My experience is that it is possible to get almost 80% electrical return
from regenerative braking (these were mobile robots with a very high mass
of about 1000kg, moderately slow speed of about 1.5 m/s, hard tires on flat
smooth concrete so very low rolling friction - if you just let them roll
starting at 1.5m/s they would travel around 15 to 20 meters before
stopping). The data recorded the total energy output of the battery during
accelerations and compared it to the total energy input to the battery
during decelerations, so it doesn't include internal losses in the battery
during charging and discharging.

I do think that it is possible - though challenging - to get 85% round-trip
efficiency from the mass-lifting system mentioned here.


On Thu, Oct 4, 2018 at 8:46 AM Denny Esterline <desterline@gmail.com> wrote=
:

> This doesn't pass the smell test for me. Really choking on the idea of 85=
%
> round-trip efficiency.
> Electricity in -> control losses -> motor losses -> gearing losses ->
> winch/cable/pulley losses -> mass lifted.
> Mass lowered-> winch/cable/pulley losses -> gearing losses -> generator
> losses -> grid tie conversion losses.
> Not to mention all the things the system has to do when it's not
> raising/lowering mass, e.g. empty hook return.
> Feel free to apply your own numbers for any of those loss points, but eve=
n
> optimistic numbers
> quickly exceed the claimed numbers.
>
>
> Still an interesting idea though. :-)
>
>
>
> On Thu, Oct 4, 2018 at 3:34 AM RussellMc <apptechnz@gmail.com> wrote:
>
> > Concrete weights stacked to store energy and destacked to provide outpu=
t.
> > It works (of course) but will have difficulty being cost competitive wi=
th
> > other storage technologies.
> >
> >
> >
> >
> https://qz.com/1355672/stacking-concrete-blocks-is-a-surprisingly-efficie=
nt-way-to-store-energy/
> >
> > Claimed end to end efficiency is around 85%.
> > LiIon efficiency said to be around 90%. (Actual figure depends on metho=
ds
> > of charge/discharge).
> >
> > ________________________________
> >
> > A "train" (or multiple units) on a track with cable connection may allo=
w
> > improved ease of charge/discharge.
> > Energy storable per mass is less per distance moved due to non-vertical
> > track, but can make use of long slopes.
> > The excessively enthused could move 'wagons' sideways at top and bottom
> to
> > increase capacity.
> >
> > A single looped cable would allow multiple 'wagons' to be pulled up or =
to
> > descend using existing chair-lift type coupling/decoupling.
> >
> > Masses & heights involved are "somewhat daunting"
> >
> > 1 kWh =3D 3,600,000 watt-seconds
> > ~=3D 360,000 kg.m  (100% efficiency)  =3D eg
> > 360 tonne x 1m
> > 36 t x 10m
> > 3.6t x 100m
> > 360 kg x 100 x 10m
> > 36 kg x 1000 x 10m
> > ...
> >
> >
> >
> > Russell
> > --
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