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Comparison of energy efficiency assessment methods: Case Bio-SNG process
Abstract
The goal of biofuel production is to partially replace fossil fuels in energy generation and transport. For the evaluation of biofuel production processes different criteria are applied and usually they include costs, efficiency aspects and emissions. However, evaluation of the energy efficiency of biofuels production is difficult since no general standard method exists for that. This paper compares three different assessment methods of energy efficiency both qualitatively and quantitatively. The methods are: thermal efficiency, exergy analysis and primary energy analysis. The feasibility of the methods is tested on a Bio-SNG (synthetic natural gas) production process which was modelled in AspenPlus and MS Excel. The results show that the exergy analysis seems to be advantageous when it comes to detailed (sub-) process analysis whereas the primary energy analysis offers the advantage of showing how the system is influencing the global primary energy resources. The results obtained by the thermal efficiency analysis do not add any new information to the results obtained by exergy and primary energy analyses. Exergy and primary energy analyses should be the preferred means for process assessment. Especially a combination of the two methods could offer the chance to develop a more holistic energy efficiency indicator.
... Thus PEE is a valuable tool comparing efficiencies of a same product that has been produced with different production chains, because PEE can compare the amount of primary energy the overall chain has consumed. PEE has been applied in analyzing end-user or building energy efficiency, but it has also been applied to multi-product applications (Kohl et al., 2013) and (Kohl et al., 2014). In Kohl et al. (2014) three different energy indicators (exergy, energy, PEE) are compared and the clear conclusions is that exergy analysis seems to be advantageous when it comes to detailed (sub-) process analysis whereas the primary energy analysis offers the advantage of showing how the system is influencing the global primary energy resources. ...
... PEE has been applied in analyzing end-user or building energy efficiency, but it has also been applied to multi-product applications (Kohl et al., 2013) and (Kohl et al., 2014). In Kohl et al. (2014) three different energy indicators (exergy, energy, PEE) are compared and the clear conclusions is that exergy analysis seems to be advantageous when it comes to detailed (sub-) process analysis whereas the primary energy analysis offers the advantage of showing how the system is influencing the global primary energy resources. Another conclusion from the work is that a combination of PEE and exergy could offer a more holistic energy efficiency indicator. ...
... Individually PEE does not work well inside production processes especially because the factors are calculated only for products of interest as was concluded in Kohl et al. (2014). Inside a process also different semi-products typically exist and these products dont have any factors available. ...
Improving energetic performance is a key factor in making societies more sustainable. One way to analyze energetic performance is to use methods based on the second law of thermodynamics. Exergy analysis is such a method. With exergy analysis thermodynamic losses of the studied system can be found. For a specific process decreasing the exergy losses decreases the need for exergy inputs and production costs. Exergy analysis can also be used to analyze the life cycle of a process or product, but then it is necessary to model the total production system. For this reason, it is important to have efficiency analysis methods that can simultaneously analyze the studied system or process and the surrounding environment around this system. The objective of this article is to present such a method where the whole energy chain needs not to be modeled, but still the effect of an energy improvement or change in a studied process can be analyzed with respect to the whole energy chain. This method is called PeXa and it combines exergy analysis and primary energy analysis. In this work we show that also the system environment affects the benefit of exergy savings in the system level depending what production does this exergy saving replace. A district heating (DH) network with different DH producing units having different exergy efficiencies is used to show the concept. It is shown that in some cases basic exergy analysis and PeXa will give different results assuming that the objective is to consider the primary energy effects of society. By considering this broader concept of environment in exergy analysis companies and societies can direct limited resources into investments that maximize primary exergy savings.
... The production and use of Bio-SNG is an alternative to nonrenewable fuels [22][23][24] . In addition, Brazil, in 2013 had sales of around 76 million tons of municipal solid waste and in the previous year produced 62 million tons 25 . ...
... In addition, Brazil, in 2013 had sales of around 76 million tons of municipal solid waste and in the previous year produced 62 million tons 25 . The country is also considered the world's largest producer of charcoal and sugarcane, second in soybean production and eighth in rice production 26 and tend to provide large amounts of waste that may be intended for the gasification and digestion 24 . The implementation of the Bio-SNG production and the stimulus for the production of biogas via anaerobic digestion can promote increased production of methane. ...
... The thermochemical process of biomass (gasification) used for the production of Bio-SNG is a promising procedure in which a series of reactions convert carbonaceous materials into gaseous fuel 24 . This technology is attractive mainly for cogeneration plants with small scale, with a power output of less than 10 MW. ...
The production of biofuels can be used in order to partially replace fossil fuels in power generation, transportation, and reducing emissions of greenhouse gases. So there is really an efficiency in the process, it is necessary to examine the deployment scenarios, checking the demand for such energy vector. In this regard, the synthetic gas from biomass (Bio-SNG) appears with a premise in terms of bio-methane generation, as well as heat and electricity. The potential energy production via the Bio-SNG production is above the primary anaerobic digestion of methane, for use in a wide range of lignocellulosic biomasses for its production, incorporating somewhat different raw materials used in energy generation. The current case study tends to demonstrate the importance of introducing this technology in Brazil, combining political and energy terms with the effective demand in the near future. © 2015, World Food Ltd. and WFL Publishers. All rights reserved.
... The challenge to overcome these mentioned difficulties are made by combining methods, the research provides a comprehensive energy assessment of production systems through the measurement of energy sustainability and the comparison of these results in terms of the scenarios before and after the changes. The relationship between LCA-based methods and energy-related assessment methods (Kohl et al., 2014) is becoming an interesting concern in energy evaluation, but requires the overcoming of certain limitations when it comes to measuring and monitoring energy sustainability performance of various functional units in the application of these methods separately (Datkov & Effenberger, 2010;Lorenzo-Toja et al., 2014. Some of the limitations that should be highlighted are, e.g.: (1) behavioral and procedural bias due to human`s measurement errors during performing energy audits (Weber & Borcherding, 1993); (2) the lack of consistency in selection of system boundary, leading to incorrect interpretations and comparisons during making decision, even using the criteria listed in ISO 14041 (Raynolds et al., 2000); (3) different data sources, their quality (Grabowski et al., 2015) and uncertainty in describing the results of the LCA-based studies (Finnveden, 2000;ISO 14044, 2006;Ciroth et al., 2016); (4) controversial methodological assumptions e.g. with regard to time aspects (Finnveden, 2000) as well as through applying procedures (Finkbeiner, 2009); (5) the use of various functional units that complicate decision making; (6) the exclusion of social impacts which might be influential to the potential of the results (UNEP/ SETAC., 2009;Guinée, 2016). ...
... The use of assessment methods for sustainability which pre-date the pre-Brundtland era are mostly established based on environmental considerations, such as resource consumption, the air emissions of hazardous substances, and their impact (Granovski et al., 2007;Rusinko, 2007). The energy efficiency evaluation methods (Azadeh et al., 2007;Kohl et al., 2014;Kluczek & Olszewski, 2017) focus on practical possibilities for profitable energy efficiency improvements and on theoretical sustainability assessment (Singh et al., 2012), which are feasible but not well represented in production systems. Most methods that are based on common LCA 5 are employed in order to provide quantitative measures concerning the environmental and economic challenges of evaluating sustainable manufacturing (Da Silva & Amaral, 2009;Petrillo et al., 2016). ...
Warsaw University of Technology (WUT) is the biggest technological university in Poland. WUT has since educated many successive generations of engineers, thereby making a significant contribution to the advancement of science and technology both in Poland and in the world. Over 500 professors deliver education to almost 31,000 students. The Faculty of Production Engineering (FPE) is one of the 19 faculties of WUT. This chapter presents the results of that Faculty, from nineteen survey respondents. The main focus of the university is put on economic issues, followed by cross-cutting themes, then environmental issues, and social issues. The faculty contribution is medium and the strength is medium. The ranking of the competences shows that Inter-disciplinary work is the highest, followed by Systems thinking and Anticipatory thinking. The ranking of the pedagogical approaches resulted in Lecturing and Project- or Problem-based learning were the highest, followed by Supply chain/Life cycle analysis. The correlation showed that Mind and concept maps, Participatory Action Research, Case studies, and Supply chain/Life cycle analysis developed the most competences. The competences most developed were Personal involvement, Communication and use of media, and Empathy and change of perspective. The results show that there is a wide divergence between the issues of each dimension. The commitment of WUT faculty and educators needs to foster a transformation in teaching to enhance the learning process in sustainability.
... The challenge to overcome these mentioned difficulties are made by combining methods, the research provides a comprehensive energy assessment of production systems through the measurement of energy sustainability and the comparison of these results in terms of the scenarios before and after the changes. The relationship between LCAbased methods and energy-related assessment methods (Kohl et al., 2014) is becoming an interesting concern in energy evaluation, but requires the overcoming of certain limitations when it comes to measuring and monitoring energy sustainability performance of various functional units in the application of these methods separately (Datkov and Effenberger, 2010;Lorenzo-Toja et al., 2014;Azapagic et al., 2016). Some of the limitations that should be highlighted are, e.g.: (1) behavioral and procedural bias due to human's measurement errors during performing energy audits (Weber and Borcherding, 1993); (2) the lack of consistency in selection of system boundary, leading to incorrect interpretations and comparisons during making decision, even using the criteria listed in ISO 14041 (Raynolds et al., 2000); (3) different data sources, their quality (Grabowski et al., 2015) and uncertainty in describing the results of the LCA-based studies (Finnveden, 2000;ISO 14044, 2006;Ciroth et al., 2016); (4) controversial methodological assumptions e.g. with regard to time aspects (Finnveden, 2000) as well as through applying procedures (Finkbeiner, 2009); (5) the use of various functional units that complicate decision making; (6) the exclusion of social impacts which might be influential to the potential of the results (UNEP/SETAC., 2009;Guinée, 2016). ...
... The use of assessment methods for sustainability which pre-date the pre-Brundtland era are mostly established based on environmental considerations, such as resource consumption, the air emissions of hazardous substances, and their impact (Granovski et al., 2007;Rusinko, 2007). The energy efficiency evaluation methods (Azadeh et al., 2007;Kohl et al., 2014;Kluczek and Olszewski, 2017) focus on practical possibilities for profitable energy efficiency improvements and on theoretical sustainability assessment (Singh et al., 2012), which are feasible but not well represented in production systems. Most methods that are based on common LCA 4 are employed in order to provide quantitative measures concerning the environmental and economic challenges of evaluating sustainable manufacturing (Da Silva and Amaral, 2009;Petrillo et al., 2016). ...
Currently growing concerns about energy efficiency and sustainability across the manufacturing sector have spurred researchers to spend their efforts on improving energy efficiency. A recent study on sustainability assessment does not provide any real measurement linkages between energy matters and sustainability dimensions at the plant level. Simultaneously, a few papers that deal with technologies, not taking the sustainability associated with optimized energy intensity as a whole into account, still attempt to include LCA-based methods into the integrated sustainability methods. Thus, an energy-led approach for sustainability assessment is adopted using all-in-one methodology: SBM-DEA + energy LCA-LCC-SLCA. In accordance with the goal of the article, this approach will be performed by improving the energy efficiency of twelve production systems. This sustainability-oriented methodology is presented in the form of relative, aggregated sustainability indicators for production systems, I ESUS, comparing quantitatively two scenarios: a baseline and a future scenario. The overall results in sustainability terms show, that improving the energy efficiency of production systems contributes significantly to energy sustainability. For the improvement scenario, the indicator amounts to I ESUS = (2.565; 2.475; 2.264)compared with I ESUS = (1.450; 2.937; 2.368)as baseline. This sustainable-oriented methodology will enable the implementation of a suitable performance measurement tool for supporting industrial energy policy-makers. If followed, the approach will allow for the improvement of energy-intensive manufacturer-dependent performance, guiding it towards energy sustainability. The robustness of the results is guaranteed by a sensitivity analysis.
... Despite this, the application of RDF as the main fuel resource in polygeneration DHC systems with SNG generation is not well-documented in the literature. Related investigations have essentially employed wood and wood-derived biomass resources [12][13][14]22,23] and organic residues [7]. Air-steam gasification has been identified as an appropriate technology for RDF upgrading. ...
... Polygeneration applied to DHC systems often involves diversification of fuel resources and products through the application of suitable technologies. A number of products can be produced in DHC systems: ethanol [3,6] and other biofuels [7][8][9][10][11], chemicals (i.e., ammonia and olefins) [7], fertilizers [11], biogas [10] and synthetic natural gas (SNG) [7,[12][13][14]. SNG emerges as a suitable product to be associated to a polygeneration DHC system. ...
Nowadays conventional district heating and cooling (DHC) systems face the challenge of reducing fossil fuel dependency while maintaining profitability. To address these issues, this study examines the possibility of retrofitting DHC systems with refuse-derived fuel (RDF) gasifiers and gas upgrading equipment. A novel system is proposed based on the modification of an existing DHC system. Thermodynamic and economic models were established to allow for a parametric analysis of key parameters. The study revealed that such an upgrade is both feasible and economically viable. In the basic scenario, the retrofitted DHC system can simultaneously produce 60.3 GWh/year of heat, 65.1 GWh/year of cold, 33.2 GWh/year of electricity and 789.5 tons/year of synthetic natural gas. A significant part of the heat load can be generated from the waste heat of the upgrading equipment. The investment in retrofitting the polygeneration DHC system presents a payback period of 3 years.
... In this zone, the temperature is not high enough to cause the decomposition of volatile matter. The temperature in this zone is approximately 100-200 °C [8]. The temperature range in the drying zone will depend on the fuel types. ...
This study aims to develop, test performance, and evaluate the environmental pollution of garbage fuel with gasification technology. Heat conduction from municipal solid waste (MSW) burning from the gasification process was studied to dispose of solid waste and produce energy for communities. There were four types of solid waste in the total amount of 5 kg (including 0.5 kg of charcoal and firewood, 1.5 kg of paper, 2.0 kg of leaf litter, 0.5 kg of plastic, and 0.5 kg of others) with 2 tested ranges of average humidity: 10–20% and 50–55%. It was found that all waste could be converted for gas production with different gas amounts. From the experiment, dried MSW with 10–15% moisture content produced synthesis gas compositions (mole percent) that were H2, CO2, N2, O2, and CH4 at 1.9–2.4, 1.8–3.2, 56.5–60.2, 3.4–4.6, and 1.2–1.6, respectively. When fuel gas composition at the equivalent ratio between 0.2–0.34 was obtained from the MSW burning test with 10–15% average humidity, MSW burning in various equivalent ratios resulted in different amounts of synthesis gas. In addition, the optimal amounts of CH4 and the heating value of the gas were in the equivalent ratio of 0.28, and the highest production efficiency of synthetic gas (ηg) was 33.46%.
... However, this technique has resulted in high water consumption and severe water pollution (Emrah et al. 2016). As a contrast, an alternative technique, which is characterized by normal operating temperature, open width and continuous type, has received much concern from researchers (Nunes et al. 2015;Kohl et al. 2014). The existing conventional dyeing process is roughly divided into three stages: pretreatment, dyeing, and finishing (Erhan and Burcu 2011). ...
To reduce pollution in cotton knitted fabric production, this study aimed at developing a novel open width and continuous pretreatment process combining plasma, padding, and enzyme washing etc. In this process, plasma destroyed oily and waxy structures, padding provided the same functions of scouring and polishing, and enzyme washing gave deoxidization. Compared with conventional one bath alkali peroxide pretreatment process in pilot experiments, the quality of products from the novel pretreatment process is higher. The superiority was attributed to not generating microfibers on the surfaces of the products, integrity of the fiber microstructure of the products, and effective removal of oils and waxes. Water consumption is only 26.4% of that used in the conventional one-bath pretreatment. Also, pollutant production is reduced; chemical oxygen demand (CODCr), total nitrogen (TN), ammonia nitrogen (NH3–N), and total phosphorus (TP) of the developed process are lower by 73.18%, 87.09%, 60.64% and 60.81% respectively, because high pretreatment efficiency of novel process leads to a lower need for water and auxiliaries.
... The implementation of energy efficiency is a powerful and costeffective way of meeting the targets of sustainable development and lowering fossil fuel dependency. Different methodologies and quantitative models have been proposed for assessing energy efficiency [20,21] and each country relies on different energy efficiency indexes, taking into account the factors influencing energy efficiency on the national level [22]. Generally, improvements in energy efficiency can be promoted by both technological innovation and consumption share adjustment [23,24]. ...
The reduction of energy demand and greenhouse gases (GHG) emissions is a main target of the chemical industry. By implementing Best Practice Technologies (BPTs) (i.e. the most advanced technologies currently in use at industrial scale) as well as by implementing recycling and energy recovery strategies through cogeneration and process intensification, consistent energy savings and CO2 emissions reduction can be achieved in the short to medium term. Long-term additional cuts may arise from development and deployment of “game changer” technologies, that re-invent the way some large-volume chemicals are made. Although still far from commercial maturity and still facing high economic and technical hurdles, switching to the use of non-food biomass as fuel and feedstock in the chemical industry may represent a suitable option. During the transition towards a more energy efficient chemistry, the environmental performance of bio-based products need to be carefully evaluated on a case-by-case basis. In this study, an overview of energy improvement options is provided and the different patterns of bioethanol as fuel to generate energy or as platform chemical to generate chemical derivatives are compared as a case study within a life cycle perspective. The consequences on the environmental sustainability of the chemical industry are envisaged.
... Bio-SNG production follows a deterministic model from data by Kohl et al. [21]: electricity input, biomass input and SNG output are linearly dependent on plant heat output P in;SNG;p ¼ 0:1418 Q DH;SNG;p (18) ...
... Model framework based on DPSR In 1993, OECD proposed the DPSIR model through the revision of the PSR model and the DSR model. The PSR model was proposed by Canadian scholars David J. Rapport and Tony Friend (Kohl et al. 2014), which the basic idea is that human activities exert pressure on the environment and resources which can change the environment quality and the quantity of resources, then the society responds to these changes by policies or measures to alleviate the pressure in order to achieve sustainable development. The model uses the Breason-state-response^to represent the causal and intercoordinated control relationships among indexes. ...
The reasonable evaluation of the enterprise energy efficiency is an important work in order to reduce the energy consumption. In this paper, an effective energy efficiency evaluation index system is proposed based on DPSR (Driving forces-Pressure-State-Response) with the consideration of the actual situation of enterprises. This index system which covers multi-dimensional indexes of the enterprise energy efficiency can reveal the complete causal chain which includes the “driver forces” and “pressure” of the enterprise energy efficiency “state” caused by the internal and external environment, and the ultimate enterprise energy-saving “response” measures. Furthermore, the ANP (Analytic Network Process) and cloud model are used to calculate the weight of each index and evaluate the energy efficiency level. The analysis of BL Company verifies the feasibility of this index system and also provides an effective way to improve the energy efficiency at last.
... SWOT analysis is a frequently used tool for the analysis and validation of strategic development plans of enterprises and the analysis and development of new businesses, enabling the assessment of the strengths, weak points, Leonel Jorge Ribeiro Nunes 20 opportunities and threats, which are identified in a further preliminary stage prior to the implementation of any new project (Kohl et al., 2014). SWOT analysis presents as its main advantage the fact that it is based on a set of analytical steps that enable the evaluation of: ...
... The SNG production processes from coal gasification and biomass gasification are involved, and the characteristics of feedstock are from references (Kohl et al., 2014;Mukherjee et al., 2014). The comparison results are shown in Fig. 6. ...
To achieve environmental-friendly and energy-efficiency synthetic natural gas (SNG) production routing from municipal solid waste (MSW), a MSW-to-SNG process is unprecedentedly presented in this work, of which the designed configuration is developed and simulated with the aid of Aspen Plus. In addition, sensitivity analyses on major operation parameters, such as equivalence volume ratio (ER), steam-to-MSW mass ratio (S/M) and methanation pressure, are performed with the discussion of process efficiencies and SNG quality. In parallel, the comparison analysis is considered by adopting various MSW material. In this work, the composition of SNG mainly consists of 87.7% CH4, 2.9% CO2, 2.3% H2 and 7.1% N2. And lower heating value (LHV) together with Wobbe index of SNG are separately 31.66MJ/Nm(3) and 45.90MJ/Nm(3). Moreover, the wood-to-SNG, MSW-to-SNG and coal-to-SNG processes are carried out to demonstrate the superiority of the MSW-to-SNG process. The results reveal that the MSW-to-SNG process is a promising option to dispose MSW environmentally, meanwhile converting MSW to the valuable SNG.
... According to [9] energy indicators used today, i.e. specific energy consumption, do not fully capture the trends of the iron and steel sector. Comparison of different methods of energy efficiency assessment has been done by Kohl et al. [10]. Influencing factors of energy efficiency on the national level have been discussed in [11], concluding that each country has a different reason (basis) for the change of energy efficiency index. ...
Energy efficiency measures and utilization of renewable energy sources have been consistently incorporated into energy strategic documents of the member states, addressing various sectors. Industry, being the backbone of the European economy, is still not sufficiently addressed, since its development is almost exclusively market driven. The importance of industrial sector for the economy is not questionable, nor its impact on the environment. More than a quarter of all final energy consumption in Europe can be attributed to industrial sector, representing one third of final energy consumption of natural gas and one third of electricity use, with more than three quarters of all final energy consumption of solid fuels. The paper presents an overview of the energy efficiency development trends in Slovenian industry. To assess the energy efficiency development, the energy efficiency index (ODEX), has been applied to the Slovenian industrial sector, also highlighting some of the non-technical changes. The methodological part of this study is significantly complemented with the data, obtained from the extensive cooperation with the real industrial environment, bridging the gap between statistics, policies and practice.
... One possibility to account for the different forms of energy is to use the primary energy approach. In this case, the process boundaries are widened so that all the energy input used in the generation process is retraced to its primary sources and all energy needed to deliver the final energy product is expressed in terms of total primary energy consumption, according to Kohl et al. (2014). ...
Novel biofuel pathways with increased product yields are evaluated against conventional lignocellulosic biofuel production processes: methanol or methane production via gasification and ethanol production via steam-explosion pre-treatment. The novel processes studied are ethanol production combined with methanol production by gasification, hydrocarbon fuel production with additional hydrogen produced from lignin residue gasification, methanol or methane synthesis using synthesis gas from lignin residue gasification and additional hydrogen obtained by aqueous phase reforming in synthesis gas production. The material and energy balances of the processes were calculated by Aspen flow sheet models and add on excel calculations applicable at the conceptual design stage to evaluate the pre-feasibility of the alternatives. The processes were compared using the following criteria: energy efficiency from biomass to products, primary energy efficiency, GHG reduction potential and economy (expressed as net present value: NPV). Several novel biorefinery concepts gave higher energy yields, GHG reduction potential and NPV.
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HIGHLIGHTS:
- Techno-economic analysis of Power-to-Fuel processes from a comparative perspective.
- Chemical plant design in Aspen Plus® for Power-to-Fuel pathways.
- All simulations with the same assumptions and under the same boundary conditions.
- Flowsheet–based, component-specific cost calculation.
- Production-specific advantages and disadvantages of various e-fuels.
ABSTRACT: Electricity-based fuels are one promising option to achieve the transition of the energy system, and especially the transport sector, in order to minimize the role of fossil energy carriers. One major problem is the lacking compatibility between different techno-economic assessments, such that recommendations regarding the most promising Power-to-Fuel technology are difficult to make. This work provides a technically sound comparison of various Power-to-Fuel options regarding technological maturity and efficiency, as well as cost. The investigated options include methanol, ethanol, butanol, octanol, DME, OME3-5 and hydrocarbons. To guarantee the comparability, all necessary chemical plants were designed in Aspen Plus® to determine material and energy consumption, as well as investment costs within the same boundary conditions and assumptions in all simulations and calculations. Individual technical aspects of the various synthesis routes, as well as their advantages and disadvantages, are highlighted.
With an assumed electrolysis efficiency of 70% and considering the energy demand for the CO2 supply and the energy and operating material demand of the chemical plants, depending on the selected electrofuel, 30–60% of the primary energy in renewable electricity can be stored in the lower heating value of the electrofuel. In the presented results, the costs of H2 supply are responsible for 58–83% of the total manufacturing costs and thus have the greatest potential to reduce the latter. For the base case (4.6 €/kgH2), various electrofuels will have costs of manufacturing of between 1.85 and 3.96 €/lDE, with DME being the cheapest.
Conventional district heating and cooling (DHC) systems are compelled to reduce their fossil fuel dependency while ensuring profitability as cooling and heating demands decline. One solution is to retrofit the system with a gasifier and product gas upgrading equipment so that the system will be able to diversify its fuel input, including biomass and waste resources, while simultaneously producing synthetic natural gas (SNG), synthetic gas (syngas) and char complementarily to heat, cold and electricity. The main objective of this study is to assess energetically and economically a polygeneration DHC system based on gasification of refuse derived fuels considering the following sub-product scenarios: char; char and syngas; char and SNG; and char, syngas and SNG. The results show that when char is the only sub-product of the modified DHC system, the investment payback is 3 years, the discounted net cash flow (DNCF) is 142 mln USD, and the system trigeneration efficiency is 83.6%. When other sub-products are supplied by the system, its performance reduces but the system DNCF increases, while the investment payback remains constant.
Biofuels from biomass gasification are reviewed here, and demonstrated to be an attractive option. Recent progress in gasification techniques and key generation pathways for biofuels production, process design and integration and socio-environmental impacts of biofuel generation are discussed, with the goal of investigating gasification-to-biofuels’ credentials as a sustainable and eco-friendly technology. The synthesis of important biofuels such as bio-methanol, bio-ethanol and higher alcohols, bio-dimethyl ether, Fischer Tropsch fuels, bio-methane, bio-hydrogen and algae-based fuels is reviewed, together with recent technologies, catalysts and reactors. Significant thermodynamic studies for each biofuel are also examined. Syngas cleaning is demonstrated to be a critical issue for biofuel production, and innovative pathways such as those employed by Choren Industrietechnik, Germany, and BioMCN, the Netherlands, are shown to allow efficient methanol generation. The conversion of syngas to FT transportation fuels such as gasoline and diesel over Co or Fe catalysts is reviewed and demonstrated to be a promising option for the future of biofuels. Bio-methane has emerged as a lucrative alternative for conventional transportation fuel with all the advantages of natural gas including a dense distribution, trade and supply network. Routes to produce H2 are discussed, though critical issues such as storage, expensive production routes with low efficiencies remain. Algae-based fuels are in the research and development stage, but are shown to have immense potential to become commercially important because of their capability to fix large amounts of CO2, to rapidly grow in many environments and versatile end uses. However, suitable process configurations resulting in optimal plant designs are crucial, so detailed process integration is a powerful tool to optimize current and develop new processes. LCA and ethical issues are also discussed in brief. It is clear that the use of food crops, as opposed to food wastes represents an area fraught with challenges, which must be resolved on a case by case basis.
Energy efficiency measures and the utilisation of renewable energy sources have been consistently incorporated into the energy strategy documents of the EU Member States in various sectors. Industry, as the backbone of the European economy, is still not sufficiently addressed, since its development is almost exclusively market driven. The importance of the industrial sector for the economy is not questionable, nor is its impact on the environment. More than a quarter of all final energy consumption in Europe can be attributed to the industrial sector, representing one third of the final energy consumption of natural gas and one third of electricity use, with more than three quarters of all final energy consumption of solid fuels. The paper presents an overview of the energy efficiency development trends in Slovenian industry. To assess the development of energy efficiency, an energy efficiency index (ODEX) is applied, also highlighting some of the non-technical, structural changes. Furthermore, the future development prospects of energy-intensive industry in Slovenia are addressed in compliance with the national legislative framework and energy efficiency targets.
This chapter presents an exergy analysis of substitute (or synthetic) natural gas (SNG) production that is a promising option to replace natural gas. SNG can be produced from various feedstocks, including fossil coal and renewable biomass. SNG production routes from both feedstocks show many similarities as they involve the same two main steps: a feedstock gasification to produce syngas and methanation of syngas to produce SNG. This chapter begins with an overview of SNG. It describes an exergy analysis of SNG production from coal that was, historically, the first feedstock used for SNG. SNG production from biomass involves two steps in which methane is produced, namely, gasification and methanation. Coal-to-SNG is an attractive technology because coal reserves are much larger and SNG is more clean and efficient fuel. The chapter also presents a detailed exergy analysis of a coal-to-SNG process, and an overview of exergetic efficiencies for various feedstocks and gasifiers.
Improving energetic performance is a key factor in making societies more sustainable. One way to analyze
energetic performance is to use methods based on the second law of thermodynamics. Exergy analysis is
such a method. With exergy analysis thermodynamic losses of the studied system can be found. Exergy
shows the maximum useful work potential that a system has at a given state and at a given environment.
Exergy is a combination property of the system and the environment, meaning that the system in the same
state in different environments has different exergy values. For a specific process decreasing the exergy
losses decreases the need for exergy inputs and production costs. But these improvements do not
necessarily improve equally much the overall exergy if the surrounding system is considered. These are
equal only when the improved process does not increase its production, just improves its efficiency. But if the
improved process replaces some less efficient production in another process, the overall system efficiency is
improved even more or less, depending on the situation. This is because the total savings depends also on
the exergy efficiency of the surrounding system where the process studied operates. This total exergy is
primary exergy. Primary exergy is exergy found in nature that has not been subjected to any conversion or
transformation process. In this work we show that also the system environment affects the benefit of exergy
savings in the system level depending what production does this exergy saving replace. A simple District
Heating (DH) network with different DH producing units having different exergy efficiencies is used to show
the concept. We propose to expand the environment in exergy analysis to consider also the system
environment. By considering this broader concept of environment in exergy analysis companies and
societies can direct limited resources into investments that maximize primary exergy savings.
The energy efficiency and the development of environmentally correct policies are current topics, especially when applied to the industrial sector with the objective of increasing the competitiveness of the enterprises. Portuguese textile dyeing sector, being a major consumer sector of primary energy, needs to adopt measures to improve its competitiveness. Biomass appears to be a viable and preferred alternative energy source for the sector, while simultaneously develops an entire forest industry devoted to the supply of forest solid fuels. This work carries out a comprehensive PEST (political, economic, social and technological) analysis, which analyses Political, Economic, Social and Technological aspects of the replacement of the fossil fuels traditionally used in this sector by biomass, providing a framework of environmental factors that influence the strategic management of the companies. The main advantages are the reduction of external dependence on imported fuel due to the use of an endogenous renewable resource, the creation and preservation of jobs, the increased competitiveness of the sector by reducing energy costs, the use of national technology and the reduction of greenhouse gases emissions.
Biomass fast pyrolysis (BFP) is a promising pre-treatment technology for converting biomass to transport fuel and in the future also for high-grade chemicals. BFP can be integrated with a municipal combined heat and power (CHP) plant. This paper shows the influence of BFP integration on a CHP plant's main parameters and its effect on the energetic and environmental performance of the connected district heating network. The work comprises full- and part-load operation of a CHP plant integrated with BFP and steam drying. It also evaluates different usage alternatives for the BFP products (char and oil). The results show that the integration is possible and strongly beneficial regarding energetic and environmental performance. Offering the possibility to provide lower district heating loads, the operation hours of the plant can be increased by up to 57%. The BFP products should be sold rather than applied for internal use as this increases the district heating network's primary energy efficiency the most. With this integration strategy future CHP plants can provide valuable products at high efficiency and also can help to mitigate global CO2 emissions.
In this work, integration of a synthetic natural gas (SNG) production process with an existing biomass CHP steam power cycle is investigated. The paper assesses two different biomass feedstock drying technologies—steam drying and low-temperature air drying—for the SNG process. Using pinch technology, different levels of thermal integration between the steam power cycle and the SNG process are evaluated. The base case cold gas efficiency for the SNG process is 69.4% based on the lower heating value of wet fuel. The isolated SNG-related electricity production is increased by a factor of 2.5 for the steam dryer alternative, and tenfold for the low-temperature air dryer when increasing the thermal integration. The cold gas efficiency is not affected by the changes. Based on an analysis of changes to turbine steam flow, the integration of SNG production with an existing steam power cycle is deemed technically feasible. Copyright © 2011 John Wiley & Sons, Ltd.
This study considers the technical potential concerning the energy efficiency attainable for vehicles with alternative powertrains within 10–20 years. The potential for electric vehicles (BEVs), hybrid electric vehicles (HEVs) and fuel-cell electric vehicles (FCEVs) is assessed and compared with the potential improvement in conventional vehicles with internal combustion engines (ICEVs). Primary energy efficiency is the measure used in this study for comparison. The calculations of primary energy efficiency are based on three different resources: fossil fuels, biomass, and primary electricity from wind, solar or hydropower. This study shows that there is potential for doubling the primary energy efficiency using alternative powertrains in vehicles such as BEVs, HEVs and FCEVs, compared with existing ICEVs. All vehicles with an alternative powertrain have a higher potential for primary energy efficiency than vehicles with an improved conventional powertrain. No “winner” amongst the alternative powertrains could be identified from a primary energy efficiency point of view.
In order to estimate the heat of condensation of fast pyrolysis product of woody biomass a model to be used in the chemical process simulation software Aspen+ has been developed based on the composition of wood fast pyrolysis product.
A simulation model for biomass fast pyrolysis was developed. The results obtained are in good accordance with values found in the literature. With more specific data (e.g. from measurements) it should be possible to adjust the flexible model to other data.
A simple method for computing pyrolysis product composition (described by 22 different substances) for multiple biomass feedstock has been described as well. The method can be further developed in order to simultaneously match mass and energy balance of different BFP processes.
It seems that the model is credible enough for further use of the product composition in terms of integration of the heat of condensation with a combined heat and power plant. As there is no data available for condensation behaviour of BFP products further evaluation is only possible once better measurement data is available.
Reaching the long term goals of climate policies requires the implementation of a portfolio of measures. This paper quantifies the potentials of energy efficiency technologies and CO2 capture and storage (CCS) for seven Dutch industry sectors between 2008 and 2040. Economically viable energy efficiency technologies offer carbon dioxide (CO2) emission reduction potentials of 25 +/- 8% in 2040 compared to 1990 levels. Economically viable CCS options can raise the industry's total emission reductions to 39-47%. These potentials require abatement costs above 90 (sic) (Euro) per tonne CO2, but they are still not sufficient to reach European Union's long term emission reduction plans. While economically viable potentials of improving energy efficiency may exist in all sectors (energy efficiency improvements of 2% per annum (p.a.)), attractive CCS potentials exist in the fertilizer, basic metal and refinery sectors with abatement costs estimated at 25-120 (sic)/t CO2 for 2040. Implementing CCS in these sectors would reduce total industry's primary energy efficiency improvement rates from 2% to 1.6% p.a. and would increase total industrial energy use by at least 10%. Reaching higher emission reductions in the Dutch industry will require the implementation of a portfolio of measures including energy and materials efficiency, renewables and CCS. (c) 2013 Elsevier Ltd. All rights reserved.
Efficient heat rejection is crucial for the overall primary energy balance of sorption systems, as it dominates the auxiliary energy consumption. Low ratios of cooling power to auxiliary electricity of 3.0 or less are still common in sorption system, so that the primary energy efficiency is not always higher than for conventional compression chillers.Whereas dry heat rejection systems require electricity for fan operation, hybrid or wet cooling systems in addition need pumping energy for the cooling water and the water itself. The energy efficiency can be improved for heat rejection to the ground, where only pumping energy is needed for the geothermal heat exchange.Dynamic simulation models were used for a single effect absorption chiller powered by solar thermal collectors via a hot storage tank. The chiller models were coupled to a three dimensional numerical ground heat exchanger model or to cooling tower models. The models were validated with operating data of a 15 kW solar cooling system installed in an office building.Primary energy efficiency ratios were determined for different heat rejection systems and improved control strategies were developed. The installed system primary energy ratios varied between 1.1 and 2.2 for auxiliary heating and between 1.2 and 2.5 for auxiliary cooling depending on the heat rejection and control strategy chosen. The low electrical energy consumption of the geothermal heat rejection saves 30% of auxiliary electricity and results in an electrical coefficient of performance of 13. The maximum primary energy ratios for solar fractions up to 88% are 2.7 for auxiliary heating and 3.2 for auxiliary cooling, i.e. nearly three times higher than for the reference electrical compression system of 1.2.
In order to react on future expected increased competition on restricted biomass resources, communal combined heat and power (CHP) plants can be integrated with biomass upgrading processes that add valuable products to the portfolio. In this paper, outgoing from a base case, the retrofit integration of production of wood pellets (WPs), torrefied wood pellets (TWPs) and wood fast pyrolysis slurry (PS) with an existing wood-fired CHP plant was simulated. Within the integration concept, free boiler capacity during times of low district heat demands is used to provide energy for the upgrading processes. By detailed part-load modelling, critical process parameters are discussed. With help of a multiperiod model of the heat duration curve, the work further shows the influence of the integration on plant operating hours, electricity production and biomass throughput. Environmental and energetic performance is assessed according to European standard EN 15603 and compared to the base case as well as to stand-alone production in two separate units.The work shows that all three integration options are well possible within the operational limits of the CHP plant. Summarising, this work shows that integration of WP, TWP and PS production from biomass with a CHP plant by increasing the yearly boiler workload leads to improved primary energy efficiency, reduced CO2 emissions, and, when compared to stand-alone production, also to substantial fuel savings.
This paper presents an exergy analysis of SNG production via indirect gasification of various biomass feedstock, including virgin (woody) biomass as well as waste biomass (municipal solid waste and sludge). In indirect gasification heat needed for endothermic gasification reactions is produced by burning char in a separate combustion section of the gasifier and subsequently the heat is transferred to the gasification section. The advantages of indirect gasification are no syngas dilution with nitrogen and no external heat source required. The production process involves several process units, including biomass gasification, syngas cooler, cleaning and compression, methanation reactors and SNG conditioning. The process is simulated with a computer model using the flow-sheeting program Aspen Plus. The exergy analysis is performed for various operating conditions such as gasifier pressure, methanation pressure and temperature. The largest internal exergy losses occur in the gasifier followed by methanation and SNG conditioning. It is shown that exergetic efficiency of biomass-to-SNG process for woody biomass is higher than that for waste biomass. The exergetic efficiency for all biomass feedstock increases with gasification pressure, whereas the effects of methanation pressure and temperature are opposite for treated wood and waste biomass.
This book consists of the following chapters: The exergy concept and exergy losses; Calculation of exergy; Physical and chemical exergy of typical substances; Exergy analysis of typical thermal and chemical processes; Cumulative exergy consumption and cumulative degree of perfection; Reduction of external exergy losses; Exergy analysis of major thermal and chemical processes; Thermoeconomic applications of exergy; and Ecological applications of exergy.
In this study we explore the effects of end-use energy efficiency measures on different district heat production systems with combined heat and power (CHP) plants for base load production and heat-only boilers for peak and medium load productions. We model four minimum cost district heat production systems based on four environmental taxation scenarios, plus a reference district heat system used in Östersund, Sweden. We analyze the primary energy use and the cost of district heat production for each system. We then analyze the primary energy implications of end-use energy efficiency measures applied to a case-study apartment building, taking into account the reduced district heat demand, reduced cogenerated electricity and increased electricity use due to ventilation heat recovery. We find that district heat production cost in optimally-designed production systems is not sensitive to environmental taxation. The primary energy savings of end-use energy efficiency measures depend on the characteristics of the district heat production system and the type of end-use energy efficiency measures. Energy efficiency measures that reduce more of peak load than base load production give higher primary energy savings, because the primary energy efficiency is higher for CHP plants than for boilers. This study shows the importance of analyzing both the demand and supply sides as well as their interaction in order to minimize the primary energy use of district heated buildings.Research highlights▶ CHP-based district heating and building energy efficiency measures were analysed. ▶ Primary energy savings was typically about 80% of final energy savings. ▶ For ventilation heat recovery the savings was about 25%. ▶ Bio-based district heat production was not sensitive to carbon emission taxations. ▶ Oversized production increase cost and reduce primary energy savings.
The paper presents the exergy analysis results concerning a biomass to synthetic natural gas (SNG) conversion process. The presented study is based on wood gasification integrated with CH 4 synthesis. The analysed temperature of gasification was 700°C and the pressure was changed from 1 to 15 bar. The main process units of biomass-to-SNG conversion technology are gasifier, gas cleaning, synthesis gas compression, CH 4 synthesis and final SNG condition. The results showed that the largest exergy losses take place in the biomass gasifier, CH 4 synthesis part and CO 2 capture unit. The overall exergetic efficiency of the biomass-to-SNG process was estimated in the range of about 62.8 – 63.9 %.
Micro-combined heat and power (CHP) systems are a key resource to meet the EUCO2 reduction agreed in the Kyoto Protocol. In the near future they are likely to spread significantly through applications in the residential and service sectors, since they can provide considerably higher primary energy efficiencies than plants generating electricity and heat separately. A 28Â kWe natural gas, automotive-derived internal combustion engine CHP system was modeled with a view to comparing constant and variable speed operation modes. Besides their energy performances, the paper addresses the major factors involved in their economic evaluation and describes a method to assess their economic feasibility. Typical residential and service sector applications were chosen as test cases and the results discussed in terms of energy performances and of profitability. They showed that interesting savings can be obtained with respect to separate generation, and that they are higher for the household application in variable speed operating conditions. In fact the plant's energy performance is greatly enhanced by the possibility, for any given power, to regulate the engine's rotational speed. From the economic viewpoint, despite the higher initial cost of the variable speed concept, the system involves a shorter pay-back period and ensures greater profit.
The production of Synthetic Natural Gas from biomass (Bio-SNG) by gasification and upgrading of the gas is an attractive option to reduce CO2 emissions and replace declining fossil natural gas reserves. Production of energy from biomass is approximately CO2 neutral. Production of Bio-SNG can even be CO2 negative, since in the final upgrading step, part of the biomass carbon is removed as CO2, which can be stored. The use of biomass for CO2 reduction will increase the biomass demand and therefore will increase the price of biomass. Consequently, a high overall efficiency is a prerequisite for any biomass conversion process. Various biomass gasification technologies are suitable to produce SNG. The present article contains an analysis of the Bio-SNG process efficiency that can be obtained using three different gasification technologies and associated gas cleaning and methanation equipment. These technologies are: 1) Entrained Flow, 2) Circulating Fluidized Bed and 3) Allothermal or Indirect gasification. The aim of this work is to identify the gasification route with the highest process efficiency from biomass to SNG and to quantify the differences in overall efficiency. Aspen Plus® was used as modeling tool. The heat and mass balances are based on experimental data from literature and our own experience.
This paper evaluates the economic effects and the potential for reduced CO2 emissions when biomass gasification applications are introduced in a Swedish district heating (DH) system. The gasification applications included in the study deliver heat to the DH network while producing renewable electricity or biofuels. Gasification applications included are: external superheater for steam from waste incineration (waste boost, WB), gas engine CHP (BIGGE), combined cycle CHP (BIGCC) and production of synthetic natural gas (SNG) for use as transportation fuel. Six scenarios are used, employing two time perspectives – short-term and medium-term – and differing in economic input data, investment options and technical system. To evaluate the economic performance an optimisation model is used to identify the most profitable alternatives regarding investments and plant operation while meeting the DH demand. This study shows that introducing biomass gasification in the DH system will lead to economic benefits for the DH supplier as well as reduce global CO2 emissions. Biomass gasification significantly increases the potential for production of high value products (electricity or SNG) in the DH system. However, which form of investment that is most profitable is shown to be highly dependent on the level of policy instruments for biofuels and renewable electricity. Biomass gasification applications can thus be interesting for DH suppliers in the future, and may be a vital measure to reach the 2020 targets for greenhouse gases and renewable energy, given continued technology development and long-term policy instruments.
With increasingly stringent CO2 emission reduction targets, incentives for efficient use of limited biomass resources increase. Technologies for gasification of biomass may then play a key role given their potential for high electrical efficiency and multiple outputs; not only electricity but also bio transport fuels and district heat. The aim of this study is to assess the economic consequences and the potential for CO2 reduction of integration of a biomass gasification plant into a district-heating (DH) system. The study focuses on co-location with an existing natural gas combined cycle heat and power plant in the municipal DH system of Göteborg, Sweden. The analysis is carried out using a systems modelling approach. The so-called MARTES model is used. MARTES is a simulating, DH systems supply model with a detailed time slice division. The economic robustness of different solutions is investigated by using different sets of parameters for electricity price, fuel prices and policy tools. In this study, it is assumed that not only tradable green certificates for electricity but also tradable green certificates for transport fuels exist. The economic results show strong dependence on the technical solutions and scenario assumptions but in most cases a stand-alone SNG-polygeneration plant with district-heat delivery is the cost-optimal solution. Its profitability is strongly dependent on policy tools and the price relation between biomass and fossil fuels. Finally, the results show that operation of the biomass gasification plants reduces the (DH) system's net emissions of CO2.
The exergy of an energy form or a substance is a measure of its usefulness or quality or potential to cause change. A thorough understanding of exergy and the insights it can provide into the efficiency, environmental impact and sustainability of energy systems, are required for the engineer or scientist working in the area of energy systems and the environment. Further, as energy policies play an increasingly important role in addressing sustainability issues and a broad range of local, regional and global environmental concerns, policy makers also need to appreciate the exergy concept and its ties to these concerns. During the past decade, the need to understand the connections between exergy and energy, sustainable development and environmental impact has become increasingly significant. In this paper, a study of these connections is presented in order to provide to those involved in energy and environment studies, useful insights and direction for analyzing and solving environmental problems of varying complexity using the exergy concept. The results suggest that exergy provides the basis for an effective measure of the potential of a substance or energy form to impact the environment and appears to be a critical consideration in achieving sustainable development.
The cement industry is an energy intensive industry consuming about 4 GJ per tonne of cement produced. A thermodynamic analysis for cogeneration using the waste heat streams is not easily available. Data from a working 1 Mt per annum plant in India is used to obtain an energy balance for the system and a Sankey diagram is drawn. It is found that about 35% of the input energy is being lost with the waste heat streams. A steam cycle is selected to recover the heat from the streams using a waste heat recovery steam generator and it is estimated that about 4.4 MW of electricity can be generated. This represents about 30% of the electricity requirement of the plant and a 10% improvement in the primary energy efficiency of the plant. The payback period for the system is found to be within two years.
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