In the face of escalating climate concerns and a growing demand for renewable energy, the concept of energy harvesting from smart roads has emerged as a promising frontier in sustainable infrastructure. Smart roads—engineered with advanced technologies—are now being explored not only for intelligent transportation systems but also for their ability to generate electricity through renewable means. This innovation could reshape the way urban centers address both energy shortages and environmental sustainability.
1. Understanding Smart Roads
Smart roads are technologically enhanced pavements that integrate sensors, IoT devices, communication systems, and, increasingly, energy-harvesting technologies. Their purpose goes beyond transportation—they gather real-time traffic data, enhance safety, and improve driving conditions. The next generation of smart roads aims to be self-sufficient by capturing ambient energy and converting it into usable electrical power.
2. Mechanisms of Energy Harvesting
There are several cutting-edge technologies that enable energy harvesting from roads:
a) Piezoelectric Materials
Piezoelectric materials generate electricity when mechanical stress is applied. When embedded beneath road surfaces, these materials produce electric charges as vehicles exert pressure on them. Each passing car can generate micro-watt to milliwatt levels of energy per square meter. While small individually, over long stretches of road and heavy traffic, the cumulative energy can be significant.
A study by Xie et al. (2020) estimated that a 1-km stretch of piezoelectric-embedded highway with heavy traffic could generate up to 44 MWh/year—enough to power dozens of households.
b) Photovoltaic (Solar) Roads
Solar panels integrated into road surfaces are another prominent technology. These are typically designed with tempered glass to endure vehicular load while capturing solar energy. Pilot projects like France’s Wattway and China’s solar expressway have shown promising outcomes.
According to Coleri et al. (2021), roads embedded with solar cells could generate up to 220 kWh/m² annually in sun-rich regions, providing a viable supplement to grid power.
c) Thermoelectric Generators
The temperature differential between road surfaces and underlying soil can be exploited using thermoelectric materials. These generators convert heat flow into electricity—a promising feature especially in urban heat islands and hot climates.
Sung et al. (2019) demonstrated that thermoelectric systems beneath asphalt could generate consistent energy even at night due to retained heat, extending their usability.
3. Applications and Benefits
Energy harvested from smart roads can be utilized in multiple ways:
- Street Lighting and Traffic Signals: Localized power can be directed to road infrastructure, reducing reliance on the grid.
- Charging Electric Vehicles (EVs): Embedded inductive charging systems, powered by harvested energy, could revolutionize EV mobility.
- Urban Sensors and 5G Poles: Self-powered sensors improve urban resilience by offering real-time monitoring without additional wiring.
- Smart Grids: Surplus energy can be fed into decentralized grids, contributing to clean energy goals.
In South Korea, a 100 km expressway section with piezoelectric and solar integration supports lighting and emergency communication systems with minimal grid input (Kim et al., 2020).
4. Challenges and Limitations
Despite its potential, energy-harvesting roads face technical and economic hurdles:
- Durability and Maintenance: Integrating sensitive materials into roads raises concerns about wear and long-term viability under heavy traffic.
- High Initial Costs: Technologies like piezoelectric and photovoltaic materials are costly, making large-scale implementation expensive.
- Efficiency: Conversion rates are still low compared to traditional renewable energy sources.
- Safety: Road surface modification for energy systems may affect traction and vehicle control if not engineered properly.
5. Future Prospects
Ongoing research is addressing these limitations. Nanomaterials, for instance, promise enhanced piezoelectric efficiency and durability. Hybrid systems—combining multiple energy-harvesting methods—are being tested for more stable output.
A 2022 EU Horizon project is developing a multi-source energy harvesting system combining solar, thermal, and vibrational sources, aiming for 70% higher efficiency over standalone systems (European Commission, 2022).
Moreover, as urban populations grow and climate change intensifies, governments are incentivizing smart, self-powered infrastructure. Integrating energy harvesting into roads can contribute to decentralized, resilient energy systems aligned with SDG 7 (Affordable and Clean Energy) and SDG 9 (Industry, Innovation and Infrastructure).
6. Conclusion
Energy harvesting from smart roads is not merely a technological novelty—it is a transformative innovation at the intersection of civil engineering, renewable energy, and sustainable urban planning. Although challenges remain, advancements in materials science and a push for green infrastructure are bringing this vision closer to reality. As pilot projects mature and cost-efficiencies improve, smart roads may soon become silent yet powerful contributors to global clean energy production.
References
- Xie, J., Li, M., & Wang, Y. (2020). Piezoelectric energy harvesting from road traffic: A case study and system design. Energy, 199, 117478.
- Coleri, E., Tang, Y., & Hein, J. (2021). Feasibility study of solar-powered roadways in urban infrastructure. Renewable Energy, 170, 1121–1130.
- Sung, H., Park, D., & Lee, S. (2019). Thermoelectric energy harvesting from asphalt pavement temperature gradients. Applied Energy, 254, 113650.
- Kim, Y., Jang, J., & Moon, H. (2020). Integration of piezoelectric roads and solar systems for smart transportation. Smart Materials and Structures, 29(4), 045015.
- European Commission. (2022). Smart Sustainable Road Energy Harvesting Project under Horizon Europe. Retrieved from https://cordis.europa.eu/project/id/101007630
