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Challenges and Opportunities of the Energy Transition and the Added Value of Energy Systems Integration

Marialaura Di Somma and Giorgio Graditi

Italian National Agency for New Technologies, Energy and Sustainable Economic Development, ENEA, Department of Energy Technologies and Renewable Sources, Rome, Italy

1.1 Energy Transformation Toward Decarbonization and the Added Value of Energy Systems Integration

The global energy t ransformation is already in place, and this represents the main reply of humanity to safeguard global climate and maintain sustainable existence on Earth. The first step toward this energy transformation and the international commitment to combating climate change, increasing energy access, and maintaining biodiversity is represented by the Paris Agreement signing at COP 21 with the goal to maintain global warming lower than 2 °C above the pre-industrial levels. Concurrent to the Paris Agreement, countries committed to the United Nations (UN) 17 Sustainable Development Goals (SDGs), representing the plan toward a better world for people and our planet to be achieved by 2030 [1]. Tackling climate change is a transversal goal for almost all SDGs. Although the international commitment is evident, challenges still remain for the successful implementation of the Paris Agreement and climate- and energy-related SDGs, and the gap between aspiration and reality in combating climate change remains significant.

Meeting these ambitious goals requires the commitment beyond the electricity sector, whereas providing decarbonization across different sectors through an integrated approach can represent a valid solution. This is the main idea behind the concept of Integrated Energy Systems that, according to the ETIP SNET Vision 2050 [2], are defined as an integrated infrastructure for all energy carriers, with the electrical system as the backbone. These systems are characterized by a high level of integration among all networks of energy carriers obtained through coupling electrical and gas networks, heating, and cooling, supported by energy storage and conversion processes. Coupling different sectors indicates increasing efforts in a synergic way by coordinating the planning and the operation of energy systems across multiple energy carriers while also achieving a more flexible, reliable, and efficient energy system as a whole.

The main energy trends toward decarbonization are discussed below along with the added value offered by energy systems integration.

Figure 1.1 Evolution of the current energy system to an electrified energy system.

Electrification is considered a valid cost-effective pathway for decarbonization of final energy consumption. This is mainly due to the fact that several technologies for converting renewable energy into electricity have recently become available at competitive prices such as PV and wind turbines. On the other hand, a large part of CO2 emissions in industries, transport, and buildings is not related to power sector but to end use of fossil fuels. That is why, a large-scale electrification, characterized by the penetration of an electricity carrier produced by renewable technologies in building, transport, and industry sectors, represents a good pathway for decarbonization. According to the International Renewable Energy Agency (IRENA) Renewable Energy Roadmap (REmap) [3], the share of electricity in final energy consumption amounts to 20% today and will reach the percentages of 29%, 38%, and 49% in 2030, 2040, and 2050, respectively.

Figure 1.1 shows the change from the current energy supply system where the electricity demand is typically satisfied by an electricity network and heat demand by gas-fired boilers supplied by a gas network to an electrified energy system, where the electricity network is used to satisfy all energy demands, including heat demand through Power-to-Heat (PtH) technologies. An electrified future poses important questions such as how much additional power network capacity do we need to satisfy all types of energy demands? Or, what happens if there is a contingency in the power system?

A strong electrification scenario creates a number of challenges for the operation of a power system, which in principle would need additional flexibility, reinforcement, and new investments for the transmission and distribution networks.

In Figure 1.2, the current energy system is compared to an integrated energy system, which is something more than an electrified energy system. In fact, in such system, multiple hybrid energy technologies are managed with high synergy to satisfy the multi-energy demand and services can be provided with the most convenient energy carrier and sector.

If electrification of final consumption is combined with the integration of energy sectors, decarbonization of energy demand would be reached through penetration of renewables in all energy end use sectors while also getting higher flexibility for the whole system by reducing the needs for reinforcing the existing network infrastructures. Moreover, energy systems integration allows increasing efficiency in the energy resources use through exploiting synergies coming from the interplay of different energy carriers and reduction of renewable energy source (RES) curtailment. In practice, for instance, in the case of excess electricity from RES, it can be converted into gas as hydrogen or synthetic methane through Power-to-Gas (PtG) technologies, stored and/or transported by existing gas infrastructures for immediate or later usage, or re-converted again into electricity when renewable electricity supply is insufficient to satisfy the loads. On the other hand, PtH technologies combined with thermal storage can shift production of thermal energy when renewable electricity is in excess, thereby representing another option for reducing RES curtailment [4].

Figure 1.2 Comparison between the current energy system and an integrated energy system.

Also, in the transport sector, electrification can be a successful strategy for decarbonization, while making the system as a whole more flexible. In fact, electric vehicles in Power-to-Mobility (PtM) application represent a valid alternative to traditional cars with internal combustion engines and can provide flexibility to the electricity system through smart charging strategies, for instance, by charging batteries during the period of low demands, thereby flattening out the electricity load profile.

Similarly, heat pumps in PtH application represent a cost-effective and more efficient alternative to conventional gas-fired boilers for heating purposes in buildings and also for reducing primary energy consumption thanks to their high conversion efficiency.

According to REmap [3], the number of electric vehicles worldwide will pass from the current 6 millions to 157, 745, and 1166 millions in 2030, 2040, and 2050, respectively, whereas the number of heat pump installations will pass from the current 20 millions to 155, 259, and 334 million in 2030, 2040, and 2050, respectively. The strong expected electrification of transportation and heating sectors could lead to higher peak loads, thereby requiring higher flexibility to match electricity demand and supply. Again, also in these latter cases, the added value of energy systems integration is given by the possibility to store excess electricity from RES and provide back-up supply to cover peak loads, thereby ensuring balance at all times with clean energy in the equation.

Another major trend in energy landscape is represented by the large-scale deployment of distributed generation(DG). In the past years, the power system has been affected by a fundamental revolution as compared to its traditional conception. The deployment of renewable technologies at a local level led to the switch from a "one-way" generation system mainly relying on a few large power plants connected to HV and EHV grids and located far from consumption areas to a "multi-directional" system, whose characterization and management are extremely complex. In the traditional electricity system, the electricity produced in large power plants reaches the users - through the transmission and distribution networks - playing the passive role of energy consumers. On the other hand, the energy model of DG mainly consists of a number of medium-small generation units (from a few tens/hundreds of kilowatts to a few megawatts) usually connected to distribution networks. DG units are usually located close to the loads to satisfy and designed to exploit renewable sources spread throughout the territory and otherwise not usable through traditional large-size generation units.

The benefits offered by this new energy model are different:

• increase of the efficiency of the electricity system thanks to the reduction of energy transport loss;
• increase of RES penetration levels and more rational use of energy; and
• optimization of the resources at local level and the local production chain.

According to REmap [3], the...