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December 17, 2015   |   Diesel Technology Forum

Policy Insider

Climate Benefits of One of the Oldest Technologies Still in Use

Thanks to decades of innovation, clean diesel technology is helping to deliver significant reductions in GHG emissions and is a major feature of the U.S. climate commitment outlined in the INDC that explains how the U.S. will cut GHG emissions by at least 26 percent by 2025.

As industry and governments work to realize the recent climate agreement reached in Paris, diesel technology is hard at work delivering people and goods and performing work on roadways and on farms across the globe. Thanks to decades of innovation in clean diesel technology – from advanced engine designs, exhaust aftertreatment solutions, and next generation bio-based diesel fuel – these innovations are helping to deliver significant reductions in greenhouse gas emissions and are a major feature of the U.S. climate commitment outlined in the Intended Nationally Determined Contribution (INDC) that explains how the U.S. will cut greenhouse gas emissions by at least 26 percent by 2025.

In the U.S., over 95 percent of commercial vehicles are powered by a diesel engine. Technologies deployed to meet the first ever fuel economy regulations for heavy-duty vehicles, the Phase 1 rule, and proposed regulations that further advance fuel economy requirements, the Phase 2 rule, are estimated to reduce carbon dioxide emissions by over 1.2 billion tons between 2014 and 2027. While diesel passenger vehicles make up a relatively small share of the overall passenger vehicle fleet in the U.S., the anticipated growth in diesel vehicles is expected to contribute to greenhouse gas reduction along with a reduction in fuel use. In fact, the Obama Administration in its “All of the Above Energy Strategy” attributes some of the reduction in transportation fuel use to growing consumer interest in diesel passenger vehicles.

Together, technologies deployed to meet fuel economy requirements for passenger and commercial vehicles are expected to deliver about 10 percent of the U.S. climate commitment outlined in the INDC.

The benefits of diesel technology are delivering much more than just greenhouse gas reduction. Much attention has been placed on reducing the use of fossil fuels. Here, diesel technology also stands out. The original patent for the diesel engine submitted by Rudolph Diesel over a decade ago envisioned the engine operating on biofuels – peanut oil in particular. Today, not much has changed. Most heavy-duty diesel engines can operate on high quality blends of biodiesel, an advanced biofuel capable of reducing carbon emissions by at least 50 percent, according to the U.S. Environmental Protection Agency. As bio-based diesel fuels are derived from waste agricultural feedstocks, primarily waste soy beans and animal fats, fuel production is not subject to “food vs fuel” issues.

Bio-based diesel fuels are growing in importance and large municipalities are committed to using these advanced biofuels as part of their sustainability initiatives. Already, the city of San Francisco announced that it is using nothing but renewable diesel fuel to power all of the city’s diesel powered vehicles and equipment. Still yet, the City of New York just announced this week that it is committed to use greater blends of biodiesel along with greater use of renewable diesel. In fact, about 34 percent of New York City’s planned greenhouse gas reduction is attributable to greater use of alternative fuels, the majority being bio-based diesel fuel.

The benefits of diesel engines go beyond their ability to operate on advanced biofuels. Engine and aftertreatment technologies that have been developed to meet strict emissions reduction requirements in the U.S. have resulted in near-zero levels of oxides of nitrogen (NOx), a smog forming compound, and emissions of a particulate matter (PM). In the U.S. about one-in-five commercial vehicles on the road today comes with an engine that meets strict emissions standards for NOx. It takes over 60 of these trucks to equal the same emissions as just one truck manufactured in the 1980s.The fleet of these near zero emissions diesel trucks reduced NOx emissions by 1.5 million tons between 2010 and 2014. The state of California estimates that these technologies, when deployed on all commercial vehicles in operation in the Los Angeles area, could improve air quality immediately by 70 percent.

The benefits of new technology diesel engines are improving air quality and helping reverse the effects of climate change far away from the U.S. The introduction of cleaner diesel fuel and newer engines in the fleet of cars, trucks and off-road equipment helps to reduce emissions of black carbon – a potent short lived climate pollutant. When deposited on Arctic ice, the solar heat trapped in black carbon particles contributes to melting polar ice. In the U.S., about half of black carbon emissions are attributable to diesel engines. Thanks to new and newer diesel engines, the share of black carbon emissions from the U.S. has fallen dramatically and is expected to continue this impressive reduction well into the future. In fact, the success of reducing black carbon from diesel engines and fuel in the U.S. is so successful that the United Nations Environment Programme is seeking to replicate features of this success around the world to help cool a warming planet.

While the diesel engines was invented over a decade ago, continual improvement to the engine and fuel is helping to reduce carbon emissions, improve air quality while keeping the global economy moving.


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Ezra Finkin
Director, Policy

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