An energy system is a
system primarily designed to supply
energy-services to
end-users.[1]: 941 The intent behind energy systems is to minimise energy losses to a negligible level, as well as to ensure the efficient use of energy.[2] The
IPCC Fifth Assessment Report defines an energy system as "all components related to the production, conversion, delivery, and use of energy".[3]: 1261
The analysis of energy systems thus spans the disciplines of
engineering and
economics.[5]: 1 Merging ideas from both areas to form a coherent description, particularly where
macroeconomic dynamics are involved, is challenging.[6][7]
The concept of an energy system is evolving as new regulations, technologies, and practices enter into service – for example,
emissions trading, the development of
smart grids, and the greater use of
energy demand management, respectively.
From a structural perspective, an energy system is like any
system and is made up of a set of interacting component parts, located within an environment.[8] These components derive from ideas found in
engineering and
economics. Taking a process view, an energy system "consists of an integrated set of technical and economic activities operating within a complex societal framework".[5]: 423 The identification of the components and behaviors of an energy system depends on the circumstances, the purpose of the analysis, and the questions under investigation. The concept of an energy system is therefore an
abstraction which usually precedes some form of computer-based investigation, such as the construction and use of a suitable
energy model.[9]
Viewed in engineering terms, an energy system lends itself to representation as a
flow network: the
vertices map to engineering components like
power stations and
pipelines and the
edges map to the interfaces between these components. This approach allows collections of similar or adjacent components to be aggregated and treated as one to simplify the model. Once described thus, flow network algorithms, such as
minimum cost flow, may be applied.[10] The components themselves can be treated as simple
dynamical systems in their own right.[1]
Economic modeling
Conversely, relatively pure economic modeling may adopt a sectoral approach with only limited engineering detail present. The sector and sub-sector categories published by the
International Energy Agency are often used as a basis for this analysis. A 2009 study of the UK residential energy sector contrasts the use of the technology-rich
Markal model with several UK sectoral housing stock models.[11]
Data
International
energy statistics are typically broken down by carrier, sector and sub-sector, and country.[12]Energy carriers (
aka energy products) are further classified as
primary energy and
secondary (or intermediate) energy and sometimes final (or end-use) energy. Published energy datasets are normally adjusted so that they are internally consistent, meaning that all energy stocks and flows must
balance. The IEA regularly publishes energy statistics and energy balances with varying levels of detail and cost and also offers mid-term projections based on this data.[13][14] The notion of an energy carrier, as used in
energy economics, is distinct and different from the definition of
energy used in physics.
Scopes
Energy systems can range in scope, from local, municipal, national, and regional, to global, depending on issues under investigation. Researchers may or may not include demand side measures within their definition of an energy system. The
Intergovernmental Panel on Climate Change (IPCC) does so, for instance, but covers these measures in separate chapters on transport, buildings, industry, and agriculture.[a][3]: 1261 [15]: 516
Household consumption and investment decisions may also be included within the ambit of an energy system. Such considerations are not common because consumer behavior is difficult to characterize, but the trend is to include human factors in models. Household decision-taking may be represented using techniques from
bounded rationality and
agent-based behavior.[16] The
American Association for the Advancement of Science (AAAS) specifically advocates that "more attention should be paid to incorporating behavioral considerations other than price- and income-driven behavior into economic models [of the energy system]".[17]: 6
The concept of an energy-service is central, particularly when defining the purpose of an energy system:
It is important to realize that the use of energy is no end in itself but is always directed to satisfy human needs and desires. Energy services are the ends for which the energy system provides the means.[1]: 941
Energy-services can be defined as amenities that are either furnished through energy consumption or could have been thus supplied.[18]: 2 More explicitly:
Demand should, where possible, be defined in terms of energy-service provision, as characterized by an appropriate intensity[b] – for example, air
temperature in the case of space-heating or
lux levels for
illuminance. This approach facilitates a much greater set of potential responses to the question of supply, including the use of energetically-passive techniques – for instance, retrofitted
insulation and
daylighting.[19]: 156
A consideration of energy-services per capita and how such services contribute to human welfare and individual quality of life is paramount to the debate on
sustainable energy. People living in poor regions with low levels of energy-services consumption would clearly benefit from greater consumption, but the same is not generally true for those with high levels of consumption.[20]
The notion of energy-services has given rise to
energy-service companies (ESCo) who contract to provide energy-services to a client for an extended period. The ESCo is then free to choose the best means to do so, including investments in the thermal performance and
HVAC equipment of the buildings in question.[21]
International standards
ISO
13600, ISO 13601, and ISO 13602 form a set of
international standards covering technical energy systems (TES).[22][23][24][25] Although withdrawn prior to 2016, these documents provide useful definitions and a framework for formalizing such systems. The standards depict an energy system broken down into supply and demand sectors, linked by the flow of tradable energy commodities (or energywares). Each sector has a set of inputs and outputs, some intentional and some harmful byproducts. Sectors may be further divided into subsectors, each fulfilling a dedicated purpose. The demand sector is ultimately present to supply energyware-based services to consumers (see
energy-services).
Energy system redesign and transformation
Energy system
design includes the redesigning of energy systems to ensure
sustainability of the system and its dependents and for meeting requirements of the
Paris Agreement for
climate change mitigation. Researchers are designing energy systems models and transformational pathways for
renewable energy transitions towards
100% renewable energy, often in the form of peer-reviewed text documents created once by small teams of scientists and published in a
journal.
Considerations include the system's
intermittency management,
air pollution, various risks (such as for human safety, environmental risks, cost risks and feasibility risks), stability for prevention of
power outages (including grid dependence or grid-design), resource requirements (including water and rare minerals and recyclability of components), technology/
development requirements, costs,
feasibility, other affected systems (such as land-use that affects
food systems), carbon emissions, available energy quantity and transition-concerning factors (including costs, labor-related issues and speed of deployment).[26][27][28][29][30]
Energy system design can also consider
energy consumption, such as in terms of absolute energy demand,[31] waste and consumption reduction (e.g. via reduced energy-use, increased efficiency and flexible timing), process efficiency enhancement and
waste heat recovery.[32] A study noted significant potential for a type of energy systems modelling to "move beyond single disciplinary approaches towards a sophisticated integrated perspective".[33]
See also
Control volume – a concept from mechanics and thermodynamics
Electric power system – a network of electrical components used to generate, transfer, and use electric power
Energy development – the effort to provide societies with sufficient energy under the reduced social and environmental impact
Energy modeling – the process of building computer models of energy systems
^
abAllwood, Julian M; Bosetti, Valentina; Dubash, Navroz K; Gómez-Echeverri, Luis; von Stechow, Christoph (2014).
"Annex I: Glossary, acronyms and chemical symbols"(PDF). In IPCC (ed.). Climate change 2014: mitigation of climate change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York, NY, USA:
Cambridge University Press. pp. 1249–1279.
ISBN978-1-107-65481-5. Retrieved 12 October 2016.
^
Kannan, Ramachandran; Strachan, Neil (April 2009). "Modelling the UK residential energy sector under long-term decarbonisation scenarios: Comparison between energy systems and sectoral modelling approaches". Applied Energy. 86 (4): 416–428.
doi:
10.1016/j.apenergy.2008.08.005.
ISSN0306-2619.
^
Bruckner, Thomas; Bashmakov, Igor Alexeyevic; Mulugetta, Yacob; et al. (2014).
"Chapter 7: Energy systems"(PDF). In IPCC (ed.). Climate change 2014: mitigation of climate change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York, NY, USA:
Cambridge University Press. pp. 511–597.
ISBN978-1-107-65481-5. Retrieved 12 October 2016.
^Morrison, Robbie; Wittmann, Tobias; Heise, Jan; Bruckner, Thomas (20–22 June 2005).
"Policy-oriented energy system modeling with xeona"(PDF). In Norwegian University of Science and Technology (NTNU) (ed.). Proceedings of ECOS 2005: shaping our future energy systems: 18th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. ECOS 2005. Vol. 2. Trondheim, Norway: Tapir Academic Press. pp. 659–668.
ISBN82-519-2041-8. Archived from
the original(PDF) on 10 January 2020. Retrieved 14 October 2016.
^
Duplessis, Bruno; Adnot, Jérôme; Dupont, Maxime; Racapé, François (June 2012). "An empirical typology of energy services based on a well-developed market: France". Energy Policy. 45: 268–276.
doi:
10.1016/j.enpol.2012.02.031.
ISSN0301-4215.
^Technical energy systems: basic concepts — ISO 13600:1997 — First edition. Geneva, Switzerland: International Standards Organization. 15 November 1997. Status withdrawn.
^Technical energy systems: basic concepts — ISO 13600:1997 — Technical corrigendum 1. Geneva, Switzerland: International Standards Organization. 1 May 1998. Status withdrawn.
^Technical energy systems: : structure for analysis : energyware supply and demand sectors — ISO 13601:1998. Geneva, Switzerland: International Standards Organization. 11 June 1998. Status withdrawn.
^Technical energy systems: methods for analysis: part 1: general — ISO 13602-1:2002. Geneva, Switzerland: International Standards Organization. 1 November 2002. Status withdrawn.
^Keirstead, James; Jennings, Mark; Sivakumar, Aruna (1 August 2012). "A review of urban energy system models: Approaches, challenges and opportunities". Renewable and Sustainable Energy Reviews. 16 (6): 3847–3866.
doi:
10.1016/j.rser.2012.02.047.
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ISSN1364-0321.