Energy harvesting uses sunlight or the mechanical vibrations produced by vehicles and pedestrians to generate electrical energy. This electricity can then be used to power road infrastructure such as lights and signals.
It can be stored in batteries for use when needed or fed into the electric power grid, and because it makes use of the existing road network. No new land space needs to be allocated.
International Standards play a key role in the development of these solutions. IEC Technical Committee (TC) 47 develops International Standards for semiconductor devices including those that harvest energy. Batteries used to store electrical energy rely on the standardization work of IEC TC 21.
IEC TC 8 and its Subcommittee (SC) 8A develop Standards for electricity supply systems, including the integration of power generated from renewable energy sources and fed into the electrical grid. A systems group, SyC Smart Energy, provides systems level standardization, coordination and guidance in the areas of smart grid and smart energy.
Techniques have been developed to place photovoltaic modules directly on top of a road surface to capture solar power. Energy can be harvested from the over 16 million kilometres of paved roads around the world that are exposed to sunlight.
Despite the challenges, many related to the grip pf road surfaces, several companies have developed photovoltaic modules that can either replace asphalt or be placed directly on top of existing roadways. While these solutions are proprietary, they rely on International Standards developed by IEC TC 82, which is responsible for solar photovoltaic energy systems.
Pilot projects are underway around the world. Recently, the Dutch provinces of Noord-Holland and Zuid-Holland have installed solar panels into 150 metres of road surface. The expected annual electricity yield per 100 metres of solar road surface is around 30,000 kWh.
Thermoelectric generators (TEGs) can also be used to harvest energy from roads. Based on the Seebeck effect, TEGs can convert geothermal energy — produced from the heat differential between the road surface and the layers beneath — into electrical energy. As the temperature differential increases, more electrical energy is produced, thus making this technology well suited to areas with extremely hot weather.
In 2017, IEC TC 47 prepared the IEC 62830–2 series of Standards which provide methods for evaluating the thermal power of thin films used in thermoelectric energy harvesting devices.
The vibrations produced by a car driving on the road can be used to generate electricity. Piezoelectricity is the electric charge produced by certain crystals when a mechanical stress is applied.
Piezoelectric crystals can also be embedded beneath a layer of asphalt. As cars drive over the road, the wheels exert a force that causes these crystals to deform and generate electrical energy.
This energy can then be used to power street lights or can be stored in batteries for later use. The IEC 62830–1 series, prepared by IEC TC 47, includes methods for evaluating the performance of vibration-based piezoelectric energy harvesting devices.
Research is currently underway in the southwest of the United States to test this technology and potentially make use of it as a back-up source of power for illuminating LED at runways and taxiways. It could be used as the sole means of lighting rural civilian airport runways.