Solar Roadways - Working prototype and pictures!

[Mookuh]

AC works for transmitting over long distances - above ground. If you put a very long cable in the ground and want to transmit a lot of power through it, what you're building is a giant capacitor. If AC is used for power transmission in said cable, the capacitor will be "charged and discharged" at the frequency of the grid, so at 50-60 hz. This doesn't take "Real Power", but it takes a lot of "Reactive Power" (AC power - Wikipedia, the free encyclopedia). When the line becomes too long, the share of Reactive Power becomes too big, and you'll hardly be able to transfer any real power through it. DC doesn't have any reactive power to it, so the problem doesn't arise. (The capacity of the cable is charged only once, when the line is turned on.)

The reason we use AC in the grid (which is mostly above ground) is, as others pointed out, because we can transform it to higher voltages much more easily than DC, and that's a prerequisite for long distance power transfer in both AC and DC (the ability to switch AC off more easily is also a big plus). With modern power electronics, HVDC lines can be realised, and they have been in a number of instances. There was a big-ish discussion in Germany about how to connect off-shore wind farms (as they have to use cables), and in the end HVDC won out because using AC through a cable of the proposed length would not have been feasible.

 

[santana338]

Thanks Mookuh. I don't think we covered this way back when I took my college power courses.

AC works for transmitting over long distances - above ground. If you put a very long cable in the ground and want to transmit a lot of power through it, what you're building is a giant capacitor. If AC is used for power transmission in said cable, the capacitor will be "charged and discharged" at the frequency of the grid, so at 50-60 hz. This doesn't take "Real Power", but it takes a lot of "Reactive Power" (AC power - Wikipedia, the free encyclopedia). When the line becomes too long, the share of Reactive Power becomes too big, and you'll hardly be able to transfer any real power through it. DC doesn't have any reactive power to it, so the problem doesn't arise. (The capacity of the cable is charged only once, when the line is turned on.)

The reason we use AC in the grid (which is mostly above ground) is, as others pointed out, because we can transform it to higher voltages much more easily than DC, and that's a prerequisite for long distance power transfer in both AC and DC (the ability to switch AC off more easily is also a big plus). With modern power electronics, HVDC lines can be realised, and they have been in a number of instances. There was a big-ish discussion in Germany about how to connect off-shore wind farms (as they have to use cables), and in the end HVDC won out because using AC through a cable of the proposed length would not have been feasible.

 

[roblab]

A mall here in New Hampshire would be better off with a solar roadway parking lot versus solar canopies. You put solar canopies up and, all of a sudden, the front-end loaders that do the bulk snow removal can't operate. *IF* the solar roadway melts it in the first place. you can consider the cost of that electricity versus the cost of plowing.

So put the panels on top of the mall. Why are we worried about snow clearance?

And if our only concern is melting the snow, you know they make resistance wires for melting snow, already, for sidewalks, driveways, roof eave edges. Why are we thinking that we need a huge hunk of glass with a solar panel attached just so we can melt snow? And if we are talking solar collection, why are we talking of putting the solar down under cars, dirt, trash, tree shade, when you can mount panels above far more cheaply, and angle them for best insolation? This whole idea seems so near unpractical and thoughtless. I don't see one advantage. I see many disadvantages. I must not be very bright, because I can't see why anyone thought this would work, at all. Can someone explain it to me?

 

[ElSupreme]

Can someone explain it to me?

I agree with you on pretty much all your points. Putting solar panels on the ground under roadways, parking lots isn't the way to go.

The only thing I can think why people are getting attached is that you don't build anything 'new' with the solar roadways. Roadways cost a lot, solar panels cost a lot. Building a solar roadway costs a lot. And because of this people don't realize how much more solar roadways would be than standard roadways, with solar panels on fixed structures above ground level.

Solar = $$$
Roadways = $$$$

Solar roadways ~ $$$$$ (poor internal estimate based on most convergence devices costing less than buying two devices). real cost probably $$$$$$$$$$

Solar + Roadways = $$$$$$$

 

[Chipper]

So put the panels on top of the mall. Why are we worried about snow clearance?

And if our only concern is melting the snow, you know they make resistance wires for melting snow, already, for sidewalks, driveways, roof eave edges. Why are we thinking that we need a huge hunk of glass with a solar panel attached just so we can melt snow? And if we are talking solar collection, why are we talking of putting the solar down under cars, dirt, trash, tree shade, when you can mount panels above far more cheaply, and angle them for best insolation? This whole idea seems so near unpractical and thoughtless. I don't see one advantage. I see many disadvantages. I must not be very bright, because I can't see why anyone thought this would work, at all. Can someone explain it to me?

Had to chuckle about being "bright" and talking about solar!!! But I am in 100% agreement with your comments! I can see little to no advantage of doing solar this way. Seems totally impractical to me!

 

[derekt75]

They acknowledged that: it would have to draw on the grid somehow. (It's one of my concerns about putting up solar panels on my roof).

The question would then be: is it better to suck up energy to melt vs the energy used to plough and salt/sand the roads (with associated wear and tear)?

That question is about as valid as: Is it better to get to the other side of the world by digging a tunnel straight through the earth all the way to the other side rather than flying all the way around?

Despite the many advantages if you could do the novel solution, the answer is no.
(at least not in the next few centuries).

 

[mibaro2]

The problem with melting snow isn't how much power can be transmitted from here to there; the problem is that melting snow takes too much energy. Why would you use an order of magnitude more power than the state currently uses just to melt snow. If you can easily create that much power, put it on the grid and sell it as electricity, not melted snow. Large scale melting of snow is simply a waste of electricity. Even on a small scale, melting snow on the edge of your roof is more costly than a snow rake, but an individual can justify the convenience. It's hard to see how spending terawatt-hours of electricity to melt snow (hundreds of billions of dollars) can justify fewer snowplows (hundreds of millions of dollars).

Perhaps the solar roadway would best be used in climates without snow. That takes away a lot of area, but also a lot of questions on how it would work melting snow.

 

[ItsNotAboutTheMoney]

AC works for transmitting over long distances - above ground. If you put a very long cable in the ground and want to transmit a lot of power through it, what you're building is a giant capacitor. If AC is used for power transmission in said cable, the capacitor will be "charged and discharged" at the frequency of the grid, so at 50-60 hz. This doesn't take "Real Power", but it takes a lot of "Reactive Power" (AC power - Wikipedia, the free encyclopedia). When the line becomes too long, the share of Reactive Power becomes too big, and you'll hardly be able to transfer any real power through it. DC doesn't have any reactive power to it, so the problem doesn't arise. (The capacity of the cable is charged only once, when the line is turned on.)

The reason we use AC in the grid (which is mostly above ground) is, as others pointed out, because we can transform it to higher voltages much more easily than DC, and that's a prerequisite for long distance power transfer in both AC and DC (the ability to switch AC off more easily is also a big plus). With modern power electronics, HVDC lines can be realised, and they have been in a number of instances. There was a big-ish discussion in Germany about how to connect off-shore wind farms (as they have to use cables), and in the end HVDC won out because using AC through a cable of the proposed length would not have been feasible.

Europe has a bunch of HVDC grid interconnects and has more planned. In particular, the UK is looking at interconnects to Norway and Iceland (both have steady renewable electricity resources) that would help the UK by allowing it to add more wind.

 

[Robert.Boston]

Europe has a bunch of HVDC grid interconnects and has more planned. In particular, the UK is looking at interconnects to Norway and Iceland (both have steady renewable electricity resources) that would help the UK by allowing it to add more wind.

We also have HVDC in the US. It's great for moving a lot of power long distances. For example, there's a 2,000 MW HVDC interconnect from Québec to New England, and similarly scaled HVDC line from Oregon to Southern California.

One advantage of using HVDC is that the linked systems do not need to be synchronized. We have four distinct interconnections in North America: East, West, ERCOT (Texas) and Québec. Therefore, any line between two of these regions must be DC.

But we wander far from the topic at hand. The solar roadways would be on the distribution network (65kV or lower), not the transmission system.

 

[jvonbokel]

On a more theoretical basis, if the energy the sun delivers to the area was enough to melt the snow, well... the sun would melt the snow.

Most of that solar energy is reflected off of the snow, though, is it not? I've been told (by Al Gore) that this is part of the reason for climate change, as shrinking polar ice caps reflect less of the sun's energy away from the earth, leaving more of it to be absorbed at the surface.

 

[chickensevil]

Correct (not because Al Gore says so), the snow reflects the sun and the water actually absorbs the sun, that is simple light mechanics. White reflects and dark colors absorb.

 

[jvonbokel]

Correct (not because Al Gore says so), the snow reflects the sun and the water actually absorbs the sun, that is simple light mechanics. White reflects and dark colors absorb.

Well put. I know the simple concept (light reflects, dark absorbs), but I wanted to make it clear that I am not a climatologist, I only play one on internet message boards.

 

[chickensevil]

Well put. I know the simple concept (light reflects, dark absorbs), but I wanted to make it clear that I am not a climatologist, I only play one on internet message boards.

I have been slowly changing positions on this as I have gained knowledge over the years and had to sift through a LOT of BS from both sides... But this is why I always take the sustainability stance on energy production. Because then it doesn't matter what you are doing to the environment, the idea that it is sustainable is usually directed toward things that are also less harmful to do.

Anyway, yeah, that is why it isn't really the sunlight that melts the snow, but rather the overall ambient temperature around it. Which is why snow that sits in shaded areas are the last to melt for the season, as things warm up, because the ambient temperature in shade is cooler. Snow on Blacktop tends to melt before the snow on grass (I am speaking of untreated blacktop). You know things like that.

 

[HVM]

Something about dead horses, flogging and so on:

 

[chickensevil]

They have actually countered quite a few of the claims being made across the various videos and articles.

Solar Roadways - Clearing the Freakin' Air

Me? I say let em have at it, at least for now. They already have double the requested money so they should at the very least push on with what they have received and let us see the next stage of the product. They should be able to get some kind of basic idea for cost, but it was interesting seeing that all they need to hit is 10k per panel to make them break even with asphalt.

 

[Mookuh]

About the suns energy being reflected from snow: True, that's something to consider. Does anyone have the numbers how much energy is being reflected by the snow? if it's less than 85%, it will be more energy on the snow still, if it's more the solar panels might just pull ahead - but the problem of the snow still blocking the solar energy (and not a lot of other energy being produced by solar in winter in general) makes heating to melt the snow non-feasible in my opinion.

About the cost: They said "They took a wild guess and said 10k per 12' by 12' unit will break even with asphalt". Unless my maths is bad, paving a 60' by 1 mile bit of road will require 2200 12' by 12' units, and at a cost of 10k, would cost 22 Million dollar. Just for the panels, nothing about the installation, roadbed, wiring etc. etc. (From a random internet source, the cost for a 4-lane highway is about 4-10 Million, Transportation FAQs | The American Road Transportation Builders Association (ARTBA))
They will pay money back over their lifetime, but I have my doubts it will be enough to offset the price increase over asphalt. A rough ballpark estimation: 12' by 12' is about 13 square meters. Solar radiation is no higher than 1300 watts / m², so at 15% efficiency that's about 2 kWp. Being generous, let's assume 1MWh anually per kWp, we end up with 2 MWh of electricity in a year for each of the proposed units. If you get 0.1$ per kWh, you end up with 200$ per year. so 4000$ in 20 years, if the system even lasts that long. These are all the figures you'd use for a regular solar installation, the numbers for roadway ones are gonna be lower as they will not be angled, likely more dirty, and occasionally be covered by cars.
Asphalt roads are expensive to maintain, however the question remains how expensive these solar roads will be to maintain. My money is on "moreso than asphalt ones".

 

[ZsoZso]

What your are missing from your calculation is that asphalt roads need re-surfacing every 2-4 years or at least major repairs if not complete resurfacing. The idea is that the tempered glass should be more durable and last about 20 years, which brings in another factor of 5x to 10x in favor of the solar roadway that you left out of your calculation.

 

[doug]

Then why aren't we already paving the roads with tempered glass?

Independently many of these "advantages" sound like bad ideas, from an engineering perspective. Not sure why together one should think they're a good idea.

Why don't we put solar panels in the road? Because there are plenty of smarter places to do it first.
Why don't we put heaters in the road to melt snow? Because it would be a massive waste of energy.

 

[chickensevil]

I can only direct you to other sources who are smarter than I on the subject, Mookuh.

I would say based on this article they may actually be tackling the task of melting snow (whether intentionally or not) in the most efficient manner: http://www.tesmar.com/html/snowmelt_design.html

It seems to me that since each panel would have it's own heating element and it has built in drainage in the system, you could heat only the panels that have snow on them, and then reduce the heating as those specific panels dry off. There would be far less waste heat generated if done in a manner of each panel has a snow melting "mind of its own", rather than a giant on/off switch for the whole road.

The current problem with any snow melting systems is that there is a ton of waste heat being kicked into the atmosphere that isn't actually going toward the task of melting snow. So I would say it could be easily designed since each panel already has its own computer, to self regulate it's own temperature during periods that melting is specifically required. They could put a temperature wire on the panel to determine the panels temperature, and then some other means to determine if it's actively snowing/precipitating. Those two combined should be able to be properly regulated to be as optimal as possible in the act of melting snow.

Unfortunately I don't know how many BTU's are generated per Watt by their heating element to start trying to guess at the absolute minimal amount of power required to run this. This is something that they would need to research further to get it into a practical application, but it seems like they are going about it in the most efficient way possible.

Regarding the panel costs, the 10k was merely saying what their "break even" would have to be if they wanted to be cost competitive with asphalt. They don't know how much it will actually cost to do their roads, but they must hit that level or exceed it in order for the system to work. Noone knows yet even roughly how much it will cost per panel that is something that they are in the process of trying to figure out right now.

But what I will say, they are designing these roads to last at least 20 years. The way they speak of this 20 year limitation is based on the lifespan of the solar panels and the electronic components, not in the lifespan of the integrity of the road. Glass is actually harder than Asphalt (and tempered glass even more so) that there is likely to be less wear on the roads simply by using the glass. I still have no clue what that will do to the tires but hopefully we will find out soon enough.

To be fair, I am on the fence on if they can even meet some of their design goals, but they seem to be thinking about a lot of the right things they should be in order to try to tackle this.

 

[chickensevil]

Then why aren't we already paving the roads with tempered glass?

Independently many of these "advantages" sound like bad ideas, from an engineering perspective. Not sure why together one should think they're a good idea.

Why don't we put solar panels in the road? Because there are plenty of smarter places to do it first.
Why don't we put heaters in the road to melt snow? Because it would be a massive waste of energy.

I mean, you could direct that argument toward Electric Vehicles... Why aren't Electric Vehicles the most prevalent car on the road? Does this mean that we are doomed because it was never a good idea before, why would it be a good idea now? (I know, I know, it was a deflection and a terrible logical fallacy to make that argument but I couldn't help myself)

On a less flawed discussion, has anyone ever tried making a glass road like this before? To me it seems like they are applying the same principles that is used in bridge building to counteract the shrinking, expanding, and overall movements of the road. It also seems to me that they are just potentially replacing the top one or two layers of the road (most roads are 4 layers) and therefore the critical bottom layers will be left as they were originally. Those bottom layers are already made out of reinforced concrete... I don't think that will be changing given the comments they have already provided.

All I could find on the subject of road building materials is stating that we currently use concrete and asphalt... and nothing stating why other materials are a bad idea, or that someone has even conducted an exhaustive testing of materials to make roads out of.

Before that, we had brick and gravel, and before that we had dirt... According to this tempered glass wasn't even patented until 1976, and it does seem counter intuitive to think of the idea of driving on glass... so it is highly possible that noone ever thought of it before. As I have tried looking and cannot seem to find anything else on the subject, can you please provide me with information which would at the very least detail what they have *tried* making roads out of?

Edit: yes, I realize that people have been attempting to "harden" glass for a very long time, with some of the first examples of such things going back many years.