IEEE Electrification - June 2019 - 13

this increased flexibility must be properly balanced within
the context of potential competition between services, e.g.,
tradeoffs when deciding whether to use water to generate
electricity or irrigate crops.
Smart and strategic use of flexibility from the demand
side and different energy technologies (e.g., from distributed devices, such as EHPs, to large technologies, such as
hydropower plants) will be critical for sustainable development based on both novel multivector and water-energy
nexus perspectives. Using examples of a smart district
and an integrated energy-water system, this article illustrates sophisticated applications of resource flexibility
that to go beyond power systems and take advantage of
joining with other energy vectors and sectors.

A Flexible Energy Future
Different Energy Futures
Figures 1-4 present different options for developing an
energy system that supplies a district with electricity and
heat. In a traditionally decoupled case (see Figure 1), dedicated systems supply customers with different energy
vectors, such as electricity and heat. This configuration
allows independent operation of each network and market, without the explicit consideration of other systems.
However, in this example, the demand side has a limited
ability to support the system, since customers would have
to change their behavior or be curtailed (which incurs discomfort) to reduce their energy demand.
Figure 2 illustrates the electricity-centered approach to
integrating intermittent RES in the electricity sector and
electrifying other energy vectors (e.g., heat). This approach
offers the advantage of allowing the RES generation to
produce heat, but the demand for heat and RES generation may be poorly correlated. This is the case in the United Kingdom, where the greatest heat demand occurs
during winter when energy generated from PV is low.
Once again, there is little flexibility for the demand side to
provide system support.

Electricity Network

Gas Network

energy sources (RES), while new or evolving systems (for
instance, in developing economies) must be planned to
manage the increasingly extreme conditions associated
with climate change. In these contexts, the flexibility to
intelligently use and invest in resources that go beyond
the power system (e.g., other energy vectors such as
heat, gas, or water dams) can be extremely valuable
from the perspective of sustainable development.
In cities, energy decarbonization and sustainable development are encouraging the electrification of transportation, heating, and other services, as well as the integration
of RES on a large scale. Take the United Kingdom as an
example. With the goal of decarbonizing transports by
2040, the sale of new gasoline and diesel cars will be
banned by 2032. Also, the U.K. government offers a sevenyear domestic renewable heat incentive for customers
who install electric heat pumps (EHPs) or other forms of
renewable heating, because heating corresponds to 40% of
domestic energy demand.
These solutions seem highly attractive at first glance,
because electricity produced with RES can be easily decarbonized and is becoming progressively cheaper. However,
accommodating the newly increasing demand for RES
generation in the electrical system is not an easy task.
Massive investments in electricity grid infrastructure (e.g.,
lines and substations) would be required to accommodate
the new power flows, as well as in generation, storage, and
other technologies that can provide reserve and active
control to balance the highly intermittent output of some
RES, such as wind and solar photovoltaic (PV). A more
effective approach would be to take advantage of the
existing assets. These resources would include district
heating and gas networks, as well as ongoing advances in
information and communication technologies (ICTs) and
automation, to allow the demand-side flexibility that is
now mostly enabled by multienergy technologies. This
multivector approach to demand-side flexibility empowers customers to use combinations of energy vectors (e.g.,
electricity, heat, and gas) to better meet their energy
needs, while also providing valuable capacity and reserve
support to the energy system.
The multivector approach to energy flexibility recognizes the attractiveness of using a suite of energy vectors and
networks to meet customer needs. Taking this vision a step
further, it may not make sense to constrain flexibility to the
energy sector in areas where little or no energy infrastructure has been installed, such as in rural areas or developing
economies. Instead, it is more valuable and sensible to consider the flexibility that investing in some infrastructures
can offer different sectors, such as hydropower plants that
merge the energy and water sectors and allow flexibility to
benefit other sectors (e.g., releasing water from the energy
sector to be used in the agricultural sector). Using resources
flexibly offers new opportunities to bring lighting, water,
food, and other valuable services to underserved customers
efficiently. However, in the so-called water-energy nexus,

Electricity
Demand

Heat
Demand

Boiler

Electricity

Heat

Gas

Figure 1. The traditionally decoupled energy services.

IEEE Elec trific ation Magazine / J UNE 2 0 1 9

IEEE Electrification - June 2019

Table of Contents for the Digital Edition of IEEE Electrification - June 2019