EV Volume  Energy density. Everyone knows t hat batteries are
heavy. Many do not realize that batteries also take up lots of
space...they have low “energy density” or stored energy per unit
volume==>   Conversely, many commentators are concerned about
the space required for compressed hydrogen storage tanks, the
preferred method of storing hydrogen on motor vehicles.   But
the useful energy density of hydrogen tanks at 35 MPa (350 bar
or 5,000 psi) including the entire fuel cell system plus a peak
power battery bank is greater than that of the older batteries,
and slightly greater than that of the advanced Li-ion battery;
several car companies are now using 70 MPa (700 bar or  10,000
psi) hydrogen tanks, which have an even greater advantage over
advanced Li-Ion batteries in terms of energy density or space
required onboard the vehicle for energy storage.  Vehicle
storage volume. While the energy density of the advanced Li-ion
battery system is almost as high as that of the fuel cell system
at 35 MPa, the batt