Cogeneration Of Heat And Power Research Articles

Comprehensive analysis of energy, exergy, economic, and environmental aspects in implementing the Kalina cycle for waste heat recovery from a gas turbine cycle coupled with a steam generator

This study introduces a transformative approach by integrating the Kalina Cycle System (KCS) within a cogeneration of heat and power (CHP) framework alongside a gas turbine (GT) cycle and a single-pressure heat recovery steam generator (HRSG). Through development of thermodynamic and thermo-economic models, a comprehensive assessment of the system's performance is conducted, emphasizing energy, exergy, and exergoeconomic considerations. The outcomes reveal a remarkable enhancement in both 1st and 2nd law efficiencies for the GT-HRSG/KCS-11 system compared to its conventional counterpart. Witnessing an ascent from 53.60 % to 54.31 % in efficiency and an increase from 50.59 % to 51.27 % in 2nd law efficiency underscores the profound impact of the proposed system. Furthermore, a parametric study scrutinizes the influence of diverse design parameters on critical objective functions, encompassing second law efficiencies and the total system cost rate. Findings spotlight the combustion chamber, heat recovery steam generator, and gas turbine as focal points of exergy destruction, revealing crucial insights for system optimization. The combustion chamber, heat recovery steam generator, and gas turbine emerge as pivotal contributors to the total cost rate, highlighting key areas for economic consideration. According to the results, the share of the environmental cost rates in the system cost rate is insignificant.

Sustainable analysis of Waste-to-Energy systems in cities by eco-efficiency assessment using DEA approach: A case study of Iran's municipalities

Municipal Solid Waste (MSW) management has become a pressing global issue due to population growth, urbanization, and changing consumption patterns, especially in developing countries. This study develops a comprehensive framework to evaluate the sustainability of MSW management systems. Also, the sustainability of Anaerobic Digestion (AD) and landfill systems with/without various Cogeneration of Heat and Power (CHP) technologies in different conditions using the framework in the municipalities of Iran. The eco-efficiency index, which considers environmental and economic aspects, is used to assess the systems sustainability. The Data Envelopment Analysis (DEA) method is applied to assess and rank the performance of the systems based on their eco-efficiency indices considering parameters such as energy production, costs, emissions, land occupation, water consumption, and employment. The results indicate that the landfill and AD systems with/without CHP have the highest priority for all provinces when the food, paper, and cardboard wastes entering the systems are at their maximum and minimum amounts. However, the systems without CHP have the lowest efficiency when the share of the wastes is 50%. Although the findings can help decision-makers in improving MSW management, there may be limitations to the research, such as data availability and assumptions made during the analysis.

Development of a novel framework for the analysis of Technological Innovation Systems by Causal Layered Analysis (CLA) in energy systems

ABSTRACT Greenhouse gas emissions from the burning of fossil fuels, as one of the main sources of anthropogenic climate change accounts for two-third of the global emissions. In this issue, Iran has adopted a set of policies and goals to consider related technology development. One of these technologies around which several national programmes have launched is the Cogeneration of Heat and Power (CHP). Nevertheless, the national goals have not been fulfilled as expected. The aim of this paper is therefore to provide a framework in order to identify the bottlenecks hindering CHP development in Iran. This framework is based on the Technological Innovation System (TIS) along with the Causal Layered Analysis (CLA) to decipher the profound and latent factors causing these problems. The results reveal a significant role of the discourses and visions both directly on the failure of the CHP innovation system functions and indirectly through affecting structural problems. A notable policy suggestion is to change the discourse of centralised power generation and to make more effort to legitimate the energy efficiency in the society. The developed framework can also be beneficial to policy-makers to formulate and analyse the future visions for the CHP plants.

Technical, Energetic and Economic Optimization Analysis of Selection of Heat Source for Municipal Sewage Sludge Dryer

The treatment of growing production of municipal sewage sludge has become a significant global problem. Drying of digested sewage sludge is a promising alternative to sludge disposal at dumping sites. The research objective of this study was to find the optimal heat source for a sludge drying plant in a large municipal sewage treatment plant (people equivalent: 250,000). Two boundary heat supply cases were analyzed in the paper: cogeneration of heat and power (CHP) units, internal combustion (IC) engines fired with natural gas, and plant supplied with a gas boiler. The aim of the research was to find the optimal size of the cogeneration unit cooperating with the gas boiler as heat sources for a given drying plant case with the maximum net present (NPV) value as the objective function. The results of the conducted optimization show higher profitability of cases with larger cogeneration unit. For the basic assumptions, the maximum NPV is obtained for the largest analyzed CHP unit: 1300 kW of thermal power output. Sensitivity analyses show that the varying gas and electricity prices can relocate the NPV maximum towards smaller CHP sizes. A supplementary energy analysis shows that implementing larger CHP units yields a higher energy efficiency of the system, up to 0.52.

Development of a PEMFC-based heat and power cogeneration system

ABSTRACTHydrogen-fed proton exchange membrane fuel cell (PEMFC) has to overcome high installation and operation cost before being adopted as a distributed power candidate. Cogeneration of power and heat is a good approach to increase hydrogen energy utilization rate. A PEMFC-based power and heat cogeneration system is proposed and established in the current study to investigate system’s technological and economical feasibility. This cogeneration of heat and power (CHP) system composes of a 2.5-kW fuel cell stack, hydrogen supply system, air supply system, water and heat management system, and heat recovery system. The control strategies to automate the system operation are realized by a programmable automation controller (PAC) system. Detailed measurement of the system is also constructed along with a web-based human–machine interface (HMI) platform to facilitate experiments and demonstration. Preliminary testing of the CHP system shows good performance of heat and power outputs. System’s electrical power conversion efficiency and thermal efficiency of the CHP system are measured at 38% and 35%, respectively. System combined efficiency therefore reached about 73%.

Heat transfer and thermal characteristics analysis of direct air-cooled combined heat and power plants under off-design conditions

The distributed energy systems and efficient utilization of traditional fossil fuel are confronting great opportunities under present energy framework in which coal power dominating and renewable energy emerging gradually. Heating technology, especially cogeneration of heat and power (CHP), has been increasingly concerned and rapidly developed in recent years. It is an effective way for direct air-cooled power units to cope with rigorous complex environmental conditions, decrease coal rate and pollutant emission. This paper analysed the heat transfer characteristics of heating network and air-cooled island and obtained the cold end parameters of steam turbine under off-design condition, which is used to stimulate the operation state combined with relative parameters. The heat transfer characteristics of air-cooled island under different operation mode of air-cooled fans was acquired by introducing heat transfer coefficient; the power consumption of air-cooled island and the net power output were calculated with the relationship between frequency and power, air-cooled based on which the optimal operation and regulation method were determined. The optimized operation mode of both heating system and air-cooled system were determined under different ambient temperature and regulation method. The result showed that a maximum 0.86 g/kW h coal consumption reduction was reached in optimal fans operation mode, which meant the method scientifically supported the development of heating technology and further improved the processes of energy-saving and CO2 reduction.

Techno-Economic Evaluation of Technologies to Mitigate Greenhouse Gas Emissions at North American Refineries.

A petroleum refinery model, Petroleum Refinery Life-cycle Inventory Model (PRELIM), that estimates energy use and CO2 emissions was modified to evaluate the environmental and economic performance of a set of technologies to reduce CO2 emissions at refineries. Cogeneration of heat and power (CHP), carbon capture at fluid catalytic cracker (FCC) and steam methane reformer (SMR) units, and alternative hydrogen production technologies were considered in the analysis. The results indicate that a 3-44% reduction in total annual refinery CO2 emissions (2-24% reductions in the CO2 emissions on a per barrel of crude oil processed) can be achieved in a medium conversion refinery that processes a typical U.S. crude slate obtained by using the technologies considered. A sensitivity analysis of the quality of input crude to a refinery, refinery configuration, and prices of natural gas and electricity revealed how the magnitude of possible CO2 emissions reductions and the economic performance of the mitigation technologies can vary under different conditions. The analysis can help inform decision making related to investment decisions and CO2 emissions policy in the refining sector.

Energy balance performance of municipal wastewater treatment systems considering sludge anaerobic biodegradability and biogas utilisation routes

The energy balance of a municipal wastewater treatment (WWT) system was evaluated considering the influence of excess biological sludge anaerobic biodegradability (BDAn) and of biogas utilisation as either fuel for co-generation of heat and power (CHP) or for vehicle transport. Sludge thermal pre-treatment prior to anaerobic digestion and high-rate carbon removal were considered as modifications of a reference municipal WWT system to impact the sludge BDAn. Both thermal pre-treatment and a high-rate process with a short sludge retention time (SRT=1–3d) led to ∼30% higher sludge BDAn than that of untreated sludge from a low-rate WWT system with long SRT (>8d), which enhanced methane yields and energy production correspondingly. An efficient separation (40% of CODin) of primary solids promoted biogas production by capturing a significant part of the incoming COD, and lowered aeration energy demands for carbon oxidation due to lower loads of particulate organics into the biological treatment. Thermal pre-treatment can most effectively increase the biodegradability of sludge originating from a low-rate WWT system with a long SRT. Sludge solubilization alone as an indicator of increase biodegradability by a pre-treatment is inadequate for sludge types with inherently high biodegradability. A WWT system with primary separation, sludge pre-treatment, and CHP from biogas can be a net electricity producer and self-sufficient in thermal energy, provided the thermal energy from CHP is available for the pre-treatment. With other types of energy carriers as inputs and outputs, the WWT performance also needs evaluation with respect to the energy economic and environmental value.

Environmental performance of gasified willow from different lands including land‐use changes

AbstractA life‐cycle assessment (LCA) of a low‐input, short rotation coppice (SRC) willow grown on different Danish lands was performed. Woodchips are gasified, producer gas is used for cogeneration of heat and power (CHP), and the ash–char output is applied as soil amendment in the field. A hybrid model was developed for the estimation of greenhouse gas (GHG) emissions from indirect land‐use changes (iLUC) induced by willow cropping on arable land (iLUCfood). For this, area expansion results from a general equilibrium economic model were combined with global LUC trends to differentiate between land transformation (as additional agricultural expansion, in areas with historical deforestation) and occupation (as delayed relaxation, DR, in areas with historical land abandonment) impacts. A biophysical approach was followed to determine the iLUCfeed emissions factor from marginal grassland. Land transformation impacts were derived from latest world deforestation statistics, while a commercial feed mix of equivalent nutritive value was assumed to substitute the displaced grass as fodder. Intensification effects were included in both iLUC factors as additional N‐fertilizer consumption. Finally, DR impacts were considered for abandoned farmland, as a relative C stock loss compared to natural regeneration. ILUC results show that area related GHG emissions are dominant (93% of iLUCfood and 80% of iLUCfeed), transformation being more important (82% of iLUCfood) than occupation (11%) impacts. LCA results show that CHP from willow emits 4047 kg CO2‐eq (or 0.8 gCO2‐eq MJ−1) when grown on arable land, while sequestering 43 745 kg CO2‐eq (or −10.4 gCO2‐eq MJ−1) when planted on marginal pastureland, and 134 296 kg CO2‐eq (or −31.8 gCO2‐eq MJ−1) when marginal abandoned land is cultivated. Increasing the bioenergy potential without undesirable iLUC effects, especially relevant regarding biodiversity impacts, requires that part of the marginally used extensive grasslands are released from their current use or energy cropping on abandoned farmland incentivized.

High temperature reactors for cogeneration applications

Abstract There is a large potential for nuclear energy also in the non-electric heat market. Many industrial sectors have a high demand for process heat and steam at various levels of temperature and pressure to be provided for desalination of seawater, district heating, or chemical processes. The future generation of nuclear plants will be capable to enter the wide field of cogeneration of heat and power (CHP), to reduce waste heat and to increase efficiency. This requires an adjustment to multiple needs of the customers in terms of size and application. All Generation-IV concepts proposed are designed for coolant outlet temperatures above 500 °C, which allow applications in the low and medium temperature range. A VHTR would even be able to cover the whole temperature range up to approx. 1 000 °C.

Estimation of marginal costs at existing waste treatment facilities

This investigation aims at providing an improved basis for assessing economic consequences of alternative Solid Waste Management (SWM) strategies for existing waste facilities. A bottom-up methodology was developed to determine marginal costs in existing facilities due to changes in the SWM system, based on the determination of average costs in such waste facilities as function of key facility and waste compositional parameters. The applicability of the method was demonstrated through a case study including two existing Waste-to-Energy (WtE) facilities, one with co-generation of heat and power (CHP) and another with only power generation (Power), affected by diversion strategies of five waste fractions (fibres, plastic, metals, organics and glass), named “target fractions”. The study assumed three possible responses to waste diversion in the WtE facilities: (i) biomass was added to maintain a constant thermal load, (ii) Refused-Derived-Fuel (RDF) was included to maintain a constant thermal load, or (iii) no reaction occurred resulting in a reduced waste throughput without full utilization of the facility capacity. Results demonstrated that marginal costs of diversion from WtE were up to eleven times larger than average costs and dependent on the response in the WtE plant. Marginal cost of diversion were between 39 and 287€Mg−1 target fraction when biomass was added in a CHP (from 34 to 303€Mg−1 target fraction in the only Power case), between −2 and 300€Mg−1 target fraction when RDF was added in a CHP (from −2 to 294€Mg−1 target fraction in the only Power case) and between 40 and 303€Mg−1 target fraction when no reaction happened in a CHP (from 35 to 296€Mg−1 target fraction in the only Power case). Although average costs at WtE facilities were highly influenced by energy selling prices, marginal costs were not (provided a response was initiated at the WtE to keep constant the utilized thermal capacity). Failing to systematically address and include costs in existing waste facilities in decision-making may unintendedly lead to higher overall costs at societal level. To avoid misleading conclusions, economic assessment of alternative SWM solutions should not only consider potential costs associated with alternative treatment but also include marginal costs associated with existing facilities.

Booster heat pumps and central heat pumps in district heating

District heating (DH) enables the utilisation and distribution of heating from sources unfeasible for stand-alone applications and combined with cogeneration of heat and power (CHP), has been the cornerstone of Denmark’s realisation of a steady national primary energy supply over the last four decades. However, progressively more energy-efficient houses and a steadily improving heat pump (HP) performance for individual dwellings is straining the competitive advantage of the CHP–DH combination as DH grid losses are growing in relative terms due to decreasing heating demands of buildings and relatively high DH supply temperatures.A main driver for the DH water temperature is the requirements for domestic hot water (DHW) production. This article investigates two alternatives for DHW supply: (a) DH based on central HPs combined with a heat exchanger, and (b) a combination of DH based on central HPs and a small booster HP using DH water as low-temperature source for DHW production. The analyses are conducted using the energyPRO simulation model and are conducted with hourly varying factors; heating demands, DH grid losses, HP coefficient of performance (COP) and spot market prices in order to be able to analyse the relative performance of the two options and their performance over the year. Results are also compared to individual boilers and individual HPs.The results indicate that applying booster HPs enables the DH system to operate at substantially lower temperature levels, improving the COP of central DH HPs while simultaneously lowering DH grid losses significantly. Thus, DH performance is increased significantly. Additionally, performance for the DH HP with booster combination is considerably better than individual boiler or HP solutions.

Conflicting strategies towards sustainable heating at an urban junction of heat infrastructure and building standards

Approaches to ‘sustainability transitions’ stress the possibility of aligning actors around a shared vision of the future, e.g. at the scale of a city. Empirical accounts reveal how difficult such coordination often is due to contradictory views involved. How can we better understand related processes of searching and negotiation? What does this mean for the organization of decision making processes regarding long-term infrastructural change?We analyze a conflict which erupted in Freiburg, Germany when two strategies of reducing environmental impacts of space heating were to be applied in the Vauban ‘model district’: A) Efficient co-generation of heat and power (CHP) combined with district heating systems (DHS), and B) Reducing heat demand by low-energy designs and ambitious energy standards (‘passive house standard’). In order to understand the politics of infrastructure development, we unravel 1) enabling factors and driving forces of the conflict, 2) normative content of opposing viewpoints, 3) resources tapped into for settling the disagreement, and 4) the institutional setup of such decision making about energy policy priorities in the municipality.We reflect on implications of such a perspective on how policies and how governance arrangements should ideally be shaped and take a brief outlook on further research needed.

Energy system impacts of desalination in Jordan

Climate change mitigation calls for energy systems minimising end-use demands, optimising the fuel efficiency of conversion systems, increasing the use of renewable energy sources and exploiting synergies wherever possible. In parallel, global fresh water resources are strained due to amongst others population and wealth increase and competitive water uses from agriculture and industry is causing many nations to turn to desalination technologies. This article investigates a Jordanian energy scenario with two different desalination technologies; reverse osmosis (RO) driven by electricity and Multi Stage Flash (MSF) desalination driven by Cogeneration of Heat and Power (CHP). The two systems impact the energy systems in different ways due to the technologies’ particular characteristics. The systems are analyses in the energy systems analysis model EnergyPLAN to determine the impacts on energy system performance. Results indicate that RO and MSF are similar in fuel use. While there is no use of waste heat from condensing mode plants, efficiencies for CHP and MSF are not sufficiently good to results in lower fuel usage than RO. The Jordanian energy system is somewhat inflexible giving cause to Critical Excess Electricity Production (CEEP) even at relatively modest wind power penetrations. Here RO assists the energy system in decreasing CEEP – and even more if water storage is applied.

Utilization of Genetic Algorithm to Optimize Biogas Production from Livestock Waste to Use in a CHP Plant in Agricultural Farms

The optimization of biogas production with respect to external influences and various process disturbances is essential for efficient plant operation. However, the optimization of such plants is a challenging issue due the underlying nonlinear and complex digestion processes. One approach to solving this problem is to use the flexibility and power of Original Research Article British Biotechnology Journal, 4(11): 1149-1164, 2014 1150 computational intelligence methods such as Genetic Algorithms (GAs). The present study utilizes GA as tools for simulating and optimizing of biogas production process. Considering the effect of digester operational parameters, such as temperature (T), total solids (TS), volatile fatty acid (VFA), pH and A/TIC-ratio (amount of Acids (A) compared to Total Inorganic Carbon (TIC)), the optimal amount of biogas was converged to be 53910 cubic meters per month. In order to reach the main goals on the energy problems, it is important to study and analyze the distributed CHP plant for agricultural companies and farms. This paper also describes a feasibility study of a biogas CHP (Cogeneration of Heat and Power )plant in a cow farm in Iran. With the developed model, it is specified that using 53,910 cubic meters of biogas, an internal combustion engine with electrical power of 375 kW can be operated continuously. Obtained results illustrated how the utilization of gaseous product from cow farm effluent (biogas) as fuel for heat and power generation can reduce primary energy consumption and its associated costs.

Life-Cycle Energy Use and Greenhouse Gas Emissions Analysis for Bio-Liquid Jet Fuel from Open Pond-Based Micro-Algae under China Conditions

A life-cycle analysis (LCA) of greenhouse gas (GHG) emissions and energy use was performed to study bio-jet fuel (BJF) production from micro-algae grown in open ponds under Chinese conditions using the Tsinghua University LCA Model (TLCAM). Attention was paid to energy recovery through biogas production and cogeneration of heat and power (CHP) from the residual biomass after oil extraction, including fugitive methane (CH4) emissions during the production of biogas and nitrous oxide (N2O) emissions during the use of digestate (solid residue from anaerobic digestion) as agricultural fertilizer. Analyses were performed based on examination of process parameters, mass balance conditions, material requirement, energy consumptions and the realities of energy supply and transport in China (i.e., electricity generation and heat supply primarily based on coal, multiple transport modes). Our LCA result of the BJF pathway showed that, compared with the traditional petrochemical pathway, this new pathway will increase the overall fossil energy use and carbon emission by 39% and 70%, respectively, while decrease petroleum consumption by about 84%, based on the same units of energy service. Moreover, the energy conservation and emission reduction benefit of this new pathway may be accomplished by two sets of approaches: wider adoption of low-carbon process fuels and optimization of algae cultivation and harvest, and oil extraction processes.

EUROPAIRS: The European project on coupling of High Temperature Reactors with industrial processes

Developers of High Temperature Reactors (HTR) worldwide acknowledge that the main asset for market breakthrough is its unique ability to address growing needs for industrial cogeneration of heat and power (CHP) owing to its high operating temperature and flexibility, adapted power level, modularity and robust safety features. A strong alliance between nuclear and process heat user industries is a necessity for developing such a nuclear system for the conventional process heat market, just as the electro-nuclear development required a close partnership with utilities. Initiating such an alliance is one of the objectives of the EUROPAIRS project (www.europairs.eu) presently on-going in the frame of the Euratom 7th Framework Programme (FP7). Although small and of short duration (21 months), EUROPAIRS is of strategic importance: it generates the boundary conditions for rapid demonstration of collocating HTR with industrial processes as proposed by the European High Temperature Reactor Technology Network (HTR-TN). This paper presents the main goals, the organization and the working approach of EUROPAIRS. It also presents the status of the viability assessment studies for coupling HTR with industrial end-user systems as one of the main pillars of the project. The main goal of the viability assessment is to identify developments required to remove the last technological and licensing barriers for a viable coupling scheme. The study is expected to result in guidelines for directing the choice of an industrial scale prototype.

Boiler Energy Conservation Performance Studies in a Commercial Facility: Setting the Stage for Cogeneration and Distributed Generation

ABSTRACT Growing attention is now being paid to energy conservation that was once considered insignificant for energy resource development. An energy efficiency study on the heating system for a commercial facility was performed using the BIN method that can be adopted by energy management practitioners. Such data-based method calculates the load and energy savings for the recommended boiler replacement. Energy consumption data, measurements and flowcharts developed were used to study the operating costs and energy savings for the facility. The study shows that the method can be used to decide if a boiler or heater replacement is worthwhile. Moreover, this study sets the stage for further energy management and reliability investment in the form of cogeneration of heat and power (CHP) or distributed generation (DG). It was determined in this study that using the prescribed strategy will result in significant energy savings for the investments made. Finally, basic data needed for cogeneration analysis resul...

Regulation strategies of cogeneration of heat and power (CHP) plants and electricity transit in Denmark

Denmark is in a situation with many scattered sources of electricity that are not controlled by the central load dispatch. At the same time, Denmark is being used as an electricity transit corridor between the hydro-based systems of Norway/Sweden and the thermal systems of Germany and continental Europe. Through energy systems analyses and load-flow analyses, it is determined that if geographically scattered load balancing utilising the regulation ability of hitherto locally controlled plants is introduced while also introducing new dispatchable loads in the form of electric vehicles and heat pumps, electricity transit is enabled to a higher degree than if central load balancing is maintained. This is the case of an intact transmission system as well as a system with inoperative transmission lines. With an intact system, the average load of the system is approximately halved when applying scattered load balancing. Utilising the regulating capacity of local plants thus improves the role of the Danish system in the Northern European system.

Enhancing our understanding of the role of environmental policy in environmental innovation: adoption explained by the accumulation of policy instruments and agent-based factors

The empirical literature reports conflicting findings on the relation between environmental policy and environmental innovation: environmental policy both encourages and impedes environmental innovation, resulting in competing theoretical explanations. To find a way out of this counterproductive debate requires new and complementary insights into the effects of different policy instruments. This research therefore advances an approach in which a set of specific policy instruments as well as firms’ behavior regarding CHP (cogeneration of heat and power) adoption are considered as two distinct factors explaining environmental innovation in the Dutch paper and board industry. Using a longitudinal research design, the focus was not on any single policy instrument but on the accumulation of policy instruments. In addition, we studied intra-organizational factors influencing the adoption decision.