Former Rolls-Royce Power Systems’ CEO Dr. Ulrich Dohle looks back on decades of engine technology development
By Roberta Prandi
Editor’s Note: Until his retirement on Jan. 1, Dr. Ulrich Dohle was chairman of the executive board and chief executive officer (CEO) of Rolls-Royce Power Systems AG, responsible for the Technology division, Operations and Sales. He was also president and CEO of the Rolls-Royce Power Systems subsidiary MTU Friedrichshafen GmbH.
An engineering graduate from the RWTH technical university in Aachen, Germany, with a specialization in combustion engines and with a doctorate in stationary combustion, Dohle has held a variety of positions in the engine industry, including 25 years at Robert Bosch GmbH and more than eight years at MTU and Rolls-Royce.
In a conversation with Diesel & Gas Turbine Worldwide, Dohle looked back — and forward — at the state of combustion engine technology.
DGTWW: You were with Rolls-Royce Power Systems since 2009 and before that at Robert Bosch for 25 years. As an expert in combustion engines, what were the major technical steps you’ve seen over the years?
Dr. Dohle: Foremost it has to be mentioned that the emissions of the large diesel engines have been significantly reduced by some 90% where it comes to particle matters and NOX emissions. At the same time the power density went up significantly, reducing the specific fuel consumption in substantial steps.
All this was made possible by cleaner and more efficient combustion processes, as well as sophisticated technologies like electronic common rail injection, high-pressure turbocharging, and controlled and cooled exhaust gas recirculation (EGR) in conjunction with NOX-reduction catalysts and particle filters.
DGTWW: At MTU and now Rolls-Royce Power Systems, you’ve been very involved in the development of several significant engines, including the MTU 1600 Series and several versions of the MTU 4000 Series. What do you see as the greatest technical accomplishment you’ve been involved with?
Dr. Dohle: This question is difficult to answer, since the company has launched many new engines or engine generations such as the Series 1600 for power generation and industrial applications, e.g., for Powerpacks. The latest Series 2000 marine application, the M96 engine is also a very important product for the yacht industry with outstanding acceleration, fuel consumption and emissions values.
The Series 4000 Terra for Tier 4 standards, based on EGR technology. This is the first successful application of technology in the large diesel engine range avoiding selective catalytic reduction (SCR) catalysts and diesel exhaust fluid (DEF) infrastructure. Also the latest generation of our classic Series 1163 engine based on electronic controls and common rail injection led to a significant improvement in fuel consumption and 20% emission reduction at the same time.
Our new mobile gas engine based on a Series 4000 unit shows high efficiency in combination with more than 30 000 hours between overhauls. Last but not least, the further developed diesel engines of the Series 4000 for marine IMO Tier 3 and EPA Tier 4 applications have been launched and are on the right way to be on the market from 2018.
DGTWW: Very early in the emissions era, MTU seemed to take a very different course from a lot of its engine industry competitors in how and where they used the various aftertreatment technologies. Has this “we do it our way” philosophy developed by happenstance or was it a conscious choice for the company to differentiate itself from other manufacturers?
Dr. Dohle: MTU decided about 10 years ago that it would be helpful for the industry to operate with a range of engines that will meet emission legislations as Tier 4 without using aftertreatment devices, especially SCR, in conjunction with DEF. This was driven by the understanding that in many applications, the provision of a second fluid on board would not be feasible. Therefore we developed series 4000 Terra engines based on a highly sophisticated EGR system in conjunction with enhanced common rail injection and turbochargers.
Nevertheless, we went with a two-path strategy by also providing SCR solutions to the market where required.
DGTWW: Is there an attainable, logical path for greenhouse gas standards for nonroad engines, similar to what’s been done on the heavy-duty truck side in North America?
Dr. Dohle: In the world of industrial engines, the demand for low fuel consumption was always driven by the need for low life-cycle cost. Simultaneously CO2 emissions have been reduced substantially. And in the future, we will probably see the amount of CH4 being admitted to be regulated because of its strong greenhouse effect.
DGTWW: Will emissions regulations ever be “finished?” Are zero-emissions engines possible?
Dr. Dohle: There will be further discussions in reducing NOX and PM beyond Tier 4 in the U.S. or in Europe or other parts of the world. It definitely would be helpful to have harmonized worldwide legislation and limits including specific national regulations or in so-called emission controlled areas within the U.S.
Today’s modern diesel engine with highly sophisticated technologies and aftertreatment systems is more or less a cleaning device.
DGTWW: What do you think are the biggest technical challenges still ahead for combustion engines?
Dr. Dohle: The major challenges will be around further emissions reductions. That will lead to more add-on costs to the engine by using more sophisticated injection devices with injection pressures above 2500 bar, exhaust gas cleaning devices, etc. All these measures will add on cost to the engine.
Alternative fuels like natural gas — in compressed or in liquid form — will play a stronger role in propulsion systems of the future. This of course is depending on fuel price and infrastructure. A further challenge to the combustion engine, especially the diesel engine, is the political impact of the “Dieselgate” affair, which led to discussions about the environmental compatibility of combustion engines.
DGTWW: What are some of the biggest changes you’ve seen to the markets and market economics over the last 30 years?
Dr. Dohle: We saw changing boundaries definitively on the technology side. We never would have believed 15 years ago how clean and efficient large diesel engines could become. The market is unpredictable, as are oil and gas prices.
Some five years ago, it was everyone’s belief that a barrel of oil would never go back below US$100. Fifteen years ago we were debating peak oil soon to come and the end of resources.
DGTWW: Is there something you regret not having done in your career, or something you would have made differently?
Dr. Dohle: All in all, I’m quite happy with the opportunities that crossed my path during my career. I think the company’s work was awesome — sound decisions regarding future technologies, products and strategies, including a full hybrid system for rail cars, propulsion systems based on LNG and a good set of integrated diesel-electric propulsion systems. There is no real regret in this perspective.
DGTWW: What would be your best counsel today to a young engineer graduating with a specialization in combustion engines?
Dr. Dohle: Actually I do counsel my son who decided to go for an engineering degree and is now working in the field of combustion engine optimization with a major engineering service provider. I think he is on the right track and I would give the same advice to other young engineers.
I believe that for the next decades, combustion engines will play a major role as propulsion systems for off- and on-road vehicles. Of course there will be electric and hybrid solutions especially in major cities and areas where the infrastructure to charge batteries can be provided at lower cost.
DGTWW: You’re entering Life 2.0. What are your plans for the future?
Dr. Dohle: Life 2.0 sounds very nice to me. I definitely will spend quality time with my family, friends and hobbies, which happen to be related to combustion engines like sports cars and motorcycles.
I also would like to stay on top of technology developments and try to stay in touch with the many people I met and enjoyed working with in our industry.