![]() In geology and mineralogy, the term "carbonate" can refer both to carbonate minerals and carbonate rock (which is made of chiefly carbonate minerals), and both are dominated by the carbonate ion, CO 2− 3. The term is also used as a verb, to describe carbonation: the process of raising the concentrations of carbonate and bicarbonate ions in water to produce carbonated water and other carbonated beverages – either by the addition of carbon dioxide gas under pressure or by dissolving carbonate or bicarbonate salts into the water. The word carbonate may also refer to a carbonate ester, an organic compound containing the carbonate group O=C(−O−) 2. In the case of electricity, most electric power plants produce emissions, and there are additional emissions associated with the extraction, processing, and distribution of the primary energy sources they use for electricity production.Ĭradle-to-grave emissions include all emissions considered on a well-to-wheel basis as well as vehicle-cycle emissions associated with vehicle and battery manufacturing, recycling, and disposal.A carbonate is a salt of carbonic acid (H 2CO 3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula CO 2− 3. In the case of gasoline, emissions are produced while extracting petroleum from the earth, refining it, distributing the fuel to stations, and burning it in vehicles. Well-to-wheel emissions include all emissions related to fuel production, processing, distribution, and use. However, their direct emissions are typically lower than those of comparable conventional vehicles. When using the ICE, PHEVs produce tailpipe emissions. PHEVs produce zero direct emissions when they are in all-electric mode, but they can produce evaporative emissions. Conversely, all-electric vehicles produce zero direct emissions. Both categories of emissions can be evaluated on a tailpipe basis, a well-to-wheel basis, and a cradle-to-grave basis.Ĭonventional vehicles with an internal combustion engine (ICE) produce direct emissions through the tailpipe, as well as through evaporation from the vehicle's fuel system and during the fueling process. Vehicle emissions can be divided into two general categories: air pollutants, which contribute to smog, haze, and health problems and greenhouse gases (GHGs), such as carbon dioxide and methane. ![]() In areas with higher-emissions electricity, all-electric vehicles and PHEVs may not demonstrate as strong a life cycle emissions benefit.ĭirect, Well-to-Wheel, and Cradle-to-Grave Emissions In geographic areas that use relatively low-polluting energy sources for electricity generation, all-electric vehicles and PHEVs typically have an especially large life cycle emissions advantage over similar conventional vehicles running on gasoline or diesel. Electricity Sources and Fuel-Cycle EmissionsĪll-electric vehicles and PHEVs running only on electricity have zero tailpipe emissions, but electricity production, such as power plants, may generate emissions. The combined emissions from vehicle and fuel production through vehicle decommissioning (i.e., recycling or scrapping) are referred to as life cycle or cradle-to-grave emissions. ![]() Estimating cradle-to-grave emissions must account for both fuel-cycle emissions (also known as "well to wheels") and vehicle-cycle emissions (material and vehicle production as well as end of life). Tailpipe emissions are only one factor in considering a vehicle's life cycle emissions gasoline and electricity fuel pathways also have upstream emissions to consider, which include extracting, refining, producing, and transporting the fuel. All-electric vehicles, plug-in hybrid electric vehicles (PHEVs), and hybrid electric vehicles (HEVs) typically produce lower tailpipe emissions than conventional vehicles do, and zero tailpipe emissions when running only on electricity.
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