Where the Interstate goes through an area that the lanes cannot be divided by a large grassy median, there are thousands and thousands of feet of concrete divider. These dividers are necessarily pretty stout - nearly two feet across at the base and about six inches across at their tops. They're made tall enough around here that there aren't those peculiar venetian-blind sort of things that allow air to pass without oncoming traffic being blinded by headlights. So the tops are solid, and flat.

Six inches wide doesn't sound like a lot, but it is. Run a strip of photovoltaic collector - four inches wide, to allow a bit of rub room - down a mile of concrete divider and the result is 1760 square feet of solar collection area. Multiply that number by however many thousands of miles of concrete divided highway there are in your country, and you can see there's an enormous potential for energy collection, using a space that is of no use otherwise.

Getting the power off the center of the highway could be problematic. Wherever that is the case, convert streetlights to energy-efficient LEDs, and let the solar system charge them up during the day.
-- elhigh, Mar 15 2006

(?) Roadside Solar Panels on the M27 http://www.osborne....ocument/ACFC315.jpg
Possibly the project that [neutrinos_shadow] referred to, or one very like it. [jurist, Mar 16 2006]

The median is in place to keep out-of-control vehicles from careening into other lanes, by colliding first with the barrier. A collision with the barrier would break the circuit of solar cells from one end to the other, and render the streetlights unusable for a night or more as the solar cells are reconnected. That's just not safe, having a mile of disabled streetlights on the interstate.
As a safety concern, when the potential out-of-control car breaks the circuit, what is the amount of energy being redirected through the metal frame of the vehicle? If it is anything substantial, there is a safety hazard for the already potentially injured (by vehicle collision) driver.
-- roleohibachi, Mar 15 2006


There is a lot of otherwise unused space on this planet that isn't currently being used for PV cells. The reason is a very compelling economic one.
-- Texticle, Mar 15 2006


So run the streetlights off solar power with redundant links to multiple battery banks (so what if one is knocked out for a few nights?) and mains backup.

As an idea to collect energy from otherwise unusable space, I'll say (+1). But solar collection via photovoltaics is a bit of a slippery slope at the moment. The initial cost of solar cell production and end-of-life cost of reclamation/recycling makes this not much better than break-even in the long run, so (-1). Overall, I'm neutral on this one until photovoltaics is significantly cheaper and less polluting in the long run than an equivalent amount of energy production by more conventional means.
-- Freefall, Mar 15 2006


Somewhere in Europe (a quick search failed to find any useful links) large numbers of solar panels have been installed at the side of the road (not on the median barrier), and closer to an optimal angle (not horizontal).
The government already owns the small strip of roadside required, they were elevated to reduce damage by cars (possibly above/beyond a concrete side barrier?), and the land isn't being used for anything else.
They only downside I can see is light reflecting back into drivers eyes from the large expanse of shiny cells.
Sorry I can't find some links...
-- neutrinos_shadow, Mar 15 2006


[Freefall], I was *this* close from saying what you just said in my previous post. Kudos for getting it out there, I didn't have the cahones.
-- roleohibachi, Mar 16 2006


[neutrinos_shadow], Geoffrey Osborne, Ltd, in conjunction with the Highways Agency and SolarCentury initiated a demonstration project in Hampshire, England, in May of 2004 by installing 2 banks of fifty-four(54) meter photovoltaic panels on south facing soundwalls paralleling the M27 highway. This may be the project you recalled, so I've added a [link]. It's an interesting project in and of itself.
-- jurist, Mar 16 2006


Light doesn't reflect off the panels into drivers' eyes, except that which impinges on the panel from an extremely low angle; remember, the panels themselves are mounted horizontally, pointing straight up, so any light hitting them must also be shining directly into a driver's eyes already, considering the mounting height at the top of the barrier.

Relatively few crashes actually surmount the top of the barriers around here. Obviously I wouldn't try to suggest that an individual circuit should be miles long, that would be dumb.

Not that this isn't a good venue for dumb.

With an industry-standard useful life of 20 years, production cost and end-of-life reclamation costs for photovoltaics are a pretty small fraction of the value of the realized power output.
-- elhigh, Mar 16 2006


//Light doesn't reflect off the panels into drivers' eyes// [n_s] was referring to the installation 'somewhere in europe', where the panels are angled from horizontal, rather than to your idea.

//Getting the power off the center of the highway// If there are streetlights already in the centre of the highway, then surely grid power is also available there, in which case the solar electricity should just be fed into the grid (far more efficient than using batteries).

Do you have a link for these concrete poles? Would they be useful for pole-sitting protesters or mystics?
-- spidermother, Mar 16 2006


Thanks, [jurist].
-- neutrinos_shadow, Mar 16 2006



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