Comparative analysis of exergy- and enthalpy-based allocation methods for cogeneration businesses in the industrial complex of South Korea

Choi, Sangmi; Kim, Soyeon; Jung, Minkyu; Lee, Jinwook; Lim, Jihun; Kim, Min Soo

doi:10.1016/j.energy.2021.122837

Cited by 12 publications

(6 citation statements)

References 14 publications

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“…𝐸 for heat. They find, that the energybased allocation distorts the real conditions and advocate a purely exergy-based allocation [10]. Concerning Germany, in their study on achieving CO2-Neutrality, Hertle et al emphasize the importance of the exergy-based allocation of CHP as the only valid method for independent and scientifically sound allocation [11].…”

Section: State Of Research 21 Allocation Methodologymentioning

confidence: 99%

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General numeric determination of ecological operation of heat pumps using power from cogeneration.

Hurst

Jentsch

Blesl³

2022

Preprint

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The combination of a combined heat and power (CHP) system with a heat pump (HP), is growing popular as an innovative heating solution in residential buildings as well as decarbonization-solution in district heating networks. Due to significant lower operational and initial costs, the predominant configuration is a CHP+HP combination, where the HP is operated by internal power supply, provided by the CHP. In this paper, the CHP+HP combination was generally analysed under exergy analysis regarding its climate protection potential, thus taking the first and second law of thermodynamics into consideration. As a result, the common conception of CHP+HP combinations being ecologically advantageous in terms of low CO2-emissions, was disproved analytically. The new, theoretical COP limit, which is derived and presented in this work gives the COP-threshold that any HP operated with internal power supply from CHP has to achieve at minimum to provide heat at lower CO2-emissions than the CHP. The COP limit derived is a function of CHP temperatures only. The graphical representation of the results allows a simple determination of the energy system conditions to check whether the HP has a positive impact on the CO2-emissions of the combined CHP+HP-system under usage of internal power supply. The evaluation based on these results confirms that the heat from a HP using either of the 2 popular heat-sources surfaced-water or ambient air, inevitably has higher specific CO2-emissions in the CHP+HP combination than the CHP heat. Only when using a sufficiently hot and emissions-free heat source, the HP-heat from a CHP+HP combination can yield to maximum of half the CO2-emissions of the CHP. Therefore, power consumption with sufficiently low specific CO2-emissions out of external source is mandatory to achieve in case of a high temperature waste heat source fully capitalize on the ecological benefits through HP operation in CHP+HP systems.

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Section: State Of Research 21 Allocation Methodologymentioning

confidence: 99%

“…), a conversion to a quasiconstant temperature is necessary. Hereby, it is sufficiently accurate, to determine 𝑇 𝐻 , simplified via the logarithmic mean [10]. The logarithmic mean itself depends on the flowtemperature (𝑇 𝐹 ) and return temperature (𝑇 𝑅 ) of the DHN:…”

Section: Thermodynamic Basics Regarding Carnotmentioning

confidence: 99%

General numeric determination of ecological operation of heat pumps using power from cogeneration.

Hurst

Jentsch

Blesl³

2022

Preprint

View full text Add to dashboard Cite

show abstract

“…𝐸 for heat. They find, that the energy-based allocation distorts the real conditions and advocate a purely exergy-based allocation [10]. Concerning Germany, in their study on achieving CO2-neutrality, Hertle et al emphasize the importance of the exergy-based allocation of CHP as the only valid method for independent and scientifically sound allocation [11].…”

Section: State Of Research 21 Allocation Methodologymentioning

confidence: 99%

“…), a conversion to a quasi-constant temperature is necessary. Hereby, it is sufficiently accurate, to determine 𝑇 𝑂 , simplified via the logarithmic mean [10]. The logarithmic mean itself depends on the flow-temperature (𝑇 𝐹 ) and return temperature (𝑇 𝑅 ) of the DHN:…”

Section: Cop Difference Of Large-scale Heat Pumps (Lshp) Vs Small Sca...mentioning

confidence: 99%

Dependency on external power supply to operate large-scale heat pumps to decarbonize Cogeneration-based District Heating Networks.

Hurst

Jentsch

Blesl

2022

Preprint

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The sector integration of large-scale heat pumps (LSHP) into existing district heating networks (DHN), most of which are operated by combined heat and power plants (CHP), is observed to grow rapidly over the past few years. Due to significant lower operational and initial costs, the predominant configuration in DHN is a CHP+LSHP combination, where the LSHP is operated by internal power supply, provided by the CHP-plant. In a dynamic simulation based on aggregated data over the course of one year, specific CO2-emissions are calculated according to the exergetic Carnot methodology, fulfilling the first and sec-ond law of thermodynamics. In order to determine and quantify the ecologic benefit of a generic sector integrated LSHP, the specific CO2-emissions of the heat of the most common CHP-plants are compared to a LSHP operated by internal (CHP+LSHP) and external power supply (electrical grid and volatile renew-able energy sources (RES)). The analysis shows, that a generic LSHP operated by internal power supply out of every examined CHP-plant, seasonally independent generates heat with higher specific CO2-emissions over the heat from the CHP-plant alone. In contrast, the heat provided by the LSHP operated with external electricity from RES, achieves 5 to 16-fold lower CO2-emissions showing, that with growing share of power from RES in the electric grid, regulation to ensure that external power supply is economically feasible will be mandatory in order to achieve ecologic beneficial operation of sector integrated LSHPs.

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“…For Co-generation of heat, we introduce two new choices not previously found in the literature reviewed in this study. EX, or allocation by exergy, is commonly used in CHP units, 58,59 even though it was not featured in the literature review. TH100, which allocates all emissions to heat, serves as a counterpoint to EL100, which allocates all emissions to electricity.…”

Section: Calculationmentioning

confidence: 99%

Towards standardized grid emission factors: methodological insights and best practices

Schäfer,

Cerdas,

Herrmann

2024

Energy Environ. Sci.

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Comparative analysis of exergy- and enthalpy-based allocation methods for cogeneration businesses in the industrial complex of South Korea

Cited by 12 publications

References 14 publications

General numeric determination of ecological operation of heat pumps using power from cogeneration.

General numeric determination of ecological operation of heat pumps using power from cogeneration.

Dependency on external power supply to operate large-scale heat pumps to decarbonize Cogeneration-based District Heating Networks.

Towards standardized grid emission factors: methodological insights and best practices

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