Investigation of hydrogen-on-demand systems (HODS)

  • #1

Main Question or Discussion Point

Hi all,

I just wanted to post some new links regarding a recent topic of large debate, the viability of these systems. Assuming that these systems were installed properly, then it appears that HODS do not work at all.

  • From the Popular Mechanics website--Published on: August 7, 2008: [Broken]

    The author built and installed a HODS and tested the device by measuring the fuel-injection pulse widths. No change occurred, so the conclusion was HODS are bunk. Plausible arguments from readers' comments that counter the author's claim include: (1) the absence of the author's data concerning the efficiency of the HODS by itself and in conjunction with the vehicle, (2) testing on only one vehicle, since electronic fuel management systems likely vary from vehicle to vehicle and that the fuel management systems of older vehicles aren't responsive to air/fuel-ratio fluctuations like new vehicles.

  • From the Popular Mechanics website--Published on: March 27, 2009: [Broken]

    The author teamed up with Dateline NBC for another investigation. An undercover representative paid an HODS specialist to install a system on his vehicle. The author performed tests before and after the installation and then performed tests at an EPA-certified emissions lab. Both studies showed that HODS do not work. The episode was to originally air on Sunday, March 29, 2009 and feature a known scammer in the HODS business, but it was canceled due to the golf match running over its designated time slot. Again, no hard data published online.

My two cents worth

Assuming that the specialist installed an efficient system correctly (which was not the case on the Myth Busters episode), then this would likely deal a heavy blow (more accurately, the death, if it is assumed that all modern vehicles have the same electronic fuel management system) of the HODS as a viable means to improve fuel economy. The conclusion regarding all of the positive claims would be a mass placebo effect.

Many would say that such testing isn't even needed because conservation of energy (COE) has already proved this to be a losing proposition. While COE can never be violated, the mechanisms behind the operation of this device are more complex than a simple application of COE, and therefore, should employ experimentation as validation. For example, the thermodynamic cycle relies on changes in the state properties, such as density and internal energy, and the path quantities, such as heat and work, the latter being process dependent. Therefore, by introducing sufficient quantities of hydrogen it is plausible to expect an alteration to the baseline thermodynamic cycle of an internal combustion engine (ICE). Peer-reviewed scientific research (see links at bottom) has shown that hydrogen does possess key properties that can enhance the thermodynamic process. The fundamental question is then whether or not the thermodynamic efficiency can supply more energy for mechanical work than used to produce the hydrogen in the first place. Something else that is important to consider is the fact that the fuel-management system monitors real-time sensor data and uses this data to plot a point on a pre-defined fuel map, which determines the duration of the pulse width for fuel-injection. By introducing new elements into the combustion process, it may be very well possible that the sensor data is shifted from its baseline, with the end result being a leaner operating engine.

While HODS may prove futile, the idea of using some sort of device to produce on-board hydrogen in conjunction with alterations to the operation of ICE does hold merit, since research has clearly shown that sufficient quantities of hydrogen and ultra-lean ICE operation can drastically improve thermodynamic efficiency. Unfortunately, this research is not applicable the current operation of modern vehicles with an installed HODS, so the Dateline NBC episode should be real interesting to watch when it finally airs.

Links to scientific research

  • Combustion of a Gasoline–Hydrogen–Air Mixture in a Reciprocating Internal Combustion Engine Cylinder and Determining the Optimum Gasoline–Hydrogen Ratio
    L. N. Bortnikov [Broken]

    Abstract: This paper reports results of an analysis of experimental data on the combustion of a gasoline–hydrogen–air mixture in a reciprocating internal combustion engine cylinder. The completeness of combustion of the mixture is shown to depend on the amount of hydrogen in the fuel mixture and the composition and physicochemical properties of the mixture. In particular, the conditions of addition of hydrogen to the gasoline–air mixture with active chemical action on the combustion process and the action of hydrogen as an additional fuel component are determined. A dimensionless universal relation is proposed that allows one to uniquely determine the initial composition of the fuel mixture (hydrogen to gasoline ratio) to accomplish combustion of the fuel mixture at the lean combustion limit.

    John F. Cassidy

    Abstract: An experimental program using a multicylinder reciprocating engine was performed to extend the efficient lean operating range of gasoline by adding hydrogen. Both bottled hydrogen and hydrogen produced by a research methanol steam reformer were used. These results were compared with results for all gasoline. A high-compression-ratio, 7. 4-liter (472-in. 3) displacement production engine was used. Apparent flame speed was-used to describe the differences in emissions and performance. Therefore, engine emissions and performance, including apparent flame speed and energy lost to the cooling system and the exhaust gas, were measured over a range of equivalence ratios for each fuel. The results were used to explain the advantages of adding hydrogen to gasoline as a method of extending the lean operating range. The minimum-energy-consumption equivalence ratio was extended to leaner conditions by adding hydrogen, although the minimum energy consumption did not change. All emission levels decreased at the leaner conditions. Also, adding hydrogen significantly increased flame speed over all equivalence ratios. Engine performance and emissions with hydrogen from the methanol reformer were about the same as those with bottled hydrogen.

  • Emissions reductions using hydrogen from plasmatron fuel converters
    L. Bromberga, D.R. Cohn, A. Rabinovich, J. Heywood

    Abstract: Improvements in internal combustion engine and aftertreatment technologies are needed to meet future environmental quality goals. Systems using recently developed compact plasmatron fuel converters in conjunction with state-of-the-art engines and aftertreatment catalysts could provide new opportunities for obtaining substantial emissions reductions. Plasmatron fuel converters provide a rapid response, compact means to transform a wide range of hydrocarbon fuels (including gasoline, natural gas and diesel fuel) into hydrogen-rich gas. Hydrogen-rich gas can be used as an additive to provide NOx reductions of more than 80% in spark ignition gasoline engine vehicles by enabling very lean operation or heavy exhaust engine recirculation. It may also be employed for cold start hydrocarbon reduction. If certain requirements are met, it may also be possible to achieve higher spark ignition engine efficiencies (e.g., up to 95% of those of diesel engines). These requirements include the attainment of ultra lean, high compression ratio, open throttle operation using only a modest amount of hydrogen addition. For diesel engines, use of compact plasmatron reformers to produce hydrogen-rich gas for the regeneration of NOx absorber/adsorbers and particulate traps for diesel engine exhaust aftertreatment could provide significant advantages. Recent tests of conversion of diesel fuel to hydrogen-rich gas using a low current plasmatron fuel converter with non-equilibrium plasma features are described.

    Y. Hacohen and E. Sher

    Abstract: A study of the effect of the amount of hydrogen on the fuel consumption and emission of a spark ignition (SI) engine is reported. In the first stage, dynamometer test results for a wide range of engine speeds, engine loads, equivalence ratio, and hydrogen enrichment under steady-state operation were obtained, and the engine requirements for minimum BSFC were specified. In the second stage, an onboard, online hydrogen generator was developed and employed to provide the required amount of hydrogen. The hydrogen was produced by a steam reforming process. A detailed model for simulating a spark ignition engine fueled with hydrogen-enriched gasoline was developed and used to predict the optimal amount of hydrogen supplement as well as the corresponding MBT, optimal throttle position, and emissions level of CO, HC, and NOx

  • Hydrogen Enhanced Combustion - History, applications and Hydrogen supply by plasma reforming
    Georgios Pechlivanoglou

    Abstract: Since the early years of internal combustion engine development, many researchers have been trying to optimize the combustion process in the engines’ chambers. The utilization of hydrogen as a combustion enhancer have also been investigated during the years of the machinedominated era, but the results were dubious. Therefore Hydrogen Enhanced Combustion (HEC) is not yet being commercially used. The aim of the following document is to present the milestones of the results on the HEC research, as well as the potential applications and the present state of the art on this field. Finally the possibility of on board hydrogen production with plasma reformer is also briefly presented and investigated.

    A. N. Migun, A. P. Chernukho, and S. A. Zhdanok

    Abstract: The influence of the addition of hydrogen and of a synthesis gas on the basic parameters of combustion of gasoline-air fuel mixtures is investigated theoretically. The possibility of feeding gasoline internal combustion engines with lean fuel mixtures with a concentration of 5 10 vol.% hydrogen is shown; this will greatly improve their ecological purity.

  • Performance of a spark ignition engine fuelled with reformate gas produced on-board vehicle
    Enzo Galloni, Mariagiovanna Minutillo

    Abstract: In recent years, the interest in the use of hydrogen, as an alternative fuel for spark-ignition engines, has grown according to energy crises and pollution problems. By comparing the properties of hydrogen and gasoline, it is possible to underline the possibilities, for hydrogen–gasoline fuelled engines, of operating with very lean mixtures, thus obtaining interesting fuel economy and emission reductions.

    In this paper, the performance of a spark-ignition engine, fuelled by hydrogen enriched gasoline, has been evaluated by using a numerical model. A multidimensional code (KIVA-3V) has been modified in order to model the engine combustion process using a hybrid combustion model adapted for dual fuelling. Based on computed results, the performance of the engine has been evaluated in different operating conditions.

    Furthermore, for the hydrogen enriched gasoline engine fuelling, the hydrogen production on-board the vehicle has been considered. A thermochemical model of a reforming system has been developed by means of the Aspen Plus code. The conversion of gasoline to hydrogen has been investigated and thermodynamic analysis of the reforming system has been conducted.

    The thermal efficiency of the fuel processor and the efficiency of the integrated reformer/SI engine system have been calculated.

  • Performance study of a four-stroke spark ignition engine working with both of hydrogen and ethyl alcohol as supplementary fuel
    Maher Abdul-Resul, Sadiq Al-Baghdadi

    Abstract: The effect of the amount of hydrogen/ethyl alcohol addition on the performance and pollutant emission of a four-stroke spark ignition engine has been studied. The results of the study show that all engine performance parameters have been improved when operating the gasoline spark ignition engine with dual addition of hydrogen and ethyl alcohol. The important improvements of alcohol addition are to reduce the NOx emission with increase in the higher useful compression ratio and output power of hydrogen-supplemented engine. The addition of 8 mass% of hydrogen, with 30 vol% of ethyl alcohol into a gasoline engine operating at 9 compression ratio and 1500 rpm causes a 48.5% reduction in CO emission, 31.1% reduction in NOx emission and 58.5% reduction in specific fuel consumption. Moreover, the engine thermal efficiency and output power increased by 10.1 and 4.72%, respectively. When ethyl alcohol is increased over 30%, it causes unstable engine operation which can be related to the fact that the fuel is not vaporized, and this causes a reduction in both, the break power and efficiency.

  • The addition of hydrogen to a gasoline-fuelled SI engine
    T. D’Andreaa, P.F. Henshawa, D.S.-K. Ting

    Abstract: The results of an experimental investigation involving the addition of hydrogen to a gasoline-fuelled SI engine are reported. Up to 66% by volume (3.7% by mass) of hydrogen as fuel was added as part of the air with little modification to the engine. Cylinder pressure traces were used to calculate the indicated mean effective pressure and mass fraction burned. Electrochemical analysers were used to measure the concentration of CO, NO and O2 in the exhaust. The added hydrogen resulted in improved work output and a reduction in burn duration and cycle-to-cycle variation while operating under lean conditions (φ<0.85). When operating closer to stoichiometric conditions (φ>0.85) little difference in engine performance was seen. This dependence of hydrogen addition effect on the fuel/air equivalence ratio was confirmed by analysis of variance tests.

  • Thermal balance of a four stroke SI engine operating on hydrogen as a supplementary fuel
    F. Yuksel, M.A. Ceviz

    Abstract: This paper investigates the effects of adding constant quantity hydrogen to gasoline–air mixture on SI engine thermal balance and performance. A four stroke, four-cylinder SI engine was used for conducting this study.

    Thermal balance tests were conducted for engine thermal efficiency, heat loss through the exhaust gases, heat loss to the cooling water and unaccounted losses (i.e. heat lost by lubricating oil, radiation), while performance tests were in respect to the brake power, specific fuel consumption and air ratio. Hydrogen supplementations were used with three different and fixed mass flow rates; 0.129, 0.168 and 0.208 kg h−1 at near three-fourth throttle opening position and variable engine speed ranging from 1000 to 4500 rpm. The results showed that supplementation of hydrogen to gasoline decreases the heat loss to cooling water and unaccounted losses, and the heat loss through the exhaust gas is nearly the same with pure gasoline experiments. Additionally, specific fuel consumption decreases, while the engine thermal efficiency and the air ratio increase. Engine performance parameters such as thermal efficiency and specific fuel consumption improved the level of the ratio of hydrogen mass flow rate to that of gasoline up to 5%.
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Answers and Replies

  • #2
Ivan Seeking
Staff Emeritus
Science Advisor
Gold Member
Excellent post! Thanks.
  • #3
Another source:

  • Environmental Protection And Energy Savings Using Plasma Technology
    Daniel R. Cohn
    Plasma Science and Fusion Center
    Massachusetts Institute of Technology [Broken]
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  • #4
Here's the link to the NBC Dateline webpage with links and video concerning the segment:

I didn't get an opportunity to view it yet, so I will post my thoughts later.
  • #5
I watched all three segments of the video and must admit that I am highly disappointed with the episode. Dennis Lee, a long-time scammer who marketed many different devices through the years, was a large focus in the episode. The HODS was installed by one of his mechanics. Obviously, the device failed the test; you can't argue against dynamometer and emissions testing by an EPA certified lab. There was no mention in the video about how the system was installed or any indication on the installed HODS typical hydrogen output. The conclusion that I drew was that the installer was a scammer as well; you can see the fidgetiness in his fingers and gulping in his throat when questioned about the failure of the HODS system in the opening minute of segment 3. In my opinion, this whole episode was biased in its presentation, showing only that scammers are out there and that HODS are a common ploy to get your money.

On a related note, Mike Allen, Popular Mechanics senior automotive editor, stated in the video that he tested many HODS and never found one to actually work. While this may be true, he does not convince his readers (see links above) very well because he presents no hard data and detailed test setups for all of these tests. There are many different types of HODS, but to my knowledge they fall under two general categories: (1) HODS consisting only of an electrolyzer and (2) HODS consisting of electrolyzer with various electronic engine management modifications. The former is the ideal setup, since the latter could cause engine damage in the long-term (because the modifications usually include leaning air/fuel ratio) and would provide a mileage increase anyways. Many people using HODS have quoted H2-O2 production up to 5-6 liters per minute, which is roughly 4 grams of hydrogen per minute (240 grams per hour) at STP. If true, then the hydrogen production is well within bounds of the amounts tested in the scientific literature (see links above), and also, the electronic modifications for leaning out the air/fuel mixture may be warranted and pose less engine risks due to the properties of hydrogen during combustion under lean engine operation as noted in the scientific literature.

In my opinion, this case is still unsolved.
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