The clean fuels panel was framed around the fact that transportation is now the nation's highest emitting sector in terms of greenhouse gases. It addressed how adopting alternative fuels or expanded electrification can reduce the GHG emissions stemming from personal and business travel. The other panelists were Rebecca Boudreaux of Oberon Fuels, a company that produces dimethyl ether (DME); Jon Coleman of Ford Motor Company; Angela Foster-Rice of United Airlines; and Ed Harte of Southern California Gas.
Most panelists focused on the opportunities and challenges associated with the particular fuel options they are pursuing. Both natural gas and DME are being targeted to replace petroleum-based diesel fuel in commercial vehicles. Airlines such as United have been testing biofuels, which have a significant role in the industry's international plan to avoid further growth in GHG emissions from air travel after the year 2020. As a manufacturer of vehicles for utilizing all of the major alternative fuels, Ford highlighted the need to carefully analyze the many factors that influence whether and to what extent a given alternative fuel might be adopted.
Not surprisingly, I sounded a note of caution about clean fuels and climate. What follows are my prepared remarks for the panel:
In terms of my own points to raise for our discussion, the first is that we need to clarify what is meant by a clean fuel from a climate perspective. Because carbon itself is an energy carrier, not just a waste product, the science is very different for climate mitigation than it is for traditional air pollution control.
It is common to equate clean fuel with alternative fuel, meaning a transportation fuel not derived from petroleum. However, petroleum fuels can now be burned very cleanly as far as criteria pollution is concerned. Low-sulfur gasoline with advanced catalytic converters enables vanishingly small levels of tailpipe emissions as seen in super-ultra-low emission vehicles, for example. Fuels with simpler molecules, such as methane or dimethyl ether, make it easier to achieve ultra-low emissions than complex hydrocarbon mixtures, especially in diesel engines. Nevertheless, criteria emissions no longer provide a strong reason for a major fuel transition.
Moreover, given the truly disruptive technology of fracking, the policy rationale to replace petroleum for economic or energy security reasons is also greatly diminished. That means that climate protection is the most important rationale going forward.
Now, plug-in electrification zeros out vehicle emissions, and so electric vehicles are inherently clean for both CO2 and conventional air pollutants. And that brings me to this next point. For climate, it comes down to this: does the fuel carry carbon to the vehicle or not? All practical combustion fuels are carbon based and so emit CO2 when burned, and there's no practical way to scrub CO2 from a tailpipe or jet exhaust. So as long as we're using liquid fuels, carbon control requires counterbalancing tailpipe emissions by speeding up the rate at which CO2 is removed from the atmosphere somewhere else.
There is no significant benefit to downstream substitution of one chemically carbon-based fuel for another. Rather, it's a matter of carbon dioxide removal, or so-called "negative emissions," in some upstream location outside the transportation sector.
This insight is crucial for understanding why biofuels have become so controversial. As far as climate is concerned, biofuels have no benefit when they are burned. Any potential benefit can only happen through additional carbon uptake somewhere upstream. And a key word here is "additional." Diverting existing biomass harvests, whether from forests or cropland, does not speed up how quickly carbon is removed from the atmosphere, and so offers no potential climate benefit no matter how efficient the biofuel production process might be.
Of course, if the fuel is literally carbon free, such as electricity or hydrogen, then the control problem is entirely upstream. Everyone gets that and indeed, shifting the carbon control upstream is part of the appeal.
To sum up, for transportation fuels and CO2, there are really just two types of mitigation options: reduce and remove. One can reduce liquid fuel demand by driving less and flying less, improving fuel economy or substituting electricity or hydrogen. The other option is to remove CO2 from the air somewhere else. That means investing in atmospheric carbon dioxide removal through terrestrial carbon management, and the all the rules governing carbon offsets come into play. The CO2 removal must be real, additional, verifiable, permanent and adjusted for leakage. And so for transportation and climate, offsets are not just a way to buy time or control costs. Because the need for liquid fuels isn't going to go away anytime soon, CO2 removal is real missing link in climate strategy and is just as fundamental as any clean tech option.