Green energy system Sankey diagrams
H2 boiler
Useful heat 100
111
Power Inputs 144
141
ALK
30
11
Figure 5. Energy flow diagram for the green hydrogen scenario.
3
Ambient heat 80
Useful heat 100
DH network
HIU
HP
112
101
32
Power inputs 33
11
1
1
Figure 6. Energy flow diagram for the green D.H. scenario.
Conclusions Due to the inherent energy losses of hydrogen manufacturing, the logical utilization of hydrogen in the future decarbonized energy system is in hard-to-electrify sectors, such as industry processes that require high-temperature heat 14 and potential long-term storage of excess renewable power. For building heating demands in urban areas, DH-based heat supply sys- tems would have significantly higher primary energy efficiency compared to a hydrogen-based heat supply system. As with recent studies on the role of hydrogen in the future energy system 15–17 , the results of this analysis highlight the ef- ficiency shortcomings of using hydrogen for fulfilling heating demands in urban areas. From an energy efficiency point of view, DH would vastly outperform a hydrogen-based heat sup- ply system. In realized systems, the advantage of DH would be- come even greater due to its ability to take advantage of any locally available surplus heat or renewable energy sources.
While direct utilization of hydrogen for building heating de- mands is vastly inferior compared to DH, there are important synergies that need to be explored. By proper planning, future hydrogen manufacturing for hard-to-decarbonize sectors can become an important source of heat for DH If realized DH would benefit from access to stable, low-cost waste heat, the hydrogen manufacturing company would benefit from a sec- ondary revenue stream from their unavoidable waste heat and the overall energy system would become more efficient.
A detailed description of the above analysis is found in 18 .
For further information please contact: Dr. Oddgeir Gudmundsson og@danfoss.com
14 Papadis E, Tsatsaronis G. Challenges in the decarbonization of the energy sector. Energy 2020;205. https://doi.org/10.1016/j.energy.2020.118025. 15 Baldino C, O’Malley J, Searle S, Christensen A. Hydrogen for heating? Decarbonization options for households in Germany in 2050. 2021. 16 Baldino C, O’Malley J, Searle S, Christensen A. Hydrogen for heating? Decarbonization options for households in the European Union in 2050. 2021. 17 Gerhardt N, Bard J, Schmitz R, Beil M, Pfennig M, Kneiske T. Hydrogen in the Energy System of the Future: Focus on Heat in Buildings. Hannover: 2020. 18 Gudmundsson O, Thorsen JE. Source-to-sink efficiency of blue and green district heating and hydrogen-based heat supply systems. Smart Energy 2022;6:100071. https://doi.org/10.1016/j.segy.2022.100071.
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