Researchers at the Georgia Institute of Technology (www.gatech.edu
have developed a strategy to capture, store, and eventually recycle
carbon from vehicles to prevent the pollutant from finding its way from
a car tailpipe into the atmosphere.
Technologies to capture carbon
dioxide emissions from large-scale sources such as power plants have
recently gained attention in the scientific community, but nearly
two-thirds of global carbon emissions are created by much smaller
polluters — automobiles, transportation vehicles, and distributed
industrial power generation applications (e.g., diesel power
The Georgia Tech team’s goal is to create a sustainable
transportation system that uses a liquid fuel and traps the carbon
emission in the vehicle for later processing at a fueling station. The
carbon would then be shuttled back to a processing plant where it could
be transformed into liquid fuel. Currently, Georgia Tech researchers
are developing a fuel processing device to separate the carbon and
store it in the vehicle in liquid form.
The research was published in
Energy Conversion and Management . The research was funded by NASA, the
U.S. Department of Defense NDSEG Fellowship Program and Georgia Tech’s
CEO (Creating Energy Options) Program.
Little research has been done to
explore carbon capture from vehicles, but the Georgia Tech team
outlines an economically feasible strategy for processing fossil or
synthetic, carbon-containing liquid fuels that allows for the capture
and recycling of carbon at the point of emission. In the long term,
this strategy would enable the development of a sustainable
transportation system with no carbon emission.
Georgia Tech’s near-future strategy
involves capturing carbon emissions from conventional (fossil) liquid
hydrocarbon-fueled vehicles with an onboard fuel processor designed to
separate the hydrogen in the fuel from the carbon. Hydrogen is then
used to power the vehicle, while the carbon is stored on board the
vehicle in a liquid form until it is disposed at a refueling station.
It is then transported to a centralized site to be sequestered in a
permanent location currently under investigation by scientists, such as
geological formations, under the oceans or in solid carbonate form.
In the long-term strategy,
the carbon dioxide will be recycled forming a closed-loop system,
involving synthesis of high energy density liquid fuel suitable for the
Georgia Tech settled on a hydrogen-fueled
vehicle for its carbon capture plan because pure hydrogen produces no
carbon emissions when it is used as a fuel to power the vehicle. The
fuel processor produces the hydrogen on-board the vehicle from the
hydrocarbon fuel without introducing air into the process, resulting in
an enriched carbon byproduct that can be captured with minimal
energetic penalty. Traditional combustion systems, including current
gasoline-powered automobiles, have a combustion process that combines
fuel and air — leaving the carbon dioxide emissions highly diluted and
very difficult to capture.
The Georgia Tech team compared the
proposed system with other systems that are currently being considered,
focusing on the logistic and economic challenges of adopting them on a
global scale. In particular, electric vehicles could be part of a
long-term solution to carbon emissions, but the team raised concerns
about the limits of battery technology, including capacity and charging
The hydrogen economy presents yet another possible solution to
carbon emissions but also yet another roadblock — infrastructure. While
liquid-based hydrogen carriers could be conveniently transported and
stored using existing fuel infrastructure, the distribution of gaseous
hydrogen would require the creation of a new and costly infrastructure
of pipelines, tanks and filling stations.
The Georgia Tech team has already
created a fuel processor, called CO2/H2 Active Membrane Piston (CHAMP)
reactor, capable of efficiently producing hydrogen and separating and
liquefying CO2 from a liquid hydrocarbon or synthetic fuel used by an
internal combustion engine or fuel cell. After the carbon dioxide is
separated from the hydrogen, it can then be stored in liquefied state
on-board the vehicle. The liquid state provides a much more stable and
dense form of carbon, which is easy to store and transport.
The Georgia Tech paper also
details the subsequent long-term strategy to create a truly sustainable
system, including moving past carbon sequestration and into a method to
recycle the captured carbon back into fuel. Once captured on-board the
vehicle, the liquid carbon dioxide is deposited back at the fueling
station and piped back to a facility where it is converted into a
synthetic liquid fuel to complete the cycle.
Now that the Georgia Tech team has
come up with a proposed system and device to produce hydrogen and, at
the same time, capture carbon emissions, the greatest remaining
challenge to a truly carbon-free transportation system will be
developing a method for making a synthetic liquid fuel from just CO2
and water using renewable energy sources, Fedorov said. The team is
exploring a few ideas in this area, he added.