DALLAS – Transport accounts for roughly one-fifth of worldwide carbon dioxide (CO2) emissions. 24% if just energy-related CO2 emissions are considered. What’s the breakdown of all modes, and which is doing more to curb its CO2 emissions?
To play fair, and in honor of Earth Day, we’ll look at global transportation emissions prior to the pandemic. The data comes from 2018 figures from the International Energy Agency (IEA).
Let’s get the obvious one out of the way. Three-quarters of transportation emissions are attributed to road travel, with the majority due to passenger vehicles, which account for 45.1%. The remaining 29.4% is accounted for by freight trucks.
Because the transportation sector as a whole accounts for 21% of total emissions and road transport accounts for three-quarters of transport emissions, road transport is responsible for 15% of total CO2 emissions.
Let’s also get the least culpable mode out of the way. Rail travel and freight emit little pollution, accounting for only 1% of total transportation emissions. Other transport accounts for 2.2%, primarily the flow of goods such as water, oil, and gas through pipelines. That leaves us with aviation and shipping.
While aviation seems to receive the most attention in conversations on action against climate change, even to the point of wondering if we should stop flying altogether “for the sake of the climate,” it accounts for only 11.6% of total transport emissions. It emits just under one billion tons of CO2 each year, accounting for around 2.5% of total world emissions.
International shipping provides a comparable amount, accounting for 10.6% of global transport CO2 emissions.
Emission-free, Sustainable Air Travel
It takes a lot of energy to launch an Airbus A380, weighing 617.3 tons, with 525 passengers (around 35.4 tons) into the sky and propel it at 500 miles (805 km) per hour. Taking off without emitting greenhouse gases into the environment is therefore a tough ask. And yet, or more likely because of it, the airline sector has vowed to be carbon neutral by 2050.
The commercial aviation industry is tackling the challenge by implementing four major measures. These include using greener fuel, implementing carbon offsets, capturing CO2 straight from the air, and harnessing the power of hydrogen.
With travel demand expected to rise post-pandemic, and considering there were an average of 100,000 flights daily in 2019, some are concerned that the industry will fall short of its goal. Airlines, however, are up to the challenge. Below are the four tactics in more detail.
The airline industry argues that replacing jet fuel with “sustainable aviation fuel” (SAF) derived from renewable sources such as plants or recycled cooking oil will be the quickest road to net-zero emissions. SAF, depending on how it is manufactured, has the potential to reduce flight emissions by up to 80%.
However, due to the high cost of SAF, it is not generally available. Subsidies are being considered by the US and other countries to reduce prices and increase supplies. Meanwhile, some aircraft are starting to incorporate small amounts into their fuel; others are flight testing engines running solely on SAF.
On March 28, 2022, Airbus announced that it had successfully operated the first A380 flight with 100% SAF on one of its engines. After the A350 and the A319neo, this was the third Airbus aircraft type to have achieved such a flight.
But again, even if SAF is able to replace fossil fuels, it will only cut emissions by about 80% at best. The remaining amount might be wiped off using carbon offsets, which are financial products that allow an emitter to pay someone else to reduce emissions.
Offset credits are earned by investing in renewable energy projects, planting trees, or participating in other types of initiatives that reduce emissions in the atmosphere. These investments are already being made by airlines and other sectors (see wren.co).
However, due to scientific uncertainty, a lack of transparency, and international quality standards, it is impossible to ensure that companies using offsets are reducing the projected emissions.
Direct Air Capture
United Airlines (UA) has avoided carbon offsets, which its CEO, Scott Kirby, describes as “the height of greenwashing.” Instead, UA is banking on direct air capture (DAC), a still-in-development technique that involves sucking carbon dioxide directly from the atmosphere and storing it underground.
The American carrier is a “minority” partner in 1PointFive Inc’s project in Texas, which aims to be the world’s first commercial direct air capture facility, capable of removing 1 million tons of CO2 from the atmosphere yearly. However, the tech is expensive, costing hundreds of dollars per every CO2 ton, and it has yet proven to scale. At least the intention is there.
Yet, the importance of DAC technology cannot be downplayed. For example, to reach net-zero for the energy sector as a whole, CO2 emissions would have to be offset by ‘negative emissions’ (e.g. the capture and storage of carbon from bioenergy or DAC) from other parts of the energy system.
Electric and Hydrogen
Other ideas being explored include whether battery capacity can be scaled up to power planes or if fuel made with renewable power can be produced in the quantities needed. While the tech is still a long way from commercialization, with electric powertrains hefty and hydrogen-powered flight in its infancy, there have been more than a few milestones in the last couple of years.
In September 2021, Rolls-Royce conducted a 15-minute test flight of a small electric plane, describing it as a “milestone on the aviation industry’s road towards decarbonization.”
The British aircraft engine manufacturer anticipates a market for electric flying taxis and eVTOLs for short distances within a few years. The company concedes that longer flights will most likely require alternative technology.
However, on April 12, 2022, a hydrogen-electric passenger aircraft was piloted for the first time between two commercial airports in Germany. H2FLY announced that its HY4 demonstrator jet, S5-MHY, flew 124 kilometers from Stuttgart (STR) to Friedrichshafen (FDH), reaching a record high altitude of 7,230 feet (2.2 kilometers) the following day.
H2FLY is focused on developing the first commercial hydrogen-electric airplane powertrain to help usher in an era of “emission-free, sustainable air travel.”
As for the two largest aerospace companies in the world, Boeing has committed to using 100% sustainable aviation fuel by 2030, while Airbus’ zero-emission concept would rely on liquid hydrogen and claims that by 2035, it will have developed the world’s first commercial airplane powered by hydrogen.
So, for those who rail against aviation, making it the poster child of climate change, it’s not that you’re barking up the wrong tree; you have bigger fish to fry.
Apologies to the trees and the fish. Happy 52nd Earth Day.