Well, hydrogen is also dangerous.

@Davemart, Storing liquid CO2 and recirculating it to the methanol production site, you think?

Agree, tailpipe emissions is not a problem for modern ICE cars. However, this information has not yet been embraced in the public opinion.

We could also consider that the peak efficiency of diesel engines could be improved significantly in the future. This would be by applying state-of-the-art technology (soon to be introduced…) from HD engines (plus some refining…) also on LD engines so that they also could reach 50% thermal efficiency. Add a rankine bottoming cycle to utilize wasted exhaust heat and we are close to 55%. This is a relative improvement of about 25% (55/44). In my own assessment, downsizing, reduced friction and pumping losses plus better turbomachinery (all part of the concept above) should yield at least similar relative improvement at low load, and, likewise, also for the drive cycle averaged efficiency. To put this in perspective, it is not possible to improve the (drive cycle average) efficiency for an electric motor from 93% by a factor of 1.25. Anything over 100% would simply be against the laws of physics; regardless of if we speak about peak efficiency or average efficiency. On the long term, we will eventually run out of fossil fuels and the so-called e-fuels will not be as efficient as electric drive even if they are utilized in diesel engines but in the meantime – while we are still producing electricity from fossil fuels – it seems stupid to rule out the diesel engine.

It would be interesting to see some actual data, e.g. EGR tolerance and how the combustion behaves near the lean limit. An issue, which appears to have been beyond the scope of this study, is that emission control is not trivial on a lean-burn engine.

It has been some time since we heard any news from Achates. Albeit that this article sounds impressive, we should also note that also conventional engines will be able to meet future CARB and US EPA emission limits. In due time, of course, since engine manufacturers are normally in no hurry to meet emission limits before they are enforced. In my quick assessment of the article, it seems as Achates might be able to meet these limits with less aftertreatment hardware and thus, reduced cost compared to a conventional engine. Nice!

@TC, right! I could add that EPA was strongly promoting methanol (including research funding) but auto&oil industries were not very enthusiastic. In principle, there were no strong stakeholders for methanol, in contrast to ethanol, which was backed by farmers. Among potential e-fuels (e.g., synthetic gasoline and diesel fuels, hydrogen, etc…) from renewables, methanol is among the most energy efficient but there are still significant losses in the conversion. On the other hand, “freewheeling” wind turbines and other renewable resources when there is surplus of electricity is, of course, worse than utilizing them for producing e-fuels. An obvious showstopper in my mind could be that such a plant should, preferably, be operated 24-7, rather than intermittently.

@SJC A closed oxygen system could also be used on combustion engines. CO2 and water will be removed from the exhaust, which is then recirculated, and oxygen is added to the mixture. Instead of nitrogen as the “bulk” gas, argon could be used. This gas mixture has much higher polytropic index (Cp/Cv) than air, which improves efficiency. The added benefit is a zero emission (!) engine. Needless to say, this system would be impractical on road vehicles, but it has some specific niches, e.g. in submarine applications.

Nikola, the biggest scam of this decade? In competition with Mr. Musk, of course. Nothing but vaporware! Nikola Tesla would turn in his grave if he knew how these two have misused his name in the last decade. https://www.youtube.com/watch?v=88fWUZhYb04 https://www.youtube.com/watch?v=56862W24HK8&t=10s

Nice to see that Achates receives funding. However, I cannot comprehend why it has to be combined with a hybrid drive at this stage. This is of course a possible option, and probably require some additional work in comparison to a traditional piston engine, but the priority now should be to complete engine development and make it ready for production. Hybridization can wait.

Motor/generators have been considered already long time ago but since this option is less efficient than “direct” drive it is not very attractive. Cost is another significant issue. Possibly, integration in a hybrid drive system could give some synergies that outweigh – at least to some extent – the efficiency issue of the motor/generator option but higher cost would still be a remaining issue. On the top of my head, I can recall that a Japanese manufacturer looked at this option, but it was a couple of decades ago and it did not reach production. The turbocompund systems used on aircraft engines are different animals than the HD engine but could be a topic for another discussion. With modern technology, such aircraft engines could be competitive with turboprop engines.

Turbocompound engines have been in production in HDVs since (about) the early 90’s. Various manufacturers have used the technology from time to time but somehow, nobody has ever been able to utilize its full potential regarding fuel consumption, and after a couple of years, production of most engines has been stopped. Now, it seems as if we have new attempt. We do not have many details in this article but if the Volvo engine can improve FE by 6%, it would be a HUGE improvement over conventional technology.

This is not the only company in this business. During the last couple of years, I have been stunned to find that companies in the US (seemingly) openly market things like “EGR delete”, “DPF delete”, “DEF (urea SCR) delete” and “Complete delete” kits. To me, it is surprising that US EPA has not reacted to this much earlier. I know there are chip tuning kits available also in the EU. Some of the “dark” cases also imply that the customer may be encouraged to remove, or tamper with, e.g., DPF and DEF, without getting any fault codes on the display. So, the situation here in the EU is not much better but at least some member states make road-side inspections to investigate and curb the problem. EGR is hardly used anymore on new HD vehicles in Europe (as in the USA) but, of course, extensively on LD vehicles. Albeit if no “delete” of hardware is made in the case of chip tuning, it might nevertheless increase emissions, primarily NOx. This might be, for example, by changing injection timing and reducing EGR (on LDVs). This is particularly tempting to do during “off-cycle” driving conditions. Well, now you perhaps recall similarities with the VW “Dieselgate” case. It is very annoying to find that when new diesel vehicles (finally) can reach very low emission levels of all emission components and under practically all driving conditions, the system is tampered with, not only by vehicle owners themselves, but by commercial companies and this on a profit basis. I agree with previous comments that such companies should be put out of business.

In the past, when bunker oil w/o any requirement that necessitated exhaust aftertreatment was the benchmark, methanol was “not viable”. Facing complicated aftertreatment with bunker oil, or LNG, as options, methanol suddenly seems very competitive. As an energy carrier in general, methanol is also competitive with hydrogen.

Just a short note about the Junkers engines: Jumo 207 was far more advanced than Jumo 205. Among other things 207C had a turb-supercharger. In particular, an experimental version of the Jumo 207C (as basis for Jumo 224 development) could be mentioned. Below is an excerpt from one of the links below. We can leave Jumo 224 for later discussions... A power level of 2,210 hp was pretty good from an engine of this size, i.e. roughly similar as the most powerful versions of RR Merlin (e.g. Spitfire) and DB 605 (Messerschmidt Bf 109), in spite of that these engines had roughly double cylinder capacity. “While the Jumo 224 was being designed, a Jumo 207C was tested to its limits to better understand exactly what output could be expected from the Jumo 224. Tests conducted in late 1944 found that with a 200 rpm overspeed (3,200 rpm), intercooling, modified fuel injectors, and 80% methanol-water injection, the Jumo 207C was capable of a 10-minute output at 2,210 hp (1,645 kW)—twice its standard rating of 1,100 hp (820 kW).” Junkers Jumo 207 D-V2 In-line 6 Diesel Engine | National Air and Space Museum (si.edu) Junkers Jumo 224 Aircraft Engine | Old Machine Press Kudos to SJC for actually participating in OP engine development, which I suppose is rare on this forum. My own experience is mainly limited to much more conventional diesel engines.

Nice to see this concept getting closer to production! The Germans got pretty far in the development of the OP concept already during WWII but they lost the war, as we know, and somehow, the industry lost interest in OP engines. Now Achates/Cummins are aiming to advance the technology one step further and it will be exciting to see the outcome.

"Too late" was also the verdict on this engine. Perhaps it could have been competitive with this "open fan" propeller. https://en.wikipedia.org/wiki/Napier_Nomad

Thanks, SJC, for the comment about NOx! I was about to write that myself. Hydrogen has among the highest flame temperatures of any fuel. Thus, its NOx production is the highest I know among potential engine fuels. NOx production can be abated with “in-cylinder” measures and in the aftertreatment system, but this is far from trivial. I will not elaborate on that further here. Regarding NOx, hydrogen is far from a “clean” fuel.

It would be nice to see this engine in production.

https://www.volvobuses.com/en-en/news/2019/may/strong-demand-for-volvo-energy-efficient-hybrid-buses.html

Why do you need a V8 in a school bus? This would be an ideal application for hybridization and downsizing of the engine.

As I have mentioned many times before, EVs will not make the particle problem go away. It could even be worse...

DME might be a diesel engine developer’s wet dream. However, it will be very difficult to create a new fuel infrastructure for a new fuel with completely different properties than most of the mainstream fuels.

Has anyone seen any comprehensive information on this engine? The article does not say anything. Another information that came out recently was about a Chinese diesel engine with 50% efficiency. While the relative difference between these engines is about what we could expect for diesel and otto engines in general, the article about the diesel engines does not say anything either. Is this just a coincidence? https://www.yicaiglobal.com/news/china-weichai-power-unveils-first-over-50-thermal-efficiency-diesel-motor

I would say that real advancement in engine technology is usually difficult to find. Most of the technology we find on new engines has normally been known for some time before we see it in production. Oftentimes, we can receive such information from the suppliers to the automotive industry. Sometimes such innovation never seems to mature or tends to be too expensive or, by the end of the day, has significant drawbacks or some other issues.