Alternatively fueled vehicles

Risks and myths

First published in Law Enforcement Technology, September 2003

It’s a clear sunny day, and you’re called to a severe traffic accident. First on the scene, you notice that despite major damage and an apparent fuel leak, you don’t see fire. But as you approach the vehicle, you recognize a small symbol that means the vehicle can use ethanol as well as gasoline for fuel. You:

a. Continue your approach. Hardly anyone uses anything but gasoline.

b. Continue your approach, but use caution. You’re not sure how ethanol acts even though you know it’s different from gasoline.

c. Return to your cruiser and call for the fire department. You know ethanol burns bright blue, so if there’s a fire, you can’t see it on this clear day.

The answer is c. Ethanol is one of several alternative fuels that, because of their cleaner combustion, are gaining popularity among environmentally conscious individuals and states. However future oriented this is, it presents new challenges to first responders at emergencies involving alternative fuels.

First, although alternative fuel vehicles (AFVs) may be marked as such, they aren’t required to be placarded, as are commercial vehicles transporting hazardous materials. Second, alternative fuels react differently to fire, air, and impact on their storage tanks than traditional petroleum-based fuels. Some fuels pose greater hazards than gasoline; others are much safer, and manufacturers are engineering safety features into AFVs to ensure a lower likelihood of leaks, fires, and explosions.

The key, says Dr. James Onder, Highway Safety Specialist with the National Highway Transportation Safety Administration (NHTSA), is for law enforcement officers to respond to alternative fuels not as hazardous materials or firefighting specialists, but as first responders who must secure the scene for themselves, passengers, the other responders, and bystanders. “You can’t avoid helping people when their electric vehicle is submerged in water,” he says.

The U.S. Department of Energy (DOE) classifies seven alternative fuels either in use or under development for future use: biodiesel, electricity, ethanol and methanol, hydrogen, and natural gas, including propane.

Biodiesel

Biodiesel, according to DOE’s website, “is a cleaner-burning diesel replacement fuel made from natural, renewable sources such as new and used vegetable oils and animal fats.” It can be used in its pure state or blended with petroleum diesel. The American Biofuels Association estimates that biodiesel could eventually account for about 8 percent of highway diesel consumption, especially in bus fleets and heavy duty trucks.

Jenna Higgins, spokesperson for the National Biodiesel Board (NBB), says “Biodiesel is basically vegetable oil without the glycerin.” A nontoxic material, biodiesel doesn’t irritate the skin and presents no inhalation danger, though it can irritate eyes. Only when it’s heated to a gaseous state can biodiesel vapors “irritate the mucous membranes and cause irritation, dizziness, and nausea,” reads a sample material safety data sheet (MSDS) from the NBB.

As for fire danger, biodiesel’s flash point, or the temperature at which it ignites when exposed to flame, “increases as the percentage of biodiesel increases,” reads DOE’s website. “Therefore pure biodiesel or blends of biodiesel with petroleum diesel is safer to store, handle, and use than conventional diesel fuel.”

Higgins says responders to incidents involving pure biodiesel (B100) need not treat it as any more hazardous than vegetable oil. However, she adds, since biodiesel is most often blended with petroleum diesel, first responders should treat such incidents like any other diesel spill or fire.

Electricity

Electricity is already used in gasoline-electric hybrid vehicles like the Toyota Prius and the Honda Insight. (See Law Enforcement Technology, September 2002, “The Dangers of Hybrids” for a more detailed explanation of hybrid issues.) Vehicles can also run solely on electricity, recharging their batteries either from charging stations or fuel cells (see section on hydrogen). In electric vehicles (EVs), a high-voltage battery runs only the engine components; other systems like the headlights and radio run on a conventional 12-volt battery.

The DOE claims, “More than 4,000 electric vehicles are operating throughout the United States (with the largest number in California and the western United States).” And, although fuel cell vehicles are yet under development, look for them within the next few years. “To date, [EVs’ safety record findings] are positive and have shown that several EV features maximize safety,” reads DOE’s website. It gives the examples of EVs’ lower center of gravity, which reduces the chance of rollovers, and their decreased potential for major fires or explosions.

However, first responders should be aware of other dangers. For instance, battery smoke is extremely toxic. Anyone entering a scene with visible battery fire or smoke must wear a self-contained breathing apparatus (SCBA). Also, EV batteries store between 200-400 volts, and “Electrolytes in the battery may cause chemical burns,” according to DOE. Even though EVs like the Prius were designed with safety features like electrolyte-absorbing material in order to prevent leaks, says Ron Shaw, founder of Extrication.com, a severe crash may have compromised other safety features. Shaw says that because batteries come in a variety of materials, it’s best to be familiar with all batteries’ material safety data sheets (MSDS) that document their hazards. With obvious hazards like fires, leaks, and electrical arcing, first responders without proper equipment should not approach.

Ethanol/Methanol

DOE’s website says ethanol is “an alcohol-based alternative fuel produced by fermenting and distilling starch crops that have been converted into simple sugars.” Ethanol can be blended with gasoline in low or high concentrations, or used in its pure form. Additionally, according to DOE, ethanol can be combined with regular Number 2 diesel to create “E-diesel.”

DOE says ethanol “is already penetrating the transportation market as gasohol [ethanol blended with gasoline at 5 to 10 percent concentration].... Higher blends of ethanol, specifically E85, are becoming increasingly available in certain regions of the United States. Nearly 150 stations are now operating in more than 20 states in the Midwest and Rocky Mountains.” And, while manufacturers, are no longer making flexible fuel vehicles (FFVs) that take methanol or methanol blends (although some still exist), hydrogen can be extracted from methanol, so DOE speculates that pure methanol could be used to provide hydrogen to fuel-cell vehicles.

The hard-to-see, bright blue color of a m/ethanol fire is only one potential hazard. Although alcohols, in their pure form or at high concentrations, are less volatile than gasoline, other m/ethanol safety issues include corrosiveness to rubber, plastic, and some metals such as aluminum and zinc (although methanol is much more corrosive than ethanol). The adverse effects on rubber gaskets and other fuel system components can lead to leaks.

Additionally, methanol (but not ethanol), according to Federal Transit Administration (FTA) information, is a neurotoxin; “excessive exposure can cause blindness and death.” In general, says Shaw, if no leaks are visible, the first responder can proceed as if the vehicle were a conventional gasoline car.

Hydrogen

In the near future, hydrogen mixed with oxygen from ambient air will power fuel cell vehicles (FCVs). A fuel cell, according to the soon-to-be-released Emergency Response Guide for Light Duty Fuel Cell Vehicles (California Fuel Cell Partnership/CaFCP), is “an electrochemical device in which the energy of a chemical reaction is converted directly into electricity. Unlike an electric cell or battery, a fuel cell does not run down or require recharging; it operates as long as the fuel and an oxidizer are supplied continuously from outside the cell.

“Today, these ... vehicles have many built-in safeguards, which make them equal to or safer than internal combustion vehicles today,” reads the guide. Responders still must be aware of the differences between the two types of vehicles: “(1) hydrogen high (and low) pressure systems and (2) high (and low) voltage systems.” A FCV’s fuel supply can be stored as compressed hydrogen, liquid (cryogenic) hydrogen, and in some cases, methanol used to extract hydrogen. With each storage method comes safety issues to consider, so emergency responders (especially in California) who expect to work with FCVs should refer to CaFCP’s guide.

Jesse Schneider, co-chairman and lead of the CaFCP’s safety team and senior mechanical engineer with DaimlerChrysler’s fuel cell project, says the guide is “a text with diagrams of each of the CaFCP manufacturing partners’ FCVs.” Although the guide won’t be available to the general public because of the diagrams’ confidentiality, Schneider says the text portion will probably be available online.

Website fuelcells.org cites a Ford Motor Company safety assessment of hydrogen fuel cell vehicles: “In retrospect, the Hindenburg was a high risk venture.... The hydrogen would be stored [not in flimsy cloth bags but] in one or more fiber wrapped composite tanks that could survive 50-mph head-on collisions, engulfment by a diesel fuel fire, and pressures at least 2.25 times design pressure without rupture.... In effect, there is no comparison between the safety aspects of the Hindenburg and those of a fuel cell vehicle.

“In a collision in open spaces, a safety-engineered hydrogen FCV should have less potential hazard than either a natural gas vehicle or a gasoline vehicle due to four factors.

“First, carbon fiber wrapped composite storage tanks (the leading high pressure storage tank material due to its low weight) are able to withstand greater impacts than the vehicle itself without rupture, thereby minimizing the risks of a large release of hydrogen as a result of a collision.

“Second, hydrogen, if released, disperses much faster than gasoline due to much greater buoyancy, reducing the risks of a post-collision fire.

“Third, the FCV will carry 60% less total energy than a gasoline or natural gas vehicle, resulting in less potential hazard should it ignite.

“Finally, the design recommended here includes an inertially activated switch in each FCV that, in the event of a collision, will simultaneously shut off the flow of hydrogen ... and will cut electrical power from the battery.” Other engineering controls, reads the CaFCP guide, include leakage sensors, a pressure or thermal release device that allows the hydrogen to vent away from fire, and in some FCVs, an emergency shut-off button.

Hydrogen is also mixed with methane to make hythane, which is used in some fleet vehicles in the U.S. and Canada. Hydrogen Components, Inc., which patented hythane, has been able to convert light-duty fleet vehicles’ engines to use hythane.

In terms of hythane’s hazards, Lynch says both hydrogen and methane are virtually identical in terms of emergency response needs. Both are flammable in air at concentrations of four percent; Lynch points out that the addition of hydrogen makes methane combustion easier, but the addition of methane makes hydrogen combustion more difficult. Hydrogen is nontoxic, methane slightly toxic. And although methane leaks are easily detectable from odorants added to the gas, hydrogen has no likewise additives.

In short, says Lynch, first responders must treat hythane incidents like they would any other natural gas incident, for example standing off at a distance of 50 feet per National Fire Protection Association guidelines.

Natural gas

Compressed natural gas (CNG), liquefied natural gas (LNG), and liquefied petroleum gas (LPG), or propane, are all in use currently. DOE estimates that there are over 75,000 natural gas-fueled vehicles in the U.S. Further, “One out of every five new transit buses in the United States is powered by natural gas.”

Natural gas in and of itself is considered relatively safe. DOE’s website says “Natural gas is neither corrosive nor toxic, its ignition temperature is high, it is lighter than air, and it has a narrow flammability range, making it an inherently safe fuel compared to other fuel sources. Natural gas contains a distinctive odorant (mercaptan) which allows natural gas to be detected at 0.5% concentration in air, well below levels which can cause drowsiness due to inhalation and well below the weakest concentration which can support combustion.”

Being able to smell natural gas at such low concentrations may make it difficult to figure out how much is present, but Shaw doesn’t see a reason for law enforcement first responders to carry combustible gas indicators. “Pressurized gas will form a visible plume,” he says, that should be enough to tell officers not to get too close.

DOE says that “Pressurized [CNG] tanks have been designed to withstand severe impact, high external temperatures, and automotive environmental exposure; they are as safe as gasoline tanks.” Onder agrees, saying that CNG tanks have been tested against high-powered rifles at point-blank range and not failed.

A brochure released by NHTSA does add that “The greatest hazard of [compromised] LPG containers exposed to fire or extreme heat is BLEVE (boiling liquid/expanding vapor explosion).... the fuel converts from a liquid to a vapor that could rapidly produce a sizeable vapor cloud which may ignite and flash back to the fuel source.” However, Shaw believes compromised LPG containers will “vent” enough of their contents not to reach the point of BLEVE. “The liquid has to boil,” he says. “A small tank [like the ones on board vehicles] will probably vent its material long before the boiling point.” A leaking or fiery fuel container does require response with appropriate breathing equipment.

LNG’s biggest threat, according to DOE, is that “[it] is cooled cryogenically to -260°F. At this temperature, bodily contact with the liquid fuel, cold metals, or cold gas can cause cryogenic burns (frostbite).”

Understanding what alternative fuels are, how they’re used, and what to expect from them is no different from understanding any other hazardous material and your role in a haz-mat incident. An example is the California Highway Patrol, which provides regular first responder training to its officers as well as a critical incident response manual that has sections dealing with isolation distances, evacuation procedures, explosions, and leaks for each type of alternative fuel.“Clearly the responder wants to know how to address issues with these vehicles prior to encountering them on the street at a crash,” says Shaw. “The only way to do this is with is with proper education and [standard operating procedures and guidelines] giving them guidance for situations which may involve spills, fire, first aid ... and extrication.”