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In this course we have introduced the notion
of infrastructure systems as complex systems,

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and the notion of infrastructure systems as
socio-technical systems.

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Both in their physical dimension and in their
social dimension,

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infrastructure systems behave as complex systems.

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Complex systems are characterized by emergent behaviour.

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The system behaviour at macro-level emerges
from the behaviour of interacting system elements

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at the micro-level.

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Emergent behaviour often cannot be predicted.

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The engineers among us may be puzzled here.

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Since all the technical parts of the system
are designed according to functional and performance

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specifications,
and since we put controls in place to make

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sure that the system behaves as intended,
how can it be that we cannot predict the behaviour

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of the overall system?

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The answer is in the interactions.

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That’s where the complexity is.

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When many simple systems are interconnected
into a larger network,

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they interact with each other,
across different time scale levels,

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and across different levels.(size levels)

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In doing so,
the system may reconfigure itself and show

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behaviour that you had not anticipated.

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The emergent behaviour of the overall system
may be predictable,

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but it may also be completely unpredictable and unexpected.

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Emergence is a phenomenon that is not that strange to you because it is everywhere around us.

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In nature,
emergent behaviour can be seen in flocks of

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birds,
shoals of fish,

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swarms of bees or termite mounds.

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Their shape and behaviour are emergent properties
resulting from interactions between the individual entities.

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The individual termites, bees, fish.

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Another example,

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Free-market theories understand economy as
an emergent feature of psychology,

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and psychology can be understood as an emergent
feature of the neurobiological processes happening

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in our brains.

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Biology can also be viewed as an emergent
property of the laws of chemistry which,

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in turn,
can be viewed as an emergent property of particle

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physics.

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In the built environment,
cities can be viewed as complex systems,

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functioning like a living organism,
consuming energy,

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water and food,
and excreting waste and waste water,

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Presenter with infrastructure systems representing
their metabolic pathways.

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Infrastructure systems themselves are complex
systems.

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The complexity of infrastructure systems has
many causes.

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We have already explained how continental
electricity networks emerged from the interconnection

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of neighbourhood networks into city networks,
followed – over decades - by regional,

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national and cross-border interconnections.

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The legacy infrastructures of the industrialized
world are a patchwork of local,

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regional and national networks,
with a vast number of decentralized controls

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at all levels of the system.

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The patchworked nature of our multinational
transport,

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energy and communication networks can be recognized
from the click national standards that still

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persist in many physical infrastructure systems.

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If you travel a lot,
you will know that you need to bring a set

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of adapter plugs,
so that you can connect your mobile phone

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and laptop rechargers to different sockets
abroad.

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Another example: railway systems in different
countries use different railway gauges.

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Moreover,
different countries selected different standards

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for railway electrification,
with different voltage levels,

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with some countries using alternating current,
Presenter and others using direct current.

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Legacy infrastructures are also a patchwork
of old and new technologies.

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Some parts of the electricity infrastructure
in Europe and the US date back more than 50

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years.

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The exact technical specifications of old
parts of the infrastructure and records of

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the exact location of underground cables and
pipelines may have been lost.

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Obviously,
in ageing infrastructures,

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wear and tear will play a role.

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Very often we do not know enough about the
aging behaviour of infrastructure components

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to predict when and how they will fail.

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Local conditions,
such as mechanical load,

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soil humidity and acidity,
will differ between locations,

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causing different aging behaviour of for example
Presenter underground cables and pipelines.

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The management of infrastructure assets has
become a new field of scientific study since

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the privatization of drinking water infrastructure
in the United Kingdom.

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In the early 1990’s,
the newly privatized Yorkshire Water company

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discovered that they were losing more than
40% of their precious drinking water on the

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way between the drinking water plant and their
customers,

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as a result of leakage from old pipelines.

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It therefore comes as no surprise that Yorkshire
Water had a keen interest in improving its

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distribution system,
and ensuring its long term robustness.

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Their efforts played a big role in the development
of asset management standards,

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which are now being adopted worldwide by operators
of capital intensive infrastructure assets.

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Another cause of complexity is changing functionality.

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The cross-border interconnectors between the
national electricity systems in Europe were

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originally intended as back-up facilities
to be used only if the system stability at

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the national level needed support.

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Nowadays,
these interconnectors need to accommodate

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massive flows of electricity that result from
electricity trading.

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This raises the question if,
and how much,

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of their capacity should be reserved for the
original technical stability support function.

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Another example: the nature of electric power
generation is changing.

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More and more power is being generated from
intermittent renewable energy sources,

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such as wind.

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In the past,
electricity supply could easily be adapted

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to fluctuations in electricity demand,
since coal and gas fired power plants can

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be controlled: they are so-called dispatchable
generators.

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The power generated by wind turbines cannot
be controlled – it just depends on the wind.

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Generally,
fossil and nuclear power plants are strategically

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located in the vicinity of the electricity
demand centers,

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the load centers,
as they are called by electrical engineers,

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such as big cities and energy-intensive industrial
sites.

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Wind parks,
however,

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not only need wind - they also require much
more physical space than a traditional power

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plant.

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Full screen Therefore,
wind parks are usually located far from the

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load centers.

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Let us have a look at the consequences.

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In Germany for example,
wind parks are largely located in the northern

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part of the country,
both on and offshore.

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The load centers are largely located in the
southern part of the country,

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and they used to be served by hydropower,
nuclear and fossil fuel based power plants

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are also located in the southern part of the
country.

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With the sudden closure of a large number
of its nuclear power plants,

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in reaction to the Fukushima disaster in Japan,
the German load centers have become more dependent

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on wind power supplies from the North.

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There is,
however,

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a lack of interconnection capacity between
the northern and the southern part of the

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country,
so that the electricity flows generated by

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the wind farms in the north need to find their
way to the German south via neighbouring countries.

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In other words,
the flow patterns in the European system are

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drastically changing,
and,

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since the amount of electricity generated
from intermittent renewable energy sources

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is increasing Click click click ,
Presenter the risk of the system becoming

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unstable is increasing.

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Electricity infrastructure differs from other
infrastructure systems in the sense that the

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system has little storage capacity in proportion
to its overall size.

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At this point in time,
the only option to store electricity on a

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commercial scale is in hydropower reservoirs.

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In times of excess electricity supply,
electricity is cheap and can be used to pump

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up water to refill hydroelectric reservoirs.

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At times of peak demand,
when electricity is expensive,

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the hydroelectric plant can then produce more
electricity.

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However,
this type of storage capacity is relatively

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scarce and geographically unevenly distributed.

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Electricity differs in another significant
aspect from most other infrastructures: the

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velocity of electricity flows approaches the
speed of light.

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In a system with little storage capacity,
this implies that the balancing of supply

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and demand Fullscreen needs to be managed
in real-time.

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If only the demand fluctuates,
while generation can be controlled,

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the balance can quite easily be maintained
by adjusting power generators.

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However,
as more and more power is generated from intermittent

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renewable energy sources,
the share of controllable generators in the

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generation mix is dwindling,
and balancing the supply and demand becomes

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far more challenging In comparison with electricity
infrastructure,

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water and gas infrastructures are far more
inert systems.

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The flows in these systems are relatively
slow,

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and since there is ample storage capacity,
including the storage capacity in the pipelines

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themselves (the so-called line pack),
Presenter the balancing of supply and demand

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is far less critical than in the electricity
system.

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Thank you for your attention,
see you in the next part.