New ORNL process allows full recovery of starting materials from tough CFRP
High-powered EV charging network, IONNA, begins operations in North America

Argonne, Achates Power developing hydrogen-powered opposed-piston engine

Researchers at the US Department of Energy’s (DOE) Argonne National Laboratory are partnering with Achates Power, a leader in designing opposed piston, two-stroke compression ignition engines (earlier post), to develop a hydrogen-powered engine primarily for long-haul commercial vehicles.

Argonne scientists recently began testing the hydrogen-powered engine in a demonstration that yielded promising results, said Essam El-Hannouny, Argonne principal engineer.


For the first time at Argonne, we demonstrated that the opposed-piston engine can run on hydrogen and produce power. We are in the early stages, but the testing provides the data we need to make changes to the combustion mode or other parts of the engine to improve performance.

—Essam El-Hannouny

Argonne’s research facilities include a single-cylinder opposed-piston engine platform with a newly designed and optimized combustion chamber for medium- and heavy-duty engine research. Facilities also include a hydrogen delivery and storage system.

The project builds on a longstanding relationship between Argonne and Achates. The venture marks the first time Achates is testing hydrogen on its engine, said Laurence Fromm, executive vice president and chief commercialization officer at Achates Power.

In the transition away from fossil fuels, there is a growing focus on developing and refining hydrogen combustion in general and hydrogen combustion in opposed-piston engines specifically. In partnering with Argonne, we can explore some of the combustion concepts developed at Achates. We can make refinements based on data generated during testing. Our goal is to develop an efficient, cost-effective hydrogen combustion opposed-piston engine that could be transformational for the transportation industry.

—Laurence Fromm

This is not a completely new idea. But recent technologies like electronic controls, electronic fuel injection and sensors that provide critical feedback can be applied to advance the opposed-piston engines of today. The opposed-piston engine has an enormous potential for decarbonization by running on hydrogen fuel.

—Douglas Longman, Argonne’s group manager, Advanced Power Systems Research.

The advanced opposed-piston engine has numerous advantages for hydrogen combustion compared to conventional engines. One advantage is the simplicity of its design. The innovative piston architecture refined by Achates Power sets two pistons moving in opposition in one cylinder. The design eliminates cylinder heads, which are a major cause of heat loss and inefficiency in conventional engines.

This is significant because hydrogen fuel has high reactivity and low ignition energy.

—Essam El-Hannouny

The engine’s two-stroke combustion cycle produces twice as many power strokes per crankshaft revolution as a standard four-stroke engine. In this way, it delivers more power. The engine is also lighter, less expensive and easier to build.

Achates is targeting its hydrogen-powered engine for medium- to large-size commercial trucks, off-road vehicles for industries such as mining and agriculture, and military vehicles.

Argonne’s testing is just getting under way. Achates will use the combustion and emission data generated during initial testing to update its computer models. The goal is to refine the engine design and improve combustion strategies. Achates engineers work remotely and on-site at Argonne to assist with engine calibration and monitoring.

The Argonne/Achates project was funded through DOE’s Vehicle Technologies Office, in the Office of Energy Efficiency and Renewable Energy, as part of DOE’s $133 million in funding for new and innovative advanced vehicle technologies research.


Ski Milburn

The rapid expansion of green hydrogen production is has already driven production costs to well below half what they were, on a trajectory to match the retail price of gasoline and diesel fuel by 2040.

First undertaken to support fuel cells and the hydrogen economy, this also foretells a revival of the internal combustion engine, currently threatened by decarbonization.

H2 ICE have some NOx issues, but relatively easy to solve in an exhaust stream with no carbon compounds. Thermal efficiency is half a fuel cell, but capital costs are so much lower that for many end users, this will be more than “good enough.”

A fly in the ointment is the hot edges of the exhaust values in a conventional engine can lead to pre-ignition issues, especially under high loads. This is resolved in engine types where the inlet and exhaust ports are far apart, like in Wankel and Opposed-Piston types.

Expect more developments on this subject.


Thanks Ski.

That sounds as though you have expertise in this area....



I am a bit surprised, on reflection, by your statement:

' Thermal efficiency is half a fuel cell, but capital costs are so much lower that for many end users,'

Here is a statement supposedly sourced from Cummins, who have both so have no axe to grind:

' Internal combustion engines tend to be most efficient under high load, which is to say, when they work harder. fuel cell electric vehicles, in contrast, are most efficient at lower loads.

For heavy trucks that tend to spend most of their time hauling the biggest load they can pull, internal combustion engines are usually the ideal and efficient choice. On the other hand, vehicles that frequently operate without any load, tow trucks or concrete agitators, tippers and tankers, they may be more efficient with a fuel cell.

Fuel cell electric vehicles can also capture energy through regenerative braking in very variable duty cycles, improving their overall efficiency.'

The Achates Power opposed piston two-stroke May wring a bit more out of a liter of H2 than a conventional four stroke engine, but at the end of the day, cost per mile and total cost of ownership determine the winner in a market economy, even when all vehicles must be zero emission.

Most of these commercial vehicles are working a full shift, and some more than that (team long haul driving for example).

Fuel cost for 100,000 miles per year x 10 years is usually much more important than the acquisition cost of the power plant.


The small version of this could be a good range extender you've got low sulfur diesel at gas stations to get plenty of miles out of every gallon with a plug hybrid. The hydrogen availability is always going to be one of those issues, it works okay at airports and truck fueling yards and so on but we have to be practical about where are you getting the fuel energy.


Hi eci:

I hope I was not too much the grumpy old man the last time we discussed stuff! The old I can't do much about, unfortunately, but I do try to contain the grumpiness.
I await my elevation from the Pope to a position as a living saint, which seems to be unaccountably delayed, perhaps on the grounds that I ain't a Catholic.

The critical point you mention:

' Most of these commercial vehicles are working a full shift, and some more than that (team long haul driving for example).'

Bunging in more hydrogen takes minutes, you don't have to hang around to charge a battery, which in any case if there were substantial numbers of very long haul BEV vehicles on the road would pose considerable challenges to the local grid, as they take one heck of a lot of oomph.
Somewhat ironically, one of the work arounds proposed for that is fuel cells at the station, converting renewables to hydrogen to provide a boost as required for charging:

The reason why they do that instead of directly using power from, say, a dedicated solar array in the midwest to charge the vehicle is not only to provide power when the sun ain't shining, but to spread the load so you have a much smaller array.

Additional stationary batteries at filling stations are only anything like economic for around 4-6 hours, and are way too expensive for round the clock.

Costs may be decreasing, but so is that of fuel cells.

The other big cost in heavy transport is maintenance.

Fortunately both BEVs and Fuel cell vehicles have excellent records in that respect, and can substantially reduce that element of cost.



By far the biggest, and I do mean by far, market in the world for long distance heavy trucking is China.

They are to build 1200 hydrogen filling stations around the country for heavy trucking in the next couple of years.

Infrastructure projects in China including renewables installation and high speed rail normally happen, although they are typically a bit messy round the edges, with poor capacity utilisation etc.

But effectively they are likely to demonstrate the tech, and iron out or at least highlight any issues.

There are also very substantial projects underway almost everywhere in Europe, with France, Germany and the low countries amongst others in the process of installing such a network.



From what I've seen, fuelling one H2 car or truck is relatively quick (around 10 minutes all-in), but then you have to wait a long while before you can refuel the next one, because of the required pressure.
That's perfectly fine when your main goal is to fill one Mirai in front of television cameras, but it's a non-starter at a busy trucking depot. Is there a workaround, other than storing large volumes of high-pressure hydrogen? No one in their right mind would allow that within 10KM of populated areas.

Any data on why batteries stop working after 5 hours? I've only ever heard it from you. I assume you mean "battery" in a very specific sense (LiFePo4?), or do you mean it in a more generic way, like "reservoirs act as batteries for electric dams"?


Hi Bernard:

What is likely to go in, at least in Europe, is Daimler's sLH2 tech, which has no such limits:

Since the tech seems to be rapidly improving, I am not going to check back for my references, but AFAIK other installers of hydrogen stations for trucks, as opposed to cars, are also well aware of the limits which early stations designed for infrequent cars had, and have upped their game too.

Roger Pham

@Ski et al,
Good point about the advantage of Achates engine having no hot spot for premature ignition of the H2. However, in diesel compression-ignition mode by direct fuel injection, cylinder hot spot is not a problem because the fuel is injected at the last moment near the end of compression stroke.

Hydrogen alone is not good for diesel engine due to the low cetane number of H2. This necessitate the addition of about 10% DME to the Hydrogen to ensure reliable ignition, due to the high cetane number of DME. This is easy to do, and the DME can be mixed with H2 already in the tank, although the DME will be liquefied and will settle at bottom at the pressure of H2 tank, necessitates a metering device to adjust the admission of the DME to mix with the H2 during direct injection.

The H2 will mix very rapidly with air, thus will result in much lower NOx than conventional diesel fuel. A diesel SCR system will have much longer interval for filling of urea, thus will be more economical exhaust wise, and may NOT need an expensive DPF (Diesel Particulate Filter) anymore, thus much less-costly exhaust emission treatment than current diesel engines.

I expect that maximum efficiency will be above 50% when using turbo-charger with exhaust turbine energy recuperation, thus can nearly match the efficiency of the Fuel Cell running at the same power setting. At lower power, a battery can provide the power needed during less demanding load when engine efficiency will be sub-optimal. Thus, a hybrid electric set up will allow the engine to operate at above 50% for nearly all of the times.

Roger Pham

Continued from above: Alternatively, the H2 can be mixed with the air at the intake manifold, and thus only a small amount of DME can be directly injected at near the end of compression stroke to initiate the combustion. In this way, liquid H2 (LH2) at low pressures can be used without requiring complicated high-pressure fuel pump, which can be difficult to generate high-pressure LH2 with mechanical pump.
Seems like a promising way to very efficiently utilize H2 at the efficiency of Fuel Cell, without the high cost of Fuel Cell.


Hi Roger.
Reading this it would appear that Cummins at least are going for a solution which does not involve DME:

' For example, differences in the physical properties of hydrogen impacts how fuel and air are metered and injected. Pre-ignition is a greater problem for hydrogen engines than for gasoline engines, because hydrogen is much easier to ignite. Direct injection is one way to overcome pre-ignition issues. Direct injection systems introduce fuel–hydrogen, in this case –directly into the cylinders, rather than into the intake manifold or ports. If the injection takes place at a time when the inlet valve is closed, backfire conditions are avoided. Another solution is to completely design the combustion system for hydrogen. '

Of course, being entirely innocent of any expertise in the subject whatsover, I may have entirely misread what they are saying, but at least they do not appear to mention DME at all!

What do you reckon?

Roger Pham

Hydrogen needs spark ignition due to much higher auto-ignition temperature of Hydrogen at 550 dgr C, vs diesel fuel at 250 dgr C, and a little lower compression ratio, hence less efficient as would compression-ignition like in a diesel. To burn Hydrogen in a diesel engine would require injection of small quantity of either diesel fuel or DME to start the ignition, then the Hydrogen will burn after the initial ignition start by the DME.

Roger Pham

Continued from above: I forgot to mention that the layout of the Achates engine would make spark ignition difficult due to the lack of engine head, hence no place to mount the spark plug centrally within the combustion chamber. So, running in diesel cycle using either diesel fuel or DME to start the ignition for Hydrogen would be easier, more practical, and more fuel efficient. Plus, the vehicle can still run on diesel fuel wherever Hydrogen won't be available, making it essentially a dual-fuel engine and thus is very versatile.

Good to see that you have not lost your sense of humor, Davemart. I actually appreciate that you and a few others here are willing to take on unpopular positions (unpopular using the measure of market share, if that is a fair way to cast it). It seems the comment section would be nearly vacant otherwise.

I agree that electric charging of the volumes of semi’s that flow through a busy Flying J or Pilot diesel station is going to be a daunting task.

But consider the case for H2 resupply: where a refueling depot requires one tanker of diesel to service a given volume of trucks, it will require 16 tube truck deliveries of hydrogen. Even if that were converted to electrons for BEVs, it would be an impressive logistics feat to maintain the supply.

That is before even mentioning the cost of the fuel.

The 16x H2 supply referenced above is for vehicles using fuel cells. Burning it in piston engines would require that quantity to be roughly doubled.



You do not source your figures, and consequently are not explicit about nor do you apparently examine let alone justify the assumptions underlying them.

I have no idea where you get your 16 times lower capacity for a hydrogen tanker from, as you do not say,

That is in the right ballpark for gaseous delivery, but according to the DOE it is around 14 times less, not your 16:

They then go on to say:

' . The liquid pathway is more economical than gaseous trucking for high market demands (greater than 300 kg/day) because a liquid tanker truck with a capacity of approximately 4,000 kg can transport more than 10 times the capacity of a typical steel gaseous tube trailer.'

ie in the ballpark of a diesel trailer.

The typical objection made is about energy efficiency.
Since renewables are rapidly falling in cost, that element is fair game to be traded off.

In addition pipeline delivery of hydrogen either in dedicated pipes or blended in natural gas is going to be an important factor going forward, in both Europe and China as both are in the process of building out networks

And where renewables are conveniently available, another possible pathway is simply to make the hydrogen where it is needed.

Analysis depends on making assumption etc explicit.

Your contention that I am some sort of outlier is, I would argue, the exact reverse of opinion within the trucking industry, which almost universally is going for hydrogen for long distance heavy trucking, which you simply dismiss as not worth considering, and with it the overwhelming bull of expert opinion on the subject.

A contrarian position is fine, but the assumption that an overwhelming consensus of expert opinion is not worth considering is to put it mildly odd in someone who attempts informed 'inside' opinion on the industry.



I would also add that were I in your position seeking to inform people of the state of play in the heavy trucking industry, as well as general transport, instead of simply dismissing what is an overwhelming consensus in the industry and presenting your own views not only as though they were the consensus of expert opinion, but absolutely the only sensible one, I would be repeatedly highlighting what the real consensus is, and indicating and vigorously arguing for my own position.

There is absolutely nothing wrong with differing from the consensus, but to present ones own views as though they were the consensus of expert opinion when they ain't is just wrong, and deeply misleading, IMO.

I have no idea what your own qualifications are, but the folk at Daimler for instance who plan their route ahead include the most highly qualified they can find or exist in the industry.

Simply to seek to dismiss their opinions without in any way presenting what they actually argue is deeply flawed and disrespectful, in my view.


It is perfectly practical anywhere which is reasonably uncrowded to generate hydrogen on site or nearly enough so that investment in transformers is not needed with a fairly compact solar or wind array.

So for instance to truck across the US with the possible exception of the coastal regions a zero emission local solution is to hand.

So there would be zero trucks.

That is way more difficult for BEV solutions, as the array needed to provide for peak usage would be massive.

In fairness since I am picky with other people I should point out that the obvious hassle is cost, and large reductions are needed in the cost of green hydrogen.

It appears though that that is well in hand.


It is also worth noting that all the companies developing hydrogen truck for long distance heavy haulage have battery solutions to hand for lighter loads and shorter distances.

So if they thought they could manage with that, why not stick it in big long distance trucks too, instead of spending large sums developing a radically different technology?

Unless the directors in the trucking industry have almost universally lost their marbles, there is no way they would do so,

And they would have had to pretty well corner the market in effective imbeciles who have nevertheless managed to obtain advanced degrees in all relevant disciplines to develop this unnecessary solution.

The obvious answer is that none of this is true, and that they are developing hydrogen for long distance heavy transport because it is the most realistic way of making it work.

Maybe a magic battery will drop out of the sky,

Maybe it won't.

I am relieved that they are not counting on it.


Mercedes just recently achieved a memorable 40-ton transport across the Alps with a battery powered truck. The total capacity of the battery pack consisted of three 200kWh LFP batteries totaling 600 kWh. There is no mentioning of the energy density of the cells but I assume that they must have been i. a. w. the SOA around 150 Wh / Ltr.
The Faradion Na-ion chemistry can now exceed the energy densities of LiFePO4//graphite Li-ion batteries with rapidly converging cycle lives, similar rate performance and charge acceptance. Faradion's newest lab achievement reached 230 wh / kg; that is almost double of what Mercedes' LFP battery managed. Additionally, this battery can be discharged to 0-V without suffering any damage. With such technical advances, who needs a questionable H2 technology?



' With such technical advances, who needs a questionable H2 technology?'

Mercedes, for one in their opinion.

Perhaps you are unaware that under the name of Daimler that is who is developing the sH2L tech we have been commenting on in the last couple of days?

Steve Reynolds

I suspect the quickest way to significantly reduce CO2 emissions from long haul trucks would be to use LNG fuel. It could be adopted quickly, since it would immediately save fuel cost for the truckers.
But political insistance on zero emissions is likely making adoption of LNG risky because it could be outlawed too soon.
This is making perfect the enemy of the good.

Roger Pham

@Steve Reynolds,
Agree. Further reduction in CO2 would be the phasing in of biomethane into the natural gas supply. The biomethane will incorporate green H2 from solar and wind energy to double the yield of biomethane per unit of biomass. Additionally, the green H2 could be added to the natural gas/biomethane mixture to even further reduce the fraction of fossil fuel.

All of these could use existing natural gas filling, storage, and transmission infrastructure to minimize new investment cost. Much cheaper and much quicker to implement than investing in a whole new H2 storage, transportation and filling infrastructure and new fuel cell manufacturing and servicing infrastructure....and the same advantage over battery-electric trucks with expensive batteries, motors, fast-charging, and servicing infrastructure.

The transportation industry is very cost sensitive, so anything to minimize cost increase for the maximum CO2 emission reduction would gain the most traction.

@Davemart: I am counting trucks on dealer lots, or in fleets, not press releases. I don’t mean that comment to be flippant, just deadpan factual.

I don’t follow markets outside of North America, this continent is big enough to keep me busy, so there may exist cheap, plentiful liquid hydrogen at retail elsewhere.

Here in California, which is practically speaking, the only place selling H2, it is crazy expensive and the stations are out of service about 50% of the time. These are simply the unvarnished on the ground facts.

At any time that H2 competes economically with actual on the road commercial BEV vehicles (or for that matter, light duty vehicles) I’ll take interest.

But out here on the frontier, the vehicles and infrastructure is vastly outnumbered by BEVs. I’ll leave it to readers of GCC to catch the numbers, which are regularly reported here.

The comments to this entry are closed.