Combined Heat And Power Installations Research Articles

Irradiance-to-power conversion based on physical model chain: An application on the optimal configuration of multi-energy microgrid in cold climate

This article is primarily concerned with the optimal configuration of multi-energy microgrid in cold climate. Although involving photovoltaic (PV) has been commonplace in works of this sort, one thing that has yet to receive sufficient care is pertained to how exactly PV power output is modeled. Indeed, refined PV modeling has an decisive effect on whether or not the configured microgrid is going to operate as intended in the long run. On this account, physical model chain, a refined way to convert irradiance to PV power output through a series of models, as opposed to the conventional one-equation conversion, is herein emphasized. Then, by adopting the mixed integer linear programming, the configuration of a microgrid with both residential and commercial buildings in cold climate, alongside a rich selection of energy converters and storage devices, is performed. The case study results suggest: (1) configurations based solely on the conventional PV model tend to exaggerate the power production from PV by 10.31%, causing a severe underestimation in total annualized cost by 8.26%; (2) thermoelectric coupling in cold climate favors the inclusion of combined heat and power (CHP) units, which occupy 17% of total capacity; and (3) when heavy carbon emission penalty is invoked, the optimal configuration requires one to double the CHP installation but only add a moderate amount of PV. To support open research, data and Python code used to generate the results are offered as supplementary materials.

Combined heat and power as a platform for clean energy systems

Many regions and countries including Europe, China, Japan, and Canada are expanding their combined heat and power (CHP) systems, often coupled with renewable fuels, to provide platforms for clean energy. In the United States, however, CHP market shares are. A cost-benefit analysis of CHP systems in Georgia (an industry-heavy state in the Southeastern U.S.) suggests that the benefits from reduced fuel costs and steam production far exceed the CHP installation and O&M costs. We estimate other benefits, as well, including jobs, cleaner air, public health, and a 2–13% reduction in Georgia’s total carbon emissions. However, the capital-intensive nature of CHP systems can be difficult for host industries, and utilities are reluctant to purchase their excess electricity. Possible approaches to address these barriers include clean energy portfolio standards, regulatory reform, financial incentives such as tax credits. By developing a comprehensive case study methodology for evaluating the expansion of CHP systems, analysts can examine the costs and benefits of cogeneration in other regions with their particular industry profiles, fuel costs, and policies. Analysis of key stakeholders and policy options adds social and behavioral insights for the design of effective government interventions to capture the economic and social benefits of CHP systems.

Cogeneration Supporting the Energy Transition in the Italian Ceramic Tile Industry

Ceramic tile production is an industrial process where energy efficiency management is crucial, given the high amount of energy (electrical and thermal) required by the production cycle. This study presents the preliminary results of a research project aimed at defining the benefits of using combined heat and power (CHP) systems in the ceramic sector. Data collected from ten CHP installations allowed us to outline the average characteristics of prime movers, and to quantify the contribution of CHP thermal energy supporting the dryer process. The electric size of the installed CHP units resulted in being between 3.4 MW and 4.9 MW, with an average value of 4 MW. Data revealed that when the goal is to maximize the generation of electricity for self-consumption, internal combustion engines are the preferred choice due to higher conversion efficiency. In contrast, gas turbines allowed us to minimize the consumption of natural gas input to the spray dryer. Indeed, the fraction of the dryer thermal demand (between 600–950 kcal/kgH2O), covered by CHP discharged heat, is strictly dependent on the type of prime mover installed: lower values, in the range of 30–45%, are characteristic of combustion engines, whereas the use of gas turbines can contribute up to 77% of the process’s total consumption.

Techno-Economic Assessment of CHP Systems in Wastewater Treatment Plants

Wastewater treatment plant (WWTP) utilization of combined heat and power (CHP) systems allows for the efficient use of on-site biogas production, as well as increased annual savings in utility costs. In this paper, a review of biogas energy recovery options, CHP prime mover technologies, and the costs associated with biogas cleaning give a broad summary of the current state of CHP technology in WWTPs. Even though there are six different prime mover technologies, the main ones currently being implemented in WWTPs are micro turbines, fuel cells and reciprocating engines. Different prime movers offer varying efficiencies, installation costs, and biogas impurity (H2S, siloxanes, HCl) tolerances. To evaluate the long-term savings capabilities, a techno-economic assessment of a CHP installation at a case study WWTP shows the payback, annual savings, and initial costs associated with the installation of a CHP system. In this case, a study a payback of 5.7 years and a net present value of USD 709,000 can be achieved when the WWTP generates over 2,000,000 m3 of biogas per year and utilizes over 36,000 GJ of natural gas per year.

Experimental and economic study of small-scale CHP installation equipped with downdraft gasifier and internal combustion engine

This paper concerns the experimental and numerical analysis of a combined heat and power (CHP) installation equipped with a biomass downdraft gasifier, gas purification system and gas piston engine. The numerical studies were aimed at identifying waste heat in the CHP installation for further utilisation. In turn, a new innovative method of heat recovery inside the gasifier was proposed and subsequently applied in the experimental CHP installation. The newly developed facility is able to produce up to 75kWe of electrical power. An extensive parametric study was performed under the steady and unsteady facility operation and was supplemented by economic analysis of the process. The main objective of the study was to examine the possibility of sewage sludge gasification and the impact of produced syngas quality on gas engine performance. During the investigation a number of different types of biomass were investigated including wood pellets, sewage sludge and their blends. The results showed a stable operation of the CHP facility in terms of produced syngas load, calorific value and content – even when dried sewage sludge was used alone. Results indicate that a 40/60% blend of wood pellets with sewage sludge is recommended, which allowed the lower heating value (LHV) of 4.45MJ/Nm3. Additionally, it was confirmed that the fixed bed gasifier is able to self-adjust to temporary changes in gasifier agent load.The economic analysis was performed taking into account policies and regulations in the Polish energy market sector. The study showed that it is more profitable to use the generated electricity and heat for its self-consumption rather than selling it on the market. Even with the supporting policies the payback time is not less than about eight years. Taking into account calorific value and limited local biomass availability, it seems justified that the described CHP installation is suitable for decentralised power generation such as small farms or horticultural businesses, where the produced electricity and heat can be sufficiently utilised. This technology also contributes to reduction of CO2 emissions into the atmosphere, which is one of the most problematic issues for energy sector today.

Experimental evaluation and ANN modeling of a recuperative micro gas turbine burning mixtures of natural gas and biogas

Previously published studies have addressed modifications to the engines when operating with biogas, i.e. a low heating value fuel. This study focuses on mapping out the possible biogas share in a fuel mixture of biogas and natural gas in micro combined heat and power (CHP) installations without any engine modifications. This contributes to a reduction in CO2 emissions from existing CHP installations and makes it possible to avoid a costly upgrade of biogas to the natural gas quality as well as engine modifications. Moreover, this approach allows the use of natural gas as a “fallback” solution in the case of eventual variations of the biogas composition and or shortage of biogas, providing improved availability.In this study, the performance and emissions of a commercial 100kW micro gas turbine (MGT) at full and part loads are experimentally evaluated when fed by varying mixtures of natural gas and biogas. The MGT is equipped with additional instrumentation, and a gas mixing station is used to supply the demanded fuel mixtures from zero biogas to the maximum possible level by diluting natural gas with CO2. A typical biogas composition with 0.6 CH4 and 0.4 CO2 (in mole fraction) was used as reference, and corresponding biogas content in the supplied mixtures was computed.This paper presents the test rig setup used for the experimental activities and reports the results, demonstrating the impact of burning a mixture of biogas and natural gas on the performance and emissions of the MGT. The results indicate that the electrical efficiency is almost unchanged and no significant changes were observed in operating parameters, comparing with the natural gas fired case. It was also shown that burning a mixture of natural gas and biogas contributes to a significant reduction in CO2 emissions from the plant by about 19% at full load operation. Given the extensive data obtained during the experimental tests, a data-driven model based on an artificial neural network (ANN) was developed to simulate the performance of the MGT. The mean relative error (MRE) was used to evaluate the prediction accuracy of the developed ANN model with respect to experimental data which were not used during the training. It was demonstrated that the ANN model can predict the performance parameters of the MGT with high accuracy and the error of most samples is less than 1%. A graphical user interface (GUI) was created for the ANN model in Microsoft Visual Basic. The GUI is presented as a user-friendly tool for modeling and condition monitoring of the plant.

Prediction and analysis of the seasonal performance of tri-generation and CO2 refrigeration systems in supermarkets

A modern supermarket energy control system has a concurrent need for electricity, space heating or cooling, and food refrigeration. The power supply to the supermarket is primarily from the national grid, where losses in efficiency are due to the processes of energy conversion and transmission. Combined heat and power (CHP) offers the potential to locally produce electrical power and heating which could save energy and reduce CO2 emissions in the long run. During the summer months, as the space heating requirement in a supermarket is relatively small, the energy efficiency of a CHP installation can be improved by using excess thermal energy to drive a sorption refrigeration system to provide space cooling or refrigeration. This process is also known as tri-generation. In recent years, the use of CO2 as a refrigerant in supermarkets has received considerable attention due to its negligible contribution to direct greenhouse gas emissions and excellent thermophysical and heat transfer properties. Consequently, the application of a tri-generation system in a supermarket with CO2 refrigeration merits further investigation.In this paper, to evaluate the performance of a tri-generation system in the supermarket, a previously tested 80kWe microturbine device was applied into an operational supermarket to generate power and provide space heating and cooling through exhaust heat. The performance evaluation and comparison for this tri-generation application is based on the prediction from an integrated model of supermarket energy control, cascade CO2 refrigeration and tri-generation systems. The results from this simulation demonstrate the feasibility of a tri-generation system in the supermarket and pave the way for further consideration towards designs in future.

Possibilities of implementation of CHP (combined heat and power) in the wood industry in Serbia

The paper presents results of techno-economic analysis of using wood residues from wood industry for CHP (combined heat and power). The aim was to determine the economic feasibility of CHP in Serbia in the light of newly adopted feed in tariffs. In the first part, costs of electricity production are calculated for five different types of CHP technology which could meet the needs of wood industry in Serbia. In the second part of the paper, sawmill wood processing and pellet production were taken into consideration. First, we found that the installation of CHP in small capacity sawmills (about 10,000 m3/year) is not economically justified. The main reasons are high investments in micro CHP (up to 100 kWel) per kW of power. Second, the approximate electricity production costs in the potential CHP installations in pellet factory with capacity about 50,000 tonne per year is only slightly lower than the offered purchase price. However, advancement in CHP technologies and increase of the number of implemented projects should lead to a drop of equipment prices. Regardless of the price increase of raw materials and labour, this drop will have a significant impact on the reduction of total costs of electricity generation with CHP becoming more attractive to investors.

Techno-economic Evaluations of Various Biomass CHP Technologies and Policy Measures Under Norwegian Conditions

This work deals with evaluations of different possible cost-effective small-scale combined heat and power (CHP) solutions based on biomass for the Norwegian market. Many CHP technologies and systems exist and can easily be proposed as candidates for introduction and/or widespread use in the Norwegian market. However, today they may be far from cost-effective given the current energy market and framework situation. These constraints can, however, change relatively fast. Hence, it is important to evaluate the feasibility of small-scale CHP technologies and systems in this perspective. What will the most promising small-scale CHP technologies based on biomass be in the near to medium term future? What are the limiting factors? What can be done to speed up the introduction of small-scale CHP solutions based on biomass in the Norwegian market? This work evaluates techno-economics of various CHP solutions based on biomass in the Norwegian market. Traditional financial indicators such as financial internal rate of return and net present value are used to assess the solutions. The methodology includes the following sequential steps: estimation of the economic production costs of various options for biomass CHP for power and heat generation and sorting these options in ascending order of costs to present the supply curve to meet the national target. Finally, the analysis includes various incentive schemes, feed-in tariffs/green certificates, investment based tax exemptions (8 years for each technology), prolonged tax exemption (+5 years for each technology), investment subsidies (in % for each technology) and low-interest loans (decided for each technology). Based on the evaluations, MSW backpressure turbine, biogas engine and industrial backpressure turbine are profitable without any subsidy under Norwegian framework conditions. With additional subsidy from grid deduction fee and green certificates, district heat ORC, district heat backpressure turbine and gasification with micro gas turbine are feasible with profitability of internal rate of return above 11%. Other gasification technologies are feasible under prevailing market conditions. In addition, a cost supply curve is generated for 10 years framework conditions based on the planned CHP installations.

Combined Heat and Power Systems in University Environment

ABSTRACT Combined heat and power (CHP) technology is still underutilized in the building sector due to the concern of insufficient economic returns related to the seasonal heating and cooling loads and the initial costs of installing these applications. In order to justify the use of CHP systems, the thermal energy created has to be used in a fashion that is favorable to the building's environment. The thermal load is used for heating, hot water, and thermal-driven cooling and humidity controls. This includes a variety of CHP technologies along with absorption chillers or desiccant dehumidification systems. This article provides a summary on some of the CHP installations in university environment. The constant influence of changing technologies and higher utility rates has forced universities and colleges to make energy management improvements. The literature survey on these universities is not vast because the new and improved systems are still in their beginning years and have not established concrete s...

A general technoeconomic and environmental procedure for assessment of small-scale cogeneration scheme installations: Application to a local industry operating in Thrace, Greece, using microturbines

Abstract The present paper describes a proposed general systematic procedure for small-scale combined heat and power (CHP) exploitation (where “small-scale CHP” refers to CHP installations with electric capacities up to 1 MW). The mentioned systematic procedure is implemented through a developed computer code and may be applied to any such small-scale project in order to assess its suitability based on technoeconomic and environmental considerations. A dynamic database based on small-scale CHP units (available in the world market) and their pertinent technical, economical and environmental features is created and, in conjunction with the developed program, is used for determination of a suitable CHP unit (or system) size and the selection of the associated proper prime mover type for any project of interest. Using well-known economic criteria, the economic analysis is performed, including the sensitivity analysis of the considered project based on the main key system parameters. In terms of the socioeconomic analysis, a carbon tax (CT) scenario is considered, and its effect on the economic behavior of the project is investigated. Last, with respect to environmental considerations, the program calculates, for any such project, the avoided main pollutants and the fuel savings when a CHP system is applied. As a case study, a small textile industry operating in the Eastern Macedonia-Thrace Region of Greece is considered, and its associated (electrical and thermal) data are used as input data to the proposed computer program. In this application, two microturbine units are selected and thoroughly evaluated, and the pertinent simulation results are presented and discussed accordingly.

Thermoeconomic analysis based on energy structure for combined heat and power

This paper proposes a unified comparison method for the calculations of thermodynamic efficiencies applied to combined heat and power (CHP) plants. Two new dimensionless indices are introduced. They are used to estimate the influence of technical and economical features on the profitability of a CHP plant. A case of a CHP installation by internal combustion engine is treated as a practical application.