IEEE Power & Energy Magazine - July/August 2021 - 79

configurations (Table 2) provide decoupling between production
and consumption for a given energy carrier and
contribute to increased flexibility. This decoupling feature
is not limited to the specific energy carrier associated
with the storage devices and can contribute to flexibility
provision in the other energy carriers. Finally, the role of
the energy networks is crucial in the operation of MESs
and the full exploitation of the systems' capabilities. Modeling
real energy networks is complex and requires taking
specific characteristics into account. For instance, in
centralized district heating, the length of networks may
range between some tens to several hundred kilometers
of (meshed) heat pipes. To exploit the benefits of energy
stored in the heat network, we developed specific models
in which the network thermal energy characteristics are
exploited to increase flexibility.
Flexibility Potential of Technology
Integration and Demand Response
The aggregation of technologies at the MES level facilitates
an increased ability to provide flexibility. This aggregation
generally requires an EMS that exploits synergies
between technologies to provide market services while
supplying the energy demand. The greater the number of
production technologies, the greater the flexibility potentially
and the complexity of the EMS. District heating (and
cooling) systems provide good examples. They generally
include a wide range of technologies and energy supply
carriers (e.g., electricity and gas), which enables several
alternative management strategies. The flexibility map
in Figure 5 illustrates how technology aggregation can
increase the (physical) flexibility margins for centralized
district heating, describing, in particular, how the progressive
aggregation of an electric boiler with one CHP, two
CHPs, and three CHPs enlarges power and heat flexibility
margins. Aggregation with gas boilers and heat storage
increases the heat flexibility (depending on the amount of
stored energy).
Demand-side management is another source of flexibility
aimed at the exploitation of cheaper fuel prices, renewable
production, and so on. In district heating systems, demandside
flexibility could, for example, include modifying the
heat demand profile within the limit of the comfort targets to
shave or move demand peaks and maximize profits. In particular,
modifying the demand profile can increase the flexibility
potential that is exploitable for market service.
Case Study
Biomass
boiler
Mälarenergi Paper Mill HOFOR
190 MW
(output)
Gas boiler -
Steam turbine 50 MW
(output)
Gas engine -
Heat pump -
Electric boiler 25 MW
(input)
Biogas storage -
Thermal
storage
Heat
Cooling
Gas
Electricity
500 MWh
(energy)
X
-
-
X
21.6 MW
(output)
33.2MW
(output)
10.5 MW
(output)
-
-
-
-
-
X
-
X
X
-
-
-
-
3/15 kW
(input/output)
5 kW (input)
-
90 kWh
(energy)
X
-
-
X
table 3. Case studies: technologies and energy carriers.
ACS
-
16 MW × 3
(output)
-
5 MW × 3
(output)
13 MW
-
1.6 MW
(output)
-
0.5 MW × 3
(output)
-
10 MW (input) -
-
58 MWh
(energy)
X
-
X
X
A cross (X) indicates whether an energy carrier was included in a case study.
*EMUASA carries biogas produced on site, not natural gas.
july/august 2021
ieee power & energy magazine
79
12.5 MWh
(energy)
-
X
-
X*
X
EMUASA
Paris-Saclay
-
18 MW (output)
-
-
1.8 MW (output)
-
-
3 MWh (heating and
cooling energy)
X
X
X
X
Energy carriers
Technology
IEEE Power & Energy Magazine - July/August 2021

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