The use of large-bore Otto gas engines is currently spreading widely considering the growing share of Power-To-Gas (P2G) solutions using renewable energies. P2G with a Combined Heat and Power (CHP) plant offers a promising way of utilizing chemical energy storage to provide buffering for volatile energy sources such as wind and solar power all over the world. Therefore, ambient conditions like air temperature, humidity and pressure can differ greatly between the location and time of engine operation, influencing its performance. Especially lean-burn Otto processes are sensitive to changes in ambient conditions. Besides, targeted use of humidity variation (e.g. through water injection in the charge air or combustion chamber) can help to reduce NO x emissions at the cost of a slightly lower efficiency in gas engines, being an alternative to selective catalytic reduction (SCR) exhaust gas aftertreatment. The ambient air condition boundaries have to be considered already in the early stages of combustion development, as they can also have a significant effect on generated measurement data in combustion research. To investigate the behavior, a test bench with a natural gas (CNG) powered single-cylinder research engine (piston displacement 4.77 1) at the Institute of Internal Combustion Engines (LVK) of the Technical University of Munich (TUM) was equipped with a sophisticated charge air conditioning system. This includes an air compressor and refrigeration dryer, followed by temperature and pressure control, as well as a controlled injection system for saturated steam and homogenizing containers, enabling the test bench to precisely emulate a widespread area of charge air parameters in terms of pressure, temperature and humidity. With this setup, different engine tests were conducted, monitoring and evaluating the engine’s emission and efficiency behavior regarding charge air humidity. In a first approach, the engine was operated maintaining a steady air-fuel equivalence ratio λ, fuel energy input (Q̇ fuel = const.) and center of combustion (MFB 50%) while the relative ambient humidity was varied in steps between 21% and 97% (at 22 °C and 1013.25 hPa). Results show a significant decrease in nitrogen oxides (NO x ) emissions (−39.5%) and a slight decrease in indicated efficiency (−1,9%) while hydrocarbon (THC) emissions increased by around 60%. The generated data shows the high significance of considering charge air conditioning already in the development stage at the engine test bench. The comparability of measurement data depends greatly on ambient air humidity. In a second approach, the engine was operated at a constant load and constant NO x emissions, while again varying the charge air humidity. This situation rather reflects an actual engine behavior at a CHP plant, where today often NO x –driven engine control is used, maintaining constant NO x emissions. The decrease in indicated efficiency was comparable to the prior measurements, while the THC emissions showed only a mild increase (5%). From the generated data it is, for instance, possible to derive operational strategies to compensate for changes in ambient conditions while maintaining emission regulations as well as high-efficiency output. Furthermore, the results suggest possibilities, but also challenges of utilizing artificial humidification (e.g. through water injection) considering the effects on THC emissions and efficiency. A possible shift of the knocking limit to earlier centers of combustion with higher humidity is to be investigated. The main goal is the further decrease of NO x emissions, increase of efficiency, while still maintaining hydrocarbon emissions.

Access to electricity is a key necessity in today’s World for economic growth and improvements in quality of life. However, the global challenge is addressing the so-called Energy Trilemma: how to provide secure, affordable electricity while minimizing the impact of power generation on the environment. The rapid growth in power generation from intermittent renewable sources, such as wind and photovoltaics, to address the environmental aspect has created additional challenges to meet the security of supply and affordable electricity aspects of this trilemma. Fossil fuels play a major role in supporting intermittent renewable power generation, rapidly providing the security of supply needed and ensuring grid stability. Globally diesel or other fuel oils are frequently used as the primary fuel or back-up fuel for fossil-fueled power generation plants at all scales, from a few kiloWatts to hundreds of MegaWatts, and helps provide millions of people with secure electricity supplies. But diesel is a high polluting fuel, emitting high levels of carbon dioxide (CO 2 ) per unit of fuel input compared to natural gas, as well as high levels of combustion contaminants that are potentially hazardous to the local environment and human health. Additionally, diesel can be a high cost fuel in many countries, with imports consuming significant portions of sometimes scarce foreign currency reserves. Most observers consider that natural gas is the ‘fuel of choice’ for fossil power generation due to its reduced CO 2 emissions compared to coal and diesel. However, access to gas supplies cannot be guaranteed even with the increased availability of Liquefied Natural Gas (LNG) and Compressed Natural Gas (CNG). Additionally where natural gas is available, operators may opt for an interruptible gas supply contract which offers a lower tariff than a firm gas supply contract, therefore there is a need for a back-up fuel to ensure continuous power supplies. While traditionally diesel or Heavy Fuel Oil (HFO) has been used as fuel where gas is not available or as a back-up fuel, propane offers a cleaner and potentially lower cost alternative. This paper compares the potential economic, operational and environmental benefits of using propane as a fuel for gas turbine-based power plants or cogeneration plants.

At the end of 2011, the Mexican Regulatory Energy Commission (CRE) has issued new rules to comply as efficient cogeneration plant. At this moment, there are some cogeneration plants under construction trying to accomplish these rules consisting in minimal design and operation parameters to overcome the current public power system efficiency. These rules can also be applied to those cogeneration plants currently operating. The approved efficient cogeneration plant can be considered as green energy in order to receive incentives to improve economic behavior of these kinds of plants. Basically, the wheeling cost is reduced compared to conventional power plants, the energy bank may be applied to swap energy and match production with demand. Also, interconnection services with public utility are offered cheaper. From the point of view of taxes the efficient cogeneration plant may be depreciated 100% the first year. However these incentives are not clear for the energy reform just signed by the Congress. This paper explains how these new rules from 2013 were applied in the design and construction of a new cogeneration plant.

The aim of this paper is to introduce readers to the UK’s Combined Heat and Power (CHP) industry, whilst identifying the key influences to the industry’s steady decline and the future diversification from an asset owner to a credible CHP or Utilities Operations and Maintenance (O&M) Service provider. There is a lack of research specific to the CHP and Utility O&M sectors that identify how to focus on attaining service excellence that adds real value to customers and stakeholders. The Service–Profit Chain (SPC) model developed by J. Heskett et al [1] is a recognised theory and business model that established the connection between profitability, customer loyalty, employee satisfaction and productivity. The application of the SPC model to the CHP and Utilities market sectors has identified a possible shortfall with the SPC model framework; in that it requires additional links to the resource support infrastructure and customer service cycle, whilst including the organization’s strategic service vision. Going beyond the application of the SPC model, this study will identify the additional management tools required to enhance and support the diversification process. An O&M SPC implementation model and a site specific Key Performance Indicator (KPI) model have been designed to complement the organization’s diversification. In addition to this, 10 golden rules have been developed in conjunction with a six tier approach to attain a meaningful O&M Service culture, which should ensure a sustainable future for an O&M Service provider.

In regions that utilize thermal desalination as part of their water supply portfolio, the cogeneration of water and power in cogeneration desalination plants couples the supply sides of the electricity and water grids. For a fixed plant design, there is a limited range of ratios of generated electric power to produced water at any given time. Due to this coupling, electricity and water require co-optimization. In an environment in which electricity supply is determined by deregulated wholesale markets, this need for co-optimization suggests a need for integrated electricity and water markets. In this market, independent power producers, independent water producers and independent cogeneration plants would submit bids to satisfy demand over a time horizon to a clearing mechanism, indicating relevant physical constraints. The mechanism would then optimize supply of both electricity and water over the time horizon of interest. Recently, a simultaneous co-optimization method has been contributed for the economic dispatch of networks that include water, power and cogeneration facilities in such an integrated market. This paper builds upon this foundation with the introduction of the corresponding unit commitment problem.

Many industries require heat or cold in their production plants. To meet these needs, companies usually equip their generation sites with combined heat and power plants. The goal of the present study is to build an accurate 1D-physical model of a cogeneration plant and to use it to optimize the plant from design phase to operation phase. The study shows that using the Modelica language and a library of plant components such as ThermoSysPro are adequate for building a modular 1D-physical model. Once the model built, optimization tools were used for optimizing both design (component specification for allowing maximized profit and minimized investment) and operation (loads of turbines and engines for maximized profit). Physical models may therefore be used for an optimization purpose. Moreover the developed tools may prove useful for engineers operating combined heat and power plants for monitoring and optimizing purposes.

Gas turbine-based power plants are very sensitive to ambient conditions and their output power and efficiency can be decreased significantly with increase in the ambient temperature. Various compressor inlet air cooling systems have been proposed and utilized to reduce inlet air temperature to the system, including evaporative systems e.g. media and fogging, and mechanical cooling systems. In this work, different techniques for compressor inlet air cooling are briefly reviewed. Then, the fogging system employed in the Whitby cogeneration power plant is explained with particular attention to the location of the system installation. A model of the gas turbine-based cogeneration plant is also developed to simulate the Whitby cogeneration power plant. The effects of fogging compressor inlet air cooling system on the performance of the plant are investigated. The results indicate that at an ambient temperature of 30°C and relative humidity of 40% the inlet cooling of as high as 8.4°C is possible which can increase output power to more than 50 MW. Also, it is found that the model can predict the gas turbine exhaust temperature and the plant’s power production with the error level of lower than 0.5% and 3%, respectively.

In waste to energy plants and certain genre of cogeneration plants, it is mandatory to condense the steam from the boiler or HRSG in a separate bypass condenser when the steam turbine is out of service. The steam from the boiler or HRSG is attemperated in a pressure reducing desuperheating valve and then condensed in a bypass condenser. To avoid flashing of condensate in downstream piping it is customary to subcool the condensate in the bypass condenser. Circulating water from the steam surface condenser is used to condense the steam in the bypass condenser. Some of the challenges involved in the design of the bypass condenser are: • High shellside design pressure and temperature • Condensate subcooling • Large circulating water (tubeside) flow rate • Relatively low circulating water (tubeside) inlet temperature • Large Log Mean Temperature Difference (LMTD) • Large shell diameters • Small tube lengths The diverse requirements complicate the mechanical and thermal design of the bypass condenser. This paper highlights the complexities in the design and performance of the bypass condenser. Similarities with the design and operation of steam surface condensers and feedwater heater are reviewed. The uniqueness of the bypass condenser’s design and operation are discussed and appropriate solutions to ensure proper performance are suggested.

Inlet air filtration systems are essential components for any power plant based on gas turbines, because poor air quality can significantly impact the operation and performance of the gas turbine. But higher pressure losses due to the filtration system have a negative impact to the power plant performance. In this paper, the field experience with a typical inlet air filtration system for a modern 100MW (electric) combined cycle cogeneration power plant (called “HKW Hafen”, Muenster, Germany) is discussed. The long-term observations demonstrated clearly the importance of the filtration system. A poor filtration performance was found for the initial system, and a re-design was initiated. With regard to this task, the use of computer-aided engineering tools (CAE) has proven its reliability. This approach enables an efficient tool for searching customized solutions for a specific power plant with a high confidence level. It was found that frequently used guidelines and supplier information are not completely sufficient for precise cost saving calculations.

Based on the mode of off-grid and supplying power for a 10,000 Chicken Farm, there is a experimental study and energy efficiency analysis on a biogas CHP. The results indicate that, the biogas CHP system can satisfy the demand on heating of biogas digester and electricity of farm’s. Reusing the gas-fired remaining heating powered in the internal engine to heat the digester, it can guarantee the temperature in the biogas digester between 32°C and 34°C, even if the climate is very cold. The power load vary obviously in 24 hours, power efficiency and energy efficiency of the biogas CHP plant increase with increasing of the power load of the farm. In low power load operation, the power generation efficiency and energy efficiency of entire system is very low, respectively 4.3%–19%, with the increasing of the load, the measured power efficiency is up to 19.2% when energy efficiency up to 47%, which is lower than that of the fossil CHP. By analyzing the main reason, it is found that the off-grid mode restricts the power load to vary with that of the farm passively, the heat efficiency exchanging is low between the cylinder water and the flue gas heat exchanger of the system, need to be reconstructed and installed gear change iso-frequency mechanism for decreasing the in-gas-fired quantity.

Many industrial processes result in tail gas wastes that must be flared or incinerated to abide with environmental guidelines. Tail gas incineration occurs in several chemical processes resulting in high-temperature exhaust gas that simply go to the stack, thus wasting all that valuable heat! This paper discusses useful heat recovery and electric power generation utilizing available heat in exhaust gas from tail gas incinerators. Tail gas, which is considered as the main fuel in this study, is typically “free” fuel. Eventhough with low heat content, when the heat is recovered and utilized properly, heat recovery of tail gas will result in significant savings to the plant. The thermodynamic and economic study presented here assumes that heat will be recovered in a wast-heat recovery boiler from the exhaust gas out of the incinerator and will produce enough superheated steam to generate 25 MW in a condensing steam turbine generator. Data for this study were provided by an operating chemical production facility in the southeastern region of the US. Energy analysis and a total project scope cost estimate were developed for this study. Actual costs were obtained for all major equipment. Different thermodynamic scenarios were considered to identify the optimum and most economical energy system design. The main goal of the study was to fulfill the plant’s power and steam requirements and sell the additional power to the local utility. An existing old steam boiler will be retired after the incorporation of the new cogeneration plant. Process steam will be supplied via a steam turbine extraction. The results indicate that the total capital cost of a ± 25% grade estimate for the supply and installation of the 25 MW cogeneration system, is estimated to be $51,000,000 in the fourth quarter of 2008 dollars with escalation through end of 2010, representing $2000/kW. Based on an internal power demand of 12 MW by the chemical plant, a balance of 13 MW is assumed be sold to the local utility. The cost of electricity used for this study was assumed to be 9 cents per kilowatt-hour for purchased power and 6 cents per kilowatt-hour for sold power. The annual plant savings in purchased power is estimated to be over $6,300,000 while the annual plant revenue from selling the remaining power is estimated to be in excess of $6,200,000. The cost analysis, when accounting for operation and maintenance, resulted in a pay back period of less than 4 years and an internal rate of return on investment of over 13 percent after 6 years.

The effort of carbon dioxide emission reduction, required to the European countries, especially to Italy, is very remarkable, particularly in the thermoelectric sector. Because between the various policies and measures it is possible to adopt the mechanism of exchange (sale/purchase) of emission rights (Emission Trading), in this work the authors intend to focus on Italian thermoelectric sector and want to illustrate the energy and economic consequences of various operational scenarios that can be conceived for power plants, fuelled by natural gas. In fact, through the Kyoto protocol and its country-specific targets, power producers are strongly driven towards CO2-reducing solutions such as, for example, power modulation. Two examples of advanced thermoelectric power plants, operating in Italy, will be described: the first power plant produces only electric energy while the second one is a cogeneration power plant (it produces heat and electric energy). For both power plants, the best management criteria will be discussed in order to attain competitive performance of such facilities. The final goal is to minimize the cost of production (or to maximize profits), taking into account, however, the specific targets for CO2 emissions.

Cimplicity is a Human-Machine interface software which acquires data from CNCs Robots and PLGs, data is then visualized on real time by an operator in a Cimplicity screen on a PC monitor. This software lets the operator perform operations, monitor and control status in a factory in an easy, natural, and intuitive way. This paper will focus on the use of Cimplicity HMI and Microsoft Excel in COMONSA, a cogeneration plant designed and installed by SEISA (International Energy Systems). The cogeneration plant is localized in Monclova, Coahuila, Mexico. This plant supplies energy and, heat to a metal manufacturing factory called INMAGUSA. In this case Cimplicity acquires data from a PLC connected to two reciprocating Engines, which are responsible of supplying heat and electrical energy to the factory, and other auxiliary devices that keep the cogeneration plant running. Cimplicity transforms the data received by the PLC and then displays it on screens while it is being stored on Excel sheets in predefined time intervals. A total of 1093 variables are displayed in 70 different screens. This paper will center on the variables, screens and programs created by the authors. Screens created for the purpose of making the process of invoicing easier for SEISA, for monitoring daily kWh and monthly factory consumption. And two algorithms programmed using Microsoft Visual Basic to facilitate optimal operation of the cogeneration plant.

One of the best methods for insuring a power plant will produce its guaranteed base load is to have an excess of circulating cold water or at least the expected guaranteed cold water temperature throughout the year. Yet, within industry today, numerous mistakes continue to be made when purchasing a cooling tower, by both the Subcontractor, and the Contractor. Only following only normal design criteria established by cooling tower Subcontractors, or an industry association, is not sufficient. Guidelines in the cooling tower industry have been established to set forth minimum standards that have helped to eliminate obvious past deficiencies. They were not established to protect the Subcontractor. Nor were they established to guarantee the Contractor receives what is thermally and mechanically necessary for a given project. Design of a cogeneration or industrial plant does not always consider the necessary requirements on a cooling tower over the range of expected operation. This type of design for a cooling tower is more complicated than the single guarantee point operational design of a power plant that is the current norm. Just as the Contractor needs to consider how to meet the thermal energy requirements over the range of expected operation of the plant, the Subcontractor of the cooling tower must do the same. Contractors must be aware that the cooling tower designer does not consider aspects that are often applicable to cogeneration plants and therefore they must include exceptions to the Subcontractors’ optimized offering in their standard cooling tower specifications. These exceptions in no way disagree with the Codes and Standards adopted by the cooling tower industry or any governing agency. This paper will address exceptions that the power plant and cooling tower designer needs to take into consideration to ensure that a reliable supply of cold water relates to the thermal duty requirements from the plant throughout the year.

The scope of modern power plant controls usually includes plant DCS, boiler control and protection, steam/gas turbine governor and protection, auxiliaries control, automatic voltage controller, automatic synchronizer and operator/engineering stations. Usually these control packages come from different manufacturers (OEM). They are typically based on various electronic hardware and software platforms. Different communication protocols often present problems during system integration; and maintenance costs of these various electronic hardware and software platforms are normally greater than that of a stand alone system. Advantages of an integrated, distributed, open architecture, digital system, (Fig. 1) which covers all the power plant needs are discussed in this paper. A common electronic hardware/ software platform allows optimization of the new constructions and upgrades, shorten delivery and commissioning time, and improve availability and safety of the new and upgraded power plants. Specific benefits of this concept are presented in the Mt. Poso controls upgrade Case Study. The common electronic hardware/ software platform installed at Mt. Poso allowed optimization of the upgrade, shortened commissioning time, improved availability, reliability and safety and reduced maintenance cost of the control systems.

This paper describes a methodology to set up models for simulation and diagnosis of energy plant components. The adopted approach consists in a simultaneous solution of modules representing plant components taking their actual behavior into account. Models are characterized by Reality Functions to adapt them to the reality of machines and apparatuses so that the New&Clean map of the real component can be established. Furthermore, to account for deterioration phenomena occurring during plant operations, Actuality Functions affecting component performance in terms of work and heat transfer, losses and effective flow functions have been introduced. Models have been validated and tested against real CHP plant data. Two applications to different kinds of power plants are presented and discussed. Results show a good capability to estimate component deterioration statuses and reproduce component actual behavior maps.