Does hydrogen enrichment make biodiesel as good as diesel?

That is not the claim and we will not make it. Fuel quality is a much broader question than combustion completeness — it covers cold-flow behaviour, oxidative stability, storage life, water uptake, elastomer and seal compatibility, filter behaviour and engine-manufacturer approval, none of which hydrogen addition speaks to at all. The specific, narrower point supported by the studies cited here is that the incomplete-combustion products and smoke measured when running a biodiesel blend were reduced by hydrogen or oxyhydrogen addition relative to the same blend without it.

Which of the cited studies actually tested biodiesel?

Uludamar et al. (2016) tested low-sulphur diesel and biodiesel blends with both hydrogen and oxyhydrogen addition on an unmodified engine. Uludamar (2018) tested microalgae biodiesel and its blends with hydroxy and hydrogen addition. The Yılmaz (2010), Saravanan & Nagarajan (2008) and Karagöz (2016) papers are diesel-fuel work included here as mechanism references, and they are labelled as such on this page rather than counted as biodiesel evidence.

Do these results transfer to my B20 in a modern tractor or truck?

Not automatically. Every study cited here is a bench test on its own engine, its own biodiesel feedstock and blend ratio, and its own gas fraction — and biodiesel is not a single fuel, since feedstock and blend level change its combustion characteristics. Treat these as direction of effect on the engines tested, not as a prediction for your equipment. The only way to establish your own result is a controlled baseline on your own fuel and duty cycle.

What about NOx on biodiesel blends?

It is disclosed here for the same reason it is disclosed everywhere else on this site: the same literature that reports lower CO, hydrocarbons and smoke frequently reports oxides of nitrogen going the other way, because more complete and hotter combustion produces fewer incomplete-combustion products and more thermal NOx. Any honest reading has to carry both results together. The per-study detail is set out above and on the visible smoke reduction page.

Does this help with a sustainability or emissions-reporting programme?

Nothing on this page is a compliance, certification, emissions-test or reporting claim, and none should be inferred. Biodiesel mandates and sustainability programmes have their own measurement and verification requirements that a combustion-enhancement system does not address. If you report under such a programme, treat any change as something your own measurement has to establish and your own scheme rules have to accept.

Is any hardware change needed to run a system on biodiesel blends?

The system produces gas on demand from purified water and delivers it to the intake; it does not touch the liquid fuel system, so it is indifferent to which diesel or blend is in the tank. Your fuel handling, filtration and service intervals remain governed by your engine manufacturer's requirements for the blend you run. Water quality for the system itself is covered in the maintenance and troubleshooting pages.

Usage case · biodiesel and blended fuels

Hydrogen with biodiesel blends: what was measured, by whom.

Operators running biodiesel blends — under a mandate, a sustainability programme, or their own choice — routinely notice that combustion behaviour and smoke characteristics are not identical to conventional diesel. Several independent studies have tested hydrogen and oxyhydrogen enrichment directly on biodiesel blends. This page sets out what each of them reported, on which fuel, under which conditions, including the results that go the wrong way.

Short answer

What do the studies report for hydrogen enrichment on biodiesel blends?

Reductions in the products of incomplete combustion — carbon monoxide, unburnt hydrocarbons and smoke opacity — relative to running the same biodiesel blend without gas addition, in the work of Uludamar et al. (2016) and Uludamar (2018), with several test points in the single-digit to low-double-digit percentage range and the size of the change depending on base fuel and engine speed. NOx generally increased in the same tests. These are attributed laboratory findings on the engines tested, not claims about our systems, and they are not a claim that hydrogen makes biodiesel equivalent to diesel.

Two of the cited studies test biodiesel blends directly; the other three are diesel-fuel mechanism references and are labelled as such.
The claim is narrow: combustion-completeness and smoke characteristics, per the cited studies' scope.
NOx behaviour is disclosed, not omitted — it frequently moves the other way.
No compliance, certification, emissions-reporting or fuel-quality claim is made.

Required disclosure · read this first

Lower CO, hydrocarbons and smoke in this literature usually come with higher NOx.

The reason is not controversial: more complete, hotter combustion leaves fewer incomplete-combustion products and produces more thermal NOx. That applies to the biodiesel-blend studies as much as to the diesel work. Visible smoke and NOx are measured and regulated separately in most frameworks, so nothing here is evidence about a test result, a certification or a defect notice. The per-study detail on smoke opacity is on visible smoke reduction, which draws on the same citation pool.

1 · Why biodiesel raises the question at all

A different fuel burns differently.

Biodiesel and its blends differ from conventional diesel in density, viscosity, oxygen content and cetane behaviour, and published engine testing of blends commonly reports combustion and emissions characteristics that differ from the neat-diesel baseline — including the soot and smoke behaviour that operators see at the stack. Direction and magnitude depend on feedstock, blend level, engine and load, which is exactly why the studies below are reported one at a time.

That is the honest framing of the problem, and it is as far as it goes. We are not making a general claim about biodiesel quality, and nothing on this page says biodiesel is a worse fuel or that hydrogen makes it "as good as" diesel. Cold-flow behaviour, storage stability, material compatibility and manufacturer approval are separate matters that hydrogen addition does not touch.

2 · The studies, one at a time

Attributed per source, with fuel and test conditions.

The two biodiesel-blend studies come first. The three that follow are diesel-fuel work, included because they establish the mechanism, and explicitly not counted as biodiesel evidence.

Uludamar et al. (2016), Int. J. Hydrogen Energy 41(26)

Fuel tested: Low-sulphur diesel and biodiesel blends, with hydrogen and with oxyhydrogen (HHO) addition.

Reported: Carbon monoxide, unburnt hydrocarbons and smoke opacity were lower with hydrogen or oxyhydrogen addition than for the corresponding base fuel, across both the diesel and the biodiesel-blend cases. Several biodiesel-blend test points sat in the single-digit to low-double-digit percentage range, with the size of the change depending on base fuel and engine speed. Engine vibration and noise were measured in the same programme.

Test conditions: Unmodified multi-cylinder compression-ignition engine, gas inducted at fixed flow rate, bench testing at several engine speeds.

NOx in the same study: NOx generally increased relative to the corresponding baseline fuel.

https://doi.org/10.1016/j.ijhydene.2016.03.179

Uludamar (2018), Int. J. Hydrogen Energy 43(38)

Fuel tested: Microalgae biodiesel and its diesel blends, with hydroxy (HHO) and with hydrogen addition.

Reported: Adding hydroxy or hydrogen gas to the biodiesel-fuelled engine reduced the incomplete-combustion products — carbon monoxide and unburnt hydrocarbons — and smoke, relative to running the same biodiesel fuel without gas addition, with performance measured in the same tests.

Test conditions: Diesel engine fuelled on microalgae biodiesel and blends, gas addition to the intake, bench test across engine speeds.

NOx in the same study: As in the author's earlier work, NOx did not move in the favourable direction; the trade-off is inherent to the mechanism.

https://doi.org/10.1016/j.ijhydene.2018.01.075

Yılmaz, Uludamar & Aydın (2010), Int. J. Hydrogen Energy 35(20)

Fuel tested: Diesel fuel with hydroxy (HHO) addition — the reference case for the blend work above.

Reported: Lower carbon monoxide, lower unburnt hydrocarbons and reduced smoke opacity with a small HHO fraction inducted into compression-ignition engines.

Test conditions: Compression-ignition test engines with an on-board HHO generator, bench testing at varied speed.

NOx in the same study: The authors report NOx increasing under the same conditions.

https://doi.org/10.1016/j.ijhydene.2010.07.040

Saravanan & Nagarajan (2008), Int. J. Hydrogen Energy 33(6)

Fuel tested: Diesel with hydrogen-enriched intake air — mechanism reference, not a biodiesel test.

Reported: Substantial reductions in smoke measured in Bosch smoke units at higher loads, on the order of a quarter to a third of the baseline reading at the reported optimum, with improvements in brake thermal efficiency.

Test conditions: Single-cylinder direct-injection diesel engine, fixed hydrogen flow into the intake, steady-state dynamometer loading.

NOx in the same study: NOx rose with enrichment as in-cylinder temperature increased.

https://doi.org/10.1016/j.ijhydene.2007.12.065

Karagöz et al. (2016), Int. J. Hydrogen Energy 41(1)

Fuel tested: Diesel with bottled hydrogen at several energy shares — mechanism reference, not a biodiesel test.

Reported: Large reductions in smoke opacity, in the order of tens of percent and above 40% at the highest hydrogen energy fractions tested.

Test conditions: Single-cylinder diesel research engine, constant speed, dynamometer loading, opacimeter measurement.

NOx in the same study: NOx increased with rising hydrogen share; the paper presents this as the principal trade-off.

https://doi.org/10.1016/j.ijhydene.2015.09.064

Independent studies report the results above on their own test engines. We do not represent them as the performance of our systems, and we publish no headline performance percentage of our own. The wider reading of this evidence base, including its limits and the negative results, is on evidence review.

3 · Mechanism, at the established-physics tier

More complete burn, fewer leftovers — whatever the base fuel.

Hydrogen's higher flame speed and wider flammability range act on the completeness and phasing of the burn of whatever primary liquid fuel is in the cylinder. Where combustion is more complete, fewer incomplete-combustion products — carbon monoxide, unburnt hydrocarbons, smoke — leave the cylinder. Nothing about that argument is specific to diesel rather than a biodiesel blend, which is why the blend studies report the same direction of effect. That is the whole mechanism described anywhere on this site; the gas path is on how it works, and the membrane rationale is on technology.

4 · Who this is for

Operators already running blends.

Agricultural operators

Farms, irrigation and harvest fleets running biodiesel blends by choice, by supply, or under a program requirement — often on older tractors and pumps, and often at part load.

Fleets under mandates or sustainability programs

Transport and civil operators required or committed to a blend, who have a legitimate technical question about combustion behaviour and stack appearance that most suppliers simply do not address.

Site power and marine on blends

Gensets and vessels bunkering blended fuel, where plume and enclosed-space conditions matter as much as consumption.

Related: agriculture, marine, generator sets. Blend operation is frequently part-load operation, which is where this literature reports the most room — idle and part-load duty cycles. Where that fuel is carted in, the economics shift too — remote fuel logistics cost.

5 · What is not claimed here

Boundaries, stated once and clearly.

No claim that hydrogen enrichment makes biodiesel equivalent to conventional diesel, and no blanket claim about biodiesel quality. The claim is limited to combustion-completeness and smoke characteristics being offset, within the scope of the studies cited.

Every figure on this page is attributed to a named study on its own engine and fuel. No unattributed or blended percentage appears here, and none of it is a statement about our systems' performance.

No compliance, certification, emissions-test or sustainability- reporting benefit is claimed or implied.

NOx behaviour is disclosed above rather than omitted. First-party operator data and the citation discipline behind it is on field results; measurement method is on fuel efficiency.

Model my own figures Ask about blend operation

No projected, typical or expected fuel-saving figure is published. Actual results vary materially with engine condition, duty cycle, load profile, fuel quality, installation and operating conditions. A controlled field evaluation on your own equipment, with baseline data captured before installation, is required before any commercial projection.

FAQ

Hydrogen and biodiesel blends: common questions.

Does hydrogen enrichment make biodiesel as good as diesel?: That is not the claim and we will not make it. Fuel quality is a much broader question than combustion completeness — it covers cold-flow behaviour, oxidative stability, storage life, water uptake, elastomer and seal compatibility, filter behaviour and engine-manufacturer approval, none of which hydrogen addition speaks to at all. The specific, narrower point supported by the studies cited here is that the incomplete-combustion products and smoke measured when running a biodiesel blend were reduced by hydrogen or oxyhydrogen addition relative to the same blend without it.
Which of the cited studies actually tested biodiesel?: Uludamar et al. (2016) tested low-sulphur diesel and biodiesel blends with both hydrogen and oxyhydrogen addition on an unmodified engine. Uludamar (2018) tested microalgae biodiesel and its blends with hydroxy and hydrogen addition. The Yılmaz (2010), Saravanan & Nagarajan (2008) and Karagöz (2016) papers are diesel-fuel work included here as mechanism references, and they are labelled as such on this page rather than counted as biodiesel evidence.
Do these results transfer to my B20 in a modern tractor or truck?: Not automatically. Every study cited here is a bench test on its own engine, its own biodiesel feedstock and blend ratio, and its own gas fraction — and biodiesel is not a single fuel, since feedstock and blend level change its combustion characteristics. Treat these as direction of effect on the engines tested, not as a prediction for your equipment. The only way to establish your own result is a controlled baseline on your own fuel and duty cycle.
What about NOx on biodiesel blends?: It is disclosed here for the same reason it is disclosed everywhere else on this site: the same literature that reports lower CO, hydrocarbons and smoke frequently reports oxides of nitrogen going the other way, because more complete and hotter combustion produces fewer incomplete-combustion products and more thermal NOx. Any honest reading has to carry both results together. The per-study detail is set out above and on the visible smoke reduction page.
Does this help with a sustainability or emissions-reporting programme?: Nothing on this page is a compliance, certification, emissions-test or reporting claim, and none should be inferred. Biodiesel mandates and sustainability programmes have their own measurement and verification requirements that a combustion-enhancement system does not address. If you report under such a programme, treat any change as something your own measurement has to establish and your own scheme rules have to accept.
Is any hardware change needed to run a system on biodiesel blends?: The system produces gas on demand from purified water and delivers it to the intake; it does not touch the liquid fuel system, so it is indifferent to which diesel or blend is in the tank. Your fuel handling, filtration and service intervals remain governed by your engine manufacturer's requirements for the blend you run. Water quality for the system itself is covered in the maintenance and troubleshooting pages.

Where this applies

Where blended fuels are already in the tank.

Biodiesel blends are most common in these applications, so the per-study findings here apply directly.

Hydrogen with biodiesel blends: what was measured, by whom.

What do the studies report for hydrogen enrichment on biodiesel blends?

Lower CO, hydrocarbons and smoke in this literature usually come with higher NOx.

A different fuel burns differently.

Attributed per source, with fuel and test conditions.

Uludamar et al. (2016), Int. J. Hydrogen Energy 41(26)

Uludamar (2018), Int. J. Hydrogen Energy 43(38)

Yılmaz, Uludamar & Aydın (2010), Int. J. Hydrogen Energy 35(20)

Saravanan & Nagarajan (2008), Int. J. Hydrogen Energy 33(6)

Karagöz et al. (2016), Int. J. Hydrogen Energy 41(1)

More complete burn, fewer leftovers — whatever the base fuel.

Operators already running blends.

Agricultural operators

Fleets under mandates or sustainability programs

Site power and marine on blends

Boundaries, stated once and clearly.

Hydrogen and biodiesel blends: common questions.

Does hydrogen enrichment make biodiesel as good as diesel?

Which of the cited studies actually tested biodiesel?

Do these results transfer to my B20 in a modern tractor or truck?

What about NOx on biodiesel blends?

Does this help with a sustainability or emissions-reporting programme?

Is any hardware change needed to run a system on biodiesel blends?

Where blended fuels are already in the tank.

Agriculture →

Continue reading.

Hydrogen combustion enhancement

Engine performance improvement

Fuel efficiency

Emissions reduction

Visible smoke reduction

Remote-site fuel logistics cost

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Installation guide

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Compare PEM systems

Does it actually work? Evidence review

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Compared with Hydrogen Fuel Systems

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