In-Chapter Pagination

More solar energy reaches Earth’s surface in one hour than all of humanity uses in an entire year, giving not just life to our planet, but also the possibility to harness that energy as electricity. This is a promise that has been understood for decades, yet it is not one we have accordingly appreciated.

To be sure, as solar power systems are currently used for less than 1% of energy production nationwide, questions as to why we aren’t using solar power more effectively are valid. But while the usual suspects in political and corporate arenas certainly share blame for this, the obstacles to implementing solar power over a large scale are as much technological as they are social. Yet today, innovative engineering approaches can solve this problem beyond the cost reductions and promising new products that have recently emerged on the solar energy market.

To elaborate how, it’s helpful to first understand some of the current obstacles to solar power, and why they are important:

Location and transmission. Electricity, like sound, weakens over distance due to resistance in transmission mediums. As a general rule, the longer electricity must travel, the weaker it becomes upon arrival to its final destination. For example, there is sufficient open space in the American southwest to place enough solar panels to power the planet several times over. Yet delivering electricity from that point to others over long distances is difficult because power lines have too much resistance within them to transmit electricity efficiently over thousands of miles. Power lines also cost millions of dollars to construct, making it expensive to transmit solar-generated electricity even if more efficient methods became technically possible.

Deployment expense and physical space. Beyond the cost to transmit electricity, solar power is still relatively expensive to implement – even in locations where electricity can be consumed at the point of generation – making financial justification more difficult. While eco-conscious households and businesses freely possess the means to do so by choice, the opposite is generally true when governments are concerned, as devoting large sums of tax dollars to solar projects is frequently met with less than enthusiastic support from an electorate. As the value of solar power is proportional to its extent of implementation, this limits its utility considerably - even as the price of solar panels continue to fall.

This problem is also made trickier by the issue of physical space: even if the political support and finances existed to construct solar power plants on large scales, the question of where to build them remains. Solar power needs a relatively large area to work, a requirement that becomes significantly more expensive as population density increases – and roofs + tops of buildings aren’t going to cut it if we’re going to generate 300% of our current electricity consumption. To that end, it’s unlikely that swaths of prime real estate could be purchased for the purpose of solar power, making widespread adoption harder.

Lack of standardization and prefabrication. As with many fledgling industries, our current approach to solar power reflects less than ideal degrees of standardization. Today, solar panels are designed to be installed on varied locations: roofs of buildings, soil, rock, motorized platforms, etc. But by diversifying and decentralizing approaches to solar power, it creates a hodgepodge of options of uncertain effectiveness, as opposed to implementing solar power through superior, modular and proven methods that can be standardized. In effect, this works to hinder prefabricated manufacturing of turnkey solar systems on a large scale, which increases end unit cost and limits solar power’s overall usability.

These problems have slowed down the adoption of solar power nationwide, and while advances in research and manufacturing have mitigated their impact to various degrees, they still remain obstacles. Yet these problems are a reflection of our current approach to solar power – not the concept as a whole.

Universal Energy's approach to solar power is geared towards already existing surfaces that can be outfitted with solar panels as a secondary function - lowering costs and providing an ideal location for standardized deployment. While two surfaces serve this role in the framework, the most important for kickstarting energy generation capability are the millions of miles of road surfaces across the United States - especially those within cities.

Solar Road Surfaces

A solar road surface is a road surface that is not poured, like asphalt or concrete, but is rather constructed with modularly installed solar panels that vehicles drive on.

The idea was first conceived and patented by a U.S. company named Solar Roadways with the goal of using solar technology to solve today’s energy-driven social problems. Since then, the idea has been taken a slightly different direction and released as a product called “Wattway” by Colas, a French road construction company.

Both companies already have fully functional prototypes ready for production that are already being deployed today. As of 2016, the Missouri Department of Transportation has bought panels from Solar Roadways to deploy as a pilot project, and the French government is planning to install 1,000 kilometers of Wattway solar road surfaces over the next five years. Both products take different approaches to address the complications surrounding solar power today, and also the constant (and expensive) decay facing existing roads.

In a nutshell, here’s how they work:

Sandwiched between a base layer and a reinforced surface of extremely strong composite, a solar road panel generates electricity from sunlight while also providing a functional driving surface for vehicles. However, in doing so it also offers features and improvements over both asphalt road surfaces and current solar technology. Let’s go over some details to see how:

Concept image of Solar Roadways. Note: LED lights provide road markings, not external paint.
Real-life image of Wattway by Colas. Panels can easily withstand weight of commercial truck.

Although they are still in prototype stages, both products can be factory-prefabricated with recycled materials sourced domestically (no rare earth metals needed), and are intended to be installed in a modular capacity. One simply fastens a panel unit into a road surface that has been modified to accept them and connects it to the local electric grid. Once installed, each panel independently generates electricity, and both Solar Roadways and Wattway have an estimated lifetime of 20 years.

They’re perfectly safe to drive on, as recent advances in chemical engineering now provide the ability to build composite surfaces that are stronger than steel – allowing the driving surface of solar road panels to be significantly stronger than traditional roads. Additionally, the driving surface can be textured to exceed the abrasiveness of asphalt so tires can grip the road surface in all weather conditions.

If you’re wondering how effective this is in real terms: modern roads are tested with machines that analyze their traction and strength. Most roads pass the test. In the case of Solar Roadways, the prototype broke the machine. To explain how, here is an explanation from Solar Roadways' chief inventor, Scott Brusaw:

"We sent samples of textured glass to a university civil engineering lab for traction testing. We started off being able to stop a car going 40 mph on a wet surface in the required distance. We designed a more and more aggressive surface pattern until we got a call from the lab one day: we'd torn the boot off of the British Pendulum Testing apparatus. We backed off a little and ended up with a texture that can stop a vehicle going 80 mph in the required distance."

In the case of Wattway by Colas, several tests have shown the composite panel covering is strong enough to withstand one million truck tires driving over them.

Actual, non-concept images from existing prototypes:

Left: tempered glass covering of Solar Roadways and deployed prototype. Right: Deployed prototype of Wattway by Colas panels.

In the case of Solar Roadways, they can come with integral conduit channels for utility lines and water runoff management (bottom-left). Additionally, they can also come with internal, grid-connected heating elements that can melt snow 24/7, avoiding the need for expensive snowplow operations. It's worth noting, however, that both Solar Roadways and Wattway have been tested with snowplows and have shown no adverse effects.

Left: conduit channels can run water, internet, gas, telecommunications and allow for instant maintenance without digging up existing roads. Right: internal heating elements melt snow off panels 24/7 and remove need for plowing.

The extreme strength of the composite covering of both Solar Roadways and Wattway allow the panels to support tens of thousands of pounds. Existing tests have shown that Solar Roadways can support up to 250,000 lbs - more than three times the legal weight limit for a semi truck.

Solar Roadway panels come embedded with LED lights that remove the need for traditional road painting. These lights can display sophisticated messages/warnings and road lines that can change instantly upon reprogramming from a municipal authority. Additionally, Solar Roadway panels come with sensors that can detect the presence of accidents, fallen trees or animals crossing up ahead, notifying motorists accordingly (only the bottom two images of animal crossings are concept, all others are real-world).

Just as importantly, solar road panels install rapidly. In the case of Solar Roadways, they are fastened down to concrete surfaces designed to accept them, and in the case of Wattway, they are glued down to existing road surfaces. Once automation and prefabrication of both panels begins earnestly, this allows us to install road surfaces in a matter of hours to days, as opposed to weeks and months with asphalt.

Left: Solar Roadways install rapidly via fastening to a concrete surface designed to accept them.
Right: Wattway panels glue securely to existing road surfaces.

Regardless of what prototype provides more utility in a given circumstance (something we'll go over shortly), solar road panels allow us to solve a lot of problems. But before we get into how they can do so, it’s worth noting that a few criticisms came up in response to their public debut. While some skeptics broadcast unfounded conclusions, other criticisms bring up valid questions that warrant a second look.

Critics have claimed that roads are a poor location to install solar panels, that this approach is prohibitively expensive, that traffic will obstruct sunlight and eventually destroy the panels themselves, and that in general, this idea makes little sense.

Anticipating this, the inventors of Solar Roadways went through extensive efforts to offer public-facing data and statistics to preemptively address these criticisms (as did Wattway by Colas, but a few skeptics jumped the gun and reported their critiques without all facts in place. As such, I’d like to take the opportunity to first draw attention to the three biggest criticisms of this approach to solar energy and address them in kind before going over the benefits of solar road surfaces in full:

  1. “Roads are poor locations to install solar panels, which are better suited for remote land, buildings or even to the side of or above roads.” Remote land is just that: remote, requiring expensive power lines that are susceptible to transmission loss over distance – problems solar roads wouldn’t have if they were built close to where their electricity was consumed. Roofs of buildings are limited in surface area and require independent investment from the building owner to install solar panels. That means if you have 10,000 buildings, to cover them all with solar panels you'd need to individually convince 10,000 building owners to buy and install them out of pocket. Across the nation, this would be equivalent to making cat-herding an Olympic sport.

    As public roads are owned by the government, they can be a single-buyer for large-scale solar surface deployment, and government is the only entity with both the authority and finances to make infrastructure investments on this scale. Compared to convincing individual property owners, it's a no-brainer.

    The sides of roads is a good idea as well (which we’ll get into with the National Aqueduct), but because solar roads can offset the high costs of road construction and maintenance – in addition to other benefits and cost reductions elsewhere (automatic snow melting, LEDs in lieu of road painting, etc.), these are the key components that make solar roads affordable and what makes road surfaces one of the most attractive locations to install solar panels we have available.

  2. “Solar road surfaces will cost trillions of dollars to deploy.” For 100% nationwide implementation, that is true. And that’s a bargain, as we already spend hundreds of billions per year at all levels of government on our roads. As roads are state-owned, solar roads can be installed by public works departments instead of asphalt roads that don’t generate revenue nor last as long - removing the need to buy land to install solar power. This is money that would have to be spent anyways on new and existing roads.

    Maintenance and productivity loss due to delays would also be minimized. Asphalt road work takes months and causes traffic delays that cost our economy an estimated $124 billion in annual productivity loss. That's roughly a trillion dollars every eight years. On top of that, the current price tag to repair our decaying infrastructure by 2020 is estimated to be $3.6 trillion. With solar road surfaces, panel installation and replacement takes hours. Both Solar Roadways and Wattway are estimated to last for 20 years, and can generate revenue through multiple sources.

    So yes, Solar Road surfaces might cost trillions of dollars if we deployed them nationwide, and so will our current roads in the future. Solar roads are just a superior product at a greater value.

  3. “Traffic will obstruct sunlight from reaching the panels and will ultimately destroy the panels and their auxiliary features over time.” Just as a hypothetical parade of ants walking on your back wouldn’t prevent you from getting sunburned if lying outside, traffic can only minimally block sunlight from solar road panels. As you can see from the following image, even at rush-hour traffic, the road surface is largely unobstructed:

    Because traffic is usually weak when the sun is strongest, rush hour conditions are less likely and instead would more commonly resemble the bottom half of the image with low vehicle coverage. As the vehicles themselves are constantly moving, what panels they cover would only be blocked from sunlight for a second, and only a few times a minute.

    As to road traffic harming the panels, it’s difficult to emphasize just how strong composite surfaces can be. They are far harder and stronger than asphalt (which is itself a liquid that is poured over gravel). On the Mohs’ hardness scale (which goes from 0-10, with diamond hardest at 10), asphalt ranks at 1.3. Plate glass (the kind in your windows) has a hardness of 6. Tempered glass, which Solar Roadways are made from, can reach 7 and is much stronger – strong enough to withstand a .50 caliber bullet. The composite surface of Wattway is similar in strength and resilience.

    Solar Roadways' current glass prototype passed two 3D Finite Element Analysis tests showing that they could withstand both compression and sheer forces up to 250,000 lbs. The maximum legal weight of a semi truck is 80,000 lbs. The textured glass surface is designed to mitigate cyclic pressures from heavy vehicles (applying weight on a small area at potentially destructive resonances), and the way road panels are fastened into place is designed to absorb shocks. In short, they’re far stronger than both asphalt and concrete and are tested to support a weight nearly twice that of an Abrams tank. That’s plenty strong enough for normal traffic. The panels would be just fine.

With these criticisms addressed, we’ll continue from here by reviewing the benefits of solar road surfaces in greater detail. Of them, the more important include:

Solar roads solve the core challenges of solar power.

Thanks in large part to social infrastructure and public works projects after the Second World War (namely the Eisenhower highway system), the United States has one of the largest and most comprehensive road systems on the planet. America’s roads and highways cover tens of thousands of square miles of surface area and they’re cleared at the sides to avoid obstructions from above. This makes roads uniquely suited for solar panels because they can simultaneously solve the three main complications with solar power: transmission, installation location and standardization.

Concerning location and transmission, consider the map above. Without exception, every major population center in our country is served by a section of these roadways, allowing us to place solar panels close to and within any municipality. This removes the problem of transmission expense and resistance over distance, as electricity can be consumed at the points of generation.

This also removes the problem of installation location. We’ve discussed how it would be prohibitively expensive to purchase land for solar power within areas of high population density. Yet solar roads can be implemented without having to buy land. Nearly every road in the nation is publicly owned – allowing any given road authority to implement them on their own.

Regarding standardization, as roads are ideal locations to install solar panels they mitigate the costs and complications surrounding the various surfaces solar panels are currently installed on. Roads are generally flat and go on for thousands of miles, and at least within the United States have universal 12-foot lane widths. This allows solar road panels to be built to a single standard – removing the need for ad-hoc, customized implementation (minus another solar surface we’ll discuss in Chapter 6).

The panels also provide a standardized method for providing road traction as well. The image below shows the raised, abrasive driving surface of Solar Roadways that is comprised of angular hexagons that also double as prisms. These prisms feed sunlight directly into the solar panels from nearly any angle, which not only increases efficiency in northern climates but also emits light from the LEDs embedded within the panels in multiple different directions – increasing visibility and overall effectiveness.