Pumped Storage Plants as an alternative to contribute to the safety of the Brazilian electrical system

In addition to the aspect related to the concession, mechanization concepts should be structured that allow the economic viability of the competitive and efficient UAB

In recent years, the Brazilian Electric Sector has witnessed a real boom in the implementation of projects of electricity generation from variable renewable sources, especially solar photovoltaic and wind. Despite the numerous positive factors of this strong exposure, its impacts on the stability and operational safety of the electrical system cannot be neglected.

One of the ways to avoid that the variability of these energy sources compromises the operational reliability of the system is the use of sources that provide controllability and operational flexibility , which can be given both by the implementation of "despacháveis" plants - as thermoelectric and hydroelectric plants -, as for the adoption of load/demand management measures and/or the use of electrical energy storage systems.

Different studies indicate that the implantation of new hydroelectric plants with large reservoirs against geographic/environmental restrictions, since the main hydrographic basins are located in the Amazon region. The implementation of new thermoelectric gas, in turn, despite the great national potential of production of this important energy, finds limitations in the face of the global concern to reduce carbon emissions.

Vitor Sarmento de Mello, sócio no Rolim Goulart Cardoso Advogados

In this context, the adoption of energy storage systems presents itself as an excellent alternative that provides the attributes that the electrical system needs to adapt to the new composition of the electric matrix, especially those using mature technology and successfully adopted in other countries, such as Pumped Storage Plants (PSP).

In fact, since at least 2016, important players in the electricity sector have started to design and study methodological solutions for the efficient and economic implementation of the so-called Pumped Storage Units (UAB). Although they can be considered as a species of the category of Reversible Hydroelectric Plants (UHR), the UAB has its own specificities and peculiarities, which is why the distinction is relevant.

The UHR and the UAB, in a similar way to the "traditional" hydroelectric power plants- namely, the Hydroelectric Power Plants (HPP) and the Small Hydroelectric Power Plants (SHP)-, use the gravitational energy of water, through the elevation difference, for electrical power generation. However, unlike "traditional" hydroelectric plants, UHR and as UAB have mechanisms for pumping water from a lower reservoir to a upper reservoir - with the use of energy from another generating source - in order to be reused in electricity generation at peak demand times.

Specifically, UAB, unlike conventional UHR, can regulate their reservoirs daily. This means that these projects are designed to have the ability to operate vis-à-vis the electrical consumption of the system, to generate energy at peak times in consumption and pump at times when consumption is lower, using, therefore, any generation surpluses.

Bernardo G. Ferreira da Silva, advogado no Rolim Goulart Cardoso Advogados

In this bias, the UAB provide an energy storage service, since they can absorb momentary excess of variable generation available (from photovoltaic and/or wind power plants, for example) or even increase the absorption of energy from hydroelectric and thermoelectric plants of the National Interconnected System (SIN), being an important tool of operational flexibility both for the generation, use and storage of energy.

These enterprises still stand out from conventional UHR because they can operate both in closed circuit, using the same water reserve, as in a semi-open circuit, being implanted next to the reservoirs of the UHEs and PCHs.

Without prejudice, the UAB present the possibility of storing power through the pumping of water between small reservoirs, existing or built when the plant is implemented, not being necessary the proximity to riverbeds for its operation. This mechanism largely decreases the use of water resources and the environmental impact caused by conventional UHR and thermoelectric plants of the same capacity; in addition, the UAB may be close to the load centers, efficiency through the postponement of investments in transmission networks and the reduction of losses associated with energy transport over long distances.

Its main attribute is to enable the provision of systemic services, energy, power, capacity, and ancillary services. This is because the service provided, in essence, is the storage of power and operational flexibility, and power generation is only marginal and associated with other products delivered.

Therefore, considering the technical and infrastructure particularities of the UABs, it is important that the regulatory requirements applicable to these plants are elaborated to the extent of their differences in relation to other types of enterprises.

Carolina Figueiredo Germano, advogada no Rolim Goulart Cardoso Advogados

For example, hydroelectric plants belong to the Union and any project with power exceeding 50 MW is operated through the granting of a concession, through the completion of the due bidding. However, the UAB, for operating in closed or semi-closed cycle and can be made viable from small reservoirs, without consunctive use of water, should not be subject to the same regulatory regime applicable to large hydroelectric plants.

Thus, there is no allocation of natural resources for public utility that condition the performance of the UAB to the granting of concession. Unlike other hydroelectric plants, the use of the public good by the UAB is "insignificant" or "not subject to grant" according to ANA Resolution nº 1.940/2017, behold, after the initial filling of the reservoirs of these plants, the use of water will occur, above all, for replacement in the face of evaporation and natural infiltration, without affecting the flow regime of water bodies. Thus, one of the reservoirs can be artificially created outside the natural circuit of the river, so that there is no reduced flow stretch, because the river trough is not affected. In addition, the relationship between the flooded area of the UAB reservoirs and their installed power is dozens of times lower than the conventional HPP reservoir that has the same installed capacity.

Therefore, UAB, by its very nature, should not be granted a Union concession, but authorization, as well as other water sources (Normative Resolution ANEEL(REN) nº 875/2020) and alternative sources (REN nº 1.071/2023) because, although they have as main characteristic the energy storage, they still contribute to the generation activity, and, therefore, they must be included among the generators.

In this regard, the position adopted by ANEEL in the establishment of the Public Consultation (CP)nº 39/2023, which indicates the intention of the regulator that the granting of UABs, denominated in the Agency documents as "reversible plants in a closed cycle" issue of Authorizing Resolution, without prior bidding.

In addition to the granting aspect, concrete mechanisms must be structured to allow the economic viability of the UAB in a competitive and efficient way. For this, there must be regulatory adjustments that enable these enterprises to earn revenues through the provision of capacity services (or ballast) and ancillary services (frequency control, support of reactive and reserve of operating power, among others) to the system.

In this line, it is of paramount importance to improve the forms of remuneration related to the provision of ancillary services and reliability services to the system, which involves the creation of new products and review of existing products, to establish a competitive market structure appropriate to the provision of those services. In addition, it is necessary to include energy storage systems in the next Capacity Reserve Auctions, as already reported by the federal government.

The inclusion of UAB in the regulatory framework, through the definition of a regime capable of providing legal certainty and predictability to investors, as well as the definition of an adequate remuneration structure, would place Brazil on the same page of the international scenario.

Thus, it is expected that sectoral institutions continue to make efforts, in dialogue with agents and society, to enable the implementation of energy storage systems, such as UAB, in the Brazilian electric matrix in order to provide the operational safety necessary to face the continuous growth of variable sources of electricity generation.

Vitor Sarmento de Mello, Bernardo G. Ferreira da Silva e Carolina Figueiredo Germano, são respectivamente, sócio e advogados no Rolim Goulart Cardoso Advogados.

Fonte: Canal Energia