The importance of green technologies for generating renewable energy and sustainable development is widely accepted. Highway pavements which are exposed to solar radiation, absorb a large amount of heat that could be harvested. This study aims to design an innovative thermoelectric generator system that utilizes the thermal gradients between the pavement surface and the soil below the pavement and converts it to electricity. This system consists of a heat collector, a thermal electric generator and a coolant module. A prototype was fabricated to embed directly into asphalt pavements. Several simulations using finite element analyses were conducted to evaluate the performance of the system components and determine their optimal design. The final design was also tested in the field. Based on the experimental and finite element results, the efficiency of the system was enhanced by improving its coolant module by incorporating a phase-changing heat sink. The optimized prototype was able to generate an average of 29 mW of electricity for South Texas conditions (i.e. temperate zone), which appears to be a promising independent source of power for road-side wireless sensors and near-field data communications.