E85 (85% ethanol, 15% gasoline) is considered an alternative fuel under the Energy Policy Act of 1992 (EPAct). It is used to fuel E85-capable flex fuel cars, which are available in a variety of models from U.S. and foreign automakers.

The 15% gasoline content in E85 enables flex fuel cars to operate normally under cold conditions; fueling a cars with pure ethanol (E100) creates problems during cold-weather operation. Ethanol can also be mixed with gasoline in lower-level blends, which provide many benefits but are not considered EPAct alternative fuels.

Chevrolet Silverado E85 Handyman Ethanol at SEMA 2006

Other than lower gas mileage, motorists will see little difference when using E85 versus gasoline. E85 has about 27% less energy per gallon than gasoline. However, E85 is typically priced lower than gasoline, so that cost per mile is comparable

E85 Stations

As of 2008, more than 1,600 U.S. fueling stations offered E85 to the more than 7 million flex fuel cars on U.S. roadways. Stations are more common in the corn belt (Minnesota, Iowa, Illinois) but are spreading throughout the country. In fact, E85 is now offered in more than 40 states

E85 Emissions

Although it is an alternative fuel, E85 emits regulated pollutants, toxic chemicals, and greenhouse gases. These emissions are primarily released by fuel evaporation or combustion. However, these emissions are generally reduced compared to those of gasoline. The following section describes the different types of emissions and compares those of E85 to those of gasolin

Evaporative Emissions

Evaporative emissions from E85 and gasoline cars enter the air through permeation, fuel tank venting, and fuel or vapor leaks.

2009 Flex-Fuel HUMMER H2

Permeation vapors, which are released through fuel-line materials, are more of an issue for regular gasoline than E85, though it does occur with E85. Fuel tank venting, which occurs when fumes escape the tank during refueling, is controlled by onboard refueling vapor recovery devices installed in all cars produced since model year (MY) 2000. Evaporative emissions, which are leaks, are becoming less prevalent since new leak-resistant materials and fittings are constantly improvin

Tailpipe Emissions

Tailpipe emissions are the by-products of fuel burning in a car’s engine and emitted from its exhaust system. Major tailpipe emissions include hydrocarbons, oxides of nitrogen (NO_x), carbon monoxide (CO) and carbon dioxide (CO2). 

When the program tested for regulated tailpipe emissions, it found that E85 resulted in higher CO emissions and lower NOx emissions. The results for non-methane hydrocarbon (NMHC) emissions were mixed but reduced in a majority of the rounds (including the one statistically significant one). Test results for total hydrocarbons (THC) were mixed to the point where no relationship could be discerned

Speciated Hydrocarbons

The mixed results of THC were clarified when the testing team separated (speciated) the hydrocarbons into groups. The test results for each type were statistically significant. E85 led to an increase in formaldehyde and acetaldehyde but emitted less 1,3-butadiene and benzene than RFG. When the hydrocarbons were weighted according to toxicity, total potency-weighted toxics (PWT) were significantly reduced in cars powered by E85.

When pollutants leading to ozone (CO and NO_x) were accounted for and weighted, the ozone-forming potential (OFP) of E85 emissions was greater than that of RFG emissions. This overrides the point that the specific reactivity (SR) of a given amount of non-methane organic gases is less for RFG than for E85.

Low-level ethanol blends are sold in every state. In fact, nearly half of U.S. gasoline now contains up to 10% ethanol (E10) to boost octane or meet air quality requirements.

The Clean Air Act Amendment of 1990 (and subsequent laws) mandated the sale of oxygenated fuels in areas with unhealthy levels of carbon monoxide. This kicked off the modern U.S. ethanol industry growth. Problems with groundwater contamination from the use of methyl tertiary butyl ether (MTBE)—the only other available oxygenate and principal octane booster—accelerated the use of ethanol in low-level blends.

The U.S. Environmental Protection Agency classifies low-level ethanol blends as "substantially similar" to gasoline, meaning they can be used legally in any gasoline-powered vehicle. Auto manufacturers also approve the use of low-level blends because they work well in gasoline engines and create no noticeable difference in vehicle performance. Low-level blends do not qualify as alternative fuels under the Energy Policy Act of 1992 (EPAct).
 

Fuel cell cars, powered by hydrogen, have the potential to revolutionize our transportation system. They are more efficient than conventional internal combustion engine vehicles and produce no harmful tailpipe exhaust – their only emission is water. Fuel cell vehicles and the hydrogen infrastructure to fuel them are in an early stage of development. 

What is a Fuel Cell Car?

Like electric cars, fuel cell cars use electricity to power motors located near the vehicle’s wheels. In contrast to electric vehicles, fuel cell vehicles produce their primary electricity using a fuel cell. The fuel cell is powered by filling the fuel tank with hydrogen.

The most common type of fuel cell for vehicle applications is the polymer electrolyte membrane (PEM) fuel cell. In a PEM fuel cell, an electrolyte membrane is sandwiched between a positive electrode (cathode) and a negative electrode (anode). Hydrogen is introduced to the anode and oxygen to the cathode. The hydrogen molecules travel through the membrane to the cathode but not before the membrane strips the electrons off the hydrogen molecules.

Honda FCX Hydrogen Fuel Cell Vehicle

The electrons are forced to travel through an external circuit to recombine with the hydrogen ions on the cathode side, where the hydrogen ions, electrons, and oxygen molecules combine to form water. The flow of electrons through the external circuit forms the electrical current needed to power a vehicle. 

Fuel cell cars can be fueled with pure hydrogen gas stored directly on the vehicle or extracted from a secondary fuel – such as methanol, ethanol, or natural gas – that carries hydrogen. These secondary fuels must first be converted into hydrogen gas by an onboard device called a reformer. Fuel cell cars fueled with pure hydrogen emit no pollutants, only water and heat. Vehicles that use secondary fuels and a reformer produce only small amounts of air pollutants.

This Hydrogen, Fuel Cells and Infrastructure Technologies Program animation shows how polymer electrolyte membrane (PEM) fuel cells work.

Fuel cell vehicles can be equipped with other advanced technologies to increase efficiency, such as regenerative braking systems, which capture the energy lost during braking and store it in a large battery.

Fuel Cell Vehicle and Infrastructure Development

Because fuel cell cars require a completely new vehicle propulsion system and new fueling infrastructure, many deployment issues can only be addressed by integrating and evaluating the components in complete systems. The U.S. Department of Energy (DOE) is developing and testing complete system solutions that address all elements of infrastructure and vehicle technology, validating integrated hydrogen and fuel cell technologies for transportation, infrastructure, and electric generation in a systems context under real-world operating conditions.

Schematic of a fuel cell vehicle

Hydrogen can be produced from diverse domestic resources, with the potential for near-zero greenhouse gas emissions. Once produced, it generates power without exhaust emissions in fuel cells. It holds promise for economic growth in both the stationary and transportation energy sectors.

Increasing Energy Security

The United States imports more than 60% of its petroleum, two-thirds of which is used to fuel vehicles in the form of gasoline and diesel. The demand for petroleum imports is increasing. With much of the worldwide petroleum reserves located in politically volatile countries, the United States is vulnerable to supply disruptions.

No matter how efficient conventional vehicles become, some of the gasoline and diesel needed to fuel them will need to be imported. Hydrogen can be produced domestically from resources such as natural gas, coal, solar energy, wind, biomass, and nuclear energy. Used to power highly efficient fuel cell vehicles, hydrogen holds the promise of an end to the nation’s "addiction to oil." View President George W. Bush’s January 2006 State of the Union Speech related to this topic.

Protecting Public Health and the Environment

About half of the U.S. population lives in areas where air pollution levels are high enough to negatively impact public health or the environment. Emissions from gasoline and diesel vehicles—such as nitrogen oxides, hydrocarbons, and particulate matter – are a major source of this pollution. Hydrogen-powered fuel cell vehicles emit none of these harmful substances. Their only emission is H₂O – water.

The environmental and health benefits are even greater when hydrogen is produced from low- or zero-emission sources such as solar, wind, and nuclear energy and fossil fuels with advanced emission controls and carbon sequestration. Because the transportation sector accounts for about one third of U.S. carbon dioxide emissions, which contribute to climate change, using these sources to produce hydrogen for transportation can slash greenhouse gas emissions. Learn more about Hydrogen Emissions. 

Fueling the Economy

The potential market for hydrogen vehicles is enormous, but the opportunities don’t stop there. Hydrogen and fuel cells can power stationary applications such as backup generators, and grid electricity production. They can also compensate for the intermittency of renewable energy production. For example, wind generators can produce hydrogen when winds are high and electricity demand is low (learn more by going to the National Renewable Energy Laboratory’s Wind to Hydrogen page). When the wind slackens or electricity demand peaks, fuel cells consume the stored hydrogen to provide grid electricity.

The potential market for hydrogen vehicles is enormous, but the opportunities don’t stop there. Hydrogen and fuel cells can power stationary applications such as backup generators, and grid electricity production. They can also compensate for the intermittency of renewable energy production. For example, wind generators can produce hydrogen when winds are high and electricity demand is low (learn more by going to the National Renewable Energy Laboratory’s Wind to Hydrogen page). When the wind slackens or electricity demand peaks, fuel cells consume the stored hydrogen to provide grid electricity