An MILP model for integrated carbon-free heat networks considering alternative energy vectors

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Abstract

Space and water heating contribute significantly to society’s demands for energy: heat demands can be several times higher than those for electricity. These demands are primarily satisfied through natural gas. The cleaner alternative of utilising renewable (or nuclear) electricity along with heat pumps is limited by the capacity of the existing electricity networks and the mismatch of available renewable energy supply to the demands (e.g. solar power is more abundant in the summer when heating demands are the lowest). An alternative approach that overcomes these limitations is therefore needed and the utilisation of hydrogen as a carrier of energy may be a suitable candidate. Low carbon hydrogen can be generated from renewable electricity using electrolysers or from natural gas through SMR coupled with CCS. Both produce clean hydrogen that has a significant advantage when used as a carrier for heat:

1. It can be transported with little loss of energy, which is an advantage over electricity networks, which have losses of about 8% of production, and certainly much lower losses than transporting heat through a hot-water network. District heating networks are limited in scale due to the cost and inefficiencies of transporting heat long distances. Therefore, hydrogen opens new possibility for centralised generation of heat and long distance transport to the points of demand.

2. Hydrogen can be stored with little or no loss. If electricity and heat pumps were to be a solution to the problem of supplying clean heat at the national level, then electricity storage devices will need to be developed that can efficiently store large quantities of energy for long periods of time (inter-seasonal) and such devices may not be available for the foreseeable future. Long term direct thermal storage is generally not possible due to the difficulty in insulating the storage devices. Thus hydrogen offers a natural solution. Natural gas is also very well suited to storage but using natural gas in domestic boilers results in CO2 emissions.

We will present the MILP model that we are developing that can be used to explore different scenarios for generation, storage and transportation of hydrogen to satisfy heat demands. The model considers the spatial distribution of heat demands and the availability of primary resources in order to make a comparison between centralised and distributed generation, as well as to determine the location of hydrogen plants and storage facilities. The temporal representation simultaneously captures the short-term operational issues and long-term planning decisions (up to 2050) to examine different pathways from now to various potential solutions. The model optimises the design and operational decisions to determine the most cost effective/environmentally-friendly transition to the future heat network while also determining what that network should be. There are many possible configurations and we will identify and present the most promising ones.
Original languageEnglish
Title of host publicationProceedings of the 2017 AIChE Annual Meeting
PublisherAIChE
Publication statusAccepted/In press - 13 Jul 2017
Event2017 American Institute of Chemical Engineers Annual Meeting - Minneapolis Convention Center, Minneapolis, USA United States
Duration: 29 Oct 20173 Nov 2017

Conference

Conference2017 American Institute of Chemical Engineers Annual Meeting
CountryUSA United States
CityMinneapolis
Period29/10/173/11/17

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