Toward Sustainable Energy Communities

Giuseppe Anastasi

and Marco Raugi

Dipartimento di Ingegneria dell’Informazione, Via Caruso 7, 56122 Pisa, Italy

Dipartimento di Ingegneria dell’Energia dei Sistemi del Territorio e delle Costruzioni, Largo Lazzarino, 56122 Pisa, Italy

Keywords: Energy Communities, Energy Self Sufficiency, Energy Systems Integration, Renewable Energy Sources.

Abstract: Currently energy resources are adapted to user requests. In the perspective of an increasingly sustainable use

of energy, it will be more and more useful to aggregate the consumption of groups of buildings of various

types (for example for residential, office, commercial and industrial use), forming the so-called "Energy

Communities". In that way the overall requests for energy can be easily adapted to the available energy

resources, in terms of both overall consumption and hourly distribution. The AUTENS (Sustainable Energy

Autarchy) project aims to identify possible solutions for the complete energy self-sufficiency of "Energy

Communities" through innovative methods optimizing the integration of electrical and thermal systems

(generators and storages), supplied only by renewable sources produced locally. This will be targeted by

means of suitable integration of ICT technologies, artificial intelligence and social sciences. We intend to

examine situations in which it is not possible, or sustainable, to use the primary power and gas grid, and

therefore the use of energy from an "Energy Community" must be made with only renewable sources to be

produced locally through solar and wind energy, geothermal and biomass. The project also proposes the

construction of some demonstrators.

1 INTRODUCTION

One of the most important challenges that awaits

humanity is to prepare society for the goal of a

decarbonized society at 2050, as clearly states also by

the European Commission President Ursula von der

Leyen “We are doing everything in our power to keep

the promise that we made to Europeans: make Europe

the first climate neutral continent in the world, by

2050”.

The initiatives promoted by Greta Thumberg have

brought climate changes to the attention of civil

society and governments. Controversial discussions

also of a scientific kind was born facing from one side

“negationism” issues based on the observation that

climate changes has been many times experienced in

the past and from the other side remarks that in our

age there is a very high speed of climate changes with

respect to the past.

However there is an aspect that cannot be

neglected, namely that the anthropization of the

planet is truly an absolute novelty compared to past

eras and this entails consequences that will most

https://orcid.org/0000-0001-6231-6690

likely strongly conflict with the habitability on the

planet and the quality of life of the human race in the

near future even in the medium term.

If it is true that a great improvement of the

"average" quality of life of many populations in the

last century is due to the use of energy and the

availability of raw materials, and that the availability

of both on the planet is limited, then it is clear that the

models of current economic development are

inadequate to reconcile an always increasing

economic development with the resources available

on the planet. The risk is that the lack of resources

makes it impossible at some point to maintain the

“wealth” achieved, prefiguring very worrying

scenarios of socio-political instability and conflict.

It is therefore necessary not only to move towards

production systems based on circular economy but in

particular to be ready to transform the present social

behaviors.

One possible way is to aggregate individual

consumption (both of individual citizens and

industries) in groups called energy communities,

where on a medium / small scale they go to reconcile

and even negotiate individual needs to ensure the

Anastasi, G. and Raugi, M.

Toward Sustainable Energy Communities.

DOI: 10.5220/0010415501250130

In Proceedings of the 10th International Conference on Smart Cities and Green ICT Systems (SMARTGREENS 2021), pages 125-130

ISBN: 978-989-758-512-8

125

needs of everyone on average. We could thus move

to a vision (whose realization today is facilitated by

the digital revolution) in which the sustenance of the

communities was provided by the resources that one

was able to self-produce. In particular, in the case of

communities of users that are close even

geographically, the self-produced energy may also

depend on the agro-energy resources available

locally, thus also preserving biodiversity.

2 BACKGROUND

The starting point of the project is a software

developed in the framework of a previous project able

to carry out an optimal evaluatation of Hybrid

Renewable Energy System (HRES) investments

(Noh et al., 2016). The software is based on a

simulation approach that consider all the involved

subsystems (photovoltaics, small wind turbines, solar

thermal, heat pump, electric and thermal storages,

heating and cooling emitters, building envelope,

traditional back-up systems) and their mutual

interactions. A multi-objective optimization finds the

Pareto frontier that maximizes Net Present Value

(NPV) and minimizes CO

emissions in three relevant

scenarios, taking into account the high sensitivity to

the conventional fuel cost variation.

The output of the methodology may steer the

decision maker to a more in-depth analysis and

characterization of the critical variables and possibly

towards a more robust design choice. and people

behaviours with regards to energy use. Furthermore,

it can improve academic teaching programmes,

steering them towards a global vision.

2.1 Software Application Example

The medium-long term planning of the construction

of an integrated thermal and electrical energy

production system fed by renewable sources – also

known as Hybrid Renewable Energy Systems

(HRES) – is an interesting, albeit tricky, investment

decision, which occurs under heterogeneous

uncertainty. In fact, in recent years, the deregulation

of the electrical energy sector and the growing

attention towards environmental concerns have

significantly stimulated the energy production market

and, consequently, have both raised the attention of

investors and added new variables and constraints

that further complicate such investment decisions

(McGovern and Hicks, 2004). For example, see the

call for reduction of greenhouse gas emissions, the

new targets for penetration of Renewable Energy

Sources (RES) in the electricity generating mix, and

the Energy Performance of Buildings Directive

(European Parliament and Council, 2012), which

requires new buildings to be nearly zero-energy by

the end of 2020.

Such trends call for a robust and integrated

investment evaluation approach to deal with the

increasing complexity of the decision context, to

reliably model the dynamics of the subsystems

involved in an HRES (Electrical, Thermal

components and Buildings), and to control their deep

interconnections.

The software presents an integrated, multi-

objective, four-stage methodology to evaluate long-

term HRES investments by comparing different

system configurations, coping with the above-

mentioned issues. The methodology includes a

simulation-based optimization procedure that

integrates the electrical generation, the thermal

systems, and the building of the investigated HRES,

and provides useful information concerning the

investment choice and the analysis of the output

reliability. Furthermore, it considers the minimization

of the equivalent CO

emissions corresponding to the

possible HRES configurations.

Simulation-based procedures are among the most

adopted approach for investigating electric

production of HRES (Bernal-Agustín and

DufoLópez, 2009a; Zhou et al. 2010) and very

effective and favorable for building-energy systems

(Hamdy et al., 2013; Kapsalaki et al., 2012) and in

building energetic studies (ASHRAE, 2009; Nguyen

et al., 2014).

The analyzed case study is a small-size building

electric system). These systems usually have strict

budget limitations, which force designers to find the

optimal sizing of technologies in terms of cost-

benefits. In smallscale systems, accurate input data

are generally available and manageable, allowing the

simulation models to deepen the analysis of the

energy system. A peculiar case of such systems is an

autonomous system, i.e. an off-grid system, serving

both electric and thermal demand, which is typical of

rural areas, mountains, and small islands and quite

common far from the urban environment and socially

important for certain communities. An autonomous

system is an example of nearly Zero-Energy

Buildings (nZEBs), as sought by international energy

directives and initiatives.

Specifically, to apply and test the proposed

methodology, we chose a stand-alone farm hostel

located in Enna, in the south of Italy, at 931 m above

sea level. The climate is cold in winter (Heating

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Degree Days: 2248) and hot in summer and the

building requires energy for space heating and

cooling, ventilation, domestic hot water (DHW)

production, induction cooking, lighting, and other

electric uses, e.g. household appliances, refrigerators,

dehumidifiers, and electronic devices. Besides,

renewable energy sources, such as sun, wind, and

biomass, are locally available.

In this site, an integrated microgeneration system

with small wind turbines, photovoltaics, and solar

thermal technologies has to be optimally designed.

Proper thermal and electric energy storages are

employed and an electrically-driven heat pump

provides the net thermal energy demand. As

mentioned, the building is off-grid, relying on

renewable energy sources, which should be optimally

exploited and managed. An electrical energy

generator (a diesel engine) is the only back-up,

needed to cope with the residual energy requirements.

The integration among energy sources and the overall

must be effectively tackled to avoid unnecessary

oversizing and inefficiencies of the installed

technologies.

For each component, the most reliable and

commercially available technology was selected. The

rationale behind this choice is due to the small scale

of the system and the investment context. Yet,

whether necessary, the methodology may be easily

extended to evaluate different available technologies

for each energy system (e.g., different PV cells or

wind turbines, etc.).

Further details on the typical hourly and seasonal

users’ presence and behavior and on the

characteristics of the building and systems for this

specific case study are given in Testi et al., (2016a).

2.1.1 The Simulation Model

The HRES design strongly depends on the dynamic

performance of its individual components, on the

available RES, and on the end uses. Figure 1

illustrates a schematic of the integrated system,

including the electric and thermal energy fluxes

Figure 1: Simulated sub-systems and interconnections.

The input variables of the simulation model and

their bounds, which define the search space, will be

shown in Table 1 for the sake of brevity.

Table 1: Design variables and bounds.

Design parameter

Bounds

Min Max

umber of small wind turbines: nWT 0 4

umber of photovoltaic modules: n

0 60

umber of solar thermal collectors: n

0 6

Volume of the thermal storage [L]: V

500 5000

Capacity of the electric energy storage [kWh]: C

1 100

lectric power of the storage converter [kW]:

6 10

lectric energy generator with/without recovery 0 1

nstallation of a biomass boiler: Yes (1) or No (0) 0 1

Thermal storage temperature for switching off the heat

ump [°C]:

TS_HPoff

46 56

2.1.2 Results and Discussion

Figure 2 shows the Pareto front determined by the

NSGA-II algorithm on the simulation data,

representing 70 points that are equally optimal for the

three selected scenarios (scenarios A, B, and C, where

diesel fuel cost is estimated to be, respectively, 1.2,

1.6, and 2.0 €/L).

When CO

eq emissions are considered, all the

presented solutions outperform the Option Zero (No-

RES configuration), which fulfils the energy demand

exclusively by means of the electric generator. Option

Zero has high CO

eq emissions (18 tons per year) and

NPV is conventionally equal to 0.

Nevertheless, some optimal designs found on the

Pareto set show a negative NPV, in particular those

belonging to scenario A and/or that minimize the

eq emissions, because they require to maximize

the adoption of energy-efficient production and

conversion technologies and energy storages.

The scenario analysis highlights that NPV is very

sensitive to the cost of fuel. This confirms the

relevance of a careful and accurate forecast of the

underlying value, such as the fuel price, or of the

electricity price in the cases of on-grid plants.

As expected, the Pareto front shows a similar

shape in all the three scenarios, while they are shifted

with respect to the NPV value. For the sake of clarity

and brevity, we discuss three relevant optimal

candidates from the nominal scenario B (B1, B2, and

B3 in Figure 2) and, in the section 5.2, only one

candidate from scenarios A and C (A1 and C2 in

Figure 2).

Toward Sustainable Energy Communities

127

Figure 2: Pareto optimal front in the three scenarios;

solutions of the Pareto optimal set, shown in a circle, are

identified to compare the sensitivity of design

configurations.

Looking at the Pareto front by an economic

perspective, the best solutions identified by NSGA-II,

which present the maximum NPV and also the

highest PI, suggest minimizing the use of wind

turbines and solar thermal collectors and not to adopt

heat recovery for the electric energy generator. The

optimal design, differently from the other solutions,

also limits the installation of electrical batteries. The

final estimate for NPV is 47.2 k€, while CO

eq saving

amount is about 170 t, which is around 50% of the

maximum CO

eq savings provided by the most

sustainability-oriented configurations.

This evidence, which remains confirmed for all

the investigated scenarios, is due to the high impact

of wind turbines and electrical battery initial capital

costs and also of battery replacement costs on the

NPV evaluation. The use of these technologies is not

justified, especially when the fuel cost is low, since

we always perform a comparison with the

highlyconsuming Zero Option. Nonetheless, in

scenario C, we can observe that the configurations of

optimal NPV have lower greenhouse emissions, since

an additional investment on renewable technologies

is economically justified by the high fuel cost.

On the opposite border of the frontier, the optimal

solution that seems to better perform in minimizing

eq emissions. Besides, the design candidate

suggests investing into heat recovery: a combined

heat and power (CHP) unit is adopted. Under these

conditions, initial installation and replacement costs

rise up. Yet, lifetime costs are still lower than the Zero

Option.

Other optimal candidates are obviously available.

The decision maker can use the Pareto front to choose

the most adequate design configuration according to

her/his own needs, balancing the economic-financial

perspective with the system sustainability.

3 AUTENS PROJECT

The AUTENS (Sustainable Energy Autarchy) project

of the University of Pisa aims to implement research

activities to the creation of new strategic ideas for

sustainable development, by studying new paradigma

for energy production from renewables and people

behaviours with regards to energy use. Furthermore,

it can improve academic teaching programmes,

steering them towards a global vision.

The Project focused also on the relationship with

local institutions in order to achieve a wider vision, to

provide new and useful tools, through responsible

cooperation, for a rapidly changing world.

Furthermore education and dissemination

instruments will be defined to inform students and

citizens on the clean and affordable energy goals as

clearly stated in the SDG 7 to strenghten the

principles of Sustainable Development and Agenda

2030 goals.

Presently the current approach for the energy

providers can be described as follows. On the basis of

an energy need (e.g. hourly production of hot water at

a certain temperature), an energy system is designed

to fulfill the request, while trying to maximize energy,

exergetic, economic and environmental performance

(the so-called 4E). Therefore the energy requirement

constitutes a constraint for the supplier who uses the

existing solutions to satisfy it.

In the perspective of an energy autonomy of users,

it is instead necessary to prefigure a completely

innovative case study, overturning the current

paradigm and providing a scenario in which it will be

necessary to adapt the energy demands of users (also

by negotiating consumption for civil and industrial

uses) with the energy resources available, in terms of

both overall consumption and hourly distribution.

4 PROGRAMMED ACTIVITIES

The AUTENS project goals are to identify possible

solutions for the complete energy self-sufficiency of

communities through innovative methods for the

integration of electrical and thermal systems

(generators and storages), feeded only by renewable

sources produced locally, through the integration of

ICT technologies, artificial intelligence and social

sciences. In particular, we intend to examine

situations in which it is not possible, or sustainable,

to use the power and gas grid, and therefore the

energy supply of civil or industrial buildings must be

made only with renewable sources to be produced

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locally through solar, wind, geothermal and biomass

energy.

This pespective push towards a strong change of

current social habits and lifestyles, both in terms of

citizens' consumption and productive activities. It is

therefore important an innovative combined

scientific-technological, social and regulatory study

that foreshadows possible solutions to be ready to

face these scenarios. Furthermore it becomes strategic

and necessary to integrate research groups that tackle

the problems by simultaneously considering the

social and technological aspects.

For this reason, the project integrates different

types of expertise with a highly interdisciplinary

approach necessary to systemically address issues

related to energy and its close connections with

economic, social and political sustainability. In

particular, the project combines the electrical,

electronic, thermal, chemical aspects related to

energy production with data analysis and artificial

intelligence techniques, as well as economic and

market ones. Furthermore, it also includes the

necessary social and legal-regulatory aspects.

To develop system corresponding to the

AUTENS scenario, it is necessary to study the ways

in which users, both in single and aggregate form, can

become completely autonomous in energy supply.

For this purpose, the project includes the following

activities.

• Socio-economic survey to (i) obtain profiles of

electrical and thermal energy needs in the current

context and (ii) understand the social acceptability

of the predicted energy self-sufficiency scenarios,

including the availability to changes in energy

consumption styles due to a limited energy

availability and negotiation with consumption for

production activities.

• Solutions for the integration of storage systems,

and renewable sources, with ICT technologies and

electronic platforms that maximize flexibility and

energy efficiency, minimizing the impact on

people's wellbeing and industry activities.

• Combination of quantities of energy production

from biomass to be grown locally according to the

climatic characteristics of the specific place.

• Development of intelligent techniques based on

the monitoring of energy consumption and

climatic conditions of buildings and industry

plants to provide users with an expert system to

support decisions. An interdisciplinary study will

be carried out to define appropriate models for the

collection, use and circulation of data, also

considering privacy aspects

• Study of regulatory norms for the self-production

of energy (Renewable Energy Community) in the

national and European legal framework, to verify

their ability to represent a real incentive for

AUTENS systems

Finally, the project will use an existing "hardware in

the loop" laboratory facility for emulation of the

systems under study. This allow to measure the

performance of hybrid thermal / photovoltaic (PV / T)

solar panels, geothermal heat pump systems (GSHP)

, the phase change accumulations (PCM). Finally, it

will be possible to implement a monitoring and

control system with machine learning algorithms.

5 CONCLUSIONS

The AUTENS project will consider innovative

methods for the integration of electrical and thermal

systems (generators and storages), supplied only by

renewable sources produced locally. Situations in

which it is not possible, or sustainable, to use the

primary power and gas grid, will be studied.

Distinctive features of the project will be suitable

integration of ICT technologies, artificial intelligence

and social sciences. Furthermore, the use of energy

from an "Energy Community" will be considered be

made of only renewable sources to be produced

locally through solar and wind energy, geothermal

and biomass. The project also proposes the

construction of some demonstrators.

ACKNOWLEDGEMENTS

Work carried out in the framework of the “AUTENS”

(Sustainable Energy Autarky) project funded by the

University of Pisa (PRA 2020 program).

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