Alta Knizley

Potential emissions reductions from the use of dual-combined heat and power systems in different climate conditions

In this paper, the potential carbon dioxide emissions (CDE) reduction from the use of a combined heat and power system with two power generation units (D-CHP) is examined for a restaurant building in nine different climate conditions. The performance of the D-CHP system is evaluated on the basis of CDE and operational cost savings. In addition, the results from the D-CHP optimised scheme are compared with the optimised results of a base-loaded CHP (BL-CHP) system and a CHP system operated following the electric load (CHP-FEL). Results show that the D-CHP system produces greater savings over BL-CHP and CHP-FEL for most of the locations examined, whether optimised based on CDE or based on cost. Moreover, the effect of the emissions and cost spark spreads for each location on the D-CHP system performance is analysed. Results indicate that higher spark spreads are shown to yield greater savings for all CHP configurations.

Evaluation of the operational cost savings potential from a D-CHP system based on a monthly power-to-heat ratio analysis

Abstract This paper focuses on the analysis of a combined heat and power (CHP) system utilizing two power generation units operating simultaneously under differing operational strategies (D-CHP) on the basis of operational cost savings. A cost optimization metric, based on the facility monthly power-to-heat ratio (PHR), is presented in this paper. The PHR is defined as the ratio between the facility electric load and thermal load. Previous work in this field has suggested that D-CHP system performance may be improved by limiting operation of the system to months in which the PHR is relatively low. The focus of this paper is to illustrate how the facility PHR parameter could be used to establish the potential of a D-CHP system to reduce operational cost with respect to traditional CHP systems and conventional systems with separate heating and power. This paper analyzes the relationship between the PHR and the operational cost savings of eight different benchmark buildings. Achieving operational cost savings through optimal operation based on monthly PHR for these building types can enhance the implementation potential of D-CHP and CHP systems. Results indicate that the PHR parameter can be used to predict the potential for a D-CHP system to reduce the operational cost.

Effect of Electric Energy Storage on the Performance of a Power Generation Unit-Organic Rankine Cycle System

Combined heat and power (CHP) systems simultaneously generate on-site electricity and provide useful heat by utilizing waste heat from a power generation unit (PGU). CHP systems can enhance energy production efficiency and energy sustainability by reducing grid dependency, often yielding cost savings in the process. Furthermore, CHP systems can provide savings over conventional systems in terms of operational cost, primary energy consumption (PEC), and carbon dioxide emissions (CDE). Typical CHP systems generate onsite power using a PGU, and the waste heat from the PGU is used to provide heating or hot water to the facility. Another variation for this system is to incorporate an organic Rankine cycle (ORC) to allow for increased potential reductions in operational cost, PEC, and CDE when compared to separate heat and power. This paper evaluates the effect of using electric energy storage on the performance of a PGU-ORC system. In the proposed system, the waste heat from a PGU is used to generate and to store electricity using an ORC coupled with electric energy storage (ES) (battery). Then, the electricity that is stored in the batteries could be used during the system operation at different times of the day so the PGU does not have to operate all the time. The PGU-ORC-ES system (with battery storage) is compared with a conventional system in terms of operational cost, PEC, and CDE. A restaurant building located in Chicago, IL is used to evaluate the potential of the proposed PGU-ORC-ES system. Results indicate that the addition of electric energy storage is beneficial to the proposed PGU-ORC system in terms of operational cost, PEC, and CDE. Furthermore, the effect of the size of the electric energy storage on the system performance is analyzed in this paper.Copyright

Optimization of a D-CHP System Based on Monthly Power-to-Heat Ratio

In this paper, a combined heat and power (CHP) system utilizing two power generation units operating simultaneously with differing operational strategies (D-CHP) is analyzed on the basis of operational cost savings. An operating cost optimization metric, based on the facility monthly power-to-heat-ratio (PHR), is presented. The PHR is defined as the ratio between the electric load and the thermal load required by the facility. Previous work in this field has suggested that D-CHP system performance may be improved by limiting operation of the system to months in which the PHR is relatively low. The focus of this paper is to illustrate how the facility PHR can be used to determine the potential of a D-CHP system to reduce operational cost. This paper analyzed the relationship between the PHR and the operational cost savings of six different benchmark buildings, including buildings that are traditionally poor candidates for CHP or D-CHP systems, due to high cost of operation as compared with conventional systems with separate heating and power (SHP). Achieving operational costs savings through optimal operation based on monthly PHR for these building types can enhance the practical implementation potential of D-CHP and CHP systems.Copyright

Evaluation of Combined Heat and Power (CHP) Systems Performance With Dual Power Generation Units

This paper evaluates the economic, energetic, and environmental feasibility of using two power generation units (PGUs) to operate a combined heat and power (CHP) system. A benchmark building developed by the Department of Energy for a full-service restaurant in Chicago, IL is used to analyze the proposed configuration. This location is selected since it usually provides favorable CHP system conditions in terms of cost and emissions reduction. In this investigation, one PGU is operated at base load to satisfy part of the electricity building requirements (PGU1), while the other is used to satisfy the remaining electricity requirement operating following the electric load (PGU2). The dual-PGU configuration (D-CHP) is modeled for several different scenarios in order to determine the optimum operating range for the selected benchmark building. The dual-PGU scenario is compared with the reference building using conventional technology to determine the economical, energetic, and environmental benefits of this proposed system. This condition is also compared to a CHP system operating following the electric load (FEL) and to a base-loaded CHP system, and it provides greater savings in operating cost, primary energy consumption, and carbon dioxide emissions than the optimized conditions for base loading and FEL.Copyright