Indeed. I have done some research on flywheels and I believe that they can be much more efficient than batteries. Another huge benefit to flywheels is that they

Indeed. I have done some research on flywheels and I believe that they can be much more efficient than batteries. Another huge benefit to flywheels is that they are consistent and do not suffer loss of capacity over their extremely long lifespan. Flywheels really should be used for this type of thing, not batteries. Regarding efficiency, the following is from a 2003 report: "Various losses in the system, including bearing losses, and electrical losses (stator losses, power converter losses), contribute to the overall conversion efficiency. The power electronics switching losses usually dominate the total losses, and the overall efficiency is a function of power, usually > 80% for power in the range 10% to 100% rated. The maximum efficiency quoted by some manufacturers is 96%. This gives rise to a typical maximum in-out efficiency of 92%." - http://www.itpower.co.uk/investire/pdfs/flywheelrep.pdf http://www.itpower.co.uk/investire/pdfs/flywheelrep.pdf