Tuning the engine through the air intake.


Combustion optimisation usually involves tricky remodelling of fuel injection parameters… but there is another approach – through the air flow.

“Currently all engines are static on the air intake side, you are limited to the ambient air available and the size of your turbocharger,” explains Marc Sima of FuelSave. “This technology gives you a whole new dimension to play with, as it adds new variables.”

It is also safe and resilient: a failure won’t interrupt engine operation.

The development has come about from another look at two slightly problematic chemistries. “People have individually played around with mixing hydrogen and methanol with the fuel supply – and both have drawbacks: hydrogen leads to slightly earlier ignition which means you can be in danger of engine knock, while methanol tends to delay it, potentially creating combustion issues,” says Sima.

But “there is a way to make the most of the synergy”, he says.

“First of all, water and methanol together in fluid form extends the premix phase,” says Sima, “while an introduction of small amounts of hydrogen and oxygen gives you a more complete burn”. However, taken alone this raises NOx emissions, created when oxygen and nitrogen fuse: “So, injecting the liquid again can mitigate this effect, by lowering the combustion temperature,” he explains.

Therefore, the FS+ system works by timed injection of hydrogen, oxygen or methanol mix at three different locations along the air intake – something that varies slightly from engine to engine – with enough pressure to reach the combustion chamber effectively. The necessary control is achieved by feedback from engine load and charge air pressure. As a result, the overall effect is “to enhance both volumetric and thermal efficiency”, Sima explains.

Further, he adds that it also raises the efficiency of the turbocharger, “which is suddenly able to push more air into the engine for the same amount of energy consumed as it’s cooler, and therefore denser”.

Importantly, the system is, at its heart, adaptable: “We aim to optimise the stoichiometric mix at every load phase,” he underlines: “In general we can configure the system for even higher fuel economies and cost savings or higher emission reduction as there is a trade-off; by default, we choose the best combination that performs within the emission tiers for which the engine is certified.”

Looking at it in more detail, the FS technology is fine-tuned for each application to yield the greatest payback in the load range for which the engine’s been optimised.

What it doesn’t need is a huge hydrogen tank. Instead, the FS+ system creates it on the spot by electrolysis, which safely splits water into H2 and oxygen. “This syngas generator has a price penalty, but it has several other advantages: as we produce and consume the hydrogen only on demand, there’s not so much worry about storage and handling, plus the related safety concerns ,” says Sima. That avoids some of the physical bunkering restrictions and regulatory issues. However, it’s worth noting that these gases won’t be premixed. “We separate the hydrogen and oxygen for safety reasons, injecting them independently,” he explains.

The methanol, however, has to be bunkered, so one element of the onboard kit is a storage tank, sized according to bunker intervals. Still, it’s only about 3% to 5% of the total fuel throughput, so – for the sake of round numbers – a ship with an annual bunker demand of 10,000 tonnes per year will use 300 tonnes of CH3OH: given a monthly bunkering call pattern, an installation would only need to find room for a 25 tonne capacity methanol tank onboard – something that shouldn’t prove too onerous.

Overall, the footprint is rather neat: the brains of the system, the control cabinet and PLC, is connected with double-walled, barrier monitored piping. It is ideally located close to the engine to minimize the installation costs and cut down response lag: the last part of the package is a modest, 1m3 service tank.

Interestingly, the system can be fairly small-scale: in fact it was first tried and proven onboard trucks before being applied to stationary power generators. This showcases another interesting point: it can be designed for each specific use case and sized according to the engine being supported.

Following these initial applications, it was installed on an auxiliary genset onboard a heavy-lift cargo ship, the MV Annette, where it stayed for two-and-a-half years. It speaks volumes that the same customer is now looking to fit the FS+ on six of its heavy lift cargo vessels, starting with the MV Trina. Here it will be applied to both the main 12.5MW 58/64CD MAN engine – the largest of this series – and three 1MW auxiliaries, for a combined engine power of 15.5MW per vessel.

Usefully, MAN ES is a stakeholder in this new project: Sima admits that, as one might expect, “there was some hesitance” in the beginning. Still, it helped that FuelSave was committed enough to engage in a detailed (and expensive) lab analysis on the technology’s effect on the engine after its lengthy run on the MV Annette. “We wanted to make sure – and have proved – there was no harm done to the operating engine… that was one of the big things to address, along with validating the system on a test bench in a laboratory environment. There’s no point in something that saves fuel but damages the engine in the long run.”

It’s a fairly sophisticated piece of kit, although a number of developmental hurdles have not arisen from the technology itself, but the rules. The system’s novelty has pushed the FuelSave team into a pioneering role: “The methanol is handled as a low flashpoint fuel and we are taking care of the hydrogen element under the IGF code. But although there are some general guidelines, there are currently no fixed regulations in place yet,” says Sima. Further, “on the MV Trina there are several components that haven’t been used onboard a vessel before” he adds. As a result “we are working closely with class to define potential solutions”.

So, what can this technology achieve? There’s an average drop of around 40% in particulate matter, 33% black carbon and 50% from NOx emissions but most importantly, the technology can carve an impressive lump – between 10% and 15% – from the fuel bill. The company is so certain of its figures that it is contractually guaranteeing 10% net OPEX savings.

This is taking the full business analysis and complete energy balance into account, asserts Sima: “When we talk about net savings, that’s what lands in the pocket of the customer after deducting the cost of onboard consumables, such as potable or technical water, electricity from the genset, plus air and methanol.”

As a result, he predicts that given fairly typical fuel prices, around half the world’s merchant fleet could see payback inside three years – especially if upcoming emission measures, such as the EU Green Deal, are taken into account.

Certain vessel types present a particularly convincing case: “Cruise ships have an extremely high onboard power demand, so the four-stroke engines supplying their hotel load could use the FS+ system… potentially seeing a return under two years.” Sima adds that the technology will also be useful for other vessels with a large auxiliary draw, for example crane ships, heavy transport vessels, cable layers, drill ships, accommodation platforms and any number of those spending significant periods on dynamic positioning.

However, while the FS+ is currently only applied to four-strokes, this will change, as Sima hopes to see the technology extended to two-stroke engines before the end of next year, broadening its applicability for main propulsion, slow speed engines.

Further, although the system may find a role onboard a swath of the current fleet, Sima predicts that – unlike many abatement technologies – it will prove itself even more useful in future.

“Timing the injection into the air intake means we can play around and influence the premix phase, flame point temperatures and ignition; plus we can also very effectively cool the combustion temperature when we want to,” he points out. “Therefore it can also be applied to new fuels with different characteristics, helping to make them more commercially competitive while mitigating the remaining emissions.”

He adds: “As this technology can help regulate engine behaviour, it can also assist the industry in its clean fuel transition.”

Unsurprisingly, given it’s current applicability, future-proof potential and last but not least, that bold, contractual savings guarantee, the FS+ is gathering a fair amount attention. “A lot of people are eyeballing the installation onboard the MV Trina,” says Sima: “We’ve promised to share the results with quite a few interested parties.”

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