THE Department of Energy (DoE) has issued a circular that provides a framework for energy storage systems (ESS) to address the growing adoption of renewable energy systems with intermittent supply.

In issuing the circular, the agency said it “recognizes the applications and the benefits of ESS as an emerging technology in the improvement of the electric power system in accordance to the objective of ensuring the quality, reliability, security and affordability of the supply of electric power.”

Some forms of renewable energy such as wind or solar would be more effective when paired with a storage component because such a system could store power generated when there is no demand for it, and then release it when required or when wind and solar plants cannot operate because of weather conditions or during nighttime.

The DoE said in other jurisdictions, technologies involving energy storage systems are applied to serve a variety of functions in the generation, transmission and distribution of electricity, including energy generation, peak shaving and ancillary services.

Ahead of the circular’s issuance, the DoE said it conducted a review of all relevant policies and guidelines, and existing practices in other jurisdictions to ensure the optimal use of energy storage systems in the Philippines.

The DoE said energy storage systems are to operate within the framework of generation companies whose facilities supply electricity to the grid or the power distribution system. The power grid is the high-voltage backbone system of interconnected transmission lines, substations and related facilities in Luzon, Visayas and Mindanao.

The system operator will provide central dispatch to grid-connected and embedded energy storage systems with material impact to the grid. This is in the interest of achieving economic operation and maintenance of quality, stability, reliability and security of the transmission system.

Energy storage systems will also follow limitations relating to market share and bilateral contracts under Section 45 of Republic Act No. 9136 or the Electric Power Industry Reform Act of 2001 (EPIRA).

Under the circular, ESS technologies include battery energy storage systems that are capable of storing electric energy electrochemically from which they are able to charge or discharge electric energy.

The other covered energy storage technologies are compressed air, flywheel and pumped-storage hydropower.

Compressed air energy storage uses electric energy to inject high-pressure air containers. When electricity is required, the pressurized air is heated and expanded in an expansion turbine driving a generator or power production.

Flywheel energy storage uses electric energy to accelerate a rotating mass, called a “rotor,” to store kinetic energy. Electricity is extracted from the system by drawing down the kinetic energy from the rotor.

Pumped-storage hydropower uses electric energy to pump water from a lower-elevation reservoir to one at a higher elevation. When required, the water flows back from the upper to the lower reservoir, powering a turbine with a generator to produce electric energy.

The DoE said proponents may apply and register their energy storage systems for a number of purposes: provision of ancillary services; provision of energy through bilateral supply contracts or trading in the wholesale electricity spot market; and to manage the penetration of renewable energy.

They may also register their facilities as auxiliary load management for generation companies; transmission/distribution facility upgrades deferment; transmission congestion relief; end-user demand management; distribution utility demand management; and distribution utility power quality management.

The DoE has called on the Energy Regulatory Commission (ERC) to assist in the implementation of the circular, which will take effect immediately after its publication in two newspapers of general circulation. The circular was published on Sept. 18, 2019. — Victor V. Saulon