Frequently Asked Questions (FAQs) - General

What is an Alternative Fuel?

A fuel that can be used instead of conventional transportation fuels (i.e., gasoline and diesel). Alternative fuels include natural gas (compressed and liquefied), propane (LPG), hydrogen, electricity, and more.

What are Alternative Fuel Vehicles (AFVs)?

AFVs are vehicles with engines that operate on an alternative fuel.

What is Smog?

Smog is the term generally used to describe air pollution. Specifically, smog is derived mainly from vehicles and industry exhaust, and requires specific meteorological conditions (i.e., stagnant air, lots of sunlight, strong inversion layer) to facilitate the chemical reactions which create smog. NOx, CO and reactive hydrocarbons are key ingredients of smog, bringing along their adverse health effects. The individual pollutants that contribute to smog include:

• Carbon Dioxide (CO₂) - A nonpoisonous gas that is a normal ingredient of the air we breathe. CO₂ is a greenhouse gas that traps the earth's heat, contributing to global climate change. CO₂ is a product of fossil fuel combustion. EVs have zero tailpipe CO₂ emissions.

• Carbon Monoxide (CO) - A main ingredient in smog. This colorless, odorless and tasteless gas is slightly lighter than air. It is poisonous if inhaled since easily inhibits oxygen transport through the body (by combining with blood hemoglobin to prevent oxygen transfer). CO is produced by incomplete combustion of fossil fuels. NGVs emit extremely low CO levels (about 70 percent lower than a comparable gasoline vehicle). EVs have zero tailpipe CO emissions.

• Evaporative Emissions - In addition to tailpipe (exhaust) emissions, where combustion products are released into the atmosphere, there is another major source of pollution emission, called evaporative emissions. Evaporative hydrocarbon emissions are present with petroleum-based liquid fuels. There are evaporative emissions from a vehicle&rsquo s fuel system, during fuel transfers at local gasoline stations and during the delivery of fuel to underground storage tanks. NGVs have a closed fuel system, thus there are essentially zero evaporative emissions. This characteristic allows NGVs to qualify as Inherently Low Emitting Vehicles (ILEVs), a federal designation for an " extra clean" vehicle (and status to ride in carpool lanes with only one vehicle occupant). EVs have no evaporative emissions and therefore also qualify as ILEVs.

• Greenhouse Gases - Natural gas contains less carbon than any other fossil fuel per unit of energy. This means natural gas produces lower CO₂ emissions per vehicle mile traveled. While NGVs do emit methane, a greenhouse gas, the small increase in methane emissions would be more than offset by a considerable reduction in CO₂ emissions, compared to other fuels. EVs have zero tailpipe greenhouse gas emissions.

• Hydrocarbons - Hydrocarbon (HC) emissions are carcinogenic and a major ingredient of smog. HC emissions are caused by incomplete combustion, and fuel evaporation from fuel system leaks and during refueling and transport. NGVs generally reduce non-methane HC emissions, the reactive emissions that react to create smog, by about 50 percent. EVs have zero tailpipe HC emissions.

• Oxides of Nitrogen (NOx) - Oxides of Nitrogen (NOx) include nitrogen monoxide (NO), nitrogen dioxide (NO₂) and other nitrogen oxides. NOx is to blame for the brown haze of polluted cities. NOx is created during the combustion process, and is a major contributor to smog formation and acid deposition.

• Particulates - Aerosol particles such as dust, smoke or smog found in air emissions. In addition to degrading visibility, particulates often carry toxic substances which are deposited deep in the respiratory system and lungs, causing long term health problems. Particulates are generated from road dust, the smoke from fuel combustion and even vehicle tire rubber wear. Diesel-fueled vehicles have significantly higher PM emissions than gasoline-fueled vehicles and these diesel emissions are a serious public health concern. NGVs provide significant PM reductions from diesel vehicles (as high as 98 percent, depending on technology).

What is Ozone?

Ozone (O₃) at ground level is the component of smog that causes the greatest problem in polluted cities. This ground level ozone causes several health problems including irritation of the respiratory tract, difficult breathing and headaches. Note that stratospheric ozone (i.e., the upper atmosphere or " ozone layer") occurs naturally and protects earth from deadly ultraviolet radiation from the sun. Children are particularly vulnerable to ozone's harmful effects.