HOT|COOL MAGAZINE SPECIAL COLLECTION 2/2022

Figure 1. Blue energy-based systems, hydrogen above, and district heating below. Adaptation of U.S. Energy Information Administration figure on Natural gas production and delivery 13 .

imum allowable blending in Europe in 2020 was in France, 6% 9 . Due to this incompatibility, an extensive renovation of the existing natural gas infrastructure, from the transmission lines to and including the end-users gas installations, would be needed to enable the grand roll-out of hydrogen. An alternative to hydrogen-based heat supply in urban areas could be modern low-temperature district heating (DH), an in- frastructure for distributing centrally produced heat, at one or more locations, via a pipe network to heat consumers in urban areas 10–12 .

energy intensity and global warming potential (GWP). As blue hydrogen is promoted as transitional hydrogen by the hydro- gen industry, the article considers blue DH, an NG-based DH, as a transitional alternative. This entire energy chain compari- son of these energy carriers highlights the large inefficiencies associated with manufacturing high-quality energy carriers for low-quality energy demands. As both supply solutions aim at solving a basic need, building heat demands, and both require extensive infrastructures to be built, an inher- ent long-term lock-in effect must be considered. Due to the lock-in effect, it is particularly important to prioritize ener- gy efficiency to minimize the environmental footprint and cost of establishing the future renewable energy generation system.

This article compares blue and green hydrogen and DH as heat supply systems for building heating demands regarding

9 IEA. Current limits on hydrogen blending in natural gas networks and gas demand per capita in selected locations. Current Limits on Hydrogen Blending in Natural Gas Networks and Gas Demand per Capita in Selected Locations 2020. https://www.iea.org/data-and-statistics/charts/current- limits-on-hydrogen-blending-in-natural-gas-networks-and-gas-demand-per-capita-in-selected-locations (accessed December 14, 2021). 10 Lygnerud K, Werner S. Implementation of Low-Temperature District Heating Systems. 2021: 2021. https://doi.org/10.1016/j.energy.2014.02.089 11 Schmidt D, Kallert A. Future low-temperature district heating design guidebook: Final Report of IEA DHC Annex TS1. Low-Temperature District Heating for Future Energy Systems. Frankfurt Am Main: 2017. 12 Lund H, Werner S, Wiltshire R, Svendsen S, Thorsen JE, Hvelplund F, et al. 4th Generation District Heating (4GDH). Energy 2014;68:1–11. https://doi.org/10.1016/j.energy.2014.02.089. 13 U.S. Energy Information Administration (EIA). Natural gas explained - Delivery and storage of natural gas. Webpage Article 2021. https://www.eia.gov/energyexplained/natural-gas/delivery-and-storage.php (accessed December 15, 2021).

21 www.dbdh.dk

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