The diesel combustion engine has been a key player in off-highway construction and earthmoving machinery for decades. However, there has been a growing push towards on-road electric automobiles and the constant stream of OEM announcements about their newest electric construction equipment, which may lead some to believe that the days of the diesel engine are numbered. But the question that a lot of people are asking is, if the death of the diesel combustion engine overblown or realistic.
Electric Equipment Sales
The selection of electrically driven construction equipment has grown significantly over the past few years, but they still represent a very small percentage of global sales. In Europe, it is only about 0.5%, and practically all of it is in the categories of tiny machines like micro excavators and compact wheel loaders. Similarly, in China, the sale of electric vehicles is slightly greater due to the availability of larger wheel loaders and excavators up to around 20t, but the proportion of sales that are made up of electric vehicles is still barely 1% at most. The off-highway environment is still dominated by diesel-powered vehicles, which presents a challenge in light of the Paris Agreement’s goal of limiting global warming to 1.5°C.
Low-Carbon Fuels
During the Diesel Advancement Summit last year, Dr. Allen Aradi, a fuels scientist at Shell Global Solutions, suggested that OEMs were growing cynical about the internal combustion engine, especially in the light vehicles area, and that it was a mistake. He argued that low-carbon fuels and the combustion systems that burn them will become very critical as we approach 2050. This suggests that the diesel engine may not be dead yet.
Battery Electric and Fuel Cell Limitations
While there will be fully electric devices in the mix, they won’t work for every building application, especially for heavy loads. Batteries contain hydrogen engine by Cummins. At CONEXPO-CON/AGG 2023, Cummins showcased their 15l fuel-agnostic engines, which provide unique humidity and thermal management issues. This means that in some challenging operating circumstances, combustion engines are still frequently preferred. Moreover, electric small track loaders can already cost more than twice as much as a diesel-powered one. This suggests that cost-effectiveness may drive purchasing decisions for contractors worldwide.
Fuel cell technology is also not yet advanced enough to replace diesel engines in every construction and earthmoving machinery application. Some claim that harsh environmental factors like humidity, altitude, dust, shock, and vibration can also damage fuel cells. While durability is expected to increase, the high cost and the fact that it is still rather challenging to obtain the hydrogen needed to power them are significant disadvantages.
Diesel Engine Pollution
Diesel engines have improved in efficiency, but not enough to address the problem of carbon emissions. To meet carbon reduction goals, the construction industry will need to transition away from diesel. However, diesel engines are already 95% cleaner than they were, and efforts to make them cleaner, particularly with regard to particle and NOx emissions, will continue. The strictest non-road vehicle emissions regulations in the world right now are Stage V requirements set by the EU, and the US is probably going to transition to Tier 5 standards, with implementation likely happening in 2026–2027. Similarly, China has implemented the first China National Standard 4 off-road standards, which add restrictions on particle counts that force the use of a diesel particulate filter and are based on EU Stage 3B.
The Future of Diesel Combustion Engines
In light of the above factors, it is unlikely that energy from “green” hydrogen fuel cells will be sufficient to provide the energy and power requirements of all construction and earthmoving machinery. It is likely that diesel engines will continue to play a critical role in off-highway construction and earthmoving machinery for the foreseeable future. However, efforts will continue to make them cleaner and more efficient, particularly with regard to reducing carbon emissions and particle and NOx emissions.
In addition, the use of low-carbon fuels, such as biofuels, synthetic fuels, and hydrogen, is expected to increase in the coming years, which will provide an alternative to diesel fuel. OEMs are also likely to continue investing in battery electric and fuel cell technology, which may become more viable options for certain applications in the future.
Seeing as how things are, it seems to me that the future of the diesel combustion engine is neither exaggerated nor unrealistic. It will continue to be a significant player in the off-highway construction and earthmoving machinery industry, but efforts will also be made to reduce its environmental impact and explore alternative energy sources.