SOURCE-TO-SINK EFFICIENCY OF DISTRICT HEATING AND HYDROGEN FOR BUILDING HEAT SUPPLY Hydrogen is commonly mentioned as a future-proof energy carrier capable of decar- bonizing the future energy system. While in principle this is correct, in practice, it has a major efficiency drawback. Due to the energy intensity of its manufacturing process, it needs to be applied in a sensible way and focused on hard-to-decarbonize sectors. For building thermal demands existing solutions like district heating for urban areas and heat pumps for rural areas are more energy-efficient applications. This article compares district heating and hydrogen-based heat supply systems for urban areas driven by natural gas and renewable energy. The results show that district heating is significantly more energy efficient than hydrogen-based heat supply; consequently, it has a much lower environmental footprint.
By Dr. Oddgeir Gudmundsson Danfoss A/S - Danfoss Climate Solutions - District Energy, Building and Leanheat - Application Center - Projects
Introduction To fulfill climate goals, it is necessary to decarbonize the ener- gy system. In principle, there are many possible paths toward achieving carbon neutrality. However, different approaches have different costs, environmental footprint, and primary en- ergy efficiency. These parameters are generally linked to the energy efficiency of the applied supply system, e.g., the higher the system efficiency, the lower the system cost, environmen- tal footprint, and primary energy need become. The key to achieving high energy efficiency is to minimize the number of energy conversion processes and match the supplied energy to the demanded energy quality. This is particularly important in relation to building heating demands, which are of low en- ergy quality nature.
The Hydrogen Council, a lobby organization for the major oil and gas producers 1 , promotes hydrogen as a viable and cost-effective way to decarbonize the heat supply in buildings currently heated by natural gas. The council encourages the idea of repurposing the existing natural gas infrastructure and avoiding developing new infrastructures. This idea is shared in a number of reports focusing on various countries, including the Netherlands 2,3 , Germany 4,5 , the United Kingdom’s govern- mental hydrogen strategy 6 , and Europe 7,8 . While the idea of repurposing existing natural gas grids is ap- pealing, research has shown that most of the components in existing natural gas grids are unable to cope with a large con- centration of hydrogen in the heat supply 5 . In fact, the max-
1 Kahya D. Unearthed today: Why oil companies want you to love hydrogen. Unearthed 2020. https://unearthed.greenpeace.org/2020/12/08/unearthed-today-why-oil-companies-want-you-to-love-hydrogen/ (accessed December 14, 2021). 2 Rongé J, François I. Use of hydrogen in buildings BatHyBuild study. 2021. 3 van den Broeck Y, François I, Martens A. A Flemish Hydrogen Strategy - 2025-2030. Turnhout: 2020. 4 Hennig E. Decarbonising Buildings: the Role of Hydrogen Hydrogen Blending: Overview of Different Approaches. COGEN EUROPE Power & Heat Boost Webinar Decarbonising Buildings: Role of Hydrogen 2021. 5 Cerniauskas S, Jose Chavez Junco A, Grube T, Robinius M, Stolten D. Options of natural gas pipeline reassignment for hydrogen: Cost assessment for a Germany case study. International Journal of Hydrogen Energy 2020;45:12095–107. https://doi.org/10.1016/j.ijhydene.2020.02.121. 6 Great Britain. Department for Business E& IStrategy. U.K. Hydrogen Strategy. London: 2021. 7 Haeseldonckx D, D’haeseleer W. The use of the natural-gas pipeline infrastructure for hydrogen transport in a changing market structure. International Journal of Hydrogen Energy 2007;32:1381–6. https://doi.org/10.1016/j.ijhydene.2006.10.018. 8 Minett S. Benefits of Hydrogen & CHP for Buildings. COGEN EUROPE Power & Heat Boost Webinar Decarbonising Buildings: Role of Hydrogen 2021.
20 HOTCOOL SPECIAL COLLECTION no.2 / 2022
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