Gasoline Keeps Getting Dirtier while Alternatives Keep Getting Cleaner

February 10, 2016

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by David Roberts (VOX) The Union of Concerned Scientists has issued a new report that takes a high-level look at three key transportation fuels: gasoline, biofuels, and electricity.

It compares their greenhouse gas emissions, taking into account their full life cycle, from production to end use. And it looks at how those life cycle emissions are evolving over time.

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It is possible to make extremely carbon-intensive biofuels and electricity. The reason they're getting cleaner is that they are being held to account. Their emissions are tracked and required by regulation to decline.

Emissions from gasoline aren't rising because cars are polluting more. They aren't. Thanks to fuel economy standards, per-gallon emissions from gasoline combustion are holding roughly steady in the US.

What's rising is emissions from oil extraction and refining.

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The switch to electric transportation could take some time, and it would be nice to have cleaner fuels in the interim. The report also goes into great detail about how biofuels can be improved, including through more efficient production, a shift to corn husks or other agricultural wastes (rather than food), or a shift to more abundant non-food sources like switchgrass. READ MORE and MORE / MORE (Biofuels Digest) Download report

Excerpt from Biofuels Digest: The gasoline used to fuel a typical car emits the equivalent of 5.7 metric tons of carbon pollution every year. While much of this is tailpipe pollution, 1.5 metric tons of this pollution—about a quarter—is generated by extraction and refining, and that number is getting worse over time.

Meanwhile, today’s ethanol produces on average 20 percent lower global warming emissions than gasoline, and moving beyond corn to more advanced biofuels will reduce emissions even more. Based on the U.S. grid average, battery-electric vehicles produce half the global warming emissions of comparable gasoline vehicles, and in some regions electric vehicles are even cleaner. Across the county EV’s will get cleaner as we move away from coal and get more of our energy from renewable power sources. As oil continues to get dirtier, the advantage of alternative power sources will only increase.

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The key findings of the report

Depending on where oil comes from and how it is produced, the global warming pollution associated with extracting, producing, and refining different oils can vary by a factor of 5.
Emissions from oil extraction and refining are now, on average, 30% higher than they were a decade ago.
Expanded use of corn ethanol and other biofuels has cut oil use significantly and ethanol has lower global warming emissions than gasoline, but we can and must do better, with cleaner non-food based cellulosic ethanol.
Cellulosic fuels made from agricultural residues and perennial grasses have the potential to cut emissions 60% or more relative to gasoline.
A battery electric vehicle is, on average, about 50% lower in emissions than gasoline, and much cleaner in states with cleaner electric grids.
As the grid gets cleaner with more renewable energy, the advantage of electric vehicles grows.

Learn more about the analysis that went into the report in a two part briefing:

February 23 Oil: Gasoline is getting dirtier, but it doesn’t have to

February 24 Clean fuels: Realizing the potential of cellulosic biofuels and renewable electricity