Canadian Biomass Magazine

Aemetis Biogas, APG convert diesel trucks to utilize up to 65% RNG

September 29, 2022
By Aemetis

Transitioning from diesel fuel to carbon negative RNG, Aemetis and the American Power Group demonstrated a dual fuel system to reduce carbon and tailpipe emissions within existing diesel fleets using lower cost RNG fuel.

Aemetis, Inc., a renewable natural gas (RNG) and renewable fuels company focused on negative carbon intensity products, and the American Power Group demonstrated the patented “Turbocharged Natural Gas Dual Fuel System” for truck engines to multiple truck fleet owners and operators who transport biofuels, animal feed, and other agricultural products for Aemetis and other businesses in the region. Earlier this week, the technology was demonstrated for regulatory agencies and policy makers in Sacramento, Calif.

The technology allows a turbo-diesel engine to operate on up to 65 per cent natural gas and 35 per cent diesel, including renewable diesel. The technology is already operating in more than 3,000 stationary engines and 1,000 trucks worldwide, complying with EPA Clean Alternative Fuel Vehicle Conversion regulations.

The American Power Group, founded in 2009, developed the patented dual fuel technology to simultaneously combust two fuels, natural gas and diesel fuel, to power a diesel engine. A truck operated using Aemetis locally produced, dairy RNG and renewable diesel or biodiesel would be carbon negative, low emission and lower cost than diesel. The system maintains the power of a 100 per cent diesel engine while using less than half as much diesel fuel, leading to significantly fewer emissions.

Annual fuel savings from using RNG to replace up to 65 per cent of diesel fuel have been shown to exceed $30,000 per truck per year, depending upon the respective cost of the fuel sources. Dairy RNG is usually $2.00 to $3.00 per diesel gallon equivalent (DGE) less expensive than petroleum diesel. Retrofit costs is about $10,000 plus the cost of an on-board natural gas tank. The system adds natural gas tanks to a Class 8 diesel tractor and uses software to manage the two fuels, saving money at the pump while reducing emissions. The dual fuel system is fully automated, eliminating the need for operator intervention.


“These dual fuel systems represent an important transition step in California’s evolution to cleaner air and ultimately net-zero carbon emissions,” stated Eric McAfee, chairman and CEO of Aemetis. “Currently, the heavy-duty vehicle fleet in California is still more than 98 per cent diesel-powered. The low-cost conversion of existing diesel trucks will drive the adoption of reduced cost, lower emission fuels such as dairy-generated RNG,” added McAfee.

“This patented technology replaces up to 65 per cent of the fuel used by a turbodiesel truck with renewable natural gas at only about a $25,000 cost of conversion that takes less than one day to complete,” said Chuck Coppa, CEO of APG. “By using Aemetis dairy RNG, a waste material is powering the replacement of diesel which significantly reduces emissions.”

APG created a digital design to safely introduce natural gas into the air induction system before the turbocharger spins up – in essence turbocharging air already going to the engine. The spinning air reaches the compression chamber to create higher energy at the point of combustion.

Aemetis is focused on producing below zero carbon intensity renewable fuels, including negative carbon intensity RNG, sustainable aviation fuel (SAF), renewable diesel (RD), and bioethanol. Aemetis is also in the process of permitting two carbon capture and sequestration (CCS) wells near its biofuel facilities in Central California. Our projects maximize the use of agricultural waste or by-products as feedstocks to produce renewable fuels, while leveraging the value of federal and state carbon reduction programs.

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