Effectively removing CO2 from the atmosphere

Date:
August 13, 2021
Source:
Paul Scherrer Institute
Summary:
Researchers have investigated the extent to which direct capture of
carbon dioxide (CO2) from the ambient air can help to effectively
remove greenhouse gases from the atmosphere. The result: With
careful planning, for example with regard to location and provision
of the necessary energy, CO2 can be removed in a climate-effective
manner.



FULL STORY ========================================================================== Researchers at the Paul Scherrer Institute PSI and ETH Zurich have
investigated the extent to which direct capture of carbon dioxide (CO2)
from the ambient air can help to effectively remove greenhouse gases from
the atmosphere. The result: With careful planning, for example with regard
to location and provision of the necessary energy, CO2 can be removed
in a climate-effective manner. The researchers have now published their analysis in the journal Environmental Science & Technology.


========================================================================== Direct air carbon capture and storage (DACCS) is a comparatively new
technology for removal of carbon dioxide from the atmosphere. Since
it would allow large amounts of CO2 to be, in effect, trapped, this
technology could also reduce the greenhouse effect. Researchers at the
Paul Scherrer Institute PSI and ETH Zurich have now investigated how effectively this could be implemented with different system configurations
of a certain process. To do this, they analysed a total of five different configurations for capturing CO2 from the air and their use at eight
different locations around the world. One result: Depending on the
combination of technology used and the specific location, CO2 can be
removed from the air with an effectiveness of up to 97 percent.

To separate CO2 from the atmosphere, air is first passed over a so-called absorbent with the help of fans. This binds CO2 until its capacity to
absorb the greenhouse gas is exhausted. Then, in the second, so-called desorption step, the CO2 is released from the absorbent again. Depending
on the absorbent, this happens at comparatively high temperatures of
up to 900 degrees Celsius or at rather low temperatures of about 100
degrees Celsius. In addition to the energy required for the production and installation of the equipment, the operation of the fans and generation
of the required heat produce greenhouse gas emissions. "The use of
this technology only makes sense if these emissions are significantly
lower than the amounts of CO2 it helps to store," says Tom Terlouw,
who conducts research at PSI's Laboratory for Energy Systems Analysis
and is first author of the study.

Efficiency of up to 97 percent In their study, the researchers focused
their examination on a system from the Swiss company Climeworks, which
works with the low-temperature process. The PSI researchers analysed the
use of the technology at eight locations worldwide: Chile, Greece, Jordan, Mexico, Spain, Iceland, Norway, and Switzerland. For each location,
they calculated the overall greenhouse gas emissions over the entire
life cycle of a plant. For example, they compared the efficiency of the
process when the required electricity is provided by solar energy or
comes from the existing electricity grid. As sources for the necessary
thermal energy they assumed, for example, solar thermal plants, waste
heat from industrial processes, or heat pumps. For the study, they drew
up five different system layouts for atmospheric CO2 capture for each of
the eight sites. With respect to efficiency, the results show an enormous range, from 9 to 97 percent, in terms of actual greenhouse-gas removal
through the use of DACCS.

No substitute for reducing emissions "The technologies for CO2 capture
are merely complementary to an overall decarbonisation strategy --
that is, for the reduction of CO2 emissions -- and cannot replace it,"
stresses Christian Bauer, a scientist at the Laboratory for Energy Systems Analysis and a co-author of the study. "However, they can be helpful in achieving the goals defined in the Paris Agreement on climate change,
because certain emissions, for example from agriculture, cannot be
avoided." Thus a net-zero emissions target can only be achieved with
the help of suitable negative-emissions technologies.

========================================================================== Story Source: Materials provided by Paul_Scherrer_Institute. Original
written by Sebastian Jutzi. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Tom Terlouw, Karin Treyer, Christian Bauer, Marco Mazzotti. Life
Cycle
Assessment of Direct Air Carbon Capture and Storage with Low-Carbon
Energy Sources. Environmental Science & Technology, 2021; DOI:
10.1021/ acs.est.1c03263 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210813100255.htm

--- up 14 weeks, 22 hours, 45 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)