The electrification of the transportation industry has gained significant traction, driven by corporate sustainability goals and regulatory requirements. The North American Council for Freight Efficiency (NACFE) has coined a term for this period — “the messy middle” — a transitional time where a mix of technologies and strategies coincide to bridge the gap between today’s reliance on diesel engines and the promise of fully electric systems.
For the trucking and refrigerated transport sectors, this period brings both challenges and opportunities. Fleets are under pressure to cut emissions without compromising reliability, cost efficiency or uptime. While full electrification remains the long-term goal, there are impactful steps fleets can take right now to begin decreasing TRU emissions and align with the shift toward zero-emission TRUs.
In this article, we’ll explore how fleets can navigate this “messy middle” with strategies that deliver immediate emission reductions and long-term readiness.
Understanding the “messy middle”
While diesel engines continue to dominate freight and cold-chain logistics due to their durability and efficiency, several factors are accelerating change:
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Regulatory push for emissions reductions
The U.S. has committed to achieving net-zero emissions by 2050, with stricter diesel emission standards introduced to combat climate change. In California, the CARB TRU Regulation requires fleets to transition toward zero-emission TRUs or verified retrofit technologies. Fleets nationwide are watching closely, as similar regulations are expected to expand beyond California.
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Rise of alternative fuels and powertrains
Renewable diesel, natural gas and hydrogen fuel cells are gaining attention as interim solutions. Hybrid powertrains—combining electric and combustion technologies—are also helping bridge the gap for regional operations. Each option has unique advantages but also challenges in scalability and cost.
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Infrastructure and cost barriers
While electric truck orders are growing, the lack of charging infrastructure and high upfront investment limit large-scale adoption. Hydrogen-fueling infrastructure remains extremely sparse: as of 2024 the U.S. had just 54 retail hydrogen stations, the vast majority located in California. Until nationwide coverage improves, TRU electrification remains constrained to regional use cases.
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Customer and supply chain expectations
End customers and logistics partners increasingly demand sustainability metrics in operations. Fleets are expected to demonstrate progress toward carbon reduction even before full electrification becomes practical. This expectation fuels demand for interim, cost-effective emission-reduction technologies.
Zero-emission TRU (eTRU) 101: where it fits and what it requires
A zero-emission TRU (eTRU) is a transport refrigeration unit powered without an internal-combustion engine—typically by batteries, shore power or hybrid electric systems.
CARB identifies eTRUs as a key compliance pathway in its Transport Refrigeration Unit Program, which mandates the transition of diesel TRUs to zero-emission alternatives over time.
Where eTRUs fit best:
- Short-haul and return-to-base routes where trucks can recharge daily
- Distribution yards with access to reliable site power or charging infrastructure
- Urban delivery zones that prioritize low-emission operations
However, for long-haul or high-duty cycles, battery weight, charging time and cost constraints remain barriers. Fleets with mixed route types often find that a blend of technologies—diesel, hybrid and electric—is the most realistic approach for the near future.
The short-term challenge: realistic implementation
TRU electrification is gaining momentum, but fleets still face near-term hurdles. Electric charging and hydrogen fueling infrastructure is expanding along major West Coast corridors—over 100 fast-charging sites along I-5 and US-101, 47+ in California, and 136+ new sites in Washington and Oregon—but coverage remains sparse, creating challenges for fleets that rely on consistent access to refueling and recharging stations for their tractor-trailers. Hydrogen fueling is mostly concentrated in California, with early stations appearing in Oregon and Washington. Nationwide, limited access makes large-scale TRU electrification a long-term project requiring strategic planning and investment.
Meanwhile, cleaner technology adoption is accelerating. About 39% of fleets use renewable diesel, 29% use biodiesel and hybrid TRUs are now mainstream—PLM operates thousands alongside 200+ electric units. Over 12% of new heavy-duty trucks sold are electric, more than 30% of large fleets have at least one and two-thirds of fleets are piloting or committing to electrification within 18 months.
These trends show clear momentum toward renewable and zero-emission solutions. But until infrastructure catches up, fleets can take immediate action to reduce TRU emissions with verified solutions like Rypos active diesel particulate filters.
Rypos DPFs: decreasing TRU emissions in the “messy middle”
As the trucking industry navigates this transitional phase, Rypos active diesel particulate filters (DPFs) offer a practical and proven solution for today’s challenges. Here is the near-term impact you can expect by implementing these DPFs into your existing TRUs while you plan for full electrification:
- Immediate emission reductions: By retrofitting TRU fleets with Rypos’ DPFs, owners can anticipate a substantial reduction in black carbon emissions of up to 95%. This immediate and notable decrease has a positive effect on combating climate change. ULETRU DPFs reduce an impressive 10-12 metric tons of CO2e per year and over 150 metric tons of CO2e for the life of a diesel TRU.
- Proven versatility: Rypos technology is compatible with a wide range of diesel-powered equipment, including reefer trailers, auxiliary power units (APUs) and stationary engines.
- Cost-effective compliance: Rypos DPFs with active regeneration require no operator intervention or any unnecessary consumption of diesel fuel to perform regeneration. This saves additional carbon emissions, minimizes required maintenance and decreases fuel costs for TRU fleet owners.
Rypos active DPF retrofits allow TRUs to perform like cleaner, newer models, achieving near-zero particulate emissions immediately and cost-effectively. It’s a bridge technology that turns environmental responsibility into operational advantage.
A suggested path forward
NACFE and leading industry groups recommend fleets adopt a pragmatic, phased approach to decarbonization:
- Assess your current TRU inventory and operating regions for emission hot spots.
- Retrofit mid-life TRUs with verified active DPF systems for near-term compliance.
- Pilot zero-emission TRUs in return-to-base or short-haul operations.
- Invest in site power and charging infrastructure incrementally.
- Track and report carbon and particulate reductions as part of ESG commitments.
By combining immediate emission reduction with strategic TRU electrification planning, fleets can navigate the messy middle confidently. Rypos provides verified technology and expertise to help you meet today’s regulatory requirements, reduce your environmental footprint and prepare for a zero-emissions future.
Contact us to learn how Rypos can support your fleet’s effort to decrease TRU emissions.
