Towards UAV-assisted monitoring of onshore geological CO2 storage site
Date
2017
Authors
Poppa, Florian
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Abstract
Scientists all over the world look for solutions to reduce
greenhouse gas emissions in an effort to achieve proclaimed
emissions reduction targets. An intriguing candidate with the
potential to make a substantial contribution to this attempt is
carbon capture and storage (CCS). The key advantage of CCS is
that it provides the possibility to make a significant impact on
the reduction of anthropogenic carbon dioxide (CO2) emissions
from power plants and carbon-rich industry processes while
maintaining existing fossil fuel energy infrastructure. The
technique could therefore be used as a transitional solution
until fossil fuels can be eliminated from the energy generation
mix, and the energy efficiency of industrial processes as well as
appliances and products is further improved.
Like other technologies, CCS comes with its risks and rewards. To
minimize possible negative impacts on humans as well as on the
environment, it is necessary to understand the risks and to
address them accordingly. A range of monitoring solutions for
geological CO2 storage sites is available. However, a
cost-effective solution for the regular observation of
atmospheric CO2 concentrations (or tracer concentrations) of
large areas above onshore geological CO2 storage sites has yet to
be developed.
This thesis discusses the use of a helicopter unmanned aerial
vehicle (UAV) to fill this gap. The robot platform and its
autopilot are designed to cope with ongoing sensor developments
in addition to providing safety features necessary for the beyond
line-of-sight operation of the UAV. The design focuses on the use
of commercial off-the-shelf components for the aerial platform in
order to shorten the development time and to reduce costs. The
autopilot does neither enforce a specific helicopter model nor
defines a set position estimation unit to be used. Access to the
control loop enables low-level extensions like obstacle avoidance
to be implemented. The developed solution allows the monitoring
of an area of approximately 750m2 with one set of batteries in
one altitude with a spatial resolution of 2m by 2m. Experiments
show that point source leaks of as low as 100kg CO2 per day can
be detected and their source located.
As opposed to autonomous take-offs of the helicopter UAV,
autonomous landings on small dedicated helipads require an
accurate localization system. A time difference of arrival (TDOA)
based acoustic localization system which is based on planar
microphone arrays with at least four microphones is proposed. The
system can be embedded into the landing platform and provides the
accuracy necessary to land the UAV on a helipad of the size of 1m
by 1m. A review of existing TDOA-based approaches is given.
Simulations show that the developed approach outperforms its
direct competitors for the targeted task. Furthermore,
experimental results with the developed UAV confirm the
feasibility of the introduced method. The effects of the sensor
arrangement onto the quality of the calculated position estimates
are also discussed.
In order to combine robotic-assisted monitoring solutions and
other monitoring strategies (e.g. sensor networks and individual
sensors) into a single solution, it is necessary to have a
framework which allows next to the measurement data analysis also
the management (path changes, robot behavior changes, monitoring
of internal robot state) of possibly multiple heterogeneous
mobile robotic systems. A modular user interface (UI) framework
is proposed which allows robots from different vendors and with
various configurations next to individual sensors and sensor
networks to be managed from a single application. The software
system introduces a strict separation between the robot control
software and UIs. UI implementations inside the UI framework can
be reused across robot platforms, which can reduce the
integration time of new robots significantly. The end user
benefits by being able to manage a fleet of robots from various
vendors and being able to analyze all the measurement data
together in a single solution.
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Keywords
Unmanned Aerial Vehicle, UAV, Environmental Monitoring
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Thesis (PhD)
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