A New Direct Air Capture System Operating on Low Grade Heat Generated from Geothermal Plants

Statement of the problem or situation that is being addressed throughout Phase I portion
of your proposal. Describe the problem or situation being addressed. (Typically one to
three sentences).
While technologies to control the emissions from stationary sources are available, the CO2
removal from small generators and transportation systems (e.g., ships, airplanes) at the source
is not practical, making Direct Air Capture (DAC) the only option to control the CO2
concentration in the atmosphere. However, the Direct CO2 capture from air is highly challenging
due to the very low concentration of CO2 in the air (less than 0.5 mbar). Because of this very
low driving force, the recovery of CO2 from air requires a much larger energy input compared to
the systems used in post-combustion capture. Integrating the DAC system with processes that
generates low grade heat may reduce the cost of capture.
General statement of how this problem is being addressed. This is the overall objective of
the Phase I project. How is this problem being addressed? What is the overall project
approach? (Ideally, two to four sentences).
TDA Research Inc. proposes to develop a new sorbent-based DAC system utilizing the waste
heat from a commercial operation to drive the carbon capture process. The small temperature
differential needed to operate the temperature swing adsorption (TSA) cycle (~50-60oC) which
will remove CO2 at ~500 ppmv and concentrate it to a high pressure, pure gas at 1 atm.
What is to be done in Phase I? (Typically three to four sentences).
In Phase I, we will optimize the operation of the new sorbent to best match the operation of the
geothermal energy generation cycle. In bench-scale proof-of-concept tests, we will demonstrate
the sorbent capabilities (i.e., CO2 uptake, energy requirement for the regeneration) and assess
the sorbent life (both chemical and mechanical stability over many cycles). In a detailed
process design and simulation, we will carry out the integration of the DAC process to the
geothermal power plant. We will estimate the carbon capture cost following DOE/NETL process
design and analysis guidelines.
Commercial Applications and Other Benefits (limited to the space provided). Summarize the
future applications or public benefits if the project is carried over into Phase III and beyond.
The new technology will reduce the cost of CO2 capture form dilute sources (including air) at low
cost. Hence, it will find immediate use various carbon capture applications.