Removing sulfur from jet fuel cools climate

December 14, 2011

A Yale study examining the impact of aviation on climate change found that removing sulfur from jet fuel cools the atmosphere. The study was published in the October 22 issue of Geophysical Research Letters.

"Aviation is really important to the global economy. We better understand what it's doing to climate because it's the fastest growing fossil fuel-burning sector and there is no alternative to air travel in many circumstances. Emissions are projected to increase substantially in the next two decades--by a factor of two--whereas projections for other sectors are expected to decrease," said Nadine Unger, the study's author and assistant professor of climate science at the Yale School of Forestry & Environmental Studies.

Particles of sulfate, formed by burning sulfur-laden jet fuel, act like tiny mirrors that scatter solar radiation back into space. When sulfur is removed from the fuel, warming occurs but it's offset by the cooling effect of nitrate that forms from nitrogen oxides in jet exhaust. The result is that desulfurization of jet fuel has a small, net cooling effect.

In 2006 the United States introduced an ultralow sulfur standard for highway diesel, and the Federal Aviation Administration (FAA) is interested in desulfurized jet fuel for its potential to improve air quality around airports. Aircraft exhaust particles lodge in the lungs and cause respiratory and cardiovascular illness. In 2006 there were more than 31 million flights across the globe, according to an FAA emissions inventory.

"It's a win-win situation, because the sulfate can be taken out of the fuel to improve air quality around airports and, at the same time, it's not going to have a detrimental impact on global warming," she said.

Unger used a global-scale model that assessed the impact of reducing the amount of sulfur in jet fuel from 600 milligrams per kilogram of fuel to 15 milligrams per kilogram, which is the level targeted by the U.S. Department of Transportation.

The study also simulated the full impacts of aviation emissions, such as ozone, methane, carbon dioxide, sulfate and contrails--those ribbons of clouds that appear in the wake of a jet--whereas previous studies examined each chemical effect only in isolation.

"In this study we tried to put everything together so that we account for interactions between those different chemical effects," said Unger. "We find that only a third of the climate impact from aviation can be attributed to carbon dioxide."

Unger also ran a simulation of aviation emissions at the Earth's surface and found that the climate impact is four times greater because the emissions occur at altitude in the upper atmosphere.

"The chemical production of ozone is greater in the upper troposphere and its radiative efficiency is greater," she said. "It's a stronger greenhouse gas when it's higher up in the troposphere, which is exactly where aviation is making it."
-end-
The paper, "Global Climate Impact of Civil Aviation for Standard and Desulferized Jet Fuel," can be found at http://www.agu.org/journals/gl/gl1120/2011GL049289/.

Yale University

Related Emissions Articles from Brightsurf:

Multinationals' supply chains account for a fifth of global emissions
A fifth of carbon dioxide emissions come from multinational companies' global supply chains, according to a new study led by UCL and Tianjin University that shows the scope of multinationals' influence on climate change.

A new way of modulating color emissions from transparent films
Transparent luminescent materials have several applications; but so far, few multicolor light-emitting solid transparent materials exist in which the color of emission is tunable.

Can sunlight convert emissions into useful materials?
A team of researchers at the USC Viterbi School of Engineering has designed a method to break CO2 apart and convert the greenhouse gas into useful materials like fuels or consumer products ranging from pharmaceuticals to polymers.

Methane: emissions increase and it's not a good news
It is the second greenhouse gas with even a global warming potential larger than CO2.

Tracking fossil fuel emissions with carbon-14
Researchers from NOAA and the University of Colorado have devised a breakthrough method for estimating national emissions of carbon dioxide from fossil fuels using ambient air samples and a well-known isotope of carbon that scientists have relied on for decades to date archaeological sites.

COVID-19 puts brakes on global emissions
Carbon dioxide emissions from fossil fuel sources reached a maximum daily decline of 17 per cent in April as a result of drastic decline in energy demand that have occurred during the COVID-19 pandemic.

Egregious emissions
Call them 'super polluters' -- the handful of industrial facilities that emit unusually high levels of toxic chemical pollution year after year.

Continued CO2 emissions will impair cognition
New CU Boulder research finds that an anticipated rise in carbon dioxide concentrations in our indoor living and working spaces by the year 2100 could lead to impaired human cognition.

Capturing CO2 from trucks and reducing their emissions by 90%
Researchers at EPFL have patented a new concept that could cut trucks' CO2 emissions by almost 90%.

Big trucks, little emissions
Researchers reveal a new integrated, cost-efficient way of converting ethanol for fuel blends that can reduce greenhouse gas emissions.

Read More: Emissions News and Emissions Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.