Piezoelectric Roadway Energy Harvesting Calculator

How to Use This Calculator

Enter the following inputs to estimate average electrical power:

• Average Vehicle Mass (kg) — Typical values:
  • Small passenger car: 1,200 – 1,600 kg
  • SUV / light truck: 1,800 – 2,500 kg
  • Fully loaded heavy truck (per axle group): 5,000+ kg
• Module Compression per Vehicle (mm) — The vertical displacement of the piezoelectric module under load. Practical design targets are usually a fraction of a millimetre to a few millimetres (for example 0.2 – 3 mm) to limit pavement deformation and fatigue.
• Conversion Efficiency (%) — Fraction of mechanical work converted to electrical energy. For prototype systems, realistic overall efficiencies (including mechanical, piezoelectric, and basic electrical conversion stages) are often in the 5 – 30% range. Use higher values only for optimistic scenarios.
• Vehicles per Hour — Average traffic flow over the module. For example:
  • Quiet local road: 50 – 200 vehicles/hour
  • Busy arterial: 500 – 1,500 vehicles/hour
  • Multi-lane highway segment: 2,000+ vehicles/hour (per direction)

The output represents the average electrical power produced by the instrumented roadway section, expressed in watts (W). You can compare this value with typical loads, such as LED street lights, roadside sensors, or communication devices, to see what might be powered in principle.

Underlying Calculation and Formulas

The calculator uses a simplified mechanical work model. When a vehicle of mass m (in kilograms) passes over the module, the normal force is approximated as the vehicle weight:

Force due to vehicle weight:

where g is gravitational acceleration, taken as 9.81 m/s².

As the module compresses by a displacement δ (in metres), the mechanical work performed on the module is roughly:

Only a fraction of this mechanical work is converted into electrical energy. Let η be the overall conversion efficiency (expressed as a decimal, so 15% becomes 0.15). The electrical energy harvested per vehicle pass is then:

with:

• E — energy harvested per vehicle (joules)
• m — average vehicle mass (kg)
• g — gravitational acceleration (9.81 m/s²)
• δ — module compression (m)
• η — conversion efficiency (0 – 1)

If the average traffic flow is V vehicles per hour, then the total energy harvested per hour is E × V. The average power P is this energy divided by the number of seconds in an hour (3,600):

This final expression is what the calculator evaluates based on your inputs (with compression converted automatically from millimetres to metres, and efficiency converted from percent to a 0–1 fraction).

Interpreting the Results

The calculator returns an estimate of average electrical power in watts. To put this into context:

• 1 W sustained over an hour corresponds to 1 Wh of energy.
• 100 W for one hour is 0.1 kWh.
• Typical small roadside sensor nodes may require tens to hundreds of milliwatts on average, while a single LED street light can require tens of watts or more.

Because each individual vehicle pass usually yields only a modest amount of energy, meaningful power levels tend to rely on:

• High traffic volumes
• Reasonable compression without damaging the pavement
• Optimised materials and energy-conversion electronics

Use the result as a way to compare different design scenarios and traffic assumptions rather than as a precise forecast for a specific installation.

Worked Example

Consider a simplified example for one lane of a busy roadway module:

• Average vehicle mass: 1,500 kg
• Module compression per vehicle: 1.0 mm
• Conversion efficiency: 15%
• Vehicles per hour: 1,000

Step 1: Convert units and efficiency.

• Compression δ = 1.0 mm = 0.001 m
• Efficiency η = 15% = 0.15

Step 2: Compute energy per vehicle.

E = m × g × δ × η

E = 1,500 kg × 9.81 m/s² × 0.001 m × 0.15 ≈ 2.21 J per vehicle

Step 3: Compute power at 1,000 vehicles per hour.

Total energy per hour = 2.21 J × 1,000 ≈ 2,210 J

Average power:

P = 2,210 J / 3,600 s ≈ 0.61 W

This result illustrates that, even with optimistic assumptions, a single module or lane section may only supply on the order of a watt of power. Larger deployments, higher traffic volumes, and multiple modules would be needed to reach tens or hundreds of watts.

Comparing Scenarios

The table below highlights how changing traffic volume and efficiency can affect approximate power output for a fixed vehicle mass (1,500 kg) and compression (1.0 mm).

These values are illustrative only. Use the calculator to explore your own combinations and to understand how sensitive the results are to each input.

Applications and Engineering Context

Piezoelectric roadway systems are most realistically suited to powering small, distributed loads near the point of generation. Examples include:

• Traffic counters and vehicle classification sensors
• Environmental monitoring nodes (temperature, humidity, air quality)
• Wireless communication repeaters or low-power gateways
• Indicator lights or signage with duty-cycled operation

Integrating energy storage (for example supercapacitors or batteries) allows short bursts of higher power consumption, even if the average harvested power is relatively small.

Assumptions and Limitations

The model used in this calculator makes several important simplifying assumptions. Keep these in mind when interpreting the results:

• Uniform compression per vehicle — The module displacement is assumed to be the same for every vehicle and does not vary along the length or width of the module.
• Vehicle mass simplification — All vehicles are represented by a single average mass and do not distinguish between axle loads or vehicle types.
• Constant gravitational acceleration — The calculation uses g = 9.81 m/s² and ignores small variations with location or elevation.
• No dynamic effects — The model neglects suspension dynamics, vibration, impact loading, braking, and acceleration forces, which can all influence instantaneous loads and energy capture.
• No thermal or aging effects — Material performance is assumed constant over time and independent of temperature, moisture, or fatigue degradation.
• Idealised conversion efficiency — The efficiency parameter is treated as a single lumped value and does not separately model mechanical losses, piezoelectric coupling, rectifiers, power electronics, storage, or cabling losses.
• Average traffic flow — Vehicles per hour is a simple average and does not capture peak periods, queuing, lane changing, or non-uniform use of the instrumented section.
• No structural design verification — The calculator does not address pavement durability, structural integrity under repeated loading, safety, or compliance with road design standards.

Because of these simplifications, the results should be treated as approximate and may differ significantly from real-world performance. Detailed engineering studies, laboratory testing, and field trials are required before any deployment decisions are made.

Using the Calculator for Scenario Planning

Within its limitations, this tool is useful for quick “what-if” evaluations. You can, for example:

• Compare different traffic levels (off-peak vs. peak hour) to understand how much additional power could be harvested.
• Explore the impact of more efficient materials or power electronics by adjusting the efficiency value.
• Evaluate how sensitive power output is to module compression and decide whether increased displacement is worth the potential structural trade-offs.

Combine these estimates with cost, maintenance, and infrastructure constraints to assess whether piezoelectric roadway harvesting is suitable for your specific application.