Environmental Engineering Reference
In-Depth Information
Primary
energy
Energy form found in
nature (a.k.a. raw fuels)
that has not been
subjected to any
transformation process.
Examples
Gas
Petroleum
Coal
Uranium
Bioenergy
Wind
Process
plants
Primary energy sources
are transformed via
conversion processes to
more adequate forms of
energy to be transported
and delivered to
end-users.
Examples
Refined fuels
Synthetic fuels
Gas plants
Power plants
End-use
services
Energy travels via carriers
or infrastructures for final
consumption to points
where demand is required
by energy systems to fulfil
societal needs.
Examples
Industry
Commerce
Domestic
Transport
Figure 1.4
Example of different stage processes within an urban energy systems
they disregard cities in their analysis and therefore urban energy systems can only be
estimated at best [13].
Figure 1.4 describes an example of the different stages of how energy is pro-
cessed in an urban energy system, from primary energy sources through conversion
systems to final energy use demands. If these processes were to be quantified, a Sankey
diagram showing the distinctive flows would be its output.
Appendix B illustrates a quantitative example of a Sankey diagram for the whole
of the UK in 2011 showing 49% efficiency in energy usage. If we go to a city level,
similar studies reported Toronto has 50% efficiency, while Helsinki has 68% effi-
ciency, mainly due to the latter using waste heat in district heating schemes [14].
From this comparison engineers would be led to believe there are clear opportuni-
ties to enhance the performance of urban energy systems; therefore, it is the goal
of this text to focus, within an urban environment, on effectively managing energy
resources through modelling of conventional energy infrastructures and innovative
conversion technologies.
1.2
Evolution of urban energy systems
Urban energy service networks, which in this publication only refer to both natural
gas and electricity infrastructures, have traditionally been designed and operated sep-
arately from one another despite both being capable of satisfying electrical power
and heating loads. Still, current factors exist that could arguably change this con-
dition because natural gas has become a common fuel of choice to reduce carbon
footprints and enhance the robustness of energy systems [15]. Thus, the task of inte-
grating energy systems creates new challenges for stakeholders, which in turn makes
them seek knowledge of the growing industries' opportunities.
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