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Details of the new flywheel

The ENERGIESTRO flywheel comprises a 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, concrete (patent pending). 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 innovates again with a special alternator with low idle losses. Conventional alternators have a good efficiency at full power, but high losses at low power, causing the discharge of flywheels in tens of minutes. ENERGIESTRO aims to store energy for tens of hours, in order to release during the night the solar energy collected during the day. This alternator needed to solve the challenge of cooling in the vacuum. 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.



ENERGIESTRO has tested its 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.



  • 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…


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