Reducing Greenhouse Gases from Flying


Rail advocates say we need to spend hundreds of billions of dollars on high-speed rail to reduce the greenhouse gas emissions from flying. But there is probably a more cost-effective way of reducing the greenhouse gas emissions from flying, such as using aviation fuel that emits fewer net greenhouse gases.

Of course, there’s no reason to think that high-speed rail would reduce greenhouse gas emissions anyway. The best study on the issue found that the huge amount of greenhouse gases emitted during construction would require 71 years of savings to balance out. But rail lines must be extensively rebuilt every 20 to 30 years, and I don’t see that the study factored the greenhouse gas emissions of such reconstruction into the analysis.

Even if high-speed rail could be built without emitting any greenhouse gases, there are ways of reducing greenhouse gases that are far less expensive. Recently, United Airlines flew a regularly scheduled plane from Chicago to Washington that exclusively used biofuels — known as sustainable aviation fuels — in one of its two engines. Federal Aviation Administration rules limit the use of biofuels to half the fuel on a commercial plane, but biofuels have been used for 100 percent of the fuels for some non-commercial test flights.

A skeptical view of sustainable aviation fuels points out that United got its fuel from corn that was grown for that purpose. It worries that “there is not enough land to keep us all up in the air.”

That’s an exaggeration: an acre of corn can produce around 460 gallons of fuel, so it would take a little more than 56 million acres of land to produce the 26 billion gallons of fuel used by domestic airlines in 2019. Considering that the United States has more than a billion acres of agricultural lands and we only grow crops on about a third of them, we have land to spare for growing corn. But growing corn for biofuels ends up emitting greenhouse gases too, so may not be the most efficient way to do it.

The same article suggests the other source of biofuels is “fats, oil, and grease,” but adds that “there is limited waste grease and oil out there, and only so much lard and beef tallow available.” However, a third source of biofuels could come from waste or by-products of agriculture and forestry, such as the branches leftover after cutting trees or the small trees thinned from a forest to allow the remaining trees grow faster.

Read the rest of this piece at The Antiplanner.

Randal O’Toole, the Antiplanner, is a policy analyst with nearly 50 years of experience reviewing transportation and land-use plans and the author of The Best-Laid Plans: How Government Planning Harms Your Quality of Life, Your Pocketbook, and Your Future.

Photo credit: Corey Seeman via Flickr under CC 2.0 License.