Integration of Energy Systems
O’Malley et
al. (2016) proposed the definition that “Energy Systems Integration (ESI) is
the process of coordinating the operation and planning of energy systems across
multiple pathways and/or geographical scales to deliver reliable, cost
effective energy services with minimal impact on the environment.”
The vectors which
transfer energy from its source to where it is needed, usually at a distance
and often at a later time, include electricity, fuels such as oil and gas, and
heat-exchanging materials such as the fluids in a central heating system. O’Malley et al. stress the interaction
between the different energy vectors, and with transport, water and
communications systems. They note that every energy system is different, that
the people involved in such systems have different motivations, incentives, and
information, and that “there may be no coordination across these domains to
determine the best option for all actors involved.” The authors identify three
areas of opportunity: streamlining existing energy systems: finding synergies
“between energy domains and across spatial scales”; and empowering the consumer
“whether through their investment decisions, their active participation, or
their decisions to shift energy modes.”
Streamlining
can involve restructuring, reorganizing, and modernizing; institutional
involvement in policies, regulations, and markets; and investment in
infrastructure. Existing synergies have included “the coupling of heat and
electricity sectors” in combined heat and power projects, but “at a grand
scale” ESI proposes that “fuel, thermal, water, and transport systems will be
systematically planned, designed, and operated as flexible “virtual storage”
resources for the electricity grid (and vice versa).” (Virtual storage refers
to the flexibility of one part of a system being integrated with another part; Cheng,
Sami, and Wu (2017) provide a discussion of methods). Empowering implies
engaging the consumer in actions such as improving home energy efficiency and
demand reduction, and adopting new modes of transport, such as electric
vehicles. The authors note in their conclusions that ESI solutions “can require
expertise from a single discipline or from a multitude of disciplines.”
The wide range
of ESI is suggested by a report from the Energy Systems Integration Facility
(ESIF, 2020). Modernization of the electricity grid involves the integration of
distributed energy resources (such as wind, solar, hydro and biomass sources,
battery storage facilities and fuel cells) and improving grid resilience and
reliability in the face of “all malicious threats, natural disasters, and other
systemic risks.”
Representing
in data the grid and what it is connected to it is part of this process, and
one of the projects described is the development of “load profiles representing
all major end uses, building types, and climate regions in the U.S.” A study at
an even larger scale aims at modelling and analysis of “the interconnection of
U.S., Canada, and Mexico power systems”, while another at city level seeks “to estimate the impacts
of Los Angeles’s transition to an all-renewable electricity service capability
by 2045”. A project on generation is
described which aims to “optimize utility-scale hybrid power plants down to the
component level” exploring the potential for wind and solar technologies to
“take advantage of their often complementary generation profiles and shared
infrastructure”.
Forecasting
is an important part of ESI: in the long term it can address the evolution of a
power system to serve demands arising from new technologies in the buildings,
transportation, and industrial sectors; and in the short term “high-quality,
probabilistic forecasting systems” can also “directly contribute to the
integration of PV generation on the grid”. Energy security and resilience can be improved
using grid data analytics and visualization methods to represent grid activity
and by modelling threats to electric and gas infrastructure, such as
earthquakes and movements of the polar vortex; by improving defences against
cybersecurity threats; and by using “microgrid technologies with largescale
energy storage” to protect vital installations.
Battery
energy storage systems have been studied in residential applications,
particularly how the system’s thermal characteristics affect performance; and
also in hybrid battery stacks where different types of battery are used in
combination. Research is reported on the inverters used to convert stored
energy to usable power microgrids. Hydrogen
and other fuels which are regarded as renewable store energy, and work is
described on improving the electrolysis of hydrogen and methods of handling it
when used in fuel cells.
Supercomputers
have been used in a range of topics including the problems of plastics
pollution, reducing the cost of biofuels and other bio-derived products,
improving materials used in solar energy conversion and in lithium-sulphur
batteries, and in catalyst development. Solutions to the challenges of
fast-charging electric commercial vehicle fleets have been explored with a view
to reducing operational bottlenecks. Topics in fluid dynamics requiring
advanced computing include improving wind turbine efficiency through studying
the wake interactions. Computational studies of distillation processes in the
chemical industry offer the prospect of substantial reductions in energy use. Artificial
Intelligence techniques such as machine learning algorithms are cited in
connection with operating and controlling “a power system with up to tens of
millions of solar energy arrays”; changing the topology of a grid system “for
optimal configuration if it is damaged”; optimizing energy efficiency of
buildings; predicting the properties of new materials; controlling distributed
wind power plant; predicting the behaviour of geothermal energy systems; and
predicting and controlling grid voltage and frequency.
A brief paper
on the integration of multiple energy systems in China, published on the
website of the Energy Systems Integration Group, provides examples of integration
methods appropriate to different geographical regions (Zhang, Wang and Kang, 2018). Four regions of China “have
different resource endowments and energy demands, thus facing different
challenges or bottlenecks to fully accommodate renewable energy”. In northeast
China, the inflexibility of heat demand leads to “huge wind power curtailment”.
The problem has been alleviated through the widespread adoption of electric
boilers, which provide heat storage for space heating. Energy demand in China
is greatest in the south east, where energy efficiency has been improved through
the integration of heat pumps, absorption chillers, combined heat and power
systems, and ice storage air conditioning systems. Northwest China has ideal
locations for concentrated solar power installations, and “a part of the
collected solar energy is used to drive a steam turbine directly, while the
remaining energy is stored in the heat storage which will be used to generate
electricity at night or during cloudy weather.” China claims about a quarter of
the world’s hydropower capacity, but at times this is subject to curtailment,
particularly in the southwest. Here surplus hydropower can be used to produce
hydrogen by electrolysis, with the hydrogen injected into the natural gas
system, and used in industrial processes and in vehicles.
The problems
of integrating energy systems in the UK are inseparable from its plans to
achieve a net zero energy system (BEIS, 2021). The “smarter, more flexible
system” that is envisaged “will utilise technologies such as energy storage and
flexible demand”, which will “need to be seamlessly integrated onto our energy
system” to meet energy needs and reach a carbon neutral future. The energy
sources to be integrated may include new large-scale nuclear plant and a number
of small modular reactors; more onshore wind and solar renewable sources; new offshore
wind (including floating wind turbines); and low-carbon fuel alternatives such as hydrogen and biofuels. The industrial transition to net
zero energy may involve the creation of new economic hubs at sites with access to
low carbon energy, and also facilities for the capture and reuse or storage of CO2. Plans to reduce the use of natural gas for
heating buildings may involve the use of hydrogen as a partial or complete
replacement, and require the widespread deployment of heat pumps. Greater use
of electricity for heating, and the electrification of transport will increase
the amount of energy carried by the electricity grid, and make necessary the
deployment of “new flexibility measures, including electricity storage,
that aim to respond to consumer demand whilst also ensuring a stable and
efficient grid.” The stated ambitions to fund the development of sustainable aviation fuel and to decarbonise the
maritime sector clearly also have implications for infrastructure.
Another
perspective on the integration of energy systems is provided by a document from
the European Commission (EUR-Lex, 2020a), which notes that the “recent decline in the cost of renewable
energy technologies, the digitalisation of our economy and emerging
technologies in batteries, heat pumps, electric vehicles or hydrogen offer an
opportunity to accelerate, over the next two decades, a profound transformation
of our energy system and its structure”, necessary in order to meet the goal of
climate neutrality by 2050. The existing energy system is still “built on
several parallel, vertical energy value chains, which rigidly link specific
energy resources with specific end-use sectors”, a model which is “technically
and economically inefficient, and leads to substantial losses in the form of
waste heat and low energy efficiency.” The authors recognise that Member States
have different starting points in the process of integration, and that
regulatory and practical barriers remain, making necessary “concrete policy and
legislative measures at EU level”.
Energy system integration is seen to have three main strands: a core of
energy efficiency in a ‘circular’ system in which “unavoidable waste streams
are reused for energy purposes, and synergies are exploited across
sectors”; greater direct electrification
of end-use sectors, such as “using heat pumps for space heating or
low-temperature industrial processes, electric vehicles for transport, or
electric furnaces in certain industries”; and “the use of renewable and
low-carbon fuels, including hydrogen, for end-use applications where direct
heating or electrification are not feasible, not efficient or have higher
costs.”
Implementation will involve applying an
‘energy-efficiency-first’ principle “consistently across the whole energy
system”; remedying the present situation in which “local energy sources are
insufficiently or not effectively used in our buildings and communities”; and
making use of the currently untapped resources of waste water and
biological waste for “bioenergy production, including biogas.”
Electrification of energy demand, “building on a largely
renewables-based power system” is likely to result in the share of electricity
in final energy consumption moving “towards 50% by 2050”. Offshore wind is seen as part of the
solution, with an EU potential of “between 300-450 GW by 2050”. Such
development could allow “the nearby localisation of electrolysers for hydrogen
production, including the possible reuse of the existing infrastructure of
depleted natural gas fields.” Heat pumps are expected to play a large part in
space heating and cooling of buildings and in the decarbonisation of low
temperature heat supply in industrial processes. Electrification at scale implies the need for
training and new skills, upgrades to the local grid infrastructure, and
rationalisation of taxes and levies on electricity, which in many EU Member
States “are higher than for coal, gas or heating oil”.
The existing gas network is seen as having the capacity to
“integrate renewable and low-carbon gases” and in some cases it may be
economical to repurpose it for hydrogen applications such as transporting
renewable hydrogen from offshore renewable electricity facilities. “Ports could
transform into centres receiving electricity produced offshore, as well as
liquid hydrogen”, so contributing to global trade in renewable hydrogen or synthetic
fuels. The role of hydrogen in reaching carbon neutrality is developed in a
separate document, “A hydrogen strategy for a climate-neutral Europe” (EUR-Lex,
2020b).
Since increasing interdependencies mean that “disruptions in one sector
can have an immediate impact on operations in others” security for both
physical and digital infrastructures becomes more important: while
digitalisation supports energy systems integration, for example by helping to
interlink energy flows and match supply and demand, it also presents challenges
in terms of cybersecurity, and also in privacy and ethics.
BEIS, 2021, Transitioning to a net zero energy system Smart Systems and Flexibility Plan 2021, BEIS, July 2021, online, accessed 22 Feb 2022
Cheng, M.,
Sami, S., and Wu, J., 2017, Benefits of
using virtual energy storage system for power system frequency response, Applied Energy, Volume 194, 15 May 2017,
Pages 376-385, online, accessed 28 Feb 2022
https://www.sciencedirect.com/science/article/pii/S0306261916308881
ESIF, 2020,
Annual Report, Energy Systems Integration Facility, online, accessed 16 Feb
2022
https://www.nrel.gov/docs/fy21osti/79354.pdf
EUR-Lex,
2020a, Powering a climate-neutral economy: An EU Strategy for Energy System
Integration, European Commission, online, accessed 19 Feb 2022
https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=COM:2020:299:FIN
EUR-Lex,
2020b, A hydrogen strategy for a climate-neutral Europe,
European Commission, online, accessed 19 Feb 2022
https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A52020DC0301&qid=1645278355551
O’Malley,
M., et al., 2016, Energy Systems Integration: Defining and Describing the Value
Proposition, International Institute for Energy Systems Integration, online,
accessed 19 Feb 2022
https://www.nrel.gov/docs/fy16osti/66616.pdf
Zhang, N., Wang Y., and Kang, C., 2018, Integrating Multiple Energy Systems to
Accommodate High Penetration of Renewable Energy in China, Energy Systems
Integration Group, online, accessed 21 Feb 2022
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