Grid Connections, Batteries, and On-Board Generation: Sources for Electric Traction

Abstract

Well over 90 percent of all motorized transportation is fueled by products of petroleum, but the end of such widespread use of oil may be in sight. Among alternative fuels for land transportation, electricity appears to be the most promising, in part because it can be renewably produced and readily transmitted. The inadequacy and high cost of on-board storage of electrical energy present major challenges to widespread deployment of electric traction, and may do so for many years. On-board generation of electrical energy also presents challenges. The third means of powering electric traction is to provide for connection to the electricity grid while in motion. Grid-connected vehicles (GCVs) are an established feature of many cities and of much inter-city transportation, chiefly as electric streetcars, buses, and trains. They may be more highly regarded by users than their counterparts fueled by petroleum products, but they are nevertheless communal transportation, considered to lack the amenity of the private automobiles in which most land-based movement of people occurs. Private electric automobiles could, in principle, be grid-connected for some or all of their journeys, as electric buses are grid-connected. An alternative is to provide public transport that is more like private automobiles. This is generally known as Personal Rapid Transit (PRT), which could comprise relatively small, fully automated GCVs—often known as pods—that carry one to six persons along reserved guideways providing direct origin-to-destination service on demand. PRT could share infrastructure with private electric automobiles, although this may not be an optimal solution. Development of such GCV applications—for freight movement too—may be a more promising strategy than the current focus on improving traction batteries and fuel cells.