Download ATGTS: Automated Trace Gas Trapping System

ATGTS: Automated Trace Gas
Trapping System
Team 7:
Sponsored by: Dr. N. Ostrom, Dr. K. Smemo, & Dr. P. Robertson
Funded by the Biogeochemistry Environmental Research Initiative
Introduction
• Global warming is catastrophic and accelerating
phenomena
• The key to addressing the global warming problem is to
further understanding the cause, CO2 and N20 cycles
• Motivated development of ATGTS
• Traps CO2 and N20 remotely at a high accuracy
Agricultural Practices
• The dynamics of CO2
& N2O are heavily
influenced by land
management
practices
• System will be used to
develop new farming
practices and test old
ones.
• Increase
accountability
Carbon Crediting
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ATGTS makes carbon trading possible
AAA act
Kyoto Protocol
Sustainable oversight
Nitrogen trading
Impacts
•
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Eliminate slash and burn
Regulate crop prices with out waste
Sustainable farming
No impact on yield or profits
Potential to reduce green house gas
emissions more than taking 210 million
cars of the road (1.6 billion tons of CO2)
• Up to ¼ reduction in net emissions
Current Problems
• Existing devices have
insufficient resolution
for Carbon Crediting
systems
• N2O flux is poorly
constrained, and its
microbial origin
pathways are not well
understood
• Thus the devotement
of an ATGTS system
Purpose of the ATGTS
• To control greenhouse gas emissions, a method of
monitoring their flux from soil is needed
• Team 7 charged with designing and constructing a
device capable of taking measurements of CO2 and
N2O on a local scale
• Provide a platform which facilitates analysis techniques
to determine microbial origins of gases via isotopic
analysis
Existing Technologies
• Most existing devices and techniques measure
emissions on large scales
• Do not provide resolution for carbon credit systems, or
data needed for isotopic analysis
Solution: ATGTS
• ATGTS uses molecular
sieve to trap trace gases
for offsite analysis
• Provides trace gas
recovery rate to avoid
isotopic fractionation
• Measures flux emitted on
a scale of meters
• Budgeted $5,000 for
prototype construction
Design Requirements
• Field operable for one
month at a time without
maintenance or reliance
on solar power
• Desiccant and chemical
traps to remove
unwanted trace gases
• Well balanced flow rate
• High recovery of trace
gases without isotopic
fractionation
Design Requirements, Cont.
• Easily deployable, yet
large enough to account
for spatial variability
• Atmospheric conditions in
the soil flux chamber
should match the outer
atmosphere of the area
• Deployed over bare soil
(e.g. Agricultural soils)
where vegetation has
been removed
Proof of Concept
• Performed by sponsors
• N2O and CO2 are effectively
removed from the sample
volume without isotopic
fractionation
• Demonstrates potential of a
full-scale version of the
ATGTS
Design of the ATGTS
• Sub-chambers are used
to reduce power
consumption while
maintaining accuracy
• System is governed by
microcontroller and timer
Microcontroller
CY3214-PSoCEvalUSB
•
Programmable System on
Chip (PSoC)
•
Visual, code-free embedded
design
•
C language base
•
Manually edit code
State Machine
• Microcontroller
simulates state machine
to operate ATGTS
• Rest, Mix, N2O, CO2,
Equilibrate
• Timer turns
microcontroller on/off
every six hours
System Flow Chart
Part Selection
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Valves
Micro-Diaphragm Pump
Flow Rate: 250 mL/min
Linear Actuator
Material Selection
• Materials in contact with the gases must be
chemically inert and gas impermeable
• Outer Casing and Sub-chambers
• White PVC – avoiding the greenhouse effect
• Desiccant Trap
• Nafion Tubing
• CO2 Chemical Trap
• 304 Stainless Steel Tubing
• Carbosorb
• CO2 and N2O Traps
• 304 Stainless Steel Tubing
• Molecular Sieve 5A
• Tubing
• PEEK
•
Trap Manifold: Constraints
• Withstand 300
degrees Celsius for at
least 3 hours.
• The traps must be
easily accessible.
• The traps need to be
easily exchangeable.
• Traps need a shut-off
valve to prevent leaks
during transport
Trap Manifold: Design
• Quick connects for easy
removal
• Manual valve cut-off air to
the traps to preserve
sample, reduce chemical
hazards
• Reducers connect quick
connects to PEEK tubing
• Made of 304 Stainless
Steel for heating and
chemical properties
Rainfall Dispersion System
• Replicating ambient
conditions requires
replicating rainfall
• Rain collector with
solenoid feeds water onto
a dispersal grate
• Rain water dropped into
soil flux chamber with
equilibrate cycle
Sub-Chamber Housing
• Subsample soil flux
chamber to conserve on
device size, power
• Sliding aluminum door and
Viton foam give airtight
seal
• Door actuated by a linear
motor
Sub-Chamber, Cont.
• Rear door included to
eliminate dead volumes
during rest and stir events
• Fan pointing into subchamber to thoroughly mix
sample volumes
Power System
• 25.2 amp-hour lithium ion
battery
• Transistor switches for
solenoids and pump
• H-bridge for linear
actuators
• Voltage regulator
supplies lower voltage for
microcontroller and pump
PWM Driver
• PWM control used on
solenoids
• 78% duty cycle used to
open, 38% used to hold
• Reduces power
consumption by 60%
• Reduces monthly amphour budget from 20AH to
13AH
Timer
• Saves energy by
disconnecting the power
to all other components
when not in use
• Activates microcontroller
every 6 hours for 10
minutes
• Internal relay can output
16A to system
Future Work
• Subchamber track will be
redesigned with an
indexing door
• Design and construction
of a device to help
remove samples from
molsiv
• Look into locking
solenoids
• Additional flow sensors
Conclusion
• ATGTS will be a useful
tool in the development of
carbon crediting systems
• Will aid future research
into the origins of
microbial N2O