Renewable Diesel Poses Viable Option

by Curt Bennink (ForConstructionPros.com) By now, most are familiar with biodiesel. It is a cost-effective and more environmentally friendly alternative to conventional petroleum-based diesel fuels when used in the correct applications.

“Biodiesel improves lubricity when compared to Ultra Low Sulfur Diesel (ULSD),” says Kaleb Little, senior communications manager, National Biodiesel Board. It also reduces emissions of hydrocarbons, particulate matter and carbon dioxide.

However, there are limitations when compared to petroleum-based diesel. Biodiesel typically has a higher cloud point, which means it may not perform well in low temperatures unless blended with traditional petroleum-based diesel; it has a tendency to absorb more moisture; and it typically produces slightly less power and fuel economy when used in higher blends.

It is also chemically distinct from petroleum diesel and has a separate ASTM standard. “Biodiesel must meet the ASTM D6751, its own separate ASTM standard that was developed back in 2002,” says Little.

Biodiesel comes blended with petroleum diesel fuel in various ratios, from B5, which is 95% petroleum diesel and 5% biodiesel, all the way up to B100, which is pure biodiesel. Engine manufacturers often publish the maximum content of biodiesel recommended, such as B10 or B20.

“Renewable diesel is a drop-in fuel,” says Joanne Ivancic, Advanced Biofuels USA. “It can replace petroleum diesel completely. Also, it has no sulfur and has other properties that make it better than petroleum-based diesel.”

“Biodiesel and renewable hydrocarbon diesel fuel offer higher cetane numbers than traditional petroleum diesel for better combustion,” notes Little. “They also both dramatically reduce life-cycle carbon emissions.

“Like biodiesel, renewable diesel helps address the over-the-road and heavy-duty challenges,” he continues.

But understanding and acceptance of renewable diesel is still in the early stages. “While biodiesel has been produced in the U.S. for more than a decade, renewable hydrocarbon diesel is relatively new to the market in commercial volumes,” says Little, “so there have been fewer statements from equipment manufacturers of support or caution.”

“Renewable diesel is a bio-based fuel, derived from a variety of waste agricultural feedstocks, that meets the same standard as traditional petroleum diesel fuel yet substantially reduces carbon emissions with additional air quality benefits,” says Allen Schaeffer, Diesel Technology Forum. “Renewable diesel fuel can immediately improve the emissions performance of older diesel vehicles and equipment and enhance the already impressive emissions reduction of new technology diesel engines, without sacrificing power or performance, at a price competitive with traditional diesel fuel.”

Technical hurdles to the adoption of renewable diesel are minimal. “As renewable diesel fuel meets the same standard as traditional diesel fuel, fleets do not incur additional fuel infrastructure investments or [need to] modify vehicles to operate on that fuel,” says Schaeffer.

Renewable diesel is often produced from a process called hydrotreating, which is already being utilized in today’s petroleum refineries. During this process, hydrogen replaces other atoms such as sulfur, oxygen and nitrogen and converts the oil’s triglyceride molecules into paraffinic hydrocarbons. The resulting renewable diesel reduces waste and by-products, yields a higher energy density and improves cold flow properties, according to the Diesel Technology Forum. This process also enhances the blended fuel storage and stability of the finished biofuel product.

But hydrotreating is only one method of producing renewable diesel. According to the Diesel Technology Forum, other methods under consideration for creating renewable diesel fuel include biomass-to-liquid (BTL) and thermal conversion process (TCP) technologies.

“In fact, renewable diesel meets the same standard as petroleum diesel fuel, as defined by ASTM International (ASTM), allowing the fuel to be easily blended into petroleum diesel fuel.”

This is a key difference between biodiesel and renewable diesel. “Since biodiesel is chemically different from petroleum diesel fuel, it must be produced to a different standard,” says Schaeffer. “Engine manufacturers approve their engines to operate on certain blends of biodiesel. Since renewable diesel meets the same standard as petroleum diesel, diesel engines can operate 100% on renewable diesel fuel.”

Volvo/Mack announced recently that their on-road engines are approved to operate on 100% renewable diesel fuel. Other engine manufacturers may also be testing engines to operate on renewable diesel fuel.

Renewable diesel has the potential to dramatically cut greenhouse gas emissions. “While renewable diesel fuel meets the same standard as petroleum diesel fuel, renewable diesel fuel is considered an advanced biofuel by the U.S. Environmental Protection Agency (EPA), capable of reducing carbon emissions by at least 50%,” says Schaeffer. “In fact, the carbon reduction of some renewable diesel fuels approaches 90%, depending upon the feedstock.

“Renewable diesel comes with the added benefit of reducing emissions of oxides of nitrogen (NOx), an ozone-forming compound, and particulate matter (PM) or soot relative to petroleum diesel fuel,” he continues. “Equipment owners who have not made the transition to the latest generation of clean diesel equipment may demonstrate clean air benefits to communities when operating older equipment using renewable diesel fuel. Equipment owners operating the latest generation of clean diesel equipment using renewable diesel fuel will demonstrate even greater air quality benefits to communities.”

“There are two U.S.-based renewable hydrocarbon diesel facilities, both in Louisiana,” says Little. “Diamond Green Diesel recently announced a plant expansion. And the REG facility is expected to resume production later this year. Domestic production remains optimal for fleets focused on big picture sustainability.”

“The City of San Francisco announced at the end of 2015 that it is using 100% renewable diesel fuel in all of the diesel vehicles and equipment in the city’s fleet. Oakland is following its sister city across the bay, while New York City announced that it intends to operate its enormous fleet on renewable diesel when the fuel is available on the East Coast. Still yet, UPS announced that it will purchase 46 million gal. of fuel for use in its fleet.” READ MORE