by Gordon Dower
Charging via exposed contacts, not normally energized, could solve the V2G (vehicle-to-
grid) connection problem for battery electric vehicles. Exchange of harmless low-level
signals, conforming to some prearranged protocol, could render this entirely safe for any
conceivable circumstance. There are various means for causing the contacts to become
energized. Below them there would be a relay or switching mechanism for turning them on.
This, and the wiring to it, would be below the surface. To energize the contacts both in the
vehicle as well as on the curb, the presence of a suitably equipped and authorized car must
be recognized, either by wireless or direct contact, according to an authorizing code that
could include billing information. The soundness of the connections and wiring both in the
ground and in the vehicle would be checked before the contacts became hot.
In many European cities, cars park overnight along the curb in unreserved spaces. One
way of dealing with this problem is to use diagonal stalls, angled to the street, into which
the cars could park, with the front wheels against the curb, which might be saw-toothed
instead of being straight along the edge of the sidewalk.
Facing the car’s front wheels, the curb would be raised into a low wall a few inches
high, substantial enough not to be damaged by the wheels coming to rest against it. Sealed
flush into the top of the wall, instead of a connector, there would be two bronze charging
contacts facing obliquely upward. To the pedestrian, these would be inconspicuous and
harmless for they would only become energized when there was a car in the stall, and its
front end would overlap them, rendering them inaccessible. The corresponding contacts on
the car would be located somewhere between the front axle and the front end of the car and
always concealed from view. They could be of carbon, like those on electric trolley buses, and face obliquely downward to make appropriate contact with a self-cleaning action. They
would also be inactive unless in communication with the bronze contacts in the curb. To
allow for variation in the heights of the contacts in the car and in the curb wall, those in the
car would be sprung to make them self-adjusting. Lateral accuracy of docking would not be
a problem if the curb contacts were wider than those on the car, allowing for some variation
from side to side in the parking stall.
Various possibilities exist for paying for the recharging energy. The simplest might be
to have a sealed meter in the vehicle keep account, thereby saving the installation of such
equipment in the charging stalls. The charging could well use a V2G system where energy
returned from the cars’ batteries to the electricity grid would smooth excessive demand. If a
great number of parked cars were included in the system, the total buffer storage available
to the utility company would be substantial. Utility companies are willing to pay for this.
From the record of such two-way exchanges correct billing and discounts could be applied.
Five problems are solved by the above parking-charging-grid-buffering system: the
limited range of the BEV, the limited energy storing capacity of the utility company,
susceptibility of charging facilities to vandalism, forgetting to plug in at night, and having
to cope with heavy and possibly wet cables and connectors—particularly troublesome for
disabled drivers.
The notion of exposed contacts, energized only when in use, can be applied to other
configurations. Where snow might be a problem with curb contacts, they could be put on
an arm to engage with contacts mounted on the leading edge of the vehicle’s roof. Instead
of the vehicle’s overhang making them inaccessible when hot (as with the curb contacts)
there could be a safety shroud. Proximity sensors could add further protection against
approach from over the roof of the vehicle.
Responding to the threat of ever more drastic climatic change, all cars must soon
become zero-emitting, and therefore electric. Consequently, cities must adapt to this form
of energy for surface transportation. Compared to the many adaptations cities have made to
accommodate automobiles, this is minor, yet it could ensure connection to the grid of every
parked car.