Biodiesel’s Lesser Known Benefit | Diesel Particulate Filter Performance

There are numerous benefits to using biodiesel. Beyond its ability to reduce harmful emissions in diesel vehicles, biodiesel supports our region’s economy and also requires little to no vehicle modification to use. But did you know that biodiesel can actually improve a vehicle’s performance as well? Research suggests that vehicles with diesel particulate filters (DPFs) produce less soot and burn at a lower temperature while using biodiesel than petroleum diesel fuel.

The National Renewable Energy Laboratory (NREL) administered research about engine performance of biodiesel blends that run in an engine that also has a diesel particulate filter. Tests were conducted using a 2002 Cummins ISB engine retrofitted with a Johnson-Matthey DPF. The impacts of using biodiesel were measured by balance point temperature (BPT, which is the DPF temperature when the rate of particle oxidation equals the rate of particle collection), filter regeneration rate (assessed by measuring the DPF pressure over time as engine temperatures rise), and emissions testing with and without the DPF.

The results were substantial. The BPT was between 45 and 112 degrees Celsius lower for B20 blends and “neat” biodiesel, respectively. Additionally, emissions tests revealed a 25% reduction in particulate matter (PM) for B20 without the DPF installed. Installing the DPF caused PM to drop by over 10 times as much as petroleum diesel fuel. As stated in the report, “the significant lowering of BPT and increase in regeneration rate might allow passive DPFs to be used in lower temperature engine duty cycles, avoiding the need for actively regenerated filters and their associated fuel economy penalty.”

What does this mean? Well, not only is biodiesel effective in reducing harmful emissions, but it also lowers the BPT, which in turn increases the regeneration rate. Soot burns off at a lower temperature and requires fewer actively regenerated filters.

Biodiesel in Washington State

Think about Washington for a moment. What are some things that come to mind? Apples, raspberries, hops, and other crops are grown with regularity here in Washington. In addition to these well-known crops, canola seed has recently burst onto the scene in the central and eastern parts of the state. Over the past two years, the amount of land dedicated to growing canola in eastern Washington grew threefold, from 15,000 acres to 45,000 acres. Local farmers are realizing the economic benefits of growing canola, which is a viable crop to add into a crop rotation. It’s also a top crop used in producing biodiesel. With an annual capacity of 107 million gallons, Washington has the seventh highest biodiesel production capacity in the country.

Local Biodiesel Refinery under New Ownership

Renewable Energy Group, Inc. (REG), a large national biofuels producer, purchased Imperium Biodiesel based out of Grays Harbor, WA, in mid-September. REG aims to increase biodiesel sales along the west coast region, especially as the Low Carbon Fuel Standard increases regional demand in California. Of REG’s 11 bio-refineries nationwide, the Grays Harbor plant will be the largest in their portfolio. One of the country’s largest biomass companies, REG has a track record of success, and Washington’s biofuel industry is poised to grow over the coming years.

Biodiesel Named Top Emissions Reducer by CARB

In early September, the California Air Resources Board (CARB) announced the results of its recent analysis of alternative fuels and their respective carbon intensities. After evaluating and comparing biodiesel against other alternative fuels such as ethanol, electricity, natural gas and hydrogen, biodiesel stood out with the lowest carbon intensity of any fuel. (CARB’s report can be found here). Each fuel was evaluated based on the lifecycle greenhouse gas associated with producing the fuel, including conversion into fuel and transportation emissions. The evaluation also included several indirect economic impacts of growth in global agriculture.

Of course, each feedstock used to produce biodiesel has its own unique pathway to becoming biodiesel. Of the five most common sources of biodiesel, used cooking oil (UCO) came in with the lowest carbon intensity of just under 20 grams per mega Joule (g/MJ). Corn oil and tallow came in around 30 g/MJ each, with canola and soy each just over 50 g/MJ. Each of these forms of biodiesel provides a significant upgrade over crude oil and diesel fuel, both of which have carbon intensities slightly above 100 g/MJ. As Don Scott of the National Biodiesel Board said, “A focus on carbon reduction and the national policy to support it, biodiesel could reduce carbon emissions by 40 tons annually.”

Biodiesel Takeaways

So there you have it. Biodiesel reduces greenhouse gas emissions and runs cleaner than petroleum diesel, improving diesel particulate filter performance. And not only is biodiesel feedstock grown right here in Washington, there’s every indication that the state’s biodiesel production will continue to grow. Biodiesel just makes sense, especially in Washington State.

Thinking about adding biodiesel to your fleet? Connect with us and let Western Washington Clean Cities be your guide.