Tech Briefs Magazine - September 2022 - 14

Solar Power for Carbon Capture
A solar thermal device converts carbon dioxide emissions into a clean energy resource.
A
device that pulls carbon out of the air on the
cheap, with renewable energy, creating fresh
fuel in the process, would help us put a harness
on our planet's runaway temperatures. Xiangkun
(Elvis) Cao, now a Schmidt Science Fellow at
MIT, created just such a device, the HI-Light Solar
Thermal Chemical Reactor, while pursuing
his Ph.D. with David Erickson at Cornell. It won
the team SAE's Create the Future Design Contest
award in 2017.
The idea was inspired by the Erickson Lab's
prior work on biofuel production from algae.
" For algae cultivation, only the top layer will get
access to light, " said Cao. " So, our lab previously
engineered waveguides for uniform light distribution
within the whole reactor for better algae
production. " They decided to apply a similar system
with non-living materials.
Cao set out to create a scalable reactor for photothermal cataconversion.
In short, incoming light irradiation into
the reactor is transmitted by glass rod waveguides with specially
designed scattering surfaces to enable uniform irradiation. The
surface of those rods is coated with a catalyst that breaks apart
CO2
lytic CO2
and other reactants, producing renewable solar fuels.
Things have come a long way since 2017, both for Cao and
for the solar reactor technology. " For me, I feel like the Create
the Future award was the starting point for my professional career, "
he said. The industrial partner for the HI-Light effort,
Dimensional Energy, was a finalist for the $20 Millon Carbon
XPrize. In 2019, Forbes featured Cao as one of their " 30 Under
30 " in Energy for North America. The reactor has progressed
2017 GRAND PRIZE WINNER
INNOVATORS: Xiangkun (Elvis)
Cao (left) and David Erickson
INNOVATION: A solar thermal
device mimics photosynthesis to
convert carbon dioxide emissions
into a clean energy resource.
methanol and other high-value hydrocarbons, which could
help reduce carbon emissions and make carbon dioxide
capture and conversion more economical.
IMPACT: The HI-Light reactor
transforms CO2
Learn more about the 20th
www.createthefuturecontest.com
14
Anniversary Contest at
and water into
in terms of efficiency, scalability, and how it's manufactured -
just how remains proprietary.
And the reactor may have abilities beyond producing fuel.
The same system can be used for other solar-driven catalytic
processes. And people on this planet may not be the only ones
to benefit from the technology. " It could potentially do a very
good job on Mars, " added Cao. " There's far more CO2
there
than on Earth, and there's evidence of subglacial liquid water
on Mars. When you feed CO2
and H2
O into the reactor, you
could produce methanol to power a spacecraft and oxygen for
the first Martians. "
Closer to home, Cao is working on pathways to integrate
various carbon capture and utilization processes. " For example,
taking pure CO2
out of the air - whatever the method
- can be costly. But if, instead, we created concentrations of
carbon at 1,000 parts per million (compared to air's 420), the
result could be used in greenhouses at little cost. " 1,000 is not
good for human health, but tomatoes really like it, " said Cao.
" There are many existing carbon capture and carbon utilization
processes out there. If we think outside of the box to
bridge carbon capture and utilization, we can create new exciting
economic opportunities while working to mitigate global
climate change. "
He's also turned his mind to policy issues and believes the
world needs to work together to create a roadmap for carbon
capture that's implemented immediately. " The United States
just banned the EPA from banning emissions from power
plants - that doesn't make sense at all, " he said. " Right now we
need a global system. We don't have a global Carbon XPrize. "
" The problem is that we have really limited time to deal with
the massive CO2
emissions, " said Cao. " I'm thinking about the
whole field: with the technologies that are out there already,
what can we do right now, not 20 years later. "
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