A Multi-Path Approach to the Future of Off-Highway Power

by Allen Schaeffer (Engine Technology Forum) From small construction machines to locomotives and tugboats, the off-highway sector is large and diverse. When viewed through the lens of the U.S. Environmental Protection Agency’s (EPA) emissions model inputs, just how large and diverse becomes clearer: 11 subsectors, 85 types of equipment, 18 classifications of horsepower range, resulting in 1,070 possibilities.

This diversity ensures that that no single “winner” technology would be best for all sectors. The future is not defined by a wholesale shift to any one power source. Instead, it is being shaped by a flexible, multi-path strategy that reflects the diversity of applications, operating environments, and energy needs across these industries.

A key foundation for understanding this transition is recognizing the progress already achieved. Since the late 1990s, increasingly stringent emissions standards have driven dramatic improvements in internal combustion engines. Technologies such as selective catalytic reduction (SCR) and diesel exhaust fluid (DEF) have enabled near-zero emissions of key pollutants like nitrogen oxides (NOx) and particulate matter.

These advancements are not theoretical, they are reflected in measurable improvements in air quality, with significant reductions in smog-forming emissions over the past two decades. This legacy of innovation demonstrates that internal combustion engines have already undergone a major transformation and continue to evolve.

In this evolving landscape, diesel remains foundational. Its combination of energy density, durability, and performance under heavy loads makes it indispensable for demanding applications, particularly in remote locations or where continuous operation is required.

Rather than being displaced, diesel technology is being refined. Modern engines are more efficient, cleaner, and increasingly compatible with renewable and low-carbon fuels. The emphasis is on optimization – extracting greater performance and lower emissions from a technology that is already deeply embedded in global infrastructure.

Electrification is a part of the future, but its role is highly dependent on use case. Battery-electric solutions are gaining traction in specific segments – especially smaller equipment, urban environments, and applications with predictable duty cycles and access to charging infrastructure.

Perhaps the most important theme shaping the future is the growing diversity of fuel options. The industry is moving beyond a binary mindset (gas or diesel) toward a more expansive energy strategy that incorporates multiple fuels and technologies.

Renewable biofuels, such as biodiesel and renewable diesel, offer immediate opportunities to lower lifecycle emissions while using existing engines and infrastructure. Natural gas and fuel blends provide additional flexibility in certain applications. Hydrogen is emerging as a longer-term option, with potential pathways in both combustion engines and fuel cells. Synthetic fuels and e-fuels are also under development, further expanding the range of possibilities.

In response, engine designs are becoming increasingly flexible. Future systems are being developed to accommodate multiple fuel types, enabling operators to choose the best option based on local availability, cost, and operational requirements. This “fuel-agnostic” approach is central to addressing the diverse needs of the off-highway sector.

The transition to lower emissions is influenced not only by technology, but also by policy and public perception. There is broad support for cleaner solutions, but less consensus on how to achieve them – particularly when cost and practicality are considered.

Many stakeholders favor approaches that improve existing technologies rather than mandate rapid transitions to entirely new systems. At the same time, there is a growing desire for policy consistency and clarity, as fragmented or overly prescriptive regulations can create uncertainty and unintended consequences with technology design and R&D as well as in the marketplace.

Effective policy will need to recognize the diversity of applications and support a range of solutions, rather than prescribing a single pathway.

Looking ahead, the future of off-highway power extends beyond the engine itself.

There is no single solution that can meet the diverse demands of the off-highway sector. Diesel, electrification, renewable fuels, hydrogen, and other emerging technologies all have roles to play.

In the end, progress will not come from choosing one path over another, but from integrating many paths into a cohesive, adaptable strategy for the future. READ MORE