Transpo. tech.: The ways less traveled – Part 2

The 27th Conference of the Parties (COP27) came to a conclusion on Nov. 20, 2022 after convening for a total of 14 days. If global warming is to be limited to a 1.5 degree Celsius rise by the end of the century compared to what the global mean surface temperature was when the Industrial Revolution went into effect in 1750, then, obviously, serious climate-change-busting action will need to be taken.

According to established protocols, the way to achieve that is to reduce, by significant amounts, those greenhouse gas emissions in the atmosphere that are human-contributed, carbon dioxide (CO2) gas being the most common of the GHGs, near-consensus within the scientific community reaching the conclusion that CO2 can remain in the atmosphere for decades if not a century or more.

Which is why CO2 has become the main GHG of concern. The goal for 2050, meanwhile, is to lower CO2 if not other GHG emissions in the atmosphere, to net-zero, which means that whatever GHG amount enters the air (from fossil-fuel burning and other human activities) must also be removed. It’s a zero-sum relationship, essentially.

How atmospheric GHGs get there

So, there are various ways GHGs can enter the atmosphere: Through combustion (whether such occurs naturally or not); deforestation; human and other life-based-source exhalation (of carbon dioxide, in this case); permafrost thaw; and a variety of other methods.

Source sectors

The sectors emitting atmospheric greenhouse gases are many. Among them are agriculture, building, chemical production, construction, demolition, energy, industry, manufacturing, mining and extraction, transportation that also includes oil refining, petroleum production and processing mainly, etc.

The sector focused on, meanwhile, for purposes of this discussion, is transportation; the narrower subset in this case including aviation, maritime and railroading. Bicycles and automobiles were covered in Part 1 (“Transpo. tech.: Come far enough or too far gone?”).


From 4 to 6 percent of all greenhouse gas emissions in the air worldwide, comes from the aviation sector.

To my trying to assign a number to the daily flights taken all around the globe, I’m not even going to go there. What I’m more confident in stating, however, are the number of U.S.-based daily commercial flights occurring; that number being 50,000. That, in itself, is huge! Though that does not include in it flights taken for the purposes of crop-dusting, helicopter rescues and corresponding transport to medical centers, those that monitor either freeway conditions or criminal activity happening on the ground from above. Now add to this the potential for the air space to become even more crowded with the prospect of flying cars, that place that is designated for flight, if that does (pardon the pun) take off, then expect more airborne traffic to follow. And with nearly all aircraft being sources of air pollution, the environmental fallout from such could become tremendous.

So, how to create a transportation mode – in this instance, the ground and air-based mode that aviation is – that is able to significantly reduce its negative air impact, is the question. Not unlike those strategies applied to other transportation modalities, to reduce pollutant emissions coming from such, many can likewise be applied to the aviation realm as well.

For starters, there are cleaner aviation fuels that can be used. This, of course, can be coupled with aviation equipment that burns fuel more cleanly and efficiently. Or, even eliminating some short-distance flights completely and supplanting with competitive rail passenger travel in the same corridors or service lanes, is but one more alternative to lower the amount of air pollution coming from aviation.

And, it can even transcend this, like with the adoption of hybridization or full-on electrification.

It is important to remember, however, that total electrification of flight still has some issues needing to be ironed out. For instance, electric aircraft require batteries to generate the power needed to make lift-off and flight possible. Depending on the application, the batteries utilized could add much in the way of weight, making this type of arrangement in some situations impractical.

And, since generating lift and thrust requires tremendous power especially in heavier, bigger aircraft, and much less so when it comes to maintaining cruising-speed at altitude, this is where hybridization (electricity and combustion generated using fossil fuels) can fill the bill. Such an arrangement can not only result in there being less negative air impact consequently providing environmental benefit, but money could be saved where capital outlays for fuel and the larger operational platform are concerned.


From an Oct. 23, 2020 press release, Transport & Environment wrote: “The impact of the decision at this week’s [International Maritime Organization] Intersessional working Group on Reducing Greenhouse Gas Emissions from Ships will not cap, let alone reduce, shipping emissions this decade.” To which I say, “This is telling.” (For more, see: “The Paris Accord, of ship-and-shore air, and other nautical insights,” right here on the Air Quality Matters blog.

Meanwhile, back in 2013 in a press release the European Commission expressed, “Emissions from the international maritime transport sector today account for 3% of global greenhouse gas (GHG) emissions and 4% of [European Union] GHG emissions.”

Maritime, with 3% global GHGs, makes maritime the second largest emissions contributor after aviation. In real numbers, maritime is responsible for releasing between 100 million and 200 million tons of GHGs annually.

Looking on the bright side, to its credit ocean- and river-shipping interests are working to address the pollution problem. The ways of mitigating emissions coming from shipping vary.

One solution, liquefied natural gas or LNG, is currently the most environmentally friendly fuel ships can use to help with air cleanup efforts.

A second resolution is filtering or filtration. Filters can be installed to remove pollutant emissions like oxides of nitrogen (NOx) and sulfur dioxide (SO2). And, yet another option still is the deployment of ship chimney scrubbers. But these methods of pollutant removal don’t come cheap.

Then there is ship retrofitting, that is, replacing, old, dirty ship-propulsion equipment with the more modern, more efficient power supplies that burn fuel more cleanly and efficiently. There is also ship replacement: When it’s time for retirement, decommissioned vessels can be supplanted by new ones.

So you’re aware (if that’s not already the case), the Danish shipping giant Maersk has purchased a total of eight ships that have zero carbon discharge, this according to what I’ve read.

As long as the will is there, shipping doesn’t have to be as polluting as it is presently.

To learn more, see: “Ramping up renewables to power the clean future of inland shipping,” a Nov. 16, 2022 Horizon Magazine article at


The least utilized of all transportation modes is, not surprisingly, railroading. Being that trains represent a small fractional portion of the total automated-movement pie, this partly explains why railroading is the least negatively environmentally impacting to the air compared to all other automated sectors within the transportation realm. Trains’ total GHG contribution to the atmosphere is a low 2 percent. But, electric operation and the fact that trains are naturally (by design) one of the most efficient forms of automated transportation going, surely this aids in that one particular aspect: cleaner-operating or driven, in other words.

Better equipment, train handling, design and improved propulsion systems have all facilitated progress on the environmental and air-quality improvement front. Everything from waste-vegetable-oil-burning steam locomotives to those supersleek, superefficient high-speed electric passenger trains and everything in between like battery powered trains, clean-diesel locomotives that emit far fewer pollutants through the exhaust systems, and dual-mode (diesel and electric, for instance) affairs. Even fuel cells have arrived on scene, hydrogen being the fuel of choice here. There is one Australian-based railway operation whose train is powered by solar energy.

And, where is the mode possibly headed next? When it comes to helping save the air, really, right now as I write this, it is anybody’s guess.


The potential is certainly there for transportation to further improve upon the progress already made in terms of air improvement or air cleanup.

Automation has been a viable part of transportation for better than 200 years, be the affected domain shipping, motoring, flying, bicycling or railroading: what a difference, automation has made! Hopefully this sector will see even further improvement coming. Stay tuned!


Text has been adjusted in places to make more clear content meaning.

– Alan Kandel

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This post was last updated on Nov. 25, 2022 at 7:17 a.m. Pacific Standard Time.