Project 2 Feasibility Report

Solar-powered Roadways

Sydnee Mizuno

August 1, 2016

Table of Contents

• Executive Summary
• Preliminary Requirements Analysis
• Feasibility
• Success Criteria
• Design
• Cost Estimates
• Reporting
• Risk Analysis
• Financial Planning
• Conclusion

Executive Summary

In 2006 the startup Solar Roadways was founded by Julie and Scott Brusaw. Solar Roadway's goal is to create solar panels that can replace existing roads. These panels are hexagonal layers of tempered glass with solar cells and LEDs in between them. By using these panels throughout the U.S. instead of concrete and asphalt roads, it is estimated that we could generate three times more electricity than we use. The embedded LEDs would offer greater visibility than painted road lines and provide smart information about oncoming traffic. Additionally, these roads with electricity and smart networks could promote a wider usage of electric vehicles.

Despite these advantages, the endeavor of replacing our country's current highway systems is unfeasible. Besides the obvious difficulties that would be encountered with the vast scope of the project, there are also issues with the solar panels themselves. The rest of this study will address the requirements needed for solar-powered roadways and how they are not met.^[i.n.]

Preliminary requirements analysis

Solar Roadway's mission is to generate clean, reneweable solar energy on roadways. To accomplish this, the startup has developed modular solar panels that can replace asphalt surfaces. By using these panels, substantial amounts of electricity could be generated. Also, embedded LEDs and sensors could create a smart highway system.

In 2009, Solar Roadways received a $100,000 grant from the Department of Transportation (DOT) to seek engineering input and write a concept paper. Then in 2011 the DOT gave another grant of $750,000 to develop a working prototype the size of a parking lot. In addition to giving Solar Roadways money for reaearch and devleoplment, the DOT is also working with them to test the safety and functionality of the solar panels. Before any major implementations could happen in the U.S., Solar Roads would need the DOT's approval.

With the use of solar roads, the existing roads in our country would need replacement. Also this new road system would need to be integrated into current electric grids.

Feasibility

The current prototype for solar-powered roads consists of two layers of glass panels that enclose a circuit board with LEDs, solar cells, and heating elements. The glass is tempered and textured to provide safety and traction for traffic. Solar Roadways has reported that this glass surface has been tested in a university lab, and that a vehicle stopped within the required braking distance. However, the DOT has not confirmed this. Also, the DOT was unable to send its impact load testing equipment to Solar Roadways, so the glass panels' load carrying capacity has only been officially tested through 3D modeling. Eric Weaver, an engineer with the Federal highway Assocation, says that the DOT will need to continue testing the panels' traction. At this time, the DOT needs to perform more field traffic evaluation. Solar Roadways has not yet decided on any specific solution to keep these panels clean. The company will need to engineer a solution that prevents dirty buildup while maintaining traction for traffic. The LEDs that are embedded in the panels would replace the need for painting road lines. They would also increase visibility. Solar Roadways envisions these LEDs flashing in response to oncoming obstacles like pedestrians and wildlife. The circuits also contain solar cells to collect energy, and they also contain heating systems to keep the panels above freezing. This would prevent the accumulation of snow and ice. Difficulties have been ecountered in the manufacture of these panels. With the rise of smart, personal electronics, companies have focused on making circuits smaller. This presents a problem with finding circuits big enough for Solar Roadways' panels. Another major issue is the efficiency of the solar cells being used. At this time, the cells have not been tested anywhere except at the Brusaws' house. Scott Brusaw has reported that the cells performed within 5% of theoretical values compared to solar cells on rooftops. One self-reported test is not enough to confirm that these solar cells function well. More independent testing across different environments will be needed for unbiased results that confirm that the solar cells work.

Solar Roadways has not completed a cost analysis yet. But in 2010, co-founder Scott Brusaw estimated that a 12 by 12 foot panel would cost $10,000. With about 29,000 square miles of paved roads in the US, it is estimated that the total replacement cost would be $56 trillion.

If these solar-powered roads were adopted, Solar Roadways would only be the manufacturer of the solar panels. The goverment and other independent companies would be left to solve the logistics of replacing the country's current transportation infastructure.

Success criteria

Solar Panel Components

• The solar panels that would make up the roadways are hexagonal pieces of tempered glass that encase a circuit board. This circuit board contains solar cells to capture energy, LEDs for road lines and displays, and heating systems to prevent snow buildup.

• Before solar-powered roads could be adopted throughout the country, they would need to be rigorously tested. The Department of Transportation and other accredited independent agencies would need to test the panels for safety, efficiency, and reliability. The Brusaws' self-reported home tests need to be confirmed by other sources to ensure that there are accurate, non-biased results. The DOT needs to use a weight deflectometer to test how Solar Roadway's panels handle impact loads. The solar cells and LEDs will need to be tested for energy efficiency and longevity. Also, field traffic evaluations will need to be run in order to test how the panels hold up to continued use. The panels need to have sufficient traction and durability.

• The Department of Transportation and other service agencies would need to handle the installation of Solar Roadways' panels. They would be responsible for creating building projects, financing them, and installing them.

Design

Cost Estimates

At this time, all costs are estimated because Solar Roadways has not conducted a cost analysis. It is estimated that the company's solar panel pieces would cost $70 per square foot. By replacing asphalt roads in the U.S. with these panels, it would cost about $56 trillion.^[i.n.]

Report

Solar Roadways has tested most of its design at the founders' home, and it has posted some of those results to the company website. Solar Roadways' website claims that weight limits have been tested with 3D Finite Element Method analysis. Scott Brusaw also says that he used micro-inverters to confirm that Solar Roadways' panels performed within 5% of theoretical values compared to regular rooftop solar panels. The company has also collaborated with the DOT and various university labs for testing traction testing. It will continue to test and report its findings to these organizations as product development continues.

Risk Analysis

There are potential risks to using solar-powered roads. One of these is the strength of the glass panels. Solar Roadways uses tempered glass, and it manufactures it similar to bulletproof and bomb blast resistant glass. The company self-reports that the roads can hold 250,000 pounds. Another risk is road traction. To increase traction, the solar panels are textured for grip. Another risk is a damaged or defective panel. Solar Roadways says the smart network of panels could report the location of a defective panel, and it could be collected and reprogrammed quickly.^[i.n.]

Conclusion

While the benefits of solar-powered roads are great in theory, there is not enough evidence to prove that they could be practically implemented throughout the U.S.

At this time, the majority of testing has been completed at the Brusaws' home, and the results have been self-reported. The DOT and other accredited organizations would need to independently test and verify the solar panels' performance. These tests would check for the panels' efficiency, durability, and safety using methods described in Technical Feasibility and Success Criteria. Also, Solar Roadways would need to run a financial analysis of its product in order for any organization to seriously consider financing it.

With the lack of official testing and the extreme cost of road replacement, it is unfeasible to adopt these new types of roads across the country. While it may be possible to expand this technology from the Brusaws' small prototype parking lot to the entire highway system, today is not that day.