Solar Highway

Possible?
http://www.wimp.com/solarhighways/

I watched the video -- it's great. Thanks for posting!

Or at least partially power vehicles?

This is the kind of American innovation we need to put our money into. Not fraudulent financial packages & never ending war.

Just over four minutes -- worth the time.

This sort of thinking is the future. Not this Malthusian based doom and despair so many in this forum advocate. Leaps in technology and innovative thinking is the solution. Not reverting to living in mud huts and eking out a living scrounging on roots and dandelions, and sitting around wringing our hands because we lost 20 feet of beach because the sea level rose 4.5 inches.

Technology is the SOLUTION, not the problem.

About time someone started working on smart roads!

Though I have to cringe at the thought of what my studded snow tires would do to those panels!

Starts off with rising costs of asphalt. And their replacement appears to be a huge, hardened iPad?

Do just a little math. The video says asphalt today costs $1,000 a ton, in a way that's supposed to sound alarming. Today, a $500 2 lb iPad costs the equivalent of $500,000 a ton.

Ok, not ALL of it needs iPad smarts. But it does all need to be on a level with, say solar PV panels. Right there you've got costs more than a magnitude higher than asphalt. For a comparison of mere PV smarts, a 200 watt panel weighs, lets say, 30 lbs and costs, lets say $600. That's only $20 a pound, which is $40,000 a ton. 40 times the cost of asphalt, and you still can't drive a truck over them. Addressing that problem will raise costs. Providing a texture so the truck won't slide like it's on ice in the rain? More costs. Keeping that texture from nullifying solar collection? More costs. Keeping that special texture from being ruined by sand/salt spreads in winter? Costs. Power storage so those LED's can shine at night? Costs. Finding a way to keep literally millions of electrical connections working while constantly immersed in ground water? Costs. Techniques for patching/repairing failures, rather than just rip out and replace? Costs. Security measures, so local kids don't hack into it and replace your 'Slow down' messages with porn? Costs. Road crew training because these can't just be poured out of the back of a truck. They have to be installed. Costs.

I could go on and on.

The world is chock full of cool ideas, and I hate dashing water on any of them. But what we need are cool ideas that are also practical and affordable. I don't see a single thing in that video that attempts to make this affordable. And I'm not convinced they are approaching practicality in any significant way.

might become practical in 20 or 50 years. I think it's an interesting concept. Maybe one day someone will make it practical. Maybe not. But this or some other innovative change will come along in due course. As PV technology improves in efficiency and costs drop I'm certain it will be more pervasive and perhaps ubiquitous.

PV technology used to be a novelty on handheld calculators; now it is commonplace. We may see entire roofs of buildings or roads or sidewalks be made from PV substances. There would be a lot of advantages to having a highly distributed electrical power source/grid...especially during natural disasters. And if you are into the global warming thing this sort of technology would have the advantage with CO2. We may see the day when even our clothing generates electricity from kinetic or solar technologies, or converted from our body heat.

I'm glad to see people investigating new ideas as I too am 'ready4change'.

I think all south facing roofs should be all solar. Shingles, panels, water heaters. It makes perfect sense there.

But buried in the ground specifically where it will be run over by traffic? Nuhuh.

Now, if some of the promises of nanotech come through, I could see some sort of self healing nano-road which not only would collect solar energy but clear and channel water for use elsewhere, melt ice, serve as a network for cars computer systems, to aid with collision avoidance, change colors as well as emit light for warnings both night AND day, and more. But that requires breakthroughs not even being mentioned here. (In fact, if those breakthroughs happen, they will turn much of what is in this video obsolete.)

What they are developing, for the reasons they are developing it, appears folly to me. Want a material to replace asphalt? We already have it. It's called 'concrete.' Good stuff. Want a warning for occupied crosswalks at night? Howabout a pole mounted FLIR camera with motion sensing, connected to a sign 200 ft up the road. When it detects a new object in the cross walk it lights the sign. It would need about the same amount of logic as the sensored glass panels, would not be exposed to constant traffic, would be raised above continuous inundation of water, salt and road grime, could have a solar panel mounted above it, do it all at a FRACTION of the cost of the videos roads, and all be built from parts available RIGHT NOW.

The only thing it wouldn't do is generate power from all that road surface. But with the money saved you could put PV panels on every roof in the country.

Today.

We should all be thinking of electric vehicles for the next car we buy.

Then this concept would be workable if they put the solar panels above the traffic, not built into the road surface. The road could power all the cars on it, would only need supplemental power on cloudy days and at night.

Since a Nissan Leaf and Chevy Volt need 200 watts and a 1990s Toyota Rav4-EV needs 350 watts to drive one mile, that's only one or two solar panels per vehicle mile (one if you use the commercial version solar PV panels that they use in solar power farms). More would be needed in northern areas but it's still doable.

...addressed in any way in the video. Impact resistance (particularly point impacts), Wear/scratching (even a diamond coating would ultimately defeat itself), and substrate integrity, where ground movement can break connections between panels and lift edges of rigid panels to leave full width voids beneath.

I would definitely want a portion of the mileage tax to go toward solar panels covering the road, powering the vehicles. Even if only for the carpool/diamond lane(s), I'd be great with that.

I tried to figure out how many panels you'd need per mile but I couldn't find reliable traffic data so I gave up. I think I was pretty close to the mark at 1 or 2 panels per electric car; so if you had 100 electric vehicles on the road you'd need 200 solar panels somewhere along that mile of road. They would definitely fit and be no more of an eyesore than the existing wires, light poles and overpasses already on the highway.

How many cars can even fit inside a mile stretch of road?

From a quick search, a Nissan Leaf has a battery pack with a 24 kW-h capacity. That's 24,000 watt hours.

A good, large solar PV panel is typically rated at about 200 watts. If this road were in an area that gets an average of 5 hours sunlight per day, that panel could provide 1000 watt hours a day. So you'd need 24 panels per leaf.

A panel like that typically costs $600. Since we'd be buying in bulk (if we can obtain bulk) lets say we could haggle that down to $500. So we'd need to invest $12,000 in panels alone, per Leaf. Then we can start talking poles to mount them on, inverters, charge controllers and energy storage, so people can charge them overnight (hard to charge while you're driving.) That's also without taking into account transmission and storage losses. Plus, 5 hours sunlight per day is a generous estimate. Southern states get that, northern states don't. Canadians would LOVE to get that much.

Pretty good chance, when you tally things up, you'd be looking at at least $20,000 per car. For 100 cars it would cost $2 million, and require 2,400 panels.

(Please feel free to double check my math and estimates. I did this quick, but would still like it to be in the ball park. Thanks.)

Sometimes I get a little hasty in my "cypherin'" and get ahead of myself a bit...
:-)

And I misstated the Leaf's energy usage per mile: it is 225 watts per mile with no heater or air conditioner usage (either of which drops your Leaf's EV range down to 70 miles -- 321 watts per mile).

But that's still 2 panels per vehicle mile traveled -- within the peak sunlight hours, you got that right. And with the need for battery storage to allow 24 hour operation that does indeed add some losses, I was hoping to avoid DC to AC conversion since the solar panels, batteries, and the EV itself can all handle DC, but it would nevertheless necessitate a new standard (a 4th Level) for EV charging. Conversion from DC to AC then back to DC would just add needless losses, wouldn't it?

So if one wanted the insanity of driving for 24 hours straight, and lived in the northern states with 4 hours of peak sunlight, one would need to supply (24/4) 6 sets of two 200 watt panels, or 12 panels per mile. How is my math so far off from yours?

PS, if you include the actual cost of using fossil fuels, your cost figures would still be a bargain. I'm talking about the cost of exploration, drilling (multiple wells till they hit one) pumping chemicals into the well to extract all of the petroleum, transport it to the refinery, refine it, pump into storage, transport to gas stations. Then there's the tiny expense (estimated at $50 billion per year) to keep the oil transport lanes open. And don't forget the health expenses that the oil companies never have to pay for (the kid with asthma has oil and coal to thank for it).

Watts measure power, not energy; I can't see that 'power per distance' has any meaning. Maybe it would help if we know where that figure comes from.

The LEAF consumes 34 kWh per 100 miles, or 340 Wh per mile, in the EPA test. Using ready4change's 1000 Wh per day per panel figure from above, and a figure of 25 miles driven per day (about 9000 per year), that's 340*25=8500Wh per vehicle, or 8.5 panels per vehicle.

8,443,338 lane miles of road in the lower 48 states, and about 250 million vehicles. So that's about 30 vehicles per lane mile. So to run the whole vehicle fleet, assuming an average energy use of that of a LEAF, we need about 250 solar panels per lane mile. Which is doable, but expensive.

The Nissan Leaf has a 24 kWh battery pack so it cannot use more than that without recharging. I also read that you can never use 100% of the battery, Nissan has limited it to 90%, ergo (24 kWh X 0.9) 21.6 kWh divided by 73 equals 295.89 watts per mile.

Nissan says that the range on that 24 kWh is 100 miles based on the EPA LA4 city cycle and it's likely that freeway speeds will give reduced range.
http://www.nissanusa.com/leaf-electric-car/index?next=header.leaf_micro.postcard.button1.#/leaf-electric-car/specs-features/index

Edmunds did a test drive and got 88 miles range:
"Nissan claims a 100-mile range for the Leaf, but the EPA recently certified the car's range at 73 miles. During our test period the Leaf consistently indicated a range of approximately 88 miles, even with much of our driving at highway speeds."
... from http://www.edmunds.com/nissan/leaf/2011/road-test2.html

If the EPA is right (73 miles range) that is 296 watts per mile.

if Edmunds is right (88 miles range) it is 245 watts per mile.

2nd topic:

Your number of lane miles of road... I'm too tired to do that much math tonight. Sorry 'bout that.

'kWh' stands for 'kilowatt hour'. So that gives us the energy needed per mile driven - whether 245, 296, or 340, we're in the same area.

ready4change and I have then decided how many miles a car will drive - ready4change's calculation assumed the battery would be fully depleted every day, while I picked a fairly modest distance per day (I see the EPA uses 15,000 miles per year, rather than my 9,000) - and used that to get a figure of panels needed per car. Your method seems to be talking about how many cars you might find on a busy stretch of road, and working out how many panels would be needed to support the driving they are doing there - is that the approach you are using?

That is what I was trying to figure out. And you are correct that our different numbers for watt hours per mile do not change the number of panels needed per mile by the method I used to calculate it.

PS, I figured that the electric cars would have a battery around the size of the Nissan Leaf and only use the solar road to extend the distance of their commute or a trip.

with an overhead wire, or a 'third rail'-type system ('first rail' in this case, I guess :) ).

If we say cars are 2 seconds apart, and travelling at 60 mph, then that is 1 mile per minute, and so that mile of lane will contain 30 cars. If we take 300 watt hours per mile as an average efficiency number, then that's 10 watt hours to move 1 car one thirtieth of a mile, and the panels must provide that every 2 seconds. There are 3600 seconds in an hour, so the panels in that thirtieth of a mile must provide power of 10 * 3600 / 2 = 18000 W, or 18kW (which sounds believable - that's about 24 hp). If a 200W solar panel is typical, then we need 90 panels in the 1/30 mile, or 2700 per mile (in each direction). That's one every 2 feet or so (and a typical 200W panel seems to be about 5 feet by 3 feet, so you'd need a continuous strip 7 or 8 feet wide).

But that's installing enough to supply that peak traffic with instantaneous power from the road without using storage batteries or drawing in electricity from roads that aren't at maximum capacity. Really, you'd want to do both of those (it's also needed for cloudy and night operation, as you said), so the 'cars per mile of road' calculation isn't that useful, I think. Maybe a modification of my '25 miles per day' would be better - '12.5 miles of highway driving per day', for instance, which would halve the numbers of panels to 4.25 per vehicle. How many miles of open highway there are in the US (as opposed to roads in cities and towns, for which the plugin capability would be used), I don't know, but it will still be on the order of the 250 panels per lane mile, I'd think.

I'm glad the original poster made this OP. The idea is doable and it's one heck of a lot better than using oil to power our vehicles.

It would be great to have all freight go by rail, high speed rail for passenger travel and solar highways for those who simply must go out on the open road.

I did mean to write "watt hours per mile" instead of "watts per mile." Oops.

You get what you pay for. We have cheaper roads that can't recoup their cost and are made from petroleum rather than help to eliminate the need for petroleum.

- Cars that drive over the road will block the light.

- Cars will also dirty up the road, again blocking the light.

- The weight of the vehicles stresses the panels.

- Repair of broken panels means you have to shut down the road.

Much better to put the panels on the side of the road.

Well summarised!
:toast: