ROUSH CleanTech: Propane Engines Reach Record Low Emissions

March 22, 2019






ROUSH CleanTech: Propane Engines Reach Record Low Emissions





Propane engines are aiming low — and for good reason. Recently, new ROUSH CleanTech technology has enabled propane engines to reach near-zero emissions, outdoing other alternative-fueled engines. These engines meet stringent certifications, reach almost no emissions, and reduce a parking management company’s environmental footprint.


Meeting Rigorous Certifications

The primary source of nitrogen oxide (NOx)is motor vehicles. According to a recent study, diesel medium- and heavy-duty vehicles are the number one source of NOx emissions in almost every single metropolitan region in the U.S. Approximately 55 percent of man-made NOx emissions come from motor vehicles.


All engines of any fuel type must be certified to the Environmental Protection Agency’s standard to control vehicle emissions. Over the years, the EPA has set tougher emissions standards on NOx. Since 2010, the NOx engine standard has been 0.20 g/bhp-hr.  The California Air Resources Board established optional low-NOx standards well below the EPA standard.


In 2017, ROUSH CleanTech developed the first propane autogas engine available in class 4-7 vehicles certified to CARB’s optional low NOx level 0.05 g/bhp-hr. These engines are 75 percent cleaner than the current emissions standard.


Then, in 2018, the alternative-fuel technology company developed an engine certified to 0.02 g/bhp-hr, which is 90 percent cleaner than the current EPA’s most stringent heavy-duty engine standard. The end result is a seamless, turnkey solution for customers.


At the 0.02 NOx level, it takes 10 propane autogas vehicles to emit as much NOx as one clean-diesel vehicle.


Reaching Near-Zero Emissions

These same engines can reach near-zero emissions by fueling with renewable propane. These ultra-low NOx propane engines can help parking management companies take a giant leap toward meeting an airport’s or state’s clean air standards while still providing a significant operating cost reduction over their current fleet.


What is renewable propane? It’s a non-fossil fuel that is produced from 100 percent renewable raw materials, such as waste, residue and sustainably produced vegetable oils. There is growing interest in renewable propane (also known as biopropane) due to its near-zero emission levels, reduced greenhouse gases and ability to help meet growing demand for cleaner products.


Reducing Emissions

Vehicle emissions can be divided into two general categories: air pollutants like NOx, which contribute to smog, haze and health problems; and greenhouse gases, such as carbon dioxide and methane.


Propane autogas is naturally lower in harmful emissions. Vehicles fueled by propane autogas emit fewer greenhouse gases, less carbon monoxide, and fewer particulate emissions than models fueled by gasoline.


When compared to conventional diesel, fueling with propane autogas results in an estimated 80 percent reduction in smog-forming hydrocarbon emissions and virtually eliminates particulate matter.


Propane autogas engines all run on nontoxic, colorless and clean-burning propane autogas, which is an approved alternative fuel under the Clean Air Act. In contrast to nontoxic propane, as little as one gallon of spilled gasoline can quickly contaminate groundwater above drinking water health advisory levels.


Lessens Environmental Effect

Nitrogen oxides are a group of gases known as a primary contributor to acid rain, smog and other air quality issues. The EPA states that exposure to NOx can trigger health problems such as asthma and other respiratory issues. That’s a main catalyst for CARB to encourage heavy-duty engine manufacturers to reduce levels below the current mandatory EPA standard.


NOx emissions are regulated under federal air quality standards because they are known to be harmful to human health and to the environment, contributing to regional ozone attainment challenges, smog and other air-quality issues. Heavy-duty diesel trucks are the single largest source of NOx emissions, contributing to smog in a majority of the nation’s most populated urban regions. According to the EPA, operating vehicles with ultra-low emission engines can make significant improvements to regional air quality and reduce a wide variety of human health impacts.


Parking management companies can significantly lower their carbon footprint by adopting clean-burning propane autogas vehicles. They can reduce costs, too. Click hereto learn how fleets can reduce their costs with propane Autogas.


Visit, reach out to Joe Rudolph at or call 800.59.ROUSH to learn more.