A Collection of Thoughts About

Hydrogen-Fueled Vehicles,

Hydrogen Safety


Hydrogen Hype

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“The squeaky wheel gets the grease.”  That is why the hydrogen hype bandwagon gets glowing headlines these days. 


Writers, reporters and others in the media recognize the need to cover the latest trends and issues, such as alternative fuels, global warming and energy dependency.  It takes a thorough scientific background to understand these things in depth and explain them in the media.  This background is often lacking, leading to inaccurate or incomplete coverage of technical issues, such as the use of hydrogen as automotive fuel. 


Hydrogen has been inaccurately portrayed as the solution to the problems of energy dependence and greenhouse gas emissions.  Well, someone once said, “The person who presents a simple solution to a problem usually doesn’t understand the problem.” 


Then, there are politicians who jump onto the current bandwagon and make pretty speeches filled with words such as hybrid or hydrogen or fuel cell or ethanol, just to let folks know they are up-to-date on the latest darling fad. 


I would dearly love for technology to solve our problems of energy dependency, air pollution and global warming; however, I am deeply troubled when I see amateurs, scientifically-challenged writers and bandwagon-jumpers steering national policy into costly and hopelessly dead-ended detours. 


I am also deeply troubled that voices of common-sense reality and practical experience are not being heard.  You should be troubled, too, over the seriously lopsided view of hydrogen that we see in books, newspapers and television.  Why don’t we hear about the dark side from scientists and emergency responders? 


What I present here does not amount to wild-eyed hysteria; for the most part the information is freely available on the Internet from respected agencies and institutions.  I’m puzzled why this readily available material is not being presented to the public and to policy-makers.  Because the media is failing to do so, my goal is to tell the rest of the story. 


A friend of mine suggested that I start out this piece by talking about the plus side.  I like his idea, but for the most part we have already heard it from other sources.  That is beyond the intent of this article.  It should be sufficient for me to say that I will enthusiastically support any good, common-sense, technically sound scientific innovations that will get us out of this mess of energy dependence, air pollution and global warming. 


Before we go any further, all of us need to understand one thing:  Here on planet earth, hydrogen is not a source of energy. 


Certainly, our oceans are filled with hydrogen oxide.  There is as much energy content in the hydrogen found in water as there is in ashes taken from a wood stove. 


It requires large amounts of energy to obtain hydrogen fuel from water.  When it is finally put to use, only a fraction of that energy is available.  Fuel cells can only extract 40 to 70-percent of the energy in hydrogen.  In other words, in this hydrogen fuel chain, anywhere from a quarter to more than half of the energy is lost when the hydrogen is consumed. 


In this hydrogen fuel chain an enormous pile of energy deficits add up:  The energy required for compression; for liquefaction (if done); for transportation; and the waste from evaporation, leakage losses, and the like. 


Now that we’ve put that to rest, let’s get on to the real reason for this article.


When it comes to talking about hydrogen-fueled transportation, I’m dismayed over the almost-complete lack of skepticism on the part of the media—unbalanced reporting, if you will.  Writers have a responsibility to be wary and, along with the hype, weigh the negatives that are, for the most part, overlooked.  I applaud authors who do not jump onto the hydrogen bandwagon. 


To illustrate the typical lack of media skepticism, I once listened to a National Public Radio program about hydrogen fuel in which the host interviewed a proponent of it.  When the aspect of safety arose, the advocate dismissed it with a glib “Hydrogen is no more dangerous than gasoline.” 


Let me emphasize that he said, “… no more dangerous than gasoline…,  I challenge that assertion.


The host let it rest at that and allowed a brash irresponsible statement to stand, unchallenged.  The issue of safety is one that deserves hours-long discussions, not canned pat answers.  The California Fuel Cell Partnership (CaFCP) Emergency Response Guide formerly posted at…




was 79-pages long, hardly something that can be flipped off with an irresponsible one-liner!  One is led to assume that neither person on that program knew much, if anything, about the properties of hydrogen.  The dramatic differences in warning properties and flame characteristics make hydrogen much more dangerous than gasoline. 


Note:  Even though the California Fuel Cell Partnership (CaFCP) Emergency Response Guide, is no longer available on the California Fuel Cell Partnership Web site, you can still obtain an archived copy, here: 





Hydrogen’s unique properties, along with its hazards—both chemical and physical—present engineering challenges that are complex and expensive to solve.  What follows here is the down side.  Much of it can be verified by consulting the CaFCP Emergency Response Guide and the U.S. Department of Energy’s free training course, Hydrogen Safety for First Responders.  I heartily recommend the DoE’s course; however, I feel it is a much too glowing and untempered endorsement of hydrogen power. 





Hydrogen’s flammable and explosive properties are much worse than those of common fuels. 

It has a very broad explosive range of 4-percent to 75-percent concentration in air.  Furthermore, its ignition energy is an order of magnitude less than that of the common fuels.  At 29-percent concentration, the energy required to initiate combustion is 0.02 milliJoules (mJ) for H2 compared to 0.24 mJ for gasoline vapor or 0.29 mJ for natural gas. 


In laymen’s terms, the faintest spark will cause hydrogen to burn or explode over a very wide range of concentrations.  Refer to the CaFCP Emergency Response Guide, page 1-7 (p. 18 in Adobe Reader).  Hydrogen can generate its own electrostatic charge merely by flowing or agitation, heightening the risk of accidental ignition.



Hydrogen cannot be detected by human senses. 

Hydrogen can be present at explosive or asphyxiating levels without anyone knowing it. 


Conventional fuels, however, have obvious warning properties; the sight or smell of spilled gasoline and the odor of leaked fuel gases give plenty of warning of danger. 


In a nutshell, today’s fuels have warning properties; hydrogen does not.  (Hydrogen is no more dangerous than gasoline?  I challenge that assertion.)


At this time there is no known odorant that can be added to hydrogen.  Even if there were one, it could not be used because it would contaminate fuel cells. 


If today’s conventional vehicles are involved in an accident, anyone with a lick of common sense can see or smell if extra caution is needed in the event of a fuel system rupture; that is not so with hydrogen.



Hydrogen fires are invisible in daylight. 

Hydrocarbon fires are visible because of incandescent carbon.  Hydrogen contains no carbon!  Therefore, an emergency responder or would-be Good Samaritan could unknowingly walk into a hydrogen fire and be horribly burned.  


For this reason, hydrogen refueling stations require flame detectors, hydrogen fueled vehicles (HFVs), likewise.  The family garage?  Probably the same.  More expense.  (Hydrogen is no more dangerous than gasoline?  I challenge that assertion.)


(Interestingly, natural fiber brooms are sometimes recommended as hydrogen fire detectors; first responders can use them to probe an accident scene.  The broom will burst into visible flame if thrust into an invisible fire.)



Hydrogen flames have very low radiant energy. 

You might be tempted to say, “So what?”  Well, radiant heat warns people to stay away if they unknowingly approach a hydrocarbon fire.  On the other hand, it is entirely possible to get dangerously close to a hydrogen conflagration and yet not know it until too late.  (Hydrogen is no more dangerous than gasoline?  I challenge that assertion.)



Hydrogen must be transported and stored as either an extremely high pressure gas or as a cryogenic liquid. 

Either way presents a whole new and unfamiliar set of hazards and energy-robbing solutions. 


Anyone with the faintest amount of industrial training knows that if a 2,000 psi compressed gas cylinder accidentally tips over and the valve is broken off, it will take off like a rocket and reach sufficient velocity to slam itself through cinder-block walls.  That kind of pressure is frightening enough, but hydrogen is stored at pressures of 5,000 psi to 10,000 psi; and, 12,500 is on the horizon. 


I once worked with 400-psi, 3,000-psi and 4,500-psi air systems.  In cases of leaks or blown seals, even those on relatively low pressure systems, the noise in itself could be terrifying.  Do you have any idea what 12,500-psi would be like?


An automotive gasoline tank is a simple thing stamped out of lightweight sheet metal at a cost of a few dollars.  It only needs to contain the unpressurized static head of a few inches of low density liquid. 


On the other hand, the tanks for HFVs are expensive things constructed of graphite fiber-wrapped aluminum; and, they need to be equipped with costly fail-safe shutoff valves and pressure relief devices that will open at elevated temperatures. 


It’s scary to think of an HFV accident if fire should break out.  The relief valve will automatically pop open, adding more fuel to the fire.  Granted, the vent goes out the top of the vehicle, but what if the car rolled over onto its top?  The vented hydrogen will rise right up through the fire.  Flames go up, leaked gasoline runs the other way; down.  



Hydrogen is the lightest element. 

By weight, it contains a remarkable amount of energy; but it is a glutton for space.  Honda’s 2003 fuel cell vehicle (FCV), the FCX, has a fuel storage volume of 156.6 liters—a whopping 41 gallons—and its cruising range is a measly 220 miles.  At this time passenger cars can store up to 5 kg of H2 at pressures up to 10,000 psi, but it is estimated that 13 kg will be needed to achieve a 300 mile driving range.  With all the space being taken up by fuel tanks, will there be any room left for passengers? 




The problem of volume becomes especially significant in transport and distribution.  A steel tube truck transport trailer will have a gross weight of 36,000 kg (39 tons), yet it will only haul 237-kilograms (521-pounds) of hydrogen!  In other words, a 39-ton truck load will only be sufficient to fill up eighteen automobiles equipped with 13-kilogram tanks!  


Let’s say the average HFV driver tops off when the tank gets down to half-full.  That translates to one truck-transport delivery for every 36 automobiles rolling into the refueling station. 


Unless there is some flaw in my logic, in an HFV-world there would be one hydrogen tanker truck on the highway for every 36 HFVs.  It certainly does not sound like an efficient system to me.  Those trucks probably get six to ten miles per gallon. 




Pipelines are not the answer, at least not yet.  The infrastructure does not exist and it probably will not, unless HFVs become commonplace.  Presently in the U.S., there are only about 700 miles of hydrogen pipeline, compared to more than one million miles for natural gas.


The transport problem may be solved by production at or near the dispensing stations; or, by liquefying the product before hauling.  Liquefied hydrogen, however, presents another set of problems and inefficiencies.  According to the US Department of Transportation, the liquefaction process is very energy intensive, requiring 30 to 40-percent of hydrogen’s heating value!  (It seems like every way we look at hydrogen, we find yet another energy thief.)




That fairly well leaves one choice: distributed production at the dispensing stations.  This makes it difficult, if not impossible, to achieve any economy of scale.  No matter whether production is via natural gas reforming or electrolysis, every one of those facilities will be an expensive complex complete with noisy high pressure compressors that are prone to wearing out and leaking. 


Furthermore, it takes a very large amount of energy to compress gas, especially to 10,000 psi.  Present technology does not attempt to recover this stored energy and it is forever lost when pressure is released as the fuel is consumed. 


Dispensing compressed H2 creates yet another problem.  The excellent on-line description of the CaFCP facilities points out that, “When gas is pushed into a volume and is pressurized, the gas temperatures rise within that volume.  Because of material design and safety limits required by the manufacturers, the tank must never be allowed to heat up to levels determined unsafe.” 


In other words, the simple process of filling compressed H2 tanks could cause dangerous overheating.  Granted, the problem can be engineered away, but it is still another trap waiting to be sprung.  




If large scale cryogenic transport should become reality, it will present yet another set of hazards.  At atmospheric pressure, hydrogen is liquid at -423° F.  Unless costly and energy-consuming refrigeration systems are employed to keep it this cold, the liquid gradually boils away (wasteful). 


Any accidental release will present a serious frostbite hazard and the danger of explosion, should it occur on the highway.  To explain:  Liquid hydrogen’s extremely low temperature can cause air to turn into a liquid.  If this liquid air drips onto tar or asphalt, an explosive mixture may result.  Even a small amount of energy could ignite such a combination.


Yet another danger of hydrogen is its rapid phase change from liquid to gas, creating the potential for pressure explosions.


“Since hydrogen is likely to be made from combustion of fossil fuels, it produces less CO2 and other greenhouse gases to burn the fossil fuel directly.”




Hydrogen, the smallest atom, is very difficult to contain. 

Anyone with a touch of plumbing experience knows it is not an easy job keeping 80 to 100 psi water pipes from leaking.  Imagine, then, how difficult it is to keep minuscule hydrogen molecules from escaping when squeezed into every crack and crevice by extreme pressures of 5,000 to 10,000 psi. 


Every home garage, service facility or dispensing station will need to be equipped with explosion-proof electrical gear, flame detectors, explosive gas monitors and dependable ventilation systems that never shut down.  These things are absolute musts. 


The Diamler Chrysler Long Beach Service facility is equipped with ventilation exhaust to keep H2 below one-percent and nine hydrogen detectors to automatically detect one-percent H2..  Granted, present safety measures may eventually be relaxed with added experience, but at this time the ceilings at some service facilities are even coated with static-suppressing paint.




Road vibrations and fender-benders are bound to cause H2 leaks in HFVs.  Granted, they are equipped with collision sensors and on-board leak detection systems that will isolate the fuel tank; but it would seem wise to also equip home garages with every safety device available. 


Most likely, city ordinances, fire codes and insurance companies will demand them if HFVs become commonplace.  All of this will add to the expense of owning an HFV. 


Personally, I am not afraid of hydrogen.

I have used hydrogen in the work place.  I am not afraid of it.  It was my job to add it to nuclear pressurized water reactors where it scavenges damaging oxygen out of the coolant.  I routinely monitored hydrogen delivery to an electrical generator and replaced the gas cylinders whenever needed. 


Many are the times when I witnessed a co-worker breathe hydrogen from a plastic bag, just to make his voice sound silly.  It was a foolish stunt, but it caused him no harm.  The main point to remember is that industrial workers have far more safety training than the average HFV driver is likely to ever receive. 


Furthermore, industrial workers who do not pack the necessary mental gear are relegated to pushing a broom; yet, any licensed driver is likely to be allowed to get behind the wheel of an HFV and park it in any enclosed space of their choosing.


U.S. industry consumes nine million tons of hydrogen per year and it has done so with a good safety record; but, hydrogen-related accidents are bound to increase with a nation full of HFVs hurtling into traffic at 75 mph, driven by someone talking on a cell phone, and eating an Egg McMuffin while juggling their hot cup of coffee. 


Fail-safe versus cost

Designers have done an outstanding job of creating HFVs with every imaginable fail-safe mechanism.  Not only will this add enormously to the cost; but, mechanisms do fail. 


I predict the day will come when a family loses a loved one because they walked into an unseen hydrogen fire. 


There will also come a day when someone crashes their HFV in a remote area and either the Good Samaritan rescuer is seriously burned because they unwittingly waded into a fire; or, perhaps on that particular day the passer-by just happened to know and heed the warnings of the CaFCP Emergency Response Guide, “Members of the public should not attempt to respond to an emergency involving a fuel cell vehicle (emphasis added) but instead should contact emergency response personnel.”  In other words, the victim could very well be toast before help arrives from an hour or two away. 


Other considerations

Note than I have said nothing about hydrogen embrittlement.  It is yet another thing that the average Jane or Joe Public may not know; but it is not worth discussing, here, because proper design practices should keep it in check.  For the most part, it is not apt to spring an unpleasant surprise upon the public; but the problem will loom large in H2 pipeline design. 






In a nutshell

Hydrogen will escape at the least excuse and it will burn or explode at the slightest provocation.  Furthermore, each step of the compression, liquefaction and transport sequence is costly and energy-robbing.  With the limitations of current technology, do you still think hydrogen makes good sense?  Do you want to pay the price?


After a few accidents, our risk-averse society could very well wake up and develop an anti-hydrogen backlash that will bring an abrupt end to the hydrogen honeymoon.


Media, where were you in the meantime?


Orrin Iseminger

January 1, 2008



An explanation

I wrote this article in March, 2007 and drew heavily upon The California Fuel Cell Partnership (CaFCP) Emergency Response Guide which was found posted to the Internet at this URL:




No longer available at the above Web site, it is archived at: 




I am grateful to Larry on the Manufacturing Forum who supplied me with this URL. 


If you are interested in further reading on this topic, you can find opinions of all persuasions in the on-line discussion, Hydrogen fuel is a bigger joke than ethanol, found here:




Pay particular attention to “Bentwrench’s” comments.  He offers an excellent perspective from an engineer’s point of view. 




I dedicate this article to a very special friend, E. Kirsten Peters, PhD.  If it had not been for Kirsten, this Web page would not exist. 


Orrin Iseminger



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