 To anyone who is aware of hydrogen's explosive power it comes as no surprise that hydrogen can also be used as a combustion fuel in internal combustion engines (ICE's). Hydrogen fueled ICE's have been around since before 1900. Since then, many companies have produced prototypes utilizing various theories and methods about which way is the best way to combust hydrogen. Today, BMW is the first major car maker to produce and sell (at least they're planning on selling it) a hydrogen powered ICE car. The BMW 750 hl (see above left) is a super classy high-tech sedan boasting a V12 engine running on liquid hydrogen (actually the hydrogen is stored as a liquid to save space, but is heated to a gaseous state prior to combustion). BMW has teamed with Dubai in the mideast to produce hydrogen by electrolysis of seawater using solar power (sun and water...sounds like catchy name for a website, eh?), and then ship the hydrogen to Germany to be dispensed in automated high-tech refueling stations (see right). As with most hydrogen ICE cars, the 750 hl is a bi-fuel gasoline car. This means the engine can run on both hydrogen and gasoline (not at the same time however). A switch inside the car is used to switch between the fuel tanks as needed. Other major auto makers have built prototypes but none have committed to bring one to the market. Of note, Ford recently announced their Focus P2000 car that uses an ICE running off gaseous hydrogen. They see hydrogen burning ICE cars as a bridge technology to fuel cells to not only get the consumer used to the idea of hydrogen, but also because the technology to build them is much less expensive and much more available than that of fuel cells. There are also a few companies using gaseous hydrogen combustion in conjunction with a hybrid architecture. These are not currently being produced however.
Why hydrogen?... Why hydrogen combustion? LOTS OF REASONS!! Remember that, per pound, hydrogen has 3 times the energy of gasoline! When hydrogen gas is burned it produces only water vapor**. Hydrogen gas burns completely and uniformly can therefore be combusted with a higher thermal efficiency than gasoline. Then you have the reasons for using hydrogen as a  fuel in general: completely zero-emission fuel cycle, is a renewable fuel and therefore has a limitless supply, the average Joe can make hydrogen at home through water electrolysis (imagine being completely independent of the oil companies!). As it turns out, the method for combusting hydrogen has a lot in common with compressed natural gas combustion. CNG vehicles are very common worldwide and the parts needed to convert an existing gasoline engine to CNG are readily available (SunWater is currently doing a conversion on a 1992 Pontiac Grand Am to a bi-fuel CNG vehicle -- see bottom of this page for details). This means that, with only two small exceptions, the parts needed to convert an existing gasoline car to a bi-fuel hydrogen car (or even a tri-fuel hydrogen, CNG, gasoline car as in Roy McAlister's tri-fuel Geo Metro above) are also readily available! What are those two small exceptions? The fuel injection system and the on-board diagnostic computer (OBD) interface. These are both explained in detail below.
(**At combustion temperatures above 4000 degrees Fahrenheit, nitrogen dioxide is also created in small quantities due to the nitrogen content of atmospheric air. This can be avoided by controlling the combustion temperature to be below the 4000 degree threshold. There are many standard ways to accomplish this.)
The fuel injection system... So what is the best way to combust hydrogen in a car? Although there is still a debate going on about the answer to that question, it is SunWater's informed opinion that the best way to accomplish hydrogen combustion is Roy McAlister's way. Roy McAlister is the president and founder of the American Hydrogen Association and an incredibly smart man when it comes to hydrogen. AHA holds a yearly class on how to convert a gasoline car to run on hydrogen and SunWater attended the 2001 class. While there I was able to analyze first-hand various hydrogen combustion vehicles. I was also taught in detail the various methodolgies of hydrogen combustion, and which way is the "best" way. Many many smart people have attempted this task with mixed results. The "secret" seems to be to combust hydrogen at the point of injection, and in excess air. Normally in a gasoline or CNG engine, the fuel is mixed with air prior to injection into the cylinder. The cylinder maintains a vacuum to suck in the fuel/air mixture. Also, spark occurs in proximity to the point of injection but not AT the point of injection. These methods simply will not do for hydrogen. For hydrogen, by igniting the gas AT the point of injection, and in excess air, you create a condition known as "stratified charge" which is well known in heat engine circles as the most efficient way to run a Carnot engine (a diesel engine operates in a similar manner). Stratified charge refers to the excess air forming an envelope around the injected hydrogen gas, and the subsequent ignition of the hydrogen heating the surrounding envelope of air in a stratified manner. The heated air consequently amplifies the combustion effect (and also protects the cylinder head walls from the high combustion temperature thereby increasing cylinder head life). Under these conditions a heat engine approaches the maximum theoretical efficiency for a Carnot cycle, around 40%. To accomplish this feat technically, Roy McAlister invented and patented what he calls a "smart plug" or injector spark plug (see above right). This little marvel accomplishes fuel injection and spark ignition at the same time. By using this device (patent # 5,394,852), and by opening the air intake to allow the engine to breathe freely, Roy has achieved a 20% increase in horsepower over the same engine running on gasoline! This is without any physical modifications to the cylinder head (such as boring it out to increase the interior volume as  some companies do). Of course, the timing of the injection and spark is also markedly different than on a gasoline or CNG engine. When combusting hydrogen the ignition is set to fire at TDC, or top-dead-center. This is because hydrogen burns very rapidly and advance timing would cause backfire**. This quality however is also what allows it to burn so lean (in excess air) and the result is significantly increased fuel economy. REMEMBER ALSO that hydrogen creates no carbon build up in the engine thereby greatly increasing the life of the engine (see above left -- this is a picture of the engine oil in Roy's hydrogen powered pickup truck; it hasn't been changed in 20 years of operation and is still as clear and clean as when it was poured!).
(**Backfiring has been one of the main obstacles to hydrogen combustion over the past 100 years. It occurs when hydrogen is mixed with air prior to injection and, upon injection, ignites prematurely before the fuel intake port can close. This ignites the mixture back into the fuel manifold and gives a nice loud "boom". Direct injection of pure hydrogen into the cylinder head using the McAlister "Smart Plug" solves this problem.)
The computer... Which brings me to the next "small exception". Normal automobiles have an on-board computer called an OBD (On-Board Diagnostics). This computer controls a number of functions including, but not limited to: ignition timing, fuel-injection timing, sensing of the oxygen sensor (and potentially many other sensors), transmission control, etc.. The problem is the computer is programmed for use on a gasoline engine. We've already learned that the timing is very different when combusting hydrogen. Even more than that, hydrogen has no emissions, so when the exhaust sensors don't see the expected amount of crap (carbon oxides, nitrous oxides, sulphur oxides, etc.) coming out the tailpipe, the computer sees this as a problem and consequently turns on the "check engine" light. Even worse, it may shut down altogether leaving your vehicle either inoperable or in a "default state", which means it runs roughly and inefficiently. How do we fix this problem so we can run on hydrogen? There are a number of different ways. The CNG vehicle conversion industry faces the same problem, since natural gas burns much cleaner than gasoline and has different timing. Their solution was to build small computers that interface directly with the OBD and provide the signals the OBD is expecting to keep it "happy". Autotronics is the only company known to produce these add-ons for the CNG vehicle industry. SunWater has contacted them to inquire about modifying their products for use with hydrogen. Not surprisingly they said that one would need to pay for a minimum of 500 units and also pay for research and development costs. These small computers also take care of ignition timing modifications. The drawback to this approach is that no one currently makes such an add-on calibrated for use with hydrogen except one, Hygen Industries LLC. Hygen is the only company in the US that does aftermarket hydrogen conversions for ICE's. Their focused market is fleet vehicles. SunWater has contacted Hygen and they are willing to sell their computer modules, although it wouldn't be cost effective unless you waited for them to produce a large number at once in connection with a large fleet conversion job. This unfortunately would only work if you were converting the exact same vehicle they were. Another method is to take the OBD out altogether and replace it with a custom built microcontroller. By using this method one could altogether ignore the sensors and just focus on controlling the ignition and injector timing. This is the method being used by the AHA in their Hydrogen ACE car (ACE = Air Cleaning Engine). The ACE (see above; closeups are available on AHA's website) uses a stock Ford 5.0 liter engine with no modifications except to clamp open the air intake valve and to replace existing spark plugs with Smart Plugs. AHA is using a microcontroller to provide the ignition/injection timing. Since there are no emissions, no catalytic converter or exhaust sensors are needed! The only drawback with this method is perhaps having to convince the EPA to not throw you in jail for having disabled the emissions control equipment on your vehicle. :)
Is there another way?... Is there another way to run a hydrogen ICE car? Well, yes. Is there a better way than the one shown above? Probably not. It's perfectly ok to combust  hydrogen in a vacuum environment using conventional spark plugs. As long as you change the ignition timing to TDC you'd be ok. Heck, hydrogen will run in a regular old Briggs and Stratton 5hp go-cart engine with just a timing modification (see left)! The original hydrogen powered truck (below right) converted by Roy McAlister for a Dr. Robert Zweig was a simple Mitsubishi 3-valve engine with the air intake clamped open, timing changed, and the fuel manifold divided into two parts (to keep the hydrogen away from the air until inside the cylinder -- see below right). What one must consider when combusting hydrogen in this manner is that there will be a reduction in horsepower output. The reason for this is simple physics... although hydrogen contains more energy per pound than gasoline, it also takes up much more space than gasoline. What some have done to counteract this is to add a turbo-charger to the engine and/or bore out the cylinder head to give more internal volume to accomodate more gas (these are the methods used by Hygen Industries LLC). The problem with this is that these modifications are extremely expensive. Hygen estimates that a single conversion job done this way would cost up to $50,000 (mass conversions would enable economies of scale and bring the price down to about $4000/vehicle if 500 or more are converted at once)! Ouch, that's expensive! Of course you could simply live with the reduction in power and walk away with your pocket book intact. The point of all this is that if you want equal or better performance than a gasoline car running hydrogen, do it Roy McAlister's way. Even without mass production, the price of a Smart Plug conversion is about 1/5th that of Hygen's. If you discount for mass production of the Smart Plugs, a conversion could cost around $2-3000. If you can live with reduced power then forget Smart Plugs and just add a tank of hydrogen and separate the fuel and air manifolds.
What about hydrogen storage?... So how do you store the hydrogen on board the car? There are many fancy schmancy methods currently being researched by the big automakers. The major ones are: carbon nanotubes, microspheres, storage in metal hydrides, and liquid hydrogen storage (BMW's method). Some more exotic methods being researched are: Millenium Cell's sodium borohydride storage, Xogen's hydrogen-on-demand device that uses tap water as the storage medium, Hydro-Environmental Resource's process that also uses tap water or seawater as the storage medium, and Powerballs which store the hydrogen in sodium hydride powder which produces hydrogen upon contact with water. All of  these methods have great advantages and any one of them could potentially revolutionize the hydrogen storage industry. The only problem with all of these is that they're either not available to the general public or they're prohibitively expensive (Powerball modules are available, but no off-the-shelf vehicle module exists as of yet and would need to incur R&D costs at first; however, their CEO predicts a system cost of under a $1000 once mass production kicks in). On the other hand, the CNG vehicle industry has been using reliable, safe, and relatively inexpensive high pressure storage tanks for over 30 years with a safety record that the gasoline tank industry can't even touch. These tanks (made of aluminum, steel, carbon fibers -- see above left) have been tested to the following standards by the Department of Transportation: 90mph head-on collision, full stick of dynamite, placed in a furnace, shot with a 9mm hand gun using police rounds, shot with a military M-16 rifle using armor piercing rounds. Out of all these, only the armor piercing rounds were able to cause any damage to the cylinders. However, even then the gas inside the cylinder vented immediately, WITHOUT IGNITING, into the atmosphere! Can gasoline tanks say that? NO! So which is the safer fuel to use for automobiles? You decide. The bottom line is that CNG storage tanks are safe, inexpensive, readily available, and can store compressed hydrogen up to 5000 psi, depending on the tank (enough for a range equivalent to a gasoline car ~ 250 - 300 miles/tank).
Where do I get the hydrogen?... So where do you get hydrogen for your car? This is by far the most difficult obstacle to overcome for hydrogen powered vehicles. Many companies are currently developing hydrogen production devices to complement the auto industry's race to sell fuel cell cars. These devices generally use electrolysis of water as the production method and require only tap water and household 220V current as inputs. Again, the problem with these is that they're not currently available to the public (with the relative exception of Powerballs). So what can we do? AHA has hydrogen delivered to them from a local industrial gas supplier. Local welding shops keep large supplies of hydrogen on hand as well. But this is generally overly burdensome for the average person to deal with. Is there hope? Can't we have hydrogen now? YES, WE CAN! SunWater has found a maker of reversible PEM water electrolysis units in Canada called Greenvolt that sells units which are scalable, depending on how fast you want to produce hydrogen. They use reversible proton exchange membrane (fuel cell) technology and therefore do NOT require a caustic electrolyte such as KOH. One such unit produces hydrogen at the rate of 2500 liters per hour (at that rate it would take about 4.9 hours to refill a typical 60 liter storage cylinder to 3000psi). SunWater is still waiting on a price quote for this unit, but is expected to be around $20,000 (ouch!). There is also a company out of Iowa called Hydrogen Wind Inc.. They sell scalable traditional electrolysis units that use caustic KOH as an electrolyte (although great care must be taken when handling KOH, it is cheap and readily available at chemical supply stores). These units are much more cost effective than the reversible membrane units, but are also bulkier and will only pressurize to 150psi which means external mechanical compressors would be needed to fill the storage cylinder. A 24 cell unit produces 340 liters per hour and costs around $3000. Although producing hydrogen by electrolysis allows one to make his own fuel at home (and without emissions if renewable power is used), the greatest problem with electrolysis is its thirst for power. It's estimated that it takes Greenvolt's unit about 67kWh of electricity to fill a typical 60 liter storage tank to 3000psi! That's a HUGE amount of energy! This is where the recent advances is hydrogen production would come in useful. Some of these new methods require no input at all except sunlight or a metal catalyst. To see a brief synopsis of these new methods, see the Hydrogen page. SunWater also highly suggests readers refer to the articles on home hydrogen production by Homepower Magazine. The articles are available for free download from their website and are a must for anyone wanting to attempt this. So once the hydrogen is produced, how do you store it in the tank at 3-5000psi? Good question. Although there are industrial compressor units that will do the job, we need something small and inexpensive to use in our garage at home. Again, auto-makers are currently developing and testing such units but they're not available to the public. Greenvolt's reversible membrane electrolysis units, mentioned above, will self-pressurize to 3000psi with no external mechanical compression. Metal hydrides, often thought of as a hydrogen storage medium, are also adept at hydrogen compression. By utilizing hot and cold running water, a hydride compression unit can compress hydrogen up to 60,000psi with no moving parts and consuming only a fraction of the electricity as mechanical compressors. Ergenics, out of New Jersey, currently sells tailored units run for about $20,000 - $40,000 (ouch!). A company called FuelMaker in Canada sells a home appliance called the FuelMaker (see above right) that is used in the CNG industry to compress natural gas for refueling of CNG cars. SunWater has contacted FuelMaker about the possibility of using the device to compress hydrogen. They strongly recommended against using their CNG compressor units to compress hydrogen but they said they're currently developing a unit especially for hydrogen compression for the fuel cell car industry. They said they'd sell me a prototype (guaranteed for 500 hours of operation) under the agreement that it would only be used in a controlled test/development environment. I give this information out to anyone wishing to pursue their offer, but I add that caution must be taken since it is only a prototype. Outside of these few, the compression obstacle remains an obstacle. :(
What about CNG vehicles?... With all the above references to the CNG vehicle industry, one might want to know why we don't just go with CNG instead of hydrogen? The reason is in the fuel. Natural gas is a petroleum byproduct and therefore is a non-renewable fuel. That aside, natural gas is much cheaper than gasoline and burns about 80% cleaner than gasoline overall (reduces sulphur and other smog emissions by 80%, reduces carbon dioxide emissions by 25%, reduces carbon monoxide emissions by 95%, reduces nitrogen oxide emissions by 60%). The Honda Civic GX runs on natural gas, is widely available, and has received an emissions rating of SULEV, thereby making it the cleanest burning ICE vehicle on the road today (see below left)! Chevrolet makes a bi-fuel gasoline/CNG Cavalier, although it only achieves an LEV emissions rating (see the emissions rating chart on the Air Pollution page). Natural gas vehicles also have the advantage of refueling right in your own garage with the FuelMaker appliance, which plugs right into your existing natural gas line. With the bi-fuel  option you get the best of both worlds, natural gas for commuting and gasoline for long trips. Finally, as mentioned earlier, natural gas conversion hardware is essentially the same as for hydrogen. You could say that by having a CNG vehicle, you're 80 - 90% of the way toward having a hydrogen bi-fuel vehicle. Also, since CNG kits are mass produced, they are widely available and relatively inexpensive (~$2500 - $3000). So whereas a cost effective hydrogen production/compression method is not yet available, CNG is available NOW and will put you in the perfect position to move toward hydrogen when home refueling units are finally released on the market. It's for these reasons that SunWater has decided to convert our own vehicles to bi-fuel CNG/gasoline. To gain experience we'll first be converting a 1992 Pontiac GrandAm. Jody Stirewalt, of the National Alternative Fuels Training Consortium in West Virginia, is considered by many to be the national expert on CNG conversions. SunWater is working with him to buy the parts and receive training. If you are considering converting a car to CNG, we highly suggest contacting Jody! Please see the running journal of our conversion experience below.
Conclusion... It was rhetorically asked by Roy McAlister, "Why waste the some 3 billion internal combustion engine cars on the road today?". That's exactly what completely moving to fuel cell vehicles would be trying to do. It will take far too much time for all existing cars to use up their life span and their owners replace them with fuel cell cars! Not to mention the incredible waste of material in scrapping that many cars. We need an answer to the transportation/energy/pollution crisis now, not in 30 years. Even when fuel cell cars do come out, how many middle class or lower class Americans will be able to afford the $40,000 price tag? Any ICE car can be converted NOW to run on hydrogen. What's more, AHA did exhaust testing on their hydrogen cars and determined that the air coming out of the tailpipe was actually cleaner than the air going into the engine! It actually "burned" the hydrocarbon pollutants out of the air (see AHA's website for the exact test results). For this reason Roy refers to hydrogen combustion vehicles as "minus emissions vehicles". When he took his truck in for an emissions check in Phoenix, AZ it actually failed because the computer couldn't detect any emissions at all and wasn't programmed to deal with that! (In a funny twist, later on he was actually stopped by a traffic cop and taken to jail because his truck had expired tags... which couldn't be updated because he couldn't pass emissions testing because it was too clean!). Imagine a city full of minus emissions vehicles that actually clean the smog out of the air as they drive! The remaining obstacles can easily be removed. All that is needed is an entrepreneur with vision and talent (and investors) to come forward and establish a company based on converting people's cars to minus emissions vehicles (MEV's). By so doing, the Smart Plugs could be mass produced and therefore reduce the cost of a conversion down to around $3 - $4000. The only reason the companies, such as Stuart Energy, that make home hydrogen refueling units haven't come forward to the market is they perceive there is no market until fuel cell vehicles come out. If a company were to show a demand NOW, they would start selling them NOW. And if you want to talk smart business plans -- tell people that for $4000 they can keep the car they currently own, only produce no emissions, have 20% more horsepower, make their own fuel for free (if they use renewable power), greatly reduce maintenance costs, and therefore be able to recoupe the conversion cost in fuel savings alone in about a year or two (and then have virtually free fuel for the rest of their lives)! This service could also be easily marketed to fleet owners, as Hygen Industries has done. Would that attract customers? You decide. SunWater strongly encourages any and all who read this to seriously consider investing in or starting such a business. Our planet, our culture, our health and quality of life depend on people taking these types of steps!
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