RNG Fuel Cost Locks Below Diesel, Clean Energy Says Engine Gap Closed

Why are fleets switching to renewable natural gas now?

Renewable natural gas delivers a stable cost per mile insulated from global diesel price swings, and the engine technology gap that kept RNG out of long-haul has closed, according to Chad Lindholm, Senior Vice President at Clean Energy. The fuel has been available for three decades but never broke into mainstream Class 8 adoption because engines couldn't match diesel performance and the fueling network had holes.

Lindholm says that calculus changed. He points to real-world fleet data, a mature infrastructure footprint, and an engine platform that now handles long-haul duty cycles without the power compromise that kept RNG relegated to short-haul and refuse routes.

The case starts with cost per mile. Diesel exposes fleets to global supply disruption. RNG is produced domestically, which walls off the price from overseas shocks. Lindholm did not cite a specific per-gallon or per-mile figure in the interview, but framed the domestic production profile as a hedge against the volatility that has whipsawed diesel settlement statements for the past four years.

What changed in the engine technology?

For years, natural gas engines in Class 8 trucks lagged diesel on horsepower and torque, which limited RNG to predictable short routes where lower power output didn't matter. Lindholm says the current generation of natural gas engines closes that gap. He did not name a specific OEM or model in the remarks, but described the platform as capable of handling the duty cycles that define long-haul freight: sustained highway speed, heavy loads, and the power demand of mountain grades.

That shift matters for fleets running irregular routes or mixed freight. A truck that can't pull a 45,000-pound load over Donner Pass doesn't work for most carriers, no matter what the fuel costs. Lindholm's claim is that the performance ceiling has lifted enough to make RNG viable beyond the dedicated lanes and light loads where it previously made sense.

FedEx Freight will add RNG tractors only when total cost of ownership beats diesel, a position that reflects the same cost-per-mile scrutiny Lindholm is addressing. The difference now, he argues, is that the engine side of the equation no longer disqualifies RNG from the comparison.

Where does the fueling network stand?

Lindholm pointed to a maturing infrastructure footprint as the second leg of the case. He did not provide a station count or lane-specific coverage map, but described the network as no longer having the gaps that previously forced fleets to route around fuel availability. That claim is harder to verify without specifics, but it tracks with the broader build-out of CNG and RNG stations along major freight corridors over the past five years.

For a small fleet, fueling infrastructure is a go/no-go question. If you can't fuel on your regular lanes, the truck sits. Lindholm's assertion is that the network now supports the routes that matter for Class 8 freight, not just the predictable loops that worked a decade ago.

What does RNG cost compared to diesel?

Lindholm did not provide a per-gallon or per-DGE (diesel gallon equivalent) price comparison in the interview. The cost argument he made is structural, not transactional: RNG's domestic production insulates it from the geopolitical and refining disruptions that move diesel prices. That stability matters more to a 10-truck fleet than a spot price advantage that disappears in three months.

The fuel is produced from landfill gas, agricultural waste, and wastewater treatment, which ties the supply to U.S. waste streams rather than global crude markets. Lindholm framed that as a cost predictability play, not a cheaper-per-mile play. The implication is that fleets can budget fuel expense with more confidence, even if the absolute cost per mile doesn't undercut diesel every week.

What's the adoption path for small fleets?

Lindholm's case is built on large-fleet data, which leaves the small-fleet adoption question open. A 50-truck carrier can't justify building private fueling infrastructure, and most don't have the capital reserves to spec a truck that costs more upfront even if the fuel saves money over five years. The fueling network claim matters here: if public RNG stations now cover the lanes a small fleet runs, the infrastructure barrier drops.

The engine performance claim matters too. A small fleet that runs mixed freight can't afford to spec a truck that can't handle every load. If the current natural gas engines match diesel on power, the operational risk of switching fuels shrinks. Lindholm did not address upfront truck cost or total cost of ownership over a typical trade cycle, which are the numbers that determine whether a small fleet can make the switch.

How does this compare to battery-electric?

Lindholm did not address battery-electric competition in the interview. The RNG case he laid out is implicitly a play for the long-haul and heavy-haul segments where battery range and charge time still don't work. Westport's HPDI engine runs on CNG or RNG now and can accept hydrogen later, which positions natural gas as a bridge fuel rather than a dead-end investment. Lindholm's framing suggests RNG is competing with diesel for the duty cycles battery-electric can't yet handle, not competing with battery-electric for the routes where it already works.

What happens next for RNG adoption?

Lindholm's argument is that the barriers that kept RNG on the sidelines for three decades have lifted. Engine performance now matches diesel, the fueling network covers the lanes that matter, and the cost structure offers predictability that diesel can't. He did not provide a timeline for adoption or a forecast for how many fleets will switch, but the case he made is that the technology and infrastructure are no longer the limiting factors.

For a small fleet, the decision comes down to upfront cost, fuel availability on your lanes, and whether the engine can handle your loads. Lindholm says the second and third questions now have answers that make RNG viable. The first question, truck cost, he did not address. That's the number that will determine whether RNG moves from viable to common in the next two years.