Construction machinery emits around 400 megatons of CO2 annually, with excavators accounting for nearly 50% of all CO2 emissions from construction vehicles. The World Green Building Council reports that materials and construction account for 11% of global carbon emissions. Given the forecasted growth of urban areas—cities are expected to house 70% of the world’s population by 2050, according to the International Energy Agency—and the corresponding need for more buildings and infrastructure, decarbonizing the construction industry is critical to lowering greenhouse gas emissions and achieving Paris Climate Agreement goals. The U.S. Department of Energy, in its recently released blueprint for decarbonizing buildings, identified lowering embodied life cycle emissions as a necessity to meet decarbonization goals.
THE PATH TO ELECTRIFICATION
Electrification holds the largest CO2 mitigation potential for construction machinery while simultaneously delivering significant environmental, health and economic benefits. But while a combination of regulations and incentives such as those in the Inflation Reduction Act have led to an increasing numbers of U.S. consumers and businesses embracing electric-vehicle technology in passenger cars, buses and trucks, there has not been the same progress with heavy-duty construction machinery.
Admittedly, there are challenges to electrifying construction vehicles. Compared to passenger cars, large machines such as excavators need to work much harder and for much longer between charges, which means they need extremely large batteries to match the productivity of their diesel equivalents. These batteries are still very expensive, making the current purchase price of an electric machine much higher than its diesel equivalent.
More investment is also needed in providing infrastructure for the electrification of construction sites. Not all worksites have enough charging energy to support a fleet of electrically powered excavators. Sufficient power and stability in the electrical grid is a challenge to electrification in all sectors.
However, technologies to decrease energy consumption and carbon emissions from construction vehicles are available. Today’s excavator systems are only 30% efficient, meaning that 70% of the energy the engine produces is wasted instead of helping the excavator bucket move earth. Whether the vehicle has an electric motor or combustion engine, the energy consumption of the vehicle can be reduced significantly by cutting down on idling and hydraulic system losses and by introducing energy recovery systems. Digital-displacement hydraulics is one technology already available that can make a significant impact on energy efficiency.
DIGITAL DISPLACEMENT
Digital displacement technology, such as Danfoss’ Dextreme system, reduces hydraulic-system losses, leading to increased productivity and lower fuel consumption. Replacing a conventional hydraulic pump with a digital-displacement pump can reduce fuel usage by an average of 15%—and with further system optimization, even up to 30% or more. The radial piston pump uses digitally controlled valves to adjust displacement. Each piston is activated individually and provides a fast and accurate response to system demands, resulting in superior machine control.
By only using the pistons that are needed to meet the load, the pump provides exceptionally high efficiency. To reduce energy losses at the system level, the pump also contains multiple independent fluid outlets, dynamically allocated to each actuator so that fluid is supplied at the pressure needed by each actuator with minimal throttling.
The technology adds a completely new toolbox to hydraulic systems. It can simplify the hydraulic circuit and, by removing system components, allow for engine downsizing due to its responsiveness. The system is controlled by software, allowing original equipment manufacturers to build customization for each machine directly into the software.
Digital displacement can also reduce the required battery size for electric machines, helping to accelerate the path toward electrification for large excavators and other off-highway machines.
The construction industry has the potential to be a large contributor to greener and more sustainable urban areas. As cities are now prioritizing decarbonization, construction OEMs and contractors will need to adopt energy-efficient solutions that lower carbon emissions while reducing energy consumption and operating costs. The technologies are available, and with improved infrastructure and continued technological innovation, the construction industry can help our cities meet their decarbonization goals.
