Optimization of Small-Scale Trigeneration Systems in Terms of Levelized Total Costs and Carbon Tax Using a Matrix Modeling Approach (original) (raw)
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Operational strategy and marginal costs in simple trigeneration systems
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As a direct result of economic pressures to cut expenses, as well as the legal obligation to reduce emissions, companies and businesses are seeking ways to use energy more efficiently. Trigeneration systems (CHCP: Combined Heating, Cooling and Power generation) allow greater operational flexibility at sites with a variable demand for energy in the form of heating and cooling. This is particularly relevant in buildings where the need for heating is restricted to a few winter months. In summer, the absorption chillers make use of the cogenerated heat to produce chilled water, avoiding waste heat discharge. The operation of a simple trigeneration system is analyzed in this paper. The system is interconnected to the electric utility grid, both to receive electricity and to deliver surplus electricity. For any given demand required by the users, a great number of operating conditions are possible. A linear programming model provides the operational mode with the lowest variable cost. A thermoeconomic analysis, based on marginal production costs, is used to obtain unit costs for internal energy flows and final products as well as to explain the best operational strategy as a function of the demand for energy services and the prices of the resources consumed.
An Optimization Model for A Proposed Trigeneration System
The combined cooling, heating, and power (CCHP) systems play an important role in the reduction of carbon emissions and the increase of energy efficiency for businesses and social organizations. Because of its potentials, tri-generation system has become a preference during the last decade. In this paper a hybrid tri-generation system is proposed for a university campus. The system is also important because it uses renewable energy sources as well as non-renewable energy sources. The objective of this paper is to propose an optimization model for this new Tri-generation system.
Environmental assessment rules for simple trigeneration systems under variable operation conditions
Environmental concerns have been a growing issue when planning energy supply systems for buildings, as the energy demands (presenting seasonal and daily variations) represent one of the most energy-intensive consumptions in industrialized societies. The optimal operation mode of a trigeneration system corresponding to several demands was obtained from the solution of a linear programming model. Surplus electricity can be sold to the national grid and part of the cogenerated heat can be wasted if this results in a decrease of operation costs and/or environmental loads. Thermoeconomic analysis, usually used to allocate energy and economic costs, is applied to the evaluation of environmental costs and the distribution of resources throughout the trigeneration system. Attention is focused on the correct allocation of the energy resources consumed (evaluated at market prices) and of the environmental loads involved in the operation of the trigeneration system (applying Life Cycle Analysis) to internal flows and final products. Appropriate rules are given to calculate energy and environmental costs. The allocation method proposed is congruent with the objectives of installing trigeneration systems that supply energy services with fewer emissions than those of separate production, and of equally benefitting the consumers of heat, cooling and electricity.
Applied Thermal Engineering, 2013
The combined production of electricity, heat and cold by polygeneration systems ensures maximum utilization of resources by reducing emissions and energy losses during distribution. Polygeneration systems are highly integrated systems characterized by the simultaneously production of different services (electricity, heating, cooling) by means of several technologies using fossil and renewable fuels that operates together to obtain a higher efficiency than that of an equivalent conventional system. The high number of distribution technologies available to produce electricity, heating and cooling and the different levels of integration make it difficult to select of the optimal configuration. Moreover, the high variability in the energy demand renders difficult the selection of the optimal operational strategy. Optimization methodologies are usually applied for the selection of the optimal configuration and operation of energy supply systems. This paper presents a scenario analysis using optimization models to perform an economic, energetic and environmental assessment of a new polygeneration system in Cerdanyola del Vallès (Spain) in the framework of the Polycity project of the European Concerto Program. This polygeneration system comprise high-efficiency natural gas cogeneration engines with thermal cooling facilities and it will provide electricity, heating and cooling for a new area in growth known as Alba park including a Synchrotron Light Facility and a Science and Technological park through a district heating and cooling network of four tubes. The results of the scenario analysis show that the polygeneration plant is an efficient way to reduce the primary energy consumption and CO 2 emissions (up to 24%).
Allocation of economic costs in trigeneration systems at variable load conditions
Lancet, 2011
This paper presents a thermoeconomic analysis of a trigeneration system interacting with the economic environment. The aim is to determine the energy and total costs of internal flows and final energy services (electricity, cooling and heat). One of the main difficulties in calculating these costs in trigeneration plants within buildings is the continuous variation of energy supply services. Fuel prices and purchase/sale electricity tariffs can also vary. As a consequence there are different operation conditions that combine the possibilities of purchasing or selling electricity, consuming heat from auxiliary boilers, and wasting the excess of cogenerated heat. A novel cost allocation method valid for all possible operation conditions of the trigeneration system is proposed. The heat produced by cogeneration modules is disaggregated into three fractions: heat that meets the heat demand directly, heat utilized to drive absorption chillers (producing cooling), and heat dissipated to the environment. Cost allocation to all cogeneration co-products is determined by applying the principle of avoided expenditures. The cost allocation proposal is applied to a trigeneration system providing energy services to a hospital with 500 beds located in Zaragoza (Spain), encouraging rational and efficient energy services production and consumption.► Thermoeconomic analysis of a trigeneration system operating at variable load conditions. ► The heat cogenerated is disaggregated into three fractions. ► Costs are allocated by applying the principle of avoided expenditures. ► Energy and total costs of electricity, heat and cooling are calculated. ► The proposal encourages rational and efficient operation of the system.
OPTIMIZATION OF A TRIGENERATION SYSTEM BASED ON ENVIRONMENTAL FACTORS SEPTEMBER 2014
Optimization of trigeneration system is frequently based on reducing the cost of operation instead of concentrating on the primary energy consumption and emission of the system. Optimizing the system based on various strategies would go a long way in improving the impact on the environment. Trigeneration systems can be operated using three different strategies which are electric load, thermal load and a hybrid mode which is a combination of the previous strategies. In this report, the strategies would be used to evaluate and optimize the trigeneration system based on the primary energy consumption, carbon dioxide emission while also including the operational cost. The system was evaluated in four separate cities. The results show that the trigeneration system has a better performance when operating in a hybrid mode than when it is operating under the electric or thermal modes. It also proves that the system is better operating under any of these operating strategies than it is operating without them. The average annual PEC and CDE reduction in the cities were 10% and 6% respectively for the hybrid trigeneration system, while the operating cost was also reduced by 54%.
Energy, 2017
The development of high-efficiency energy systems is a pressing issue nowadays, motivated by economic, environmental, and social aspects. Trigeneration systems allow for the rational use of energy by means of appropriate energy integration and provide greater operational flexibility, which is particularly interesting for buildings, often characterized by variable electricity, heating, and cooling demands. The benefits of trigeneration systems can be enhanced by the incorporation of thermal energy storage (TES), which decouples production and consumption. This paper analyses the operation of a simple trigeneration system including TES. The optimal operation is obtained by a linear programming model that minimizes the total variable cost. A thermoeconomic analysis based on marginal cost assessment of the internal flows and final products of the system is carried out, allowing to explain the optimal operation of the system and the role of the TES in achieving the optimal solution. The analysis unravels the marginal cost formation process, presenting a clear route from the final products obtained to the resources consumed. This information can aid the design of new plants, the retrofit of existing ones, and the operational management to achieve the minimum operational cost.
Technology , optimization and decision-making review for cogeneration and trigeneration systems
2018
There is an increasing concern about the need for energy security and impact of greenhouse gas emission all over the world. Energy efficiency has been identified as part of the solution to ensure the energy supply as well as lower the greenhouse gas emissions. Combined Heating and Power generation (CHP) and Combined Cooling, Heating and Power generation (CCHP) systems can contribute to the reduction of primary energy consumption and greenhouse gas emissions in residential and tertiary sectors, by reducing fossil fuels demand and grid losses with respect to conventional systems. The trigeneration systems are characterized by very high energy efficiency (80 to 90%), as well as a less polluting aspect compared to the conventional energy production, since the waste heat is recovered from the engine cooling system and exhaust gases that are being used for process heating, and excess heat is also used to drive an absorption cooling system. In this paper, we will show a review on the studi...
OPTIMIZATION OF A TRIGENERATION SYSTEM BASED ON ENVIRONMENTAL FACTORS
Optimization of trigeneration system is frequently based on reducing the cost of operation instead of concentrating on the primary energy consumption and emission of the system. Optimizing the system based on various strategies would go a long way in improving the impact on the environment. Trigeneration systems can be operated using three different strategies which are electric load, thermal load and a hybrid mode which is a combination of the previous strategies. In this report, the strategies would be used to evaluate and optimize the trigeneration system based on the primary energy consumption, carbon dioxide emission while also including the operational cost. The system was evaluated in four separate cities. The results show that the trigeneration system has a better performance when operating in a hybrid mode than when it is operating under the electric or thermal modes. It also proves that the system is better operating under any of these operating strategies than it is operating without them. The average annual PEC and CDE reduction in the cities were 10% and 6% respectively for the hybrid trigeneration system, while the operating cost was also reduced by 54%.
Thermoeconomic Analysis of Simple Trigeneration Systems
Trigeneration is the combined production of heating, cooling and power from the same source of energy. In this paper, the operation of a simple trigeneration system is analyzed. The system is interconnected to the electric utility grid, both to receive electricity and to deliver surplus electricity. For any given demand required by the users, a great number of operating conditions are possible. The operational mode with the lowest variable cost is obtained through a linear programming model. Three different approaches to determine the costs of internal flows and final products of the simple trigeneration systems are presented: marginal costs corresponding to optimal operation, costs obtained when production costs are distributed to the final products according to their market prices, and internal costs corresponding to a thermoeconomic analysis of the operation mode of the system. As expected, the costs obtained with the approaches mentioned are different and it can be concluded that there are no general rules to decide which approach is best: it depends on the issue under investigation.