Details of the new flywheel

The ENERGIESTRO flywheel comprises a prestressed concrete cylinder (1) that can resist a high rotational speed in order to store kinetic energy. A motor/alternator (2) transfers electrical energy to the flywheel (acceleration) then recovers it (braking). Upper (3) and lower (4) bearings are ball bearings. A passive magnetic thrust bearing (5) bears the weight of the flywheel . A sealed chamber (6) maintains the flywheel in a vacuum to remove air friction. An electronic converter (not shown) transforms the DC voltage at the terminals of the flywheel into a high frequency AC voltage for the motor/alternator.


ENERGIESTRO innovates with a flywheel made of a low cost material, prestressed concrete (patented worldwide). Before, flywheels were made of high performance, very expensive materials: carbon fibers or high tensile steel. The new material from ENERGIESTRO will decrease by a factor of ten the cost of energy storage. ENERGIESTRO aims to store energy for 24 hours, in order to release during the night the solar energy collected during the day. In order to further reduce cost, ENERGIESTRO does not use expensive magnetic bearings, but simple ball bearings, assisted by a passive magnetic thrust bearing, which needed to solve the problem of lubrication in a vacuum (Patented worldwide).



ENERGIESTRO has tested its metal flywheels by powering several pilot sites for several years: a house, two GSM antennas, our factory… They have accumulated tens of thousands of hours and hundreds of thousands of cycles.
The new concrete flywheel has been successfully tested in our laboratory.



  • Unlimited life: battery life is limited to a few thousand cycles.
  • Resistance to extreme temperatures: batteries do not tolerate them.
  • No toxic or strategic materials: batteries contain lead, cadmium, lithium, cobalt…


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