All Pathways to Reduced Emissions Should be Pursued

A survey of statutory requirements set by states to promote cleaner automobiles shows California and nine others have set a quota for sales of “zero emission vehicles” (ZEVs), such as electric (battery-powered) and hydrogen fuel cell cars and light trucks.

But efforts to reduce carbon emissions from our transportation system by mandating the availability of ZEVs do not come without challenges. An extended period of cheap gasoline that has sparked a resurging consumer interest in light trucks and sport-utility vehicles, and the relatively high costs and elevated depreciation rates of electric vehicles can make ZEV sales difficult.

That is evidenced by figures from the Department of Transportation showing electric vehicle sales dropped six percent in 2015, compared to the previous year, and other data showing total electric vehicle sales through last December have reached about 400,000, far short of the goal of 1 million set by the White House.

Policy makers should be reminded that there remain a number of viable pathways that must be included in any policy discussions aimed at achieving a significant reduction in greenhouse gas (GHG) emissions from our transportation system ‑ most notably biofuels. In fact, recent research makes clear that biofuels are a necessary element in reaching serious climate change goals.

A wide-ranging study published last fall in the research journal Environmental Science and Technology looked at more than two dozen scenarios, all benchmarked against a 50-percent petroleum-reduction target and an ambitious 80-percent GHG-reduction target. Regardless of consumer preferences between hybrid, plug-in hybrid or electric vehicles, high electrification scenarios (40 percent of miles traveled) corresponded to 26 percent of light duty transport energy being supplied by electricity.

At that level, both no-carbon electricity (from wind and solar, for example) and substantial volumes of low-carbon liquid fuels such as biofuels compliant with the federal Renewable Fuel Standard (RFS) would be required to meet an 80-percent GHG reduction target. Researchers show that to meet this target, approximately 80 percent of the total energy needed to power cars and trucks must still be met by high-energy density, low-carbon liquid fuels such as biofuels.

Another study, looking at the issue on a global level, came to similar conclusions when it addressed the question of whether the world needs biofuels by examining the feasibility of doing without them. Even with aggressive reductions in miles traveled, shifts to mass transportation, strong efficiency improvements, and deep market penetration by vehicles running on electricity and hydrogen, there remains a large demand for dense liquid fuels in 2050 (80 percent of transportation fuel) and even in 2075 (50 percent), researchers say.

As asserted in this space last November by Bruce Dale, a professor of chemical engineering at Michigan State University who was involved in both studies, “Low carbon biofuels are not optional. We must have them if we are to simultaneously achieve energy security and climate security. Electrified vehicles simply can’t do the job on their own.”

The now well-demonstrated value of biofuels underscores the need to not only maintain, but build upon ongoing research initiatives that boost the development of hybrid vehicles, and cars and light trucks that burn mid-level (E25-30) to high-level (E85) ethanol-gasoline blends. There is already considerable research showing higher ethanol blends can also offer higher octane ratings that help engines burn more cleanly and efficiently.

The studies show both the necessity and the GHG-reduction value of biofuels are part of a wider array of research confirming that, with the proper production practices and processes, bioenergy sources (biomass for power, for example) offer not only low-carbon alternatives, but even negative-carbon energy options.

It is critical that policy makers consider biofuels ‑ and all bioenergy sources ‑ as principal tools in the carbon-reduction tool box.

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