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Stepsol, the hydraulic, gravity-powered energy storage system

Energy Storage

Didier Pierrat-Agostini is the president of STEPSol, a company founded in 2016 in Corsica. STEPSol has been working for three years to develop a hydraulic, gravity-powered energy storage solution. The company will showcase its work at the ENGIE Energy Lab at Vivatech in June 2017.

Experimental platform at Paglia Orba (University of Corsica-CNRS-CEA)

Hello Didier, can you give us a quick introduction to STEPSol?

STEPSol is working in partnership with CEA/LITEN to develop an innovative, optimized solution for generating energy from photovoltaics for non-interconnected zones. The micro-STEP is a robust and durable storage system that is used with solar energy to avoid the intermittency and randomness that often comes with PV.

This R&D program has been approved by the CAPENERGIES competitiveness cluster and is being financed by the Corsica region and the South-East SATT. The teams began working on the experimental platform at Paglia Orba (University of Corsica-CNRS-CEA). We are currently preparing the next step, which involved developing the first two demonstrators with support from Corsica and the ERDF 2014-20 Fund.

Q- In what way is your project innovative?

STEPS (Pumping Power Station) are used on dams for 99% of energy storage currently in existence in the world. It’s a simple, mature technology, but the large dimensions of the ponds and pipes it requires considerably limit where it can be used.

STEPSol reuses this technological storage technique, but with less power involved (36kW to 1MW), thanks to the micro-STEP techniques that have been developed for solar power plants to provide controlled, predictable electricity production. Solar micro-STEPs are installed next to a river or other body of water, and can be customized to fit the relief of the land, sunshine levels and other site specifics.

The challenges with the technology are economic and financial, and require the system to be innovatively designed and operated to:

  • Minimize the amount of land used,
  • Optimize the energy stored,
  • Implement strategies to control the pumping/turbine system and how it is managed with relation to solar resources available,
  • Creatively accounting for connections to the grid and administrative/regulatory constraints

Our modular, locally-adaptable solution is also designed to be a functioning component of a global or regional smart grid system.

An energy management system developed for STEPSol with SATT SE and the University of Corsica will be used for piloting energy in the smart grid (prediction, managing expansion, etc.)

Q- What are you going to showcase at Vivatech?

Our well-rounded team and an animated film about our innovative technology.
Q- What do you expect to get from being at Vivatech with ENGIEWe want to have meetings that will lead to developing our network but also positive discussions about getting industrial and financial support, primarily from ENGIE.
Q- What question would you have liked me to ask you? And your answer?You could have asked me, What are the limits to the energy transition at the moment?

The major flaw in renewable energy sources is the fact that they are intermittent. It’s particularly difficult to guarantee the balance between production and consumption when you have random or non-controllable sources. If the network operator doesn’t properly control this balance, not only will consumers no longer be guaranteed continuous electricity service, but the network can become vulnerable to instability and even collapse.

There are several solutions for overcoming this major fault: energy sobriety, controlling consumption (shaving), expansion, and storing energy produced. For example, we connect solar power stations to micro-STEP storage to manage our energy production, and thus actively and locally reinforce the network while including renewable energy generation in it.

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