Emissions Performance of Electric Vehicles

Emissions Performance of Electric Vehicles – In addition to the instruments and of course the safety system, there are some important additions in an electric car. But to know this, it’s good to read some of the articles that I have listed below to increase knowledge about electricity in electric cars.

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Emissions Performance of Electric Vehicles

The amount of pollution created by EVs depends mostly on the source of the electricity used to charge them. This makes it difficult to determine if electric vehicles pollute less than internal combustion engine vehicles without considering where they are to be deployed and by what sources of electricity they are to be powered. An EV that is charged with energy from a clean source, like hydroelectric power, will produce very little pollution, while one charged with energy from an unclean source, like coal or oil, may produce more pollution than an internal combustion engine vehicle. The sources of energy for most regions fall somewhere between these two extremes. While not ready to be used everywhere, electric vehicles have the potential to pollute much less than internal combustion engine vehicles.

Mitsubishi Outlander PHEV. Source: thecarguy

A battery electric vehicle (BEV) produces zero vehicular emissions. However, emissions are produced at the generation site when the source fuel is converted into electrical power. The emissions of electric cars, therefore, depend on the emissions profile of regional generating plants.

Some researchers conclude that, in regions serviced by coal-fired plants, a switch to EVs may actually increase emissions of sulfur oxides (SOx) and particulate matter (PM), and perhaps increase emissions of carbon dioxide (CO2). Conclusions, however, are usually based on the existing mix of coal-fired plants, and often they do not consider the effect of newer and cleaner plant designs. Studies generally conclude that emissions of SOx, PM, and CO2 are reduced in regions that rely on natural gas, and virtually eliminated in regions supplied by hydroelectric and nuclear power.

According to Electric Power Research Institute (EPRI), substituting EVs for conventional vehicles (CVs) would reduce urban emissions of nonmethane organic gases (NMOG) by 98%, lower nitrogen oxide (NOx) emissions by 92%, and cut carbon monoxide (CO) emissions by 99%. In addition, EPRI estimates that, on a nationwide basis, EVs in the U.S. will produce only half the CO2 of conventional vehicles. In another study of four U.S. cities, BEVs reduced hydrocarbon (HC) and CO emissions by approximately 97%, regardless of the regional source fuels mix. In comparison to large generating plants, conventional cars produce large amounts of HC and CO emissions, mainly because of cold starts and short trips that do not allow vehicles to become fully warmed up. 

The environmental benefits of an HEV depend on the design of the hybrid power system. Designs using a combustion engine for on-board electrical generation and an operating schedule that is heavily biased toward the engine/generator system (genset) produce the greatest amount of harmful emissions. But even in this worst case scenario, emission levels are lower than those of a typical CV. This is due to the fact that a hybrid vehicle genset is either switched off, and therefore producing zero emissions, or it is operating at a predetermined output where it produces the fewest emissions and achieves the best fuel economy per unit of output.

Typically, a hybrid genset is not throttled for variable output, as is the engine in a conventional vehicle. This leads to more effective emission controls because it is technically easier to control combustion-engine emissions when the engine runs continuously and at a constant output. When the hybrid-operating schedule is biased more toward the energy storage system (relies more on the battery, rather than the genset), emission levels become more like those of a BEV, and with fuelcell hybrids, vehicular emissions are virtually eliminated.

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