Hydrogen fuel enhancement
Hydrogen fuel enhancement is the process of using a mixture of hydrogen and conventional hydrocarbon fuel in an internal combustion engine, typically in a car or truck, in an attempt to improve fuel economy, power output, emissions, or a combination thereof. Methods include hydrogen produced through an electrolysis, storing hydrogen on the vehicle as a second fuel, or reforming conventional fuel into hydrogen with a catalyst.
There has been a great deal of research into fuel mixtures, such as gasoline and nitrous oxide injection. Mixtures of hydrogen and hydrocarbons are no exception. These sources say that contamination from exhaust gases has been reduced in all cases, and they suggest that a small efficiency increase is sometimes possible.
Many of these sources also suggest that modifications to the engine's air-fuel ratio, ignition timing, emissions control systems, electronic control systems and possibly other design elements, might be required in order to obtain any significant results. A modified vehicle in this way may not pass mandatory anti-smog controls. Due to the inherent complexity of these subsystems, a necessity of modern engine design and emissions standards, such claims made by proponents of hydrogen fuel enhancement are difficult to substantiate and always disputed.
To date, hydrogen fuel enhancement products have not been specifically addressed by the United States Environmental Protection Agency, as no research devices or commercial products have reports available as per the "Motor Vehicle Aftermarket Retrofit Device Evaluation Program." They do, however, point out that installation of such devices often involves illegally tampering with an automobile's emissions control system, which could result in significant fines. Environment Canada does have a research paper on the subject. In tests done in their laboratory in 2004 they found no improvement in engine efficiency or fuel economy.
In addition to this, there are several research papers outside of both the USA and Canada     that give examples of both bench and real-world testing that gives a more balanced outcome with lowering of emissions and NOx.
There are also many aftermarket kits available for sale outside of the USA. The fitting of these kits outside the USA may not contravene laws in those countries where fitted.
Hydrogen fuel enhancement from electrolysis (utilizing automotive alternators) has been promoted for use with gasoline-powered and diesel trucks, although electrolysis-based designs have repeatedly failed efficiency tests and contradict widely accepted laws of thermodynamics (i.e. conservation of energy). Proponents, who sell the units (often called "HHO devices"), claim that the dynamics are often misconstrued, and due to the chemical properties of the resulting mixture, it is possible to gain efficiency increases in a manner that does not violate any scientific laws. Many tests by consumer watch groups have shown negative results. This technique may seem appealing to some at first because it is easy to overlook energy losses in the system as a whole. Those unfamiliar with electrodynamics may not realize that the electrolytic cell drains current from a car's electrical system causing an increase in mechanical resistance in the alternator that will always result in a net power reduction.  Since it requires more energy to separate hydrogen from oxygen than would be gained from burning the hydrogen produced in this method, the concept of such a device is often stated to be in direct violation of the first and second laws of thermodynamics. Monetary prizes have been offered to sellers or promoters of these devices to demonstrate their claims of increased fuel economy are true, with very few sellers taking the challenges and no device passing the challenges.
Arvin Meritor, a Tier 1 supplier of automotive technology, at one time, was experimenting with a plasma reformer technology which would use hydrogen produced from the fuel to enhance engine combustion efficiency and reduce emissions of NOx. This reference states that a 20% to 30% increase in engine thermal efficiency is possible. However, this requires that the engine should be modified to operate in the ultra-lean region of the plot of compression ratio vs. air/fuel equivalence ratio (lambda), along with other modifications. This technology would not work well as a retrofit to unmodified engine technology. This research was conducted in conjunction with the Sloan Automotive Laboratory at MIT. Eventually, the division conducting this research was sold off to an equity investment firm.
- NASA Technical Note, May 1977, "Emissions and Total Energy Consumption of a Multicylinder Piston Engine Running on Gasoline and a Hydrogen–Gasoline Mixture" (Accessed 2008-08-08)
- Hydrogen Internal Combustion Engine Vehicles Archived 2012-12-12 at Archive.today Idaho National Laboratory
- G. Fontana; E. Galloni; E. Jannelli; M. Minutillo (January 2002). "Performance and Fuel Consumption Estimation of a Hydrogen Enriched Gasoline Engine at Part-Load Operation". SAE Technical Paper Series (2002–01–2196): 4–5.
- Mathur H.B.; Das L.M. (1991). "Performance characteristics of a Hydrogen Fueled SI Engine using Timed Manifold Injection". International Journal of Hydrogen Energy. 16 (vol 16, pp. 115–117, 1991): 115–127. doi:10.1016/0360-3199(91)90038-K.
- Per Tunestal; Magnus Christensen; Patrik Einewall; Tobias Andersson; Bengt Johansson (January 2002). "Hydrogen Addition For Improved Lean Burn Capability of Slow and Fast Natural Gas Combustion Chambers". SAE Technical Paper Series (2002–01–2686): 7–8.
- Tsolakis A, Megaritis A, Wyszynski ML, "Application of exhaust gas fuel reforming in compression ignition engines fueled by diesel and biodiesel fuel mixtures" Energy & Fuels 17 (6): 1464–1473 NOV-DEC 2003.
- Yougen Kong; Sam Crane; Palak Patel; Bill Taylor (January 2004). "NOx Trap Regeneration with an On-Board Hydrogen Generation Device". SAE Technical Paper Series (2004–01–0582): 6–7.
- Thorsten Allgeier; Martin Klenk; Tilo Landenfeld (January 2004). "Advanced Emissions and Fuel Economy Control Using Combined Injection of Gasoline and Hydrogen in SI-Engines". SAE Technical Paper Series (2004–01–1270): 11–12.
- Water-Powered Cars: Hydrogen Electrolyzer Mod Can't Up MPGs, Mike Allen, August 7, 2008, Popularmechanics.com
- See list of devices tested under EPA Gas Saving and Emission Reduction Devices Evaluation
- US Environmental Protection Agency, "Devices and Additives to Improve Fuel Economy and Reduce Pollution - Do They Really Work?"
- [Barton, P.J. 2004. Study of Heavy Duty Vehicle Exhaust Emissions and Fuel Consumption with the use of a JetStar™ Hydrogen Gas Generator. Environment Canada, ERMD Report No. 2004-32v2]
- Business Name
- Wired magazine: Truckers Choose Hydrogen Power
- "GreenChek Technology corporate website". Retrieved 2009-02-12.
- Greenville News Looking Out 4 You: Water 4 Gas Fails to Boost Mileage Archived 2008-09-24 at the Wayback Machine
- "Hydrogen conversion claims put to the test - Video". 3 News. Retrieved 4 October 2011.
- http://www.consumeraffairs.com/news04/2008/07/water4gas.html Consumer Affairs Water4gas
- Allen, Mike (2 July 2008). "The Truth About Water-Powered Cars: Mechanic's Diary". Popular Mechanics. Retrieved 21 May 2012.
- Genepax Water Car: Too Good to be True? Yeah
- Professor doubts water car claims – A leading alternative fuels expert throws water on Japanese company claims that it's developed the world's first car powered by just water. Professor Theodosios Korakianitis at Queen Mary University of London says water by itself would not be enough to get your car going. 
- Ball, Philip (September 14, 2007). "Burning water and other myths". Nature News. doi:10.1038/news070910-13. Retrieved 2008-12-08.
(...) the definitive verdict of thermodynamics: water is not a fuel. It never has been one, and it never will be one. Water does not burn. Water is already burnt — it is spent fuel. It is exhaust. (...) And then there is poor Stanley Meyer, inventor of the 'water-powered car'. (...) How else can you extract energy by burning water, if not via a mythical substance?
- "Archived copy" (PDF). Archived from the original (PDF) on 2008-09-24. Retrieved 2008-08-03.CS1 maint: Archived copy as title (link)
- Schadewald, Robert J. (2008). Worlds of Their Own - A Brief History of Misguided Ideas: Creationism, Flat-Earthism, Energy Scams, and the Velikovsky Affair. Xlibris. ISBN 978-1-4363-0435-1.
- Hydrogen-Enhanced Combustion Engine Could Improve Gasoline Fuel Economy by 20% to 30%
- ArvinMeritor to Sell its Emissions Technologies Group