The technology for storing sun and wind

Published on Tuesday, 27 December 2016

“The development of wind and solar is increasingly connected to the creation of energy storage systems. It will be a topic of debate in the coming years and is an area of focus for our experimentation and research.”

– Francesco Venturini, CEO of Enel Green Power

Predicting the Unpredictable

The most advanced photovoltaic panels can capture even the feeblest rays of the sun, and the most evolved wind turbines work with even the lightest of breezes.

Solar farms do not produce at night, and wind farms stop when air currents cease to blow. Unpredictability and intermittency are natural characteristics of the sun and the wind.

“The technology of renewables is becoming more effective every day. But, its race to maximum efficiency has an inevitable obstacle: the sun and wind cannot be controlled.”

Storing electricity when the sun and wind are available means making the most of all its potential and using the energy produced when it’s most needed, without having to introduce it into the grid and consume it instantly.

The Battery that Captures the Sun

In Catania (Sicily, Italy), we opened our first pilot stationary storage plant integrated with a renewable one of a commercial size in September 2015.

Enel Green Power’s solar farm hosts a system of storage developed by General Electric, with whom we’ve signed a partnership agreement including experimental activities to increase the integration of plants powered by unpredictable renewables into the grid.

The Durathon “sodium-metal halide” storage system, of 1MW/2MWh, was integrated into the Sicilian photovoltaic plant, with 10 MWp and potential limited to 8 MW because of grid constraints, then updated with advanced technological solutions that increase its flexibility and allow it to run remotely for a full integration with the storage system.

The energy-oriented technology is optimal for the low randomness of the photovoltaic yield, simultaneously allowing quick compensations in case of sudden changes in production.

As If the Wind Were Always Blowing

The energy storage system integrated by EGP at the Potenza Pietragalla wind farm (Basilicata, Italy) was the first system of its kind in Italy.

Opened in November 2015, it is an important step forward for the entire technological supply chain of wind energy and, more generally, of renewables. 

“Advanced storage systems like the one at Potenza Pietragalla allow us to limit intermittency and manage the low programmability of some sources in an optimal way, helping guarantee stability and management of the grid. ”

– Riccardo Amoroso, Head of Innovation and Sustainability for Enel Green Power

The storage system of Potenza Pietragalla (2MW/2MWh) uses the Samsung SDI technology of lithium ions, able to guarantee very high levels of performance.

The storage integrated into Enel Green Power’s wind farm allows for the almost complete return of stored electric energy and enables high levels of power, necessary for the storage system to have a quick response to the variations in energy produced by the wind plant.

Customised Solutions

Among the storage solutions available, there are electrochemical accumulators – commonly called batteries – which allow for a response to various needs of the electrical system thanks to their versatility and modularity.

Storage technologies offer solutions both for energy generators and for grid operators. For the former, they intervene on the deferred introduction of produced energy over time (energy shift); for the latter, they allow introduction according to uniform pattern (peak leveling) and the reduction of the intermittency of non-programmable sources (peak shaving).

The size of the storage systems can vary from a few kW, as in the case of domestic applications, to dozens of MW for systems connected to the transmission grid, while the capacity can vary from dozens of seconds (power intensive application) to dozens of hours (energy intensive application).

“Enel Green Power’s goal is to transfer the know-how acquired in Italy to other plants abroad, determining its applications according to the context and the specific business possibilities. ”

Other possible introductions of storage systems are being studied in Europe (Romania, Spain), in Latin America (Chile, Mexico, Peru) and North America, as well as in other areas of the world where we are already present or we have ongoing business development activities.