Are Star Trek's roads about to come to a city near you?

When I look at the surface, I can say it looks almost exactly like the metallic roads seen in San Francisco in Star Trek; Into Darkness.

This being complete with glowing lines that are straight out of Tron, I’m not sure if they’ll be able to take as much traffic as an asphalt or concrete surface before they need replacing, but it only goes to show that it may be within a few centuries before we see nearly every piece of tech from every 20th century science fiction movie.

Now if we had cars that come straight out of I Robot, that would be the icing on the cake :slight_smile:

To boldy go where no man has gone before…a Klingon ship behind the tree…


Hurgh. After someone posted this on my facebook newsfeed, I replied:

So solar panels absorb the suns energy. They convert this to electricity. Great, it’s clean and green, right?

Wrong. First off the manufacturing process for these includes refining silicon. Some analysis we did in my Engineering course says you have to run a solar panel for about 10 years before it repays it’s energy debt. The operational life is only about 20 years as well.

Also, as a solution to global warming, it’s pathetic. Put your hand on a solar panel. It’s warm. Why? Because it’s absorbing the suns heat. So while it may convert some of the sun’s energy into electricity, more goes into heat. Normally the earth will reflect it back to the sky and (some of it) out to space. Even asphalt roads reflect a lot of light/heat. The solar panel will trap it at ground level.
I haven’t run any numbers, but I think solar panels would increase global warming quite a bit.

@@sdfgeoff Compare it to the heat lost in burning coal or a combustible engine.

sdfgeoff: should we also maybe avoid wearing dark clothing, dark cars and anything dark in general because of heat absorption?

I think Blonder and Morio have a point, have you actually tried to walk on asphalt barefoot during the summer? Your feet will end up burned if you stay on it for more than a minute, I can’t imagine these panels being a lot hotter (that and how asphalt already traps a lot of heat to release at night).

Asphalt on a cool day. Still you can feel stones on them if you choose to walk on a cool day.


I could see these panels wearing out quite quickly, but the idea of LED road displays is pretty awesome - mostly because eventually someone will manage to get a parking lot to play tetris or something.

Add in a piezoelectic layer, and a thermionic layer, they can make power from heat, solar and virabtion, you would need a post into the ground for a cold side though. Also, you can heat citywide hot water instead of thermionic, potentially enough to create steam?

One side note: speed of repair, this road is modular…a single robot could probably “print” roads, and “unprint” them.

Let’s have a look at the energy consumed in producing 1m square of photovoltiac cells. We have to:

  • Mine the siicon and metal ores
  • Purify the silicon (and the metal ores)
  • Make glass fronting (or in this case, whatever synthetic substance they’ve used)
  • Make it into a PV cell

Power consumed in construction of 1m2: ~2MWh using current manufacturing processes

Power output: ~160W per m2 in optimal conditions.
Assuming 5 hours of average optimal use per day, this is 800Wh per day, or 292kW per year. So how many years to pay back the construction energy? About 7 years, give or take. More if it’s a climate like where I live and you get probably 2-4 hours full sun per day on average.

How often do you resurface a road? About every 15 years.
So for the first seven years, the solar cells on a road are doing nothing for the energy balance. Assuming no losses or manufacturing costs in the use of the energy they produce, the cells are simply paying themselves off.

So after that, we have another 2MWh of energy produced over it’s life. Let’s put this in terms of a car. A car uses about 120kwh on 12km of travel using 1litre of fuel. So over the course of seven years, our solar panel will drive a car 24000km, saving roughly 1700 litres of fuel.

Now all politicians care about is money. To buy a 1m2 solar cell capable of that output would cost me about $8,000 NZD. The equivalent amount of fuel costs (at ~3$ per liter) only $5100
This isn’t per road either, this is per meter squared. To do a whole road using these solar cells the difference would be staggering. It really is cheaper to buy the fuel. I don’t have access to specifics about solar cell manufacturing in terms of heat produced and CO2 emitted, but I’m willing to bet it’s pretty similar to that of burning the equivalent amount of fuel.

And this is ignoring the installation costs (including pollution from road-working machinery) of said solar cells. We also have to take into account that solar cells are best perpendicular to the sun, and a road is flat. So we can expect an even longer Energy Payback time from solar cells made into roads.
So from a money and energy point of view, installing solar cells is pretty ‘bad.’ I’m all for clean green energy, but check how clean and green it is first. Take for instance New Zealands Hydroelectric plants. They have a very good Energy Payback time, from memory it’s somewhere under two years, and they operate pretty much without further costs for another 40-50 years.

Let’s have a look at solar cells again, this time the energy they produce. Each solar cell produces 160W per m2. How much energy actually falls on it in that time? 1.366 Kilowatts. So about 10% of the energy is converted. The other 90% is either reflected or retained as heat. Bear in mind this 10% retained through conversion to electricity is then converted to heat in, say, a car or a light.
So your argument is that a solar cell doesn’t have much of a difference to asphalt in terms of retained energy? Well, we can tell this using … albedo! The measure of how reflective a material is.
Asphalt: 0.1
Tarmac: 0.1
Concrete: 0.5
Solar Cell: 0.25

So the amount of light reflected by a solar cell is … higher than asphalt. So solar cells reflect more light/heat than asphalt. So you are correct in saying that replacing asphalt roads with solar cells would drop the energy retained.

As I said in the post, I had not researched it. Now I have, and my guess was wrong.

Oh, and random thing I found out while researching:

The manufacturing of solar panels emits nitrogen trifluoride or NF3. NF3 is a greenhouse gas 17,000 times more potent than CO2.

So what alternatives are there to solar cells? As I’ve shown, they’re a long way from being cost or energy effective. To me it’s a fundamental problem with solar cells. 2/3rds of their life they are in the dark, or at a non-optimal angle. Putting them in space they will recieve a lot more energy, but they are then less useful for us guys on earth.
Nuclear? You could only run the earth for a couple of decades if you replaced every coal station with an equivalent Nuclear one. You’d run out of uranium.
Fusion? Has potential, but I doubt it will be effective when we start running short on fossil fuels.
Hydro is the only feasible one at the moment

But to be honest, I prefer a different option:

  • Change how much energy we use.

I’m all for modern comforts such as laptops, housing and heating, but when you look at this graph, you see something: the biggest energy use is in the transportation.
How far do people travel to work each day? - on average 25km.
How far does your food travel to get to you? - the other side of the planet, particularly tropical fruits etc.

See the problem?
My solution:

  • Live close to work
  • Bike
  • Buy locally produced foods

Anyone ever seen this short film? Quite long, but worth it, and in my mind, fairly accurate from either perspective.

Concentrated solar, focused on a target material in a vacume can radiate its heat as electricity…

This effect has not been upgraded in some time… I suspect it could be quite efficient.

Sdfgeoff; And yet going hydro means mass habitat destruction through mass flooding. By your argument, the absolute greenest thing to do (because who knows what chemicals are used in the making of bikes) is turn the clock on human progress all the way back to the 1st century (complete with 40 years of life expectancy and the vast majority of humanity toiling away on family farms in small hamlets). Better yet, let’s all go back to living the exact same life as the animals that scientists think we evolved from (is anyone here fluent in caveman speak?)

Luckily, you still haven’t mentioned Thorium reactors (using an element that’s extremely potent, yet much cleaner than Uranium as well as much more plentiful). The point is there’s nothing we can do to maintain modern living and not leave any sort of footprint on the environment (even the Romans had to dig out mines to get stone for their cities), the only thing that can be done is to minimize the impact and the extent.

Also in a lucky sense, we can just keep on using coal and oil to (hopefully) triple the amount of Co2 to make plants worldwide fill in deserts and grow like crazy elsewhere, meaning much higher crop yields and enough food for everyone (I don’t buy the global warming stuff considering that it’s one of the arguments where it’s seen as acceptable to engage in name-calling, character attacks, and the calling for the imprisonment or even the execution of people who disagree).

Number three, solar panel technology is seeing some very promising material advancements that will rocket the efficiency from around 20 percent to over 80 percent, I’m sure the manufacturing methods will improve as well to reduce environmental impact.

I think there has to be a way with materials science, to extract insane amounts of energy from a very small substrate, targeted by concentrators made of glass, made by melting sand with the sun

Print machines out of sand, that print machines out of sand …

Side note, Combine a rijke tube, with concentrated solar, and piezoelectricity,

Hydro does mean flooding. But how big is a coal mine?
All I suggested was reducing the amount of transport by doing things more locally. There is no need to de-increase the life expectancy or to go back in any way except the expectation that people can travel however far they like with very little cost.

I have not heard of Thorium Reactors. But it seems to me to be a fine process for quite an abundant material. Go for it, use Thorium reactors. The only disadvantage that I see is the increased fuel production costs, leading to an overal reactor efficiency decrease.
The only thing constant is change. And hopefully that is progress not regress. In my opinion, the use of Roman stone was progress because the destruction it caused is small compared to the progress it allowed. But for fuel? It’s passed it’s progress stage. It allowed humans to discover flight, to do lots of stuff, but not it’s continued use is having more destructive effects than constructive effects. And again, in my opinion, the use of fuel should be phased out for something else. As to what, I’m not sure.

I don’t think tripling the Co2 content will allow trees to grow in deserts. It would probably poison them, and the reason plant’s don’t grow in deserts isn’t high oxygen content, it’s lack of water.
For reference about Global Warming: We had three lectures on climate modeling in one of my uni course. Not climate change modeling, just climate modeling. By the end of it, 400 engineering students were all firm believers in climate change, despite many initial migivings and the lectures not actually being about it.
Heard of the IPCC? It’s the ‘Intergovernmental Panel of Climate Change’ Every couple of years they publish a report on the climate. It is a massive project, with thousands of authors and scientists. Go check out their website and download the report. It has some really interesting stuff, though it is really heavy reading. If you are concerned about it’s scientific validity, consider that they even have a chart defining what ‘Extremely likely’ means compared to ‘Very likely’ in terms of probability. My final word on climate change is this one from popular science:
Let’s hope those solar panels get to their 80% efficiency, and that manufacturing energy goes down. It is feasible if someone would donate several billion to studying it.

Or if it becomes automated and pollutionless.

Actually, higher CO2 has been shown to increase plant water efficiency as well as the required temperature for maximum photosynthesis. (go to for more information). There’s even been studies showing that plants have genes that are permanently turned off because the concentration of the gas is not high enough. Otherwise you might try to convince your local greenhouse operator that he is delusional and crazy because he has the level at 1000PPM.

I don’t question the climate is changing, I’m just skeptical that one can conclude that humanity can suddenly override 1000’s of years of natural shifts before we even know all of the variables (noting that a brutal ‘little ice age’ period was occurring just over 200 years ago. There’s also been a lot of model runs from the 90’s that are by no means matching observed data so it also doesn’t help that case either.

Lucky we have trees and leaves for photosynthesis to occur. Very Scientiific.


Everyone acts as if carbon is a bad thing… the US has even passed laws now catagorizing carbon as a toxic substance. That’s laughable because all life is cabon based on earth. Also, far less than 1/10th of 1 percent of the atmostphere even contains carbon. I’m not saying we should polute, because if we do, we wind up like China running around with surgical masks on so we can walk around outside.

Sorry folks, #1 Global warming doesn’t exist, that’s why they’re trying to rename it “climate change”, because everyone knows global warming is BS.

I’m still all for being a good keepers of the planet, but lets not get all crazy.

At the end of the day, when you consider everything, fossil fuels like coal, gas and oil are still the most efficient way to generate electricity. The efficiencies aren’t really great, but when you consider the energy to produce solar cells, fossil fuels still come out on top as having a smaller carbon footprint.

It’s not just you’re using, but how you use it. Elon Musk, a big supporter of solar technology pointed out that electricity from fossil fuels used to charge his cars are more efficient than burning gasoline individually in separate engines. So it’s not just what you’re using, the scale comes into play too. The most efficient way to generate electricty is in large scale enviroments like power plants.

Another good example of this is US goverment program to give money to people to encourage them to buy newer more fuel efficient cars. Part of the deal was that the car you’re replacing cannot be sold, and had to be taken off the road. Huge amounts of energy went into making those cars, and many of those cars had alot of miles left in them, and all that energy that went to produce cars (some as new as 2 years old). That wasted energy far outweighed the energy saved by giving people, who already could afford a new car, a $4000 freebie to entice them to go out and get a new one.

What it boils down to is that global warming (I refuse to call it climate change, Al Gore beat “global warming” into my head for 30 years) is a political pawn that politician used as an excuse to tax you, or prevent one party from moving foward so another (they one’s that greased their palms) can step in and take over. It’s all about power and money, not the climate.

A few posts back, someone posted some rediculous “the debate is over” style pie chart that someone made up in photoshop or excel and posted it as if it’s some sort of proof. There are plenty of people who don’t believe the sky is falling, and anyone refusing to debate it is either ignorant, or stands to loose money. That’s the sad part. Scientists are forced to agree with something they know isn’t true just to continue to get funding to continue their work.

Well, I respect peoples ability to believe in there own …religion?

I am not sure what to call if,
There are facts, and then there is beliefs,

Look at data, point at data,
Otherwise your a snake oil salesmen.

The most efficient way to travel is to use ambient energy, to create infrastructure to create ambient energy. Then use that to travel.

If I design a system, that smelts sand and metal using the sun, that prints usng glass and metal, it can recycle metal, and print glass. If this system prints another system, that prints another, we are not talking about fuel negated, we are talming about negating the need for fuel at all.

If these systems after x replications, all printed energy collection mechinisms…

Like solar panels , your not talking about fossil fuels at all…

Btw when they say a panel cost this much fossil fuels, they are talking about how.much ENERGY, not plastic, not fossile fuels…

A single large lens, can smelt glass in my yard… so if there were many lenses per system, and the light was directed into a vacume sputtering chamber…

No fossil fuel used…

If the materials are sand, and the labor is automated, what is cost?