The Solar Energy Future

Glen Hiemstra has an article about what I think is a likely future development in the use of solar energy, which is solar roads that generate electricity. Combined with the ability to transfer electricity wirelessly to vehicles, I think this may ultimately replace our current system of inert roads and gas-guzzling cars.

With the caveat that I am hardly an expert on the physics of all this (and I’d certainly like to hear from those who are) and that there are some obvious technical hurdles to overcome, this all seems entirely plausible to me:

What is a road? A strip of asphalt, concrete, dirt, or cobblestone on which wheeled vehicles roll. Road materials have advanced since Roman days, but not all that much, really. It is still just a hard surface, designed to support the weight of vehicles and keep us out of the mud. Twenty four hours a day, roads, parking lots, and sidewalks just sit there, and in the day time they mostly just sit there collecting heat and light but not doing anything with it.

Imagine, as Solar Roadways has, that you could replace the concrete or asphalt with solar cells beneath a layer of glass. Operating at 15% efficiency the U.S. road system would provide more than four times our current electricity needs, or about as much electricity as the whole world uses. It’s a lot of potential power.

It turns out it is not that hard to take “off the shelf” material and build a layer of solar cells between sealed layers of glass, and construct a roadway surface of the resulting panels. The primary complication is manufacturing glass that is strong enough for an 18-wheeler to drive on, that is clear enough to allow sunlight in but opaque enough not to emit too much glare, with sufficient traction and durable enough to last for years. The glass design challenge is one that Solar Roadways is working on, among others, and one they plan to test with their first road panels installed in a parking lot in the spring of 2013.

Then combine that possibility with this one:

The second infrastructure re-invention company is Wave, which stands for Wireless Advanced Vehicle Electrification. Its goal is to enable electric buses to become more cost effective than diesel or natural gas buses, and without the need for being connected to overhead wires. In order to run continuously on rechargeable batteries, a bus has to carry a lot of them, since recharging happens only at the base station. This makes the bus inefficient, heavy, and costly.

However, the people at Wave knew that electricity can be transmitted wirelessly though magnetic induction. The question is how to build magnetic induction equipment into the infrastructure. Their simple solution is genius. Install a wave induction receiving unit on the bottom of the bus, and then at various bus stops install a magnetic induction power transfer system in the road. When the bus stops to pick up passengers, the magnetic induction unit wirelessly sends a charge to the batteries, and this frequent re-charging enables to bus to run all day, until it returns to base for a full re-charge overnight. Fewer batteries, less weight, more economical.

All that is needed at the bus stop is a way to connect the magnetic induction system to a power source. Solar Roadways might just have a built in solution to that! Wave notes on their website that technical hurdles remain to reach ultimate efficiencies but they are installing magnetic induction bus systems at Utah State University, for the Monterey Trolley in California, University of Utah, and in partnership with Advanced Energy Solution in Prague, Czech Republic.

If those technical problems can be overcome, and it seems to my relatively uneducated mind that they can be, it could spell the end of the use of oil for anything other than making products (like plastic) and lubrication. As the conversion of solar power to energy becomes more efficient and versatile, I think our energy future lies in covering as many things as we can — roads, buildings, etc — with solar cells in one form or another. It may seem farfetched, but 25 years ago the modern internet probably seemed even more revolutionary an idea.


  1. Artor says

    TGAP, you realize glass can be textured any way you like, right? It could be frosted diamondplate, made specifically for traction, and would probably be a better surface to drive on than slick asphalt. This technology could also probably heat the roadway a little so that snow & ice just don’t ever stick.

  2. says

    Vitrify nuclear waste and put it into the glass used for the roadbeds.

    Seriously, If you were going to do such a thing, the induction paths would probably have enough “grab” to keep cars from swerving on slippery surfaces.

    It sounds like it might cost a bit more than putting all of the Teabaggists on a ship to Regulus.

  3. matty1 says

    I like these ideas, the main problem I see apart from the technical issues is that the initial costs of replacing miles of road are likely to be very high even if there are long term advantages and this will put off those who could fund the necessary changes.

  4. Doug Little says

    it could spell the end of the use of oil for anything other than making products (like plastic) and lubrication.

    and air transportation.

  5. Pierce R. Butler says

    Take a pane of hardened glass, plexi, whatev, and glue it on a well-traveled road.

    Come back a week later, pry it up, look through it – if you can.

    Who’s gonna wash that light-blocking gunk off these arrays?

    Is this a sneaky solution for persistent unemployment?

  6. Doug Little says

    This technology could also probably heat the roadway a little so that snow & ice just don’t ever stick.

    Would almost have to be a necessity and a damn fine idea to boot.

  7. Crip Dyke, MQ, Right Reverend Feminist FuckToy of Death & Her Handmaiden says

    @Pierce, #7:

    I’m with you…that’s the problem I see with this plan.

    You can texture the glass for traction all you like, but adding traction = making more things stick to it = less efficient light transfer.

    Making it hydrophobic would help, but not necessarily nearly enough.

  8. Cholmondely Haberdash says

    P. Butler & Crip Dyke MQ beat me to it. Maybe a good pilot project
    to test this idea would be vast parking lots made out of these things.
    The traffic wear & tear wouldn’t be as heavy & arrangements for keeping
    them clean would be easier to make.

  9. says

    Small crack in road => some water gets in => water freezes => ice expands => bigger crack => water gets in… This is a big problem in northern states.

    Next problem: potholes, etc. break the connections between segments. Now the power, even if it’s still being generated, can’t get to where it’s collected. You can add redundancy, of course… at the expense of reduced efficiency.

  10. Paulino says

    Piezoeletric generators for the roads, perhaps? Solar at parking lots, and industrial plants.

  11. julial says

    I’m dubious.
    The generation of 4x electricity needs looks like sky-pie.
    Incredible costs for construction and maintenance. Or are we getting solar cell fabricators to be used like asphalt paving machines and run by knuckle dragging public works employees?
    Solar generation, to this point, been largely limited by the optical purity of the devices, meaning clean and smooth surfaced transmission media.
    Roads OTOH need to be rough for traction and are never clean.
    Perhaps in addition to non-contact power transmission we’ll be getting hovercraft or maglev vehicles which polish the glass as they move, hoverbuffers.
    As a ‘futurist’ Heimstra’s job specifications include “making shit up” and he is making a career of it. Doesn’t mean that anything he says is rational.

  12. leftwingfox says

    Option B: Above the roads? A simple metal structure over the roadways can help shelter the drivers from extremes of sun, snow and rain, and the lights can be hung beneath them.

    I’m remembering the carpark shelters in Palm Desert; you could shelter an entire parking lot with those to reduce the amount of sun baking the cars, while providing the infrastructure for solar panels

  13. flex says

    Not as sexy, but probably a little more technically feasible would be to use the thermal gradient between the road surface and a couple meters below the road surface to generate electricity using the peltier effect.

    The peltier junctions could be buried far enough below the surface of the road to allow for the surface asphalt to be repaired without damaging the junctions.

  14. ethanol says

    Ya I’m afraid this is a pretty bad idea. The limiting factor in solar installations is not available area but cost. We have plenty of places to put conventional panels (that get considerably better sun exposure than a road face) just not enough money to put them there. This proposal would assuredly be vastly more expensive per panel, and even more expensive per watt hour, especially when you consider the accumulation of dirt/rubber! As to the wirelessly recharged buses, if they are recharging only while picking up passengers, that is an awfully high power transfer, both for the wireless system and for the batteries.

  15. Azkyroth Drinked the Grammar Too :) says

    There are some serious engineering challenges to overcome but I can see it happening, if we can get past the initial capital investments, the knee-jerk pessimism about alternative energy, and in particular the fuckheads who have so much emotional investment in the idea that industrial civilization needs to be thrown away for the planet to survive that they refuse to recognize ANY technological solution to ANY environmental problem.

  16. gingerbaker says

    There is no need to make the road itself the electrical generator. Electricity can be generated from afar and moved around a smart grid. Most of the U.S. has suboptimal solar characteristics – it doesn’t make a lot of sense to spend the money on putting solar arrays everywhere.

    We don’t put hydroelectric generating systems on homeowner’s garden water features, we construct huge dams on huge rivers. We should be locating PV panels where the sun shines intensely and continuously – and that means the American southwest.

    Wireless inductive charging looks like it can work. Inductive coils could be cost-effectively retrofitted to our highways. Buried under the roadway, they can charge cars and trucks on the fly. On-vehicle batteries could be made much much smaller, which will make electric cars much much less expensive. A 100% electric fleet could be achieved very quickly.

    From :

    Study co-author Richard Sassoon, the managing director of the Stanford Global Climate and Energy Project (GCEP), explained to the Stanford Report: “What makes this concept exciting is that you could potentially drive for an unlimited amount of time without having to recharge. You could actually have more energy stored in your battery at the end of your trip than you started with.”

  17. baal says

    Scifi rebuilt of current physcialinfrasctructure and social design or actually changing things for the better immedately….

    Many of the comments rightly point out the technical issues and strongly imply that the solution of solar roads isn’t a good implementation. Also, rare earths needed for solar might be the limiting factor. I’d rather see housing redesigned for integrated solar and leave cars as hydrocarbon or electric.

    If you really want to reduce energy consumption and help on the atmospheric carbon forcing (i.e. burning stuff); you could do a lot by amping up zoning regulations so that we don’t need a car centric economy and lifestyle. Next, you could add in better mass transit based on rails. Rails are much more fuel efficient and the tech is off the shelf as of 100 years ago. In MN, the (R) keep sniping at even a modest light rail system and forced the designers to use a low end version of the rider car (it’s faintly nausiating to ride). That’s not a limit of the technology.

  18. The Lorax says

    Buses and 18-wheelers are big. Lot’s of surface area. Why can’t they carry around a few square meters of solar panels? They have the room, bloody use it.

  19. lldayo says

    Maybe we could contact the Wraith and get some of their regeneration technology used on their hive ships? This way the road could repair itself!

  20. wscott says

    I wasn’t able to read the full article (browser glitching), but based on the quoted portions I’m skeptical. In addition to the problems with keeping it clean and other issues identified above, do you have any idea how quickly asphault and even concrete roads wear out and need replacing? I find it difficult to imagine that drivable solar panels are going to be more durable than asphault, and considering the high replacement costs I can’t imagine any State DOT having the money to maintain them. The parking lot suggestion sounds marginally more feasible, but I wouldn’t hold my breath. Neat idea in theory tho.

  21. otrame says

    Oh, for FSM’s sake. We already have square miles upon square miles of unused space available for solar energy production, all over the country, not requiring feats of engineering and not even requiring destruction of any natural habitat. It is very likely that some of that currently unused space is over your head at this very moment.

    It’s not that the idea is bad (though many upthread have pointed out issues), it’s that we need to cover the roofs of all the Walmarts and Home Depots, not to mention our houses, before we seriously consider such things. The only reason it isn’t happening right now is capital outlay and some maintainence issues (along with the usual human shortsightedness). No feats of new engineering needed.

    If the government offered to lease the roof of a Walmart for energy production, splitting the income until the cost was paid for do you suppose they’d go for it? Would you?

  22. Johnny Vector says

    And along with the absolute idiocy of suggesting we put our solar panels in the worst possible place for solar panels, the idea of recharging buses at bus stops is useful only as a starting point for some kind of nerd improv sketch. Let’s see, a typical electric car runs about 30 kW average when driving. Let’s assume buses are so much more efficient that they only use 3x as much power, so 100 kW. If they spend 10% of their time at stops, that means you need to be transferring 1 MW when it’s stopped, if you want to maintain charge on average. By induction, no less. While keeping fringing fields down to a level that won’t pull people’s pocketknives right through their pockets onto the floor (or, y’know, turning off people’s pacemakers).

    Both of these ideas are ridiculous.

  23. collinc says

    I was trying to think of any way that I would ever want to include this as part of pavement project that I was designing. And not a good one comes to mind. If you want to put solar where pavement is put some poles in the ground and have the cells in the air. There have been a number of cool retro fits of parking lots with solar cell covers – don’t even need to tear up the pavement – put the supports in the existing islands.

    The other issue is maintenance. Not in a fancy engineering sense, but in plain old who’s gonna clean the things, replace and pay for em. Getting my clients to pay for simple maintenance programs on the pavement projects that I design is hard to say the least, and thats just crack sealing, R&R patching, and striping not replacing solar panels.

    Also a slight quibble with roads not changing much. In general they haven’t changed – a hard flat surface that you can drive on – cause it works. In the particulars they changed massively. Various cement additives to change cure times, various binder types for different driving applications, etc.

    Ed – I’ve enjoyed reading your blog for several years, not sure I’ve seen a pavement related post before. Thanks for all the interesting posts.

  24. Reginald Selkirk says

    Such an article can only be written by someone who lives in a snow-free area and cannot do math.

  25. Reginald Selkirk says

    Some highway history: Bott’s dots. These are reflectors which are glued to the road surface between lanes and at the edge of the roadway. They both reflect light and provide a ‘rumble’ effect if you drift out of your lane. They are a great idea.
    They are not used in areas with snow plows.

  26. Johnny Vector says


    As for buses recharging at each stop, that’s been successfully tested for urban-rail vehicles

    No it has not. The company site you point to consists of a lot of corporate fluff and zero technical information. They claim to have their system in use in three places: Braunshweig, which “has been kicked off”, meaning nothing is built, Lommel, which is a test program (not even a pilot program), to demonstrate that power can be transferred at all (and for which they provide no results), and Augsburg, in which trains receive power continuously as they travel.

    The numbers just don’t work for recharging only when stopped to discharge passengers. You have to either get it along the route or spend most of your time stopped. Existing (conductive) charging systems for electric cars top out at a charging rate about 1/4 to 1/3 the rate the vehicles run down the batteries when traveling. Inductive systems with that kind of power transfer capacity, especially ones not requiring accurate positioning of the vehicle, are much harder to arrange. It would be great to have, and the limits are engineering problems rather than violations of basic physics, but we’re a very long way from making it work.

    Getting power continuously along the route is technically doable, although really expensive to install. That could conceivably happen in a few demonstration projects, but I wouldn’t recommend it as an investment.

  27. Johnny Vector says

    Reginald: Actually I see a lot of lane-divider reflectors around Maryland and Pennsylvania, where there are plenty of plows. The reflectors are placed in small depressions that are carved out of the road, probably by a machine designed specifically for that job. A clever solution to the problem of plows! As I’m sure there are solutions to all the issues facing the two ideas presented in this article. It’s just that the solutions don’t exist yet, and will be very expensive not even counting the development costs.

  28. gingerbaker says

    Getting power continuously along the route is technically doable, although really expensive to install. That could conceivably happen in a few demonstration projects, but I wouldn’t recommend it as an investment.

    The idea of ROI when it comes to global warming is an idea that almost doesn’t apply anymore. Failure to bring emissions down to zero within ten years or so implies such gigantic costs to society that almost any expense is now cost-effective.

    Adding inductive charging to our roads might cost a trillion dollars ( who knows?) – it would still be an enormous bargain. I have read one guy on the internet supposedly speaking with authority that the addition of inductive charging to new road construction would add only 10% to total costs. True? No idea.

    The fascinating thing is that even after thirty years of attempts to lower carbon emissions, we do not even have a clue what the actual costs of large-scale public projects that could quickly and decisively solve the climate crisis would cost. And that, I think, is because the fossil fuel industry has been very good at keeping the national conversation relegated to thinking about renewable energy as a proposition that must be solved within the free market. Well, we don’t need to solve it that way, and I don’t think we have a snowball’s chance in hell that such a capitalism-dependent approach will solve this problem in time.

    I believe that what we need is a Federal Renewable Energy Utility. Large-scale coordinated system approach resulting in a citizen-owned renewable-only energy generation and distribution system. To sell the program, the utility should provide all our nation’s energy at the true cost of solar and wind. Which is zero. As the taxpayer assumes a larger national debt, he buys the equipment. After that, the energy generated from the sun and wind actually costs essentially nothing. Considering how incredibly important it is that we have zero CO2 emissions asap, this seems like a guaranteed way to accomplish the transition from a carbon-based to a renewable future.

    It is also virtually guaranteed to be the most cost-effective way to accomplish the goal. Paying for millions of redundant rooftop arrays has got to be the most expensive.

  29. Brain Hertz says

    Vitrify nuclear waste and put it into the glass used for the roadbeds.

    This would have a great side benefit of reducing costs for lighting by having the road surface glow in the dark.

  30. Doug Little says

    This would have a great side benefit of reducing costs for lighting by having the road surface glow in the dark.

    And also keep the ice and snow off.

  31. Suido says

    I’ve seen this proposed a few times. From a civil engineering point of view, here’s a quick summary of my immediate thoughts on the solar panel roads (I’ll leave the wireless electricity idea alone; I already consider electrical engineering with wires to be a Dark Art).

    Three problems: Maintenance, maintenance, and maintenance.

    As already noted by others, keeping the panels clean of tire rubber, exhaust particles, dust etc will be a considerable problem. Hydrophobic surface would help, as would nanotech cleaning, and I’m sure there are other possibilities, but it’s likely to be a significant extra expense.

    Design: Asphalt is a flexible surface, and the road structure and substructure is designed for that. Unless the solar panels have similar flexibility, the road structure as a whole will likely need to be redesigned. This isn’t a major problem, but it has implications for maintenance of defects, such as…

    Pot holes: Pot holes are typically not a failure of the asphalt, but of the road base aka subgrade (earth formation under the asphalt). Drainage causes the subgrade to lose cohesion and strength, heavy axle loads then push the asphalt down into the weakened subgrade, making a hole. Current asphalt surfaces are repaired by simply dropping in more asphalt, or caulking cracks with bitumen. If one solar panel breaks, do we have to replace it completely, and what effect will that have on adjacent panels and current flows? Not insurmountable issues, but must be dealt with.

    Panel edges: Two problems here. One, expansion and contraction of materials due to temperature changes. The layout would have to encourage lateral movement, towards the roadsides, instead of longitudinal movement along the road.
    Two, the expansion gaps will create hotspots for impact loads from wheels. Solar panel edges that bear the brunt of impact loads will wear out much faster than the rest of the panel. If this isn’t taken into consideration at the design stage it will have maintenance problems down the road. Heh.

    I do like the idea, but I think it’s very pie in the sky at the moment. If a bunch of these issues can be resolved, I’m looking forward to some proof of concept trials sometime in the 2020s.

  32. lancifer says

    Such an article can only be written by someone who lives in a snow-free area and cannot do math.-Reginald Selkirk

    Hey man! Are you a shill for the oil companies or do you just hate the earth?

    Don’t rain on the solar parade with facts you evil “denialist”.

Leave a Reply