Christoph Rofka of ABB Turbocharging: step changes in turbocharging technology

From an engine design and operation perspective, what do you think have been the most important technological innovations during your career?

I’m a mechanical engineer by training, with a specialisation in turbomachinery, so one example from my own experience would be the improvement in the reliability of equipment for 4-stroke medium-speed engines operating on heavy fuel oil (HFO) starting in the late 90s. It’s funny to think about it with the challenges of zero-carbon and new fuel types that we’re facing now, but that work took us a decade.

From a wider turbocharging perspective, you could point at the IMO Tier II legislation, which led to a quantum leap in turbocharger performance. We had previously become used to incremental improvements in pressure ratios, and suddenly the legislation created an incentive for engine designers to utilise extremely high-pressure ratios, without loading the engine more. For a company like ours, which prides itself on its technological leadership, that was a great time. The quantum leap in pressure ratios meant we could bring to market our performance enhancements.

And after that we had the introduction of two-stage turbocharging, which has also led to a step change in performance. The technology is slowly becoming established in medium speed commercial engines: the genie is out of the bottle, and the technology will become increasingly widely used.

Finally, if we look away from turbocharging towards wider engine developments, the introduction of electronic controls, such as common rail, and variable valve timing have been significant.

As a mechanical engineer by training, how do you see the future role of the internal combustion engine? Will it remain the main mover for marine transportation in the future?

I expect engine technology will remain the prime mover of marine propulsion, particularly for deep-sea shipping. I have not seen any alternatives that come even close to the capabilities of today’s propulsion systems for deep-sea ships.

We might see the emergence of alternative solutions in short-sea market like fuel cells and complementary to auxiliary engines in deep-sea shipping, although they are only likely to gain a small place in the market.

There is likely to be a greater range of solutions in the short-sea market, where we are seeing some fragmentation, or in the high-speed market. But that range of solutions brings with it its own challenges – it is hard for OEMs to benefit from economies of scale with too many options.

So, we expect the prime movers of deep-sea vessels will continue to be fuelled by fuels with a low to zero carbon footprint. The transition will definitely be in the fuels.

How do you see the increasing focus on emissions reduction influencing fuel choices and product design considerations?

If we are serious about reducing emissions, we need to develop solutions that address emissions from the deep-sea fleet, which accounts for around 80 per cent of emissions from shipping.

From the big picture, we are in a transition phase. We do not know what the eventual future fuel or fuels will be and there are different perspectives within the industry. One interesting aspect of working at ABB is that we can see increasing demand for alternative fuel from outside the marine industry, from players looking at transportation solutions for alternative fuels.

But we have seen greater cooperation between different parts of the industry, to ensure that the industry can make its voice heard. This is important – we know at ABB that shipping’s comparatively limited share of fuel consumption means our influence over the supply side is limited. Fuel availability will be as important as technical solutions in a potential fuel transition.

From a product design perspective, when the topic of fuel transition was first raised, we were concerned that there would be a very wide choice of different fuels, forcing the industry to manage a wide range of fuels.

We are pleased that the choice has narrowed down to a level that the industry can handle, as we have now moved beyond discussion into development. The main engine developers are all developing solutions capable of burning alternative fuels, and we are involved in a range of development projects.

And positively we have seen much closer collaboration between OEMs, engine designers, and other system suppliers in order to develop solutions.

We spoke about the challenges of prioritising the development of solutions for different fuel types in Vancouver in 2019. How is ABB Turbocharging prioritising the development of solutions for the varying demands of ammonia, methanol and other fuels?

At ABB, we are concentrating on the development of solutions for a smaller number of fuels. You’ll be surprised to learn we are not investing in technology to deal with heavy fuels any longer. [Laughs]

We are closely working with OEMS to understand the impact of different fuels on combustion, to see where turbochargers can help support combustion and emissions. We know ammonia and hydrogen have different combustion characteristics. Ammonia combustion is relatively slow and challenging to maintain while combustion of hydrogen is fast and prone to knocking and glow ignition. This is likely requiring differentiated turbocharging solutions starting with quite different air-to-fuel ratios. However, this is not far enough advanced to lead to specific product development.

In parallel with this research, we are focusing on developing the performance of core turbine and compressor technologies, looking at higher efficiency and higher specific capacity.

This is leading us to focus on component level advances, so that we have a suite of components that can be introduced when the specific requirements of a turbocharger for an ammonia or hydrogen-fuelled engine are defined. The development of a suite of components around a core is also a cost-effective approach to managing development amid uncertainty – the largest proportion of the costs of product development occur during the final stages of a commercial launch.

But when it comes to commercial developments, we still have to avoid proliferation within our product range. I don’t see much scope for taking competing products to market, such as two turbocharger families within the same output range for different fuel types.

Apart from the fuels, we have introduced a new way of developing products to shorten the lead time to develop technology demonstrators and test engine installations before bringing new solutions to market.

This should shorten the development cycle to under two and a half years, compared with the previous typical five-year development cycle.

Away from alternative fuels, how do you see the rise in interest in battery hybridisation solutions influencing ABB Turbocharging solutions?

There are likely to be a range of different hybrid solutions. From a product perspective, we expect base engines to operate with a relatively high-power density. But the way I see it, the effect will be more of a simplification.

The greater risk is that the market fragments, both in terms of products and also variants, which would lower the potential volumes for new products, and ultimately impact the economic case. So you have to find a way to launch your product in a modular way to obtain some scale effect.

Turning to the two-stroke market, how is ABB’s focus on improving fuel efficiency and lowering emissions in its single-stage solutions progressing?

We have been continuing with the development of sequential turbocharging. We concluded the first official engine test of the Flexible integrated Turbocharging System for Two-Stroke Engines (FiTS2) a few weeks ago and expect to commission the first installation of the solution aboard a vessel in Q1 2021. We have established that the system offers fuel efficiency savings of up to 6 grams per kWh (3 – 5 percent). Both the major two-stroke engine designers have approved the system.

Looking further ahead, we are continuing to develop new single-stage solutions for 4-stroke diesel & gas engines. As part of our development project, we are targeting a higher maximum pressure ratio of 6.5 for single stage solutions from today’s 5.8, combined with efficiencies of over 70 percent for up to 5 MW output small- and medium-size turbochargers.

The prototyping process is far advanced, and we are planning to demonstrate its capabilities to the engine OEMs. This may lead to us beginning product development. This would represent the single largest step change in turbocharger performance for decades.

Finally, how is ABB planning to develop its two-stage solution for the four-stroke market?

While our two-stage solution offers significant advantages in terms of engine power density and fuel efficiency, the higher CAPEX and greater complexity of the solution has slowed uptake. We are undertaking development to make the two-stage turbocharging product more compact, lighter and modular.

With the exception of some four strokes at the lower end of the range where fuel efficiency is not a decisive factor, the development of a simplified design, which will improve its on-engine accommodation, will improve its applicability, particularly among upper range engines.