Sector coupling

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Sector coupling and various Power-to-X technologies
Comparison of certain efficiency chains of today's fossil energy system and an electrified renewable energy system

Under sector coupling (also sector en coupling or English. Sector Coupling or Integrated Energy , the networking of the sectors is called) energy and industry understood the coupled, so in a common holistic approach should be optimized. Traditionally, the electricity , heating (or cooling ), transport and industry sectors have been viewed largely independently of one another.

The idea behind the concept is to leave behind solutions that are tailored to individual sectors , which only consider solutions within the respective sector, and instead to come to a holistic view of all sectors, which enables a better and cheaper overall system. Sector coupling offers three main advantages:

Precisely because the sector coupling enables synergy effects in the integration of high proportions of renewable energies , it is viewed as a key concept in the energy transition and the development of energy systems with 100% renewable energies. There is broad consensus that sector coupling is necessary in order to implement the energy transition and to meet the climate protection goals.

A sector-coupled energy system is also known as a hybrid network; a system that is integrated, holistically conceived and operated in an optimized manner over several energy infrastructures becomes engl. Called Smart Energy System .

definition

Michael Sterner and Ingo Stadler define sector coupling as the connection between the "electricity, heat, and transport sectors" and the "non-energetic consumption of fossil raw materials (especially chemicals) via energy storage and energy converters." The coupling of the different sectors makes it possible to use renewable electrical energy as an important energy carrier to decarbonise the other sectors.

The starting point and core of the sector coupling is the electricity sector, which supplies energy from renewable sources for all other consumption sectors. Energy Brainpool recommends the use of storage gases (power-to-gas -> gas storage -> gas-to-power & heat) to weather the so-called "cold dark doldrums" . In addition to electromobility, the use of synthetic fuels is being discussed to link up the transport sector.

concept

Achieving the climate protection goals requires reducing emissions from all energy sectors to zero. The need for sector coupling arises from the fact that, with wind energy and solar energy, the most important renewable energy sources are much better suited for generating electricity than for producing fuels and heat. In countries like Germany, the potential of other renewable energy sources such as bioenergy , geothermal and solar thermal is limited, so that for this reason, too, the majority of energy has to be produced by wind power and photovoltaic systems . The core element of the sector coupling is therefore the conversion of the heating and transport sectors to green electricity , so that this becomes the most important form of energy for the entire energy supply. A strategy path is then derived from this, which consists of the rapid expansion of renewable energy sources as the energetic basis of sector coupling and is supplemented by a parallel expansion of heat pump heating and electromobility . In such a system, heat pumps and electric cars act as a load that can be flexibly switched on if required. The use of heat pumps and e-cars instead of fossil-fueled heating systems and vehicles already leads to a reduction in carbon dioxide emissions in almost every region of the world with the current electricity mix .

In the research literature, there is an increasing view that decarbonising electricity generation, followed by electrification of almost all sectors of the energy system, will be the cheapest solution for a sustainable, climate-friendly energy system. In its special report 1.5 ° C global warming, the IPCC also assumes that the electrification of end users in combination with the decarbonization of the electricity sector is the most important means of decarbonizing other consumption sectors of the energy system. Three quarters of the experts surveyed in a Delphi study believe that an All Electric Society will be a reality by 2040 , i.e. a society in which the various energy consumption sectors such as heat generation, transport and industry are primarily powered by electricity from renewable sources.

The challenges of the fluctuating supply, especially of solar and wind energy, could be significantly reduced through this coupling of the individual sectors. While z. B. Approaches that only consider the electricity sector alone, often requiring comparatively high and expensive electricity storage capacities, the sector coupling enables a significantly lower use of electricity storage, since the fluctuating generation of wind and solar electricity no longer only has to be balanced in the electricity sector, but among other things the heating sector or the transport sector can also provide the necessary flexibility to compensate for fluctuations. So excess electricity z. B. can be stored as heat, cold, synthetic fuels, etc., without the need for expensive electricity storage.

In this way, significant cost reductions can be achieved in the overall system, since heat, gas and fuel storage systems have orders of magnitude lower investment costs than electricity storage systems. For example, the investment costs for heat storage with the same storage capacity are around a factor of 100 lower than for electricity storage. In the cases mentioned, the reconversion of electricity would result in very low levels of efficiency; but this is meaningless, since the reconversion of electricity is usually not provided at all. Instead, the purpose of sector coupling is to flexibly couple the various sectors in order to compensate for the lack of flexibility in renewable energies such as wind and photovoltaics. This load management across the individual consumption sectors can serve as a so-called functional electricity storage system to dampen fluctuations in renewable electricity production and thus take on the same tasks as real electricity storage systems. Since such a load management is almost always cheaper than conventional energy storage, it is pointed out in the specialist literature that it should be used with priority for reasons of cost.

At the same time z. For example, more fossil fuels can be saved if surplus electricity is used in the heating and transport sector via heat pumps and electric cars than if the surplus electricity is stored directly. In particular, the coupling of the electricity and heating sector with heat pump heating is important, as this is considered to be the most efficient form of electricity-heat coupling. So z. B. the use of (large) heat pumps in district heating systems as one of the most promising ways to increase the energy efficiency of heating networks and to achieve climate protection goals. Sector coupling is therefore also important insofar as it enables the creation of an energy-efficient overall energy system that is both economically and ecologically feasible. In addition to heat pumps, the electricity and heating sectors can also be linked via classic power-to-heat systems such as variably operated electrode boilers , heating rods and electric boilers . Both types of coupling, together with heat storage, enable a favorable and variable demand for electrical energy. In this way, the heating sector can provide the electricity sector with the flexibility needed to offset the fluctuations in electricity generation from wind and solar energy. Conversely, the residual load can be efficiently covered by converting storage gases back into electricity using combined heat and power, if the supply-dependent generation is not sufficient to cover the load. This corresponds to a coupling of the line-based infrastructures for gas, thermal and electrical energy in the sense of an energy hub.

While the “first phase of the energy transition” focused on promoting climate-neutral electricity generation, the “second phase” was about focusing on the energy system as a whole and adding incentive structures for intelligent energy systems and the utilization of electricity peaks as well as addressing load management on the part of the electricity user. Due to the sector coupling, the energy transition in Germany is expected to result in higher electricity consumption than it is today, but the primary energy demand will decrease due to the use of renewable sources and the resulting increased energy efficiency in electricity generation. So far, fossil fuels have been used almost exclusively in the heating and transport sectors. With the use of the mechanisms of sector coupling, according to a study by dena, a net increase in renewable energies of an average of up to 8.5 gigawatts per year is necessary by the year 2050.

The need for additional power lines is different depending on whether the power sector is viewed in isolation or all three energy sectors. Since significantly more energy is required in winter due to the heat demand, it is advisable to design the capacities in such a way that there is an oversupply in summer, which can be buffered via a long-term storage device and thus kept available for the winter. Generally speaking, electricity is quite easy to transport, but storing it is expensive. On the other hand, heat is difficult to transport over (longer) distances, but it is easy to store. Electricity can also be converted very easily into heat, while the other way round is significantly more complex.

Connecting elements between the sectors

There are a large number of technologies available as connecting elements between the sectors, the interaction of which has yet to be designed. The following coupling elements, often summarized under the umbrella term " Power-to-X ", are currently being used or tested:

  • Power-to-Chemicals : Use of excess electricity in industry for the targeted generation of basic chemicals for chemical products
  • Power-to-gas : Generation of energy gases from renewable surplus electricity through electrolysis (splitting of water into hydrogen and oxygen) and, if necessary, subsequent methanation (production of renewable natural gas by adding hydrogen to carbon atoms) as a central coupling element between electricity and Gas infrastructure with the aim of creating additional flexibility.
  • Power-to-Heat : Use of excess amounts of electricity in the heating market through the use of controllable heating elements in local heat storage systems, in district heating systems or the connection of heat pumps .
  • Power-to-Liquids : Process for the production of fuels from excess electricity by means of electrolysis / hydrogen production to usable basic chemicals (methanol) or fuels from synthetic hydrocarbons (dimethyl ester, kerosene, etc.)
  • Power-to-Mobility: Use of excess electricity to charge electric vehicles , which in theory would also enable the battery content to be fed back into the grid. Alternative use of methane generated from power-to-gas processes for CNG and LNG mobility or of hydrogen for fuel cell mobility
  • Combined heat and power (Gas to Heat & Power): combined generation of electricity and heat with combined heat and power plants , combined heat and power plants or fuel cells

There are a number of solution elements for the joint optimization of the sectors:

  • Charging of (e.g. car) batteries in times of excess solar or wind energy
  • Feedback from (e.g. car) batteries ( V2G ) to bridge deficits in the electricity supply system
  • Power-to-gas plants can be built close to the main points of generation of renewable electricity; gas transport can, under certain circumstances, reduce the construction of new electricity lines
  • Thanks to the power-to-liquid technology, energy optimization can take place across national borders, as fuels produced in a climate-neutral manner can be transported inexpensively. These can be used in areas that are difficult to convert (for example in air traffic, shipping, heavy goods transport).
  • Systems for the combined generation of power and heat (CHP) can be operated with renewable gas in order to generate electrical energy to cover the positive residual load and to operate heat sinks or heat storage systems
  • With battery and gas storage systems, short-term and long-term fluctuations in electricity generation and consumption can be balanced out.

Web links

literature

Individual evidence

  1. ↑ a b c d e Henrik Lund et al .: Smart energy and smart energy systems . In: Energy . tape 137 , 2017, p. 556-565 , doi : 10.1016 / j.energy.2017.05.123 .
  2. ↑ Philipp Pfeifroth, Benjamin Steinhorst: Functional electricity storage. FfE, May 31, 2018, accessed May 31, 2018 .
  3. ↑ Sector coupling: the most important part of the turnaround | Heinrich Böll Foundation . In: Heinrich Böll Foundation . ( boell.de [accessed on September 29, 2018]).
  4. ↑ a b Brian Vad Mathiesen et al .: Smart Energy Systems for coherent 100% renewable energy and transport solutions . In: Applied Energy . tape 145 , 2015, p. 139–154, here p. 141 , doi : 10.1016 / j.apenergy.2015.01.075 .
  5. ↑ Christoph Stiller, Markus C. Weikl: Industrial production and use of conventional, low-CO2 and green hydrogen , in: Johannes Töpler, Jochen Lehmann (Ed.): Hydrogen and fuel cells. Technologies and market prospects . 2nd edition, Berlin Heidelberg 2017, 189–206, p. 204.
  6. ↑ Robert Tichler, Simon Moser: Systemic necessity for the further development of hybrid networks . In: Electrical engineering and information technology . tape 134 , no. 2 , 2017, p. 222-228 , doi : 10.1007 / s00502-017-0499-x .
  7. ↑ Michael Sterner , Ingo Stadler (Ed.): Energy storage. Need, technologies, integration. 2nd edition, Springer Verlag, Berlin Heidelberg 2017, p. 28.
  8. ↑ Michael Sterner , Ingo Stadler (Ed.): Energy storage. Need, technologies, integration. 2nd edition, Springer Verlag, Berlin Heidelberg 2017, pp. 60f.
  9. ↑ F. Huneke, C. Perez Linkenheil, M. Niggemeier: Kalte Dunkelflaute - Robustness of the electricity system in extreme weather. (PDF; 1.7 MB) Energy Brainpool, May 12, 2017, accessed on May 31, 2018 .
  10. ^ NN: Documentation E-Fuels. (PDF; 0.3 MB) Scientific Services, German Bundestag, January 22, 2018, accessed on May 31, 2018 .
  11. ↑ a b c d e f Sector coupling through the energy transition, requirements for the expansion of renewable energies to achieve the Paris climate protection goals , taking into account the sector coupling , by Volker Quaschning, University of Applied Sciences (Berlin), June 20, 2016
  12. ↑ Holger Rogall : 100% supply with renewable energies. Conditions for global, national and local implementation . Marburg 2014, p. 178.
  13. ↑ See Holger Rogall : 100% supply with renewable energies. Conditions for global, national and local implementation . Marburg 2014, pp. 178–180.
  14. ↑ Jiawei Wang et al .: Energylab Nordhavn: An integrated community energy system towards green heating and e-mobility . In: Transportation Electrification Asia-Pacific (ITEC Asia-Pacific), 2017 IEEE Conference and Exp . 2017, doi : 10.1109 / ITEC-AP.2017.8080846 .
  15. ↑ Florian Knobloch et al .: Net emission reductions from electric cars and heat pumps in 59 world regions over time . In: Nature Sustainability . 2020, doi : 10.1038 / s41893-020-0488-7 .
  16. ↑ Nancy M. Haegel et al .: terawatt-scale photovoltaics: Transform global energy . In: Science . tape 364 , no. 6443 , 2019, p. 836-828 , doi : 10.1126 / science.aaw1845 .
  17. ↑ IPCC 2018: Mitigation Pathways Compatible with 1.5 ° C in the Context of Sustainable Development, p. 137 . Special report 1.5 ° C global warming . Retrieved June 19, 2019.
  18. ↑ Kapferer et al .: BDEW, May 2016, accessed on June 8, 2018 .
  19. ^ Henrik Lund : Energy Storage and Smart Energy Systems . In: International Journal of Sustainable Energy Planning and Management . tape 11 , 2016, p. 3–14 , doi : 10.5278 / ijsepm.2016.11.2 .
  20. ↑ Michael Sterner , Ingo Stadler (Ed.): Energy storage. Need, technologies, integration. 2nd edition, Berlin Heidelberg 2017, p. 77.
  21. ^ Andre Sternberg, Andre Bardow: Power-to-What? - Environmental assessment of energy storage systems . In: Energy and Environmental Science . tape 8 , 2015, p. 389-400 , doi : 10.1039 / c4ee03051f .
  22. ↑ Philip Witte, Martin Kaltschmitt : Decentralized control of a pool of heat pumps based on game theory methods . In: Zeitschrift für Energiewirtschaft . tape 134 , no. 3 , 2017, p. 222-228 , doi : 10.1007 / s12398-017-0201-3 .
  23. ^ MA Sayegh et al .: Heat pump placement, connection and operational modes in European district heating . In: Energy and Buildings . tape 166 , 2018, p. 122-144 , doi : 10.1016 / j.enbuild.2018.02.006 .
  24. ↑ Michael Sterner , Ingo Stadler (Ed.): Energy storage. Need, technologies, integration. 2nd edition, Berlin Heidelberg 2017, p. 151.
  25. ↑ Max Fette, Hans Christian Gils: Short study on the role of CHP in the energy transition. (No longer available online.) B.KWK, March 2018, archived from the original on June 12, 2018 ; accessed on June 9, 2018 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.bkwk.de
  26. ^ Martin Geidl et al .: The Energy Hub - A Powerful Concept for Future Energy Systems. ETH Zurich, March 13, 2007, accessed on June 9, 2018 .
  27. ↑ Integrated, digital, efficient: Success factors for the energy transition ( Memento of the original from May 15, 2016 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , by Andreas Kuhlmann ( dena ), IRES Symposium, 2015 @1@ 2Template: Webachiv / IABot / www.eurosolar.de
  28. ↑ Use renewable energy instead of wasting it! , Trend - Journal for Social Market Economy, December 22, 2015
  29. ↑ Newly linked ( memento of the original from July 10, 2016 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. , in Dena Magazin, May 2016, p. 16 @1@ 2Template: Webachiv / IABot / www.dena.de
  30. ↑ Volker Quaschning : Regenerative Energy Systems. Technology - calculation - simulation . 8th updated edition. Munich 2013, p. 49.
  31. ^ The energy transition according to COP 21 - Current scenarios of the German energy supply , by Joachim Nitsch , February 17, 2016
  32. ↑ Renewable energies in transport Potentials and development prospects of various renewable energy sources and energy consumption of the modes of transport ( Memento of the original from July 10, 2016 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. , by D. Kreyenberg, A. Lischke (DLR), F. Bergk, F. Duennebeil, C. Heidt, W. Knörr, ( IFEU ), T. Raksha, P. Schmidt, W. Weindorf (LBST), K. Naumann, S. Majer, F. Müller-Langer ( DBFZ ) Ed .: German Aerospace Center e. V. ( DLR ), March 10, 2015 @1@ 2Template: Webachiv / IABot / www.bmvi.de
  33. ↑ a b sector coupling , RP-Energie-Lexikon
  34. ↑ Andreas Kuhlmann And others: dena lead study: Integrated energy transition: Impulses for shaping the energy system by 2050. German Energy Agency (dena), accessed on June 8, 2018 .
  35. ↑ Stefan Krauter : Simple and effective methods to match photovoltaic power generation to the grid load profile for a PV based energy system . In: Solar Energy . tape 159 , 2018, p. 768-776 , doi : 10.1016 / j.solener.2017.11.039 .