A Sandia-led team built two mobile facilities that are designed to measure greenhouse gases and other species so that they could be traced and identified. The system was deployed recently to the Atmospheric Radiation Measurement (ARM) facility in Oklahoma. Photo: Hope Michelsen |
Researchers at Sandia
National Laboratories have designed and built a mobile research facility to
trace and identify the origin of greenhouse gases.
In addition to
pinpointing the chemicals’ location, the unique mobile facility can help
researchers learn whether the gases are biogenic (coming from plant sources) or
anthropogenic (coming from man-made sources). This is important when officials
look at ways to mitigate emission impacts in their communities, regions, or
states.
“Information from
this kind of facility should be useful to both researchers and policymakers,”
says Hope Michelsen, a combustion and atmospheric chemist at Sandia and one of
the lead researchers on the project. “To figure out whether emissions reduction
policies are effective, we need a way to measure emissions by emissions sector,
such as power generation or transportation. We currently don’t have the tools
in place to do these types of measurements, so we hope our idea can be part of
the solution.”
The mobile system
consists of two moving van-sized trucks, each equipped with instrumentation and
equipment. Included are instruments that measure greenhouse gases, such as
carbon dioxide and methane, and species co-emitted with greenhouse gases, such
as sulfur dioxide, nitrogen oxide, carbon monoxide, ozone, and other traditional
pollutants.
“Elected officials
who have enacted new policies to help reduce unwanted greenhouse gas emissions
could conceivably find a mobile facility to be of great use,” says Michelsen. “To figure out whether emissions reduction policies are effective, we need a
way to measure emissions by emissions sector, such as power generation or transportation,”
Michelsen continues. “We currently don’t have the tools in place to do these types
of measurements, so we hope our idea can be part of the solution.”
While the instruments
are all commercially available, another current project funded internally at
Sandia aims to build an instrument to more accurately measure black carbon
soot, formed through the incomplete combustion of fossil fuels, biofuels, and
biomass. Black carbon soot is believed by atmospheric scientists to be one of
the strongest absorbers of solar radiation.
Atop each truck sits
an antennae-like mast that draws in air, sends it down into the truck, and
distributes it to the various instruments, including a mass spectrometer that
sorts out hydrocarbons and helps to distinguish between emission sources, which
can range from traffic to pine trees.
A piece of equipment
provided by Lawrence Livermore National Laboratory (LLNL) captures samples in
flasks for analysis at LLNL’s Center for Accelerator Mass Spectrometry to
measure the radiocarbon fractionation of carbon dioxide.
Because radiocarbon
is severely depleted in fossil fuels, it is a powerful indicator of man-made
carbon dioxide sources. Some of these samples were also sent to the National
Oceanic and Atmospheric Administration and to the University
of California, Davis for further trace gas and isotopic
analysis.
The mobile laboratory
has already been deployed once to the Atmospheric Radiation Measurement
(ARM) facility
in Oklahoma, The ARM location in Oklahoma, said Sandia
researcher Ray Bambha, was selected because of its solid history as a climate
research site, and ARM instruments were used to validate some of the
measurements from the mobile lab. Bambha served as the principal investigator
for the field experiment, alongside several other Sandians serving in key
roles. Collaborators from both LLNL and Los Alamos National Laboratory joined
the Sandia team for portions of the Oklahoma
deployment.
The pilot deployment,
Bambha says, was successful in that the system collected large quantities of
data, which are still in the process of being analyzed. It allowed the team to
test instruments that hadn’t been used previously, and it helped them to
understand the atmospheric community’s need for an “uncertainty quantification”
capability—a method of assigning a confidence level to an estimate—and tracer
measurements, which provide a more effective method for identifying the source
of certain emissions. Michelsen says Sandia is in the process of building a
team of researchers that can take the next step with the system and begin to
use wind information and inverse modeling to more accurately identify emission
sources.
In the short-term,
Michelsen says, program development efforts are well under way in hopes of
securing follow-on funding for other test deployments. The long-term vision for
the program calls for a full network of mobile facilities that could be
deployed strategically in select regions, states, or cities, to enable the
capturing of a broad spectrum of emissions and related information.
