What role do energy storage systems play in the energy transition?
Energy storage systems play a fundamental role in the energy transition, acting as a stabilizing element for renewable sources and for the entire electrical grid. Their importance is crucial because renewable sources, such as solar and wind, are inherently intermittent: they produce energy only when weather conditions permit (sun or wind), not always in line with demand peaks.
Role in the Energy Transition
Storage systems overcome the challenge of intermittency by allowing excess energy produced during high generation periods to be stored and released when demand exceeds production or when renewable sources are not active (e.g., at night). This balancing ensures a continuous and reliable energy supply, making renewables a viable alternative to fossil fuels.
Stabilization of the Electrical Grid
In addition to compensating for intermittency, these systems offer important ancillary services to the electrical grid:
- Frequency management: they keep the grid frequency within operational limits, releasing or absorbing energy in real-time to instantly balance supply and demand.
- Peak load management: they reduce the need to start up fossil fuel power plants to meet demand peaks, charging during periods of lower demand and discharging when consumption is higher.
- Resilience: they provide an emergency reserve in the event of power outages (blackouts), ensuring continuity in the energy supply.
Main Storage Technologies
There are various storage technologies, each with specific characteristics and applications. The most common are:
- Electrochemical storage (batteries): batteries, especially lithium-ion ones, are the most versatile and widespread, ideal for residential, commercial, and large-scale applications.
- Mechanical storage:
- Pumped hydro storage: this is the most widespread large-scale storage technology globally. Excess energy is used to pump water to an upper reservoir, which is then released to generate electricity when needed.
- Flywheels: they store kinetic energy in a rotor that spins at high speed, releasing it quickly for grid regulation services.
- Compressed air: energy is used to compress air in underground tanks, which is then released and expanded through a turbine to generate electricity.
- Thermal storage: it converts electrical energy into heat or cold for later use.
- Power-to-Gas (hydrogen): excess energy is used to produce hydrogen (or other synthetic gases) through electrolysis, which can be stored and converted back into electricity or used as a clean fuel.