wood procurement applying a newly-developed supply chain based on whole-tree bundling. In 2007, the first prototype of the bundle harvester capable of incorporating compaction into the cutting phase was launched. Cost savings, especially in primary and secondary transportation, can be achieved by increasing the load sizes by replacing undelimbed whole trees with bundles. The bundles can be hauled by a standard forwarder to the roadside storage area, from where they are transported by a standard timber truck to the pulp mill. Batches of bundles are then fed into a wood flow consisting of conventional delimbed pulpwood. Separation of the bundles into pulpwood and energy wood fractions does not take place until the wood reaches the debarking drum.In this feasibility study, the required productivity level of bundle harvesting (i.e., cutting and bundling) in Scots pine-dominated stands was assessed by comparing the total supply chain costs based on whole-tree bundling with those of the other pulpwood and energy wood supply chains by means of system analysis. The cost calculations indicated that whole-tree bundling enables the procurement costs to be reduced to below the current cost level of separate pulpwood and energy wood procurement in early thinnings. The greatest cost-saving potential lies in small-diameter (d_1.3 = 7-10 cm) first-thinning stands, which are currently unprofitable for conventional pulpwood procurement.     

Modeling stump biomass of stands using harvester measurements for adaptive energy wood procurement systems

The value and volumes of industrial stump fuel supply are increasing for energy production. Accurate estimates of aboveground and belowground biomass of trees are important when estimating the potential of stumps as a bioenergy source. In this study two stump biomass equations were adapted and tested using them as calibrated stump biomass models computed as the cumulative sum by a local stand. In addition, variables derived from stem measurements of the forest harvester data were examined to predict stump biomass of a stand by applying regression analysis. The true stump yield (dry weight) was used as the reference data in the study. Both biomass models performed well (adjusted R² ˜ 0.84) and no advance was found in using other stem dimensions as independent variables in the model. The stand-level model can be used in innovative stump biomass prediction tools for increasing efficiency of energy wood procurement planning to stands within a certain area. In practice, wood procurement managers would need to adapt developed system and decide whether the degree of accuracy/precision provided by the models is acceptable in their local stand harvesting conditions.     

Prioritizing the weights of hydrogen energy technologies in the sector of the hydrogen economy by using a fuzzy AHP approach

KIER, government supported research institute, establishes a long-term strategic energy technology development roadmap essentially with selection and specialization of energy technology R&D and for Korea's national security. In this paper, we establish a strategic hydrogen energy technology roadmap taking economic impact, commercial potential, inner capacity, and technical spin-off into account. We suggest a methodology to prioritize the relative weights of hydrogen energy technologies of hydrogen energy technology roadmap (ETRM) as we allocate R&D budget effectively using a fuzzy analytic hierarchy process (AHP), which reflects the vagueness of human thoughts instead of crisp numbers efficiently. In the sector of the hydrogen ETRM which is composed of 6 hydrogen energy technologies, PEMFC technology is the most preferred and technology (0.29), followed by DEFC tech (0.28), SOFC tech (0.24), Hydrogen separation & storage tech (0.10), and Hydrogen production tech (0.09).     

Integrated harvesting of energy wood and pulpwood in first thinnings using the two-pile cutting method

In order to increase the harvesting volumes of energy wood and pulpwood from first thinnings, harvesting costs have to be reduced significantly. Metsäteho Oy studied the integrated harvesting of pulpwood and energy wood based on a two-pile method, where industrial roundwood (pulpwood) and energy wood fractions are stacked into two separate piles when cutting a first-thinning stand. The productivity and cost levels of the integrated, two-pile cutting method were determined, and the harvesting costs of the two-pile method were compared with those of conventional separate wood harvesting methods.In the time studies, when the size of removal was 50 dm³, the productivity in conventional whole-tree cutting was 6% higher than in integrated cutting. With a stem size of 100 dm³, the productivity of whole-tree cutting was 7% higher than in integrated cutting. The results indicated, however, that integrated harvesting based on the two-pile cutting method enables harvesting costs to be decreased to below the current cost level of separate pulpwood harvesting in first-thinning stands. The greatest cost-saving potential lies in small-sized (d_1.3 = 7-11 cm) first thinnings. The costs of forest haulage after integrated pulpwood and energy wood cutting were higher than those of separate wood harvesting because of lower removals in integrated harvesting. The results showed that when integrated wood harvesting is based on the two-pile cutting method, the removals of both energy wood and pulpwood should be more than 20-25 m³ ha⁻¹ at the integrated harvesting sites in order to achieve economically viable integrated procurement.     

Supply chain cost analysis of long-distance transportation of energy wood in Finland

The increasing use of bioenergy has resulted in a growing demand for long-distance transportation of energy wood. For both biofuels and traditional forest products, the importance of energy efficiency and rail use is growing. A GIS-based model for energy wood supply chains was created and used to simulate the costs for several supply chains in a study area in eastern Finland. Cost curves of ten supply chains for logging residues and full trees based on roadside, terminal and end-facility chipping were analyzed. The average procurement costs from forest to roadside storage were included. Railway transportation was compared to the most commonly used truck transportation options in long-distance transport. The potential for the development of supply chains was analyzed using a sensitivity analysis of 11 modified supply chain scenarios.For distances shorter than 60 km, truck transportation of loose residues and end-facility comminution was the most cost-competitive chain. Over longer distances, roadside chipping with chip truck transportation was the most cost-efficient option. When the transportation distance went from 135 to 165 km, depending on the fuel source, train-based transportation offered the lowest costs. The most cost-competitive alternative for long-distance transport included a combination of roadside chipping, truck transportation to the terminal and train transportation to the plant. Due to the low payload, the energy wood bundle chain with train transportation was not cost-competitive. Reduction of maximum truck weight increased the relative competitiveness of loose residue chains and train-based transportation, while reduction of fuel moisture increased competitiveness, especially of chip trucks.     

Thermodynamic analysis of a novel energy storage system with carbon dioxide as working fluid

Recently, energy storage system (ESS) with carbon dioxide (CO₂) as working fluid has been proposed as a new method to deal with the application restrictions of Compressed Air Energy Storage (CAES) technology, such as dependence on geological formations and low energy storage density. A novel ESS named as Compressed CO₂ Energy Storage (CCES) based on transcritical CO₂ Brayton cycle is presented in this paper. The working principle of CCES system is introduced and thermodynamic model is established to assess the system performance. Parametric analysis is carried out to study the effect of some key parameters on system performance. Results show that the increase of turbine efficiency is more favorable for system optimization and the effect of minimum pressures on system performance is more significant compared with maximum pressures. A simple comparison of CCES system, liquid CO₂ system and Advanced Adiabatic Compressed Air Energy Storage (AA-CAES) system is conducted. It is shown that the system efficiency of CCES is lower than that of AA-CAES system but 4.05% higher than that of liquid CO₂ system, while the energy density of CCES system is 2.8 times the value of AA-CAES system, which makes CCES a novel ESS with potential application.     

Soft-linking energy systems and GIS models to investigate spatial hydrogen infrastructure development in a low-carbon UK energy system

This paper describes an innovative modelling approach focusing on linking spatial (GIS) modelling of hydrogen (H₂) supply, demands and infrastructures, anchored within a economy-wide energy systems model (MARKAL). The UK government is legislating a groundbreaking climate change mitigation target for a 60% CO₂ reduction by 2050, and has identified H₂ infrastructures and technologies as potentially playing a major role, notably in the transport sector. An exploratory set of linked GIS–MARKAL model scenarios generate a range of nuanced insights including spatial matching of supply and demand for optimal zero-carbon H₂ deployment, a crucial finding on successive clustering of demand centres to enable economies of scale in H₂ supply and distribution, the competitiveness of imported liquid H₂ and of liquid H₂ distribution, and sectoral competition for coal with carbon sequestration between electricity and H₂ production under economy-wide CO₂ constraints.     

Productivity and cost of mechanized energy wood harvesting in Northern Scotland

At present, the utilization of timber in the Northern part of the Scottish Highlands is low due to a lack of a wood utilizing industry. As a consequence, the majority of forest owners do not receive any income from timber and in some cases stumpage prices can even be negative. At the same time, increasing prices of oil, gas and electricity pose a great challenge for local industries and homeowners. The establishment of wood fueled heating systems is therefore expected to improve the situation and at the same time create a market for the local timber resources. Consequently, a local energy source to produce heat and electricity at a competitive price would have positive benefits for both local industries and forest owners. Due to the current lack of competition, roundwood could be chipped for fuel, which has many associated benefits compared to the harvesting and chipping of logging residues. It is the aim of this research to apply existing Finnish know-how in regards to wood fuel harvesting in order to develop and investigate the price level of sustainable and local wood fuel supply chains.To determine the most suitable supply chain for forest fuels, various research methods were applied. An estimation of the forest resources in the Wick area was the first step of the research. The different cost components of the supply chain such as cutting, forwarding and chipping were then calculated based on Finnish experiences and adapted to conditions in Northern Scotland. Detailed transportation distance calculations and cost of transportation were calculated using GIS tools.Of the various supply chain designs considered, chipping at the landing seems to be the most suitable option. Chipping the roundwood at a central terminal would also be feasible; however, a suitable site would have to be identified since chipping of the material at the heating plant is not an option. Calculations indicate that forest chips can be delivered starting from approximately 20 € MWh⁻¹ within a 50 km transportation distance when chipping is at roadside. If the transportation distance is 100 km wood chips could be delivered at approximately 23 € MWh⁻¹. Results from the GIS analysis indicate that a sufficient supply of raw material will be available in the future. According to these calculations forest fuels can be a competitive energy source for heat and electricity production in Northern Scotland.     

A comparative analysis for multiattribute selection among renewable energy alternatives using fuzzy axiomatic design and fuzzy analytic hierarchy process

Renewable energy is the energy generated from natural resources such as sunlight, wind, rain, tides and geothermal heat which are renewable. Energy resources are very important in perspective of economics and politics for all countries. Hence, the selection of the best alternative for any country takes an important role for energy investments. Among decision-making methodologies, axiomatic design (AD) and analytic hierarchy process (AHP) are often used in the literature. The fuzzy set theory is a powerful tool to treat the uncertainty in case of incomplete or vague information. In this paper, fuzzy multicriteria decision- making methodologies are suggested for the selection among renewable energy alternatives. The first methodology is based on the AHP which allows the evaluation scores from experts to be linguistic expressions, crisp, or fuzzy numbers, while the second is based on AD principles under fuzziness which evaluates the alternatives under objective or subjective criteria with respect to the functional requirements obtained from experts. The originality of the paper comes from the fuzzy AD application to the selection of the best renewable energy alternative and the comparison with fuzzy AHP. In the application of the proposed methodologies the most appropriate renewable energy alternative is determined for Turkey.     

Multi-criteria fuzzy algorithm for energy management of a domestic photovoltaic panel

This paper presents a fuzzy algorithm which makes decision so as to connect domestic apparatus on either the electrical grid or a photovoltaic panel (PVP). The decision is made in real time with respect to multi-energy save criteria and upon the PVP maximum available power and apparatus states. The algorithm is validated on a 1 kW peak (kWp) PVP and domicile apparatus of different powers installed at the Energy and Thermal Research Centre (CRTEn) in the north of Tunisia. Criteria are verified on the system behaviour during days covering the different seasons of the year. The power audit, established using measures, confirms that the energy save during daylight reaches 90% of the PVP available energy.     

A combined methodology based on Z-fuzzy numbers for sustainability assessment of hydrogen energy storage systems

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Evaluating and ranking energy performance of office buildings using Grey relational analysis

Traditional methods of evaluating energy performance of building tend to focus on comparing the observed energy consumption with the average value of energy consumption by regression method or theoretical value calculated by simulation analysis. For evaluating and ranking the energy performance of buildings, this paper proposed a perspective of multiple objective outputs to evaluate the energy performance of buildings and then use a multiple attribute decision-making approach, Grey relational analysis (GRA), to rank the evaluated buildings. The energy performance of 47 office buildings in Taiwan were evaluated and ranked to serve as a case study to illustrate the procedure and effectiveness of the proposed approach.     

Carbon and footprint-constrained energy planning using cascade analysis technique

This work presents algebraic targeting techniques for energy sector planning with carbon (CO₂) emission and land availability constraints. In general, it is desirable to maximize the use of low- or zero-carbon energy sources to reduce CO₂ emission. However, such technologies are either more expensive (as with renewable energy) or more controversial (as in the case of nuclear energy or carbon capture and storage) than conventional fossil fuels. Thus, in many energy planning scenarios, there is some interest in identifying the minimum amount of low- or zero-carbon energy sources needed to meet the national or regional energy demand while maintaining the CO₂ emission limits. Via the targeting step of pinch analysis, that quantity can be identified. Besides, another related problem involves the energy planning of biofuel systems in view of land availability constraints, which arises when agricultural resources need to be used for both food and energy production. Algebraic targeting approach of cascade analysis technique that was originally developed for resource conservation network is extended to determine targets or benchmarks for both of these problems.     

Improving energy use efficiency of canola production using data envelopment analysis (DEA) approach

In this study energy use pattern for canola production in Golestan province of Iran was studied and the degrees of technical and scale efficiency of producers were analyzed using a non-parametric data envelopment analysis technique. The study also helped to identify the wasteful uses of energy by inefficient farmers and to suggest reasonable savings in energy uses from different inputs. Further, the effect of optimization of energy on energy ratio and energy productivity was investigated. Data used in this study were obtained from 130 randomly selected canola farms from Golestan, the most important center of canola production in Iran. The inputs were human labor, diesel, machinery, fertilizers, chemicals, water for irrigation, seeds and electrical energies; while the yield value of canola was considered as output. The results revealed that, the total energy of 17,786 MJ ha⁻¹ was consumed for canola production; about 15% of farmers were found to be technically efficient and the mean efficiency of farmers was found to be 0.74 and 0.88 under constant and variable returns to scale assumptions, respectively. The results also suggested that, on average, a potential 9.5% (1696 MJ ha⁻¹) reduction in total energy input could be achieved provided that all farmers operated efficiently.     

Dynamic and energy analysis of a liquid piston hydrogen compressor

Liquid piston compressor is the most promising compressor to be used for hydrogen-refueling stations. However, their energy transfer and the energy dissipation processes of are poorly studied and not well understood. In this paper, a new energy analysis method for an ionic-liquid type liquid piston compressor is proposed. In the compressor section, porous media is used to promote heat transfer from the hydraulic oil during the compression process. A mathematical model has been formulated considering the heat transfer and damping effects of the porous media on the compressor performance. Moreover, the compressibility of the hydraulic oil and its overflow loss on the compressor performance were also established. In the model, the seven stages of the entire working cycle of the compressor were look into in detail, alongside with its energy efficiency. The results show that the key parameters governing the energy efficiency of the compressor are the heat transfer efficiency of the compressor and the overflow losses of the hydraulic oil.     

Systems interactions analysis for the energy efficiency improvement of a Kraft process

Several techniques are available to improve the energy performance of a process (internal heat recovery, water reutilization, condensates return, energy upgrading and conversion, elimination of non-isothermal mixing). They are applied to specific energy systems on the utility or process side (steam production and distribution, hot or cold water networks, process heat sources and sinks). Since those systems are interconnected, actions taken on one of them may have effects on another. These effects can be positive (synergies) or negative (counter-actions). A systematic, stepwise methodology has been developed to ensure that synergies are exploited and counter-actions avoided, and is presented. It has been validated by application to an existing Kraft pulping mill. Key performance indicators and the evolution of the thermal composite curves were used to monitor progress as the successive steps of the methodology were implemented. It was found that the combined direct and indirect effects of water reutilization constituted the most important source of potential energy savings. Water reutilization also reduced the need for additional purchased heat exchanger area. Overall, the water intake by the mill could be reduced by 33% and steam savings could be 26% of current production. This would liberate sufficient steam production capacity for the installation of a 44.4 MW cogeneration unit.     

Optimum energy management of a photovoltaic water pumping system

This paper presents a new management approach which makes decision on the optimum connection times of the elements of a photovoltaic water pumping installation: battery, water pump and photovoltaic panel. The decision is made by fuzzy rules considering the battery safety on the first hand and the Photovoltaic Panel Generation (PVPG) forecast during a considered day and the load required power on the second hand. The optimization approach consists of the extension of the operation time of the water pump with respects to multi objective management criteria. Compared to the stand alone management method, the new approach effectiveness is confirmed by the extension of the pumping period for more than 5 h a day.     

Use of multi-criteria decision analysis to explore alternative domestic energy and electricity policy scenarios in an Irish city-region

In this paper, multi-criteria decision analysis (MCDA) was used to assess 6 policy measures or scenarios relating to residential heating energy and domestic electricity consumption, using an Irish city-region as case study. The analysis was undertaken using a modified version of MCDA based on the NAIADE (Novel Approach to Imprecise Assessment and Decision Environments) software and involved a decision output based on a mix of qualitative and quantitative assessment, which offered a ranking of options. It was concluded that Scenario 2, which proposes reducing energy and electricity consumption, was the most preferable option and Scenario 3, which proposes increasing the contribution of wood waste, was the least preferable option. This suggests that absolute reduction and demand management should be prioritised over fuel substitution or renewable energy technologies.