Efficiency Is Key as Companies Diversify Equipment Power Sources

By John Somers, Vice President, Construction & Utility Sector, Association of Equipment Manufacturers and Speaker on ”Decarbonized Power Options for Zero-Emission Off-Highway Machinery” at the #DZOMUSA EXPO in December 2024.

The change of power source from an internal combustion engine (ICE) to an alternative, such as a battery, is often referred to as a transition. I prefer to think of it as more of a diversification initiative.

The off-road equipment sector is not exempt from the drive towards zero-emission technologies gaining global momentum. Typically, machines in the construction and agriculture industries have relied on engines powered by diesel or other fossil fuels. With the push for sustainability, there is significant development toward zero-emission alternatives such as battery-electric.

This push is primarily driven by worldwide governments as they implement stricter regulations to reduce carbon footprints. While reducing emissions is a goal we all should have, an additional consideration needs to be how this power source change will impact systems integrated into the machine. Multiple effects on the end user should also be considered.

Energy Usage

The energy-dense engines these machines use provide the necessary power to drive hydraulic systems, used in today’s machines for lifting, digging, and pushing. These heavy-duty tasks are necessary to get the work done. While battery technology continues to increase in energy density and become more cost-effective, it also introduces many new challenges.

Electric motors are used instead of traditional combustion engines in battery-electric equipment. These motors, powered by rechargeable batteries, offer fewer moving parts and may be more efficient. It’s also possible that they will be more cost-effective as they typically require less maintenance compared to their diesel counterparts. 

If we can look beyond the lack of infrastructure to support charging this equipment, moving toward electric powertrains may essentially force changes in the hydraulic systems. Fluid power systems are the core of many off-road machines, as these systems are used to perform tasks such as moving booms, lifting heavy loads, and powering attachments. The hydraulic pump, valves, cylinders, and fluid lines all work together to transfer the needed energy.

Typically, the hydraulic pump is driven directly by the diesel engine. To function seamlessly under various loads and conditions, the engine needs to provide a consistent and reliable source of power. Smooth operation is important in many environments, especially where precision is needed to complete the task.

Changes to the hydraulic systems will most likely need to be made when moving from a diesel engine to a battery-electric power source. One of the key challenges is ensuring that the hydraulic system continues to operate efficiently and effectively with a battery-electric powertrain. Several factors come into play when considering the impact on hydraulics.

Systems Integration

Integrating electric powertrains with hydraulic systems requires careful consideration of how the two systems will interact. In some cases, hybrid hydraulic systems that combine electric and hydraulic technologies are developed to take advantage of the strengths of both systems. The hydraulic pump is often mechanically connected to the engine, diesel-powered machines. This means the pump’s performance is directly related to the engine’s speed. 

However, in electric machines, an electric motor drives the hydraulic pump. This allows the pump to deliver precise hydraulic power as needed. These electro-hydraulic systems combine the benefits of processing signals electronically with hydraulic drives. This creates versatile and reliable control systems that help optimize performance and provide precise control. Operators are then empowered to perform complex tasks efficiently and safely.

Since these systems offer high-speed, high-precision control, this increases productivity and reduces production costs. As more 3D digital models are created and loaded into a machine-advanced control system, this precision is important to meet the job’s requirements. An example of this would be using a GNSS receiver to perform a grading application. This allows for achieving accuracy through electro-hydraulic control of up to an eighth of an inch.

Other advantages are improved energy efficiency and reduced heat being generated. Since electric hydraulics can adjust output based on demand rather than fixed-speed operation, there is less wear on the components. This improves the system’s life and reduces maintenance costs.

Energy Management

The fear of running out of stored energy in the battery, along with anticipated long charge times, creates “range anxiety.” To combat this in a meaningful way requires extensive energy management practices. The battery’s capacity and charge percentage are the limited factors in available power. Hydraulic systems must be designed to operate efficiently to avoid draining the battery too quickly.

Electric pumps can be turned on and off as needed, only running when power is necessary. This is one option to minimize battery drain and is similar to when a vehicle’s engine shuts off when stopped at a light. This strategy also reduces wasted energy, improving overall efficiency. Another strategy, similar to regenerative brakes in on-road vehicles, is to capture excess hydraulic energy and store it back in the battery. When a boom is being lowered, gravity can do much of the work and the system can act as a generator to convert the energy back into electrical energy to recharge the battery.

Noise Reduction

If you’ve ever been on a construction job site, you know things can get loud. Beyond the noise generated by breaking concrete or milling an asphalt road, diesel engines in a machine also contribute to the noise environment. One of the advantages of battery-electric equipment is the significant reduction in noise compared to diesel-powered machines. In addition to producing less vibration, which makes the cab more comfortable for an operator, electric motors are also quieter. This reduces the noise levels for both operators and surrounding environments.

However, hydraulic systems, coupled with high-pressure fluid flows through valves and cylinders, can still be a significant noise source. Manufacturers are exploring ways to reduce hydraulic system noise by integrating quieter pumps and optimizing fluid flow. All of this leads to a more enjoyable work environment and makes it easier for people to communicate on the job site.

End User Impacts

As stated earlier, the implementation of zero-emission equipment should be integrated into a fleet alongside diesel equipment to meet the needs of different use cases and working environments. A major takeaway is understanding the advantages of equipment with an alternative power source provide. It’s not just about zero tailpipe emissions. It also allows for simpler systems, lower maintenance costs, less frequency maintenance, reduced noise, reductions in operating costs, and more precise operation. The adoption makes sense but does call for substantial changes for equipment end users.

Any new technology poses some challenges. Earlier, I mentioned the challenge of availability for charging infrastructure, whether it’s grid integrity or the lack of power on a job site. As systems including hydraulics become more digital, the knowledge of a maintenance technician needs to evolve. Mechanics accustomed to working on a diesel engine will need to learn new skills and understand systems with different complexities to optimally perform routine and unplanned maintenance.

The Future

Electric powertrains and hydraulic systems will continue to see significant innovation as more manufacturers develop and offer zero-emission equipment. For hydraulic systems, the focus should remain on maximizing energy efficiency and improving precision control. The advancement and improvements in these systems will ensure hydraulic systems remain a reliable component in off-road machinery in the years to come.

By continuing to innovate, manufacturers can help drive a more sustainable future. Beyond thinking about the reduction in emissions and overall environmental footprint, the impact on society should also be considered. More precision equals less rework, which leads to quicker job completion. There will be a reduction in the time the general public spends being disrupted by road closures or noisy living environments.

The question is, should we wait for alternative power equipment to be a viable and available option or drive toward these efficiencies now?