Techno-economic and environmental impacts of hybridization and low-carbon fuels on heavy-duty trucks

Abstract

Heavy-duty trucks account for a significant share of petroleum consumption and CO₂ emissions in the automotive sector. However, their transition to low-carbon renewable energy has lagged behind that of passenger vehicles. This study systematically evaluates the performance, energy consumption, total cost of ownership (TCO), and well-to-wheel (WTW) CO₂ emissions of various low-carbon fuel powertrains and fuel-electric hybrid systems for heavy-duty long-haul trucks. The fuels considered include liquefied natural gas (LNG), methanol, hydrogen, and electricity, while the hybrid systems evaluated are series, parallel, and series–parallel configurations. Design parameters of these diesel-electric hybrid systems were first optimized to achieve improved performance and cost-efficiency. The series–parallel design emerged as the most effective configuration and was subsequently applied to other fuel hybrid systems. The analysis revealed that hybrid trucks consistently outperformed conventional engine trucks in energy consumption, TCO, and CO₂ emissions across all fuel types. Diesel-, LNG- and methanol-electric hybrid trucks were more cost-effective than battery-electric trucks, underscoring hybridization as a pivotal technology for energy savings and emissions reduction in logistics. Hydrogen engine and hydrogen hybrid trucks exhibited higher TCOs compared to diesel-based systems, while LNG and methanol hybrid trucks offered the lowest TCOs, highlighting the economic barriers to widespread hydrogen adoption. The WTW CO₂ emissions were highly dependent on the production pathways of methanol and hydrogen. For instance, trucks fueled by coal gasification-derived hydrogen emitted 2.64 times the CO₂ of diesel trucks, whereas hydrogen produced from renewable electricity reduced CO₂ to just 29.3% of diesel levels. Similarly, coal-derived methanol increased CO₂ emissions by 3.95 times compared to diesel, while methanol synthesized from industrial CO₂ exhausts and hydrogen from coke oven gases achieved a 22.8% reduction. These findings highlight that transitioning heavy-duty trucks to methanol and hydrogen fuels requires a parallel shift toward sustainable, low-carbon fuel production methods to maximize environmental benefits.