PUBLICATIONS: The Missing Link in Sustainable Energy: Techno-economic consequences of large-scale heat pumps in distributed generation in favour of a domestic integration strategy for sustainable energy

Title:      The Missing Link in Sustainable Energy: Techno-economic consequences of large-scale heat pumps in distributed generation in favour of a domestic integration strategy for sustainable energy
Categories:      Smart Energy Systems Analyses
BookID:      8
Authors:      Blarke, Morten Boje
ISBN-10(13):      0000000003
Publisher:      Aalborg University
Publication date:      2008
Edition:      1
Number of pages:      304
Language:      English
Price:      0.00 DKK
Rating:      5 
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This thesis investigates options for handling the problem of intermittency related to large-scale penetration of wind power into the West Danish energy system. But rather than being a story about wind power, the thesis explores the principles by which distributed energy plants could be better designed and operated to provide energy system services, supporting intermittent supply, while reducing the need for central power plants and cross-national transmission capacities. In essence, the thesis assesses the consequences of integrating largescale heat pumps with distributed cogenerators in favour of a domestic integration strategy for handling intermittency towards a sustainable energy system.

It is found that large-scale transcritical compression heat pumps are suitable and ready for integration with existing cogenerators, but that system-wide energy, environmental, and economic benefits are very sensitive to actual concepts of integration. The innovative CHP-HP-CS concept that relies on heat recovered from cooling and condensation of flue gasses, adds, in addition to a heat pump, a cold storage for storing recovered heat, which allows for independent operation of cogenerator and heat pump. While this concept results in increasing a typical plant’s fuel efficiency from 92 % to 97 %, the plant’s reduced electricity production results in plant-related system-wide CO2 emissions increasing by as much as 20 %. The increase in CO2 emissions is minimized by disallowing concurrent operation of cogenerator unit and heat pump unit. The CHP-HP-GS concept that relies on unconstrained heat recovered from ground sources offers a 10 % reduction in the plant’s systemwide CO2 emissions when disallowing concurrent operation. The thesis shows that concepts for integrating heat pumps with cogenerators comes with significant variations in boiler operation and cogeneration being substituted, with the heat pump entering as an intermediate-load heat production unit with full-load hours as few as 1350 hours according to concept, and that the resulting overall economic costs of heat production typically increases by 2 % to 8 %. However, the thesis claims that increased costs may be acceptable as these concepts will reduce the need for investments in cross-national infrastructure.

The most cost-effective concepts for increasing the wind-friendliness of existing distributed generators relies on installing a relatively small heat pump, limiting the electric capacity of the heat pump to no more than 10 % of the electricity generating capacity of the distributed generator. The most cost-effective heat pump concepts are more cost-effective than concepts for integrating an electric boiler. The thesis provides new metrics, like the relocation coefficient, for evaluating the wind-friendliness of distributed generators, and the costeffectiveness hereof, and offers a new interactive modelling framework that allows for researchers and local operators to interact on evaluating options for domestic integration with respect to energy, environmental, and economic consequences.

Keywords: sustainable energy system design, intermittency, largescale heat pumps, distributed cogeneration, cold storage, relocation, domestic integration of wind power, interactive techno-economic modelling software.

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