Transport refrigeration units (TRUs) are the backbone of the cold chain, but they come with a major drawback: the emissions from diesel-powered engines. While fleets can’t afford to jeopardize cargo integrity, regulators are tightening standards on particulate matter (PM) and black carbon, pushing operators to take action sooner rather than later.
Rypos, an environmental services company based in Franklin, Massachusetts, recently addressed the topic in a new white paper that examines how diesel particulate filters (DPFs), optimized TRU practices, and system-level planning can reduce environmental impact without compromising load integrity or system uptime.
“Fleet managers face a dual challenge,” said Wayne Benson, Rypos national account manager for sustainability. “They must protect food safety and keep operations running while reducing emissions that affect public health and climate goals.”
Load protection comes first
The carbon footprint of refrigerated cargo is significant, ranging from 8,000 kg CO2e for apples to over 1.4 million kg for beef, Benson said. Losing a single load can erase any benefits from operational changes. For this reason, fleets seldom stray from OEM-recommended temperature and cycling settings. Ensuring product quality remains the main priority.
Stricter regulatory laws ahead
The California Air Resources Board’s Ultra-Low Emission TRU (ULETRU) rule and the EPA’s proposed Tier 5 standards are transforming the compliance landscape. Even TRUs marketed as “Tier 4 Final” often emit particulate matter well above California’s limit of 0.02 g/bhp-hr. For fleets operating in urban or high-density areas, this poses not only compliance challenges but also reputational risks.
DPFs as a ready solution
While low-emission TRUs are available on the market, many fleets cannot replace equipment quickly. That’s where diesel particulate filter (DPF) retrofits come into play.
“Installing a verified DPF can reduce particulate emissions by up to 95%, and it doesn’t interfere with refrigeration performance,” Benson explained. “Most installations are completed in less than a day, which means fleets see an immediate impact with minimal downtime.”
The payoff is substantial: a TRU operating 2,200 hours annually releases about 15,300 kg of CO2e from PM alone. Retrofitting with a DPF can reduce roughly 14,500 kg of that impact each year, providing measurable results in short-lived climate pollutants.
Building toward long-term goals
While electrification and other zero-emission technologies are the future, DPF retrofits provide a near-term bridge that helps fleets meet current regulations and prepare for what’s ahead.
“Reducing emissions is no longer optional,” Benson concluded. “With the right technologies, fleets don’t have to choose between sustainability and reliability—they can have both.”
