In times of extensive discussion about e-mobility and zero emissions, internal combustion engines are under fire. Christoph Rofka, Head of Technology at ABB Turbocharging, is nonetheless convinced: Anyone writing off the internal combustion engine has failed to recognize its potential.
charge!: The internal combustion engine has fallen into disrepute. Many are prophesying its demise.
Christoph Rofka: But the internal combustion (IC) engine is, and will be, a success story. It is the principal prime mover that transforms the fuel energy into useful mechanical power. It does it very efficiently and consistently, is very robust and requires very little upkeep. You can install an IC engine practically anywhere. Its scope of application is enormous, from emergency generator-sets in hospitals to 200 MW baseload power stations, and for the propulsion of a small boat up to a 400 m container ship. In addition, they are enormously flexible in terms of fuel and fuel quality. These are all points in favor of IC engines. The challenges are its emissions, e. g. nitrogen oxides, particulates and CO2.
So, a success with snags. What can be done?
I cannot follow the logic of simply saying that IC engines must be replaced. They must be developed further in a sensible way. There is still great potential in a technology that might appear to have reached its limits. But we need commitment, imagination and money for innovation, which legislation must also be prepared to support. Otherwise, not much will happen. Unfortunately, in recent years the development steps have been on average rather small.
The IMO wants a reduction in the total emissions from shipping of 50 percent by 2050 and a reduction in the average carbon intensity of 40 percent by 2030 and 70 percent by 2050, compared to 2008. These are ambitious targets.
We are actively supporting these goals. The industry is now challenged to come up with the relevant measures. But there are different aspects to be taken into account such as ship design, equipment, and operation. If we want IC engines to be a convincing factor in the future, we have to press on with technological advances. In the short to medium term, significant increases in efficiency and reductions in raw emissions are still possible: Via new designs and internal changes, via further attenuation of emissions by means of cleaner fuels and by optimizing exhaust aftertreatment. Long-term, and above all with regard to the year 2050 targets, IC engines must re-establish themselves as the source of power, by burning alternative fuels and synthetic fuels.
What can ABB Turbocharging’s contribution be?
A very decisive one, thanks to clever air management by means of optimized turbocharging and variable valve timing, because both are key technologies for engine performance. Looking to the future, they will gain importance in terms of the new synthetic fuels and a potential deterioration or greater variation in fuel characteristics. But even short-term, with fossil fuels, turbocharging and variable valve timing possess huge possibilities for reducing raw emissions and raising engine efficiency.
How exactly?
ABB’s Power2 two-stage turbocharging system is not merely a proven way of multiplying power, but Power2 also contributes to as much as a 60 percent reduction in NOx emissions. The system has been successfully introduced to the market (more on Power2 in the sidebar). At the same time, we are further developing this technology and making the system lighter and compacter and, as such, more attractive for engine builders.
In what direction is variable valve timing being developed and what can it do?
We have already tested our Valve Control Management (VCM) system intensively on gas engines and been able to extract considerable improvements in engine power density, controllability, efficiency and robustness, while at the same time proving VCM’s durability. All tests show clearly the positive effect of VCM on stable combustion during fluctuations in fuel quality and thus on maintaining high engine performance. More recent studies have also revealed interesting potentials for VCM on diesel engines. As well as increasing the width of their operating range, power density and efficiency, VCM can also be utilized to control the temperature of exhaust gases reaching aftertreatment (more on VCM in the box). With the potentials described here and its contribution to ever more popular modular engine concepts, going forward VCM is set to gain and gain in importance.
So-called next generation fuels are going to replace fossil fuels. What are the alternative fuels and what influence will they have on turbocharging?
Long-term, the vision is to replace fossil fuels as far as possible with alternative and synthetic fuels. Biomass and excess electricity from wind and solar energy production can be converted into intermediate energy reserves (Power-to-Fuel or E-Fuel) – for example to gases like hydrogen, methane or into liquid fuels, which is a somewhat more elaborate procedure. With the fuel from the intermediate reserve, electrical or mechanical power can be produced. Again, IC engines come into their own. In terms of turbocharging, according to the combustion characteristics of the fuel and the combustion process, it might be necessary to rematch the turbocharger’s turbine and the compressor and apply other materials. Variable valve timing systems like VCM will play a central role in all this.
« Even short-term, with fossil fuels, turbocharging and variable valve timing possess huge possibilities for reducing raw emissions and raising engine efficiency. »
VCM on diesel engines
Stricter NOx and soot emission regulations are now on the horizon for land-based diesel engine applications. These regulations apply for a wide range of operating points and ambient conditions and can only be fulfilled with catalyst based exhaust gas after treatment. These systems are only effective and reliable within a constrained temperature window, making it necessary to elevate the exhaust gas temperature, especially at low loads and low ambient temperatures. In-house simulation studies have shown ABB’s variable valve-train VCM to have considerable potential in this area. By continuously varying the valve timing and lift, the engine airflow can be controlled in order to achieve a higher exhaust gas temperature. VCM could also be employed as part of a cylinder deactivation system, which may be additionally required to reach the target exhaust temperature level under harshest conditions.
In combination with ABB’s two-stage turbo- charging system Power2, VCM also enables an improvement in fuel efficiency and transient behavior and an extended engine operating map by adapting charging conditions to each operating point.
With the described regulations now looming, the application of VCM as proposed here, with all its additional benefits, is catching the atten- tion of the OEMs.
The age of E-Mobility has dawned in the automotive industry. Can this branch be compared with the large engine sector?
A parallel aim of E-Mobility is to reduce noise and noxious emissions in ever denser conurbations. This is a strong driver of electrification in the automotive industry. For transport over long distances by methods with high power outputs, like those of ocean going vessels, this technology is neither available nor feasible. At the same time, new combinations of electrical and engine power have been developed, in the form of hybrid drives. It’s all a question of where this technology can be usefully employed – i. e. for which operating profiles do hybrid systems make sense and where they can be used cost-efficiently.
And what’s your answer?
Hybrid technology is appropriate in applications where there are short peak loads and extreme and sudden increases in load, for example in offshore supply vessels or for ferries. Hybridization will be adopted in certain applications, and a number of basic systems including non-electrical alternatives, will be possible. Per se, the technology is less disruptive than a change to synthetic fuels.
So, the internal combustion engine can still look forward to a long and interesting life?
In future scenarios the IC engine will have to reposition itself in the same way that synthetic fuels will need to establish themselves as intermediate energy sources. But even fuel cells, if one day those ever become a valid performance unit for our applications, can be turbocharged. It’s a big playing field. The trick is to fully leverage the potential of the internal combustion engine and to position it as an attractive technology in the era of CO2 neutrality.
VCM on diesel engines
Stricter NOx and soot emission regulations are now on the horizon for land-based diesel engine applications. These regulations apply for a wide range of operating points and ambient conditions and can only be fulfilled with catalyst based exhaust gas after treatment. These systems are only effective and reliable within a constrained temperature window, making it necessary to elevate the exhaust gas temperature, especially at low loads and low ambient temperatures. In-house simulation studies have shown ABB’s variable valve-train VCM to have considerable potential in this area. By continuously varying the valve timing and lift, the engine airflow can be controlled in order to achieve a higher exhaust gas temperature. VCM could also be employed as part of a cylinder deactivation system, which may be additionally required to reach the target exhaust temperature level under harshest conditions.
In combination with ABB’s two-stage turbocharging system Power2, VCM also enables an improvement in fuel efficiency and transient behavior and an extended engine operating map by adapting charging conditions to each operating point.
With the described regulations now looming, the application of VCM as proposed here, with all its additional benefits, is catching the attention of the OEMs.
Power2’s unrestricted potential
What are the advantages and opportunities Power2 presents to operators today and will continue to offer in the future? Already with the benefits that come from a proven and reliable technology, ABB’s state-of-the-art two-stage turbocharging system was developed to satisfy demand for increasing engine efficiency and power density and is currently the most potent power booster for four-stroke engines.
Its wide range of application – on high-speed and on medium-speed engines, for marine main propulsion as well as for power plants – makes Power2 the perfect all-rounder, suitable for every engine environment, anywhere on the planet.
Operators applying Power2 are clear on this: they benefit from substantial fuel economy improvements and significant reductions in NOx. With Power2, operators are perfectly placed to counter potential increases in fuel prices. And to face up to stringent emissions legislation, those now in force and the ones to come, whether national or international. And in addition to optimized lifecycle costs, Power2 means a lower total cost of ownership (TCO) compared to other turbocharging systems.
Power2 is fully fuel-flexible since it runs on diesel, dual-fuel and gas applications. The increase in importance of the latter has already been significant, while the general share of gas, LNG and dual-fuel applications will continue to rise substantially in the future.