I don't follow. If I have an industrial process that reacts crushed rock with
air CO2 to make and store dissolved or solid (bi)carbonate, I have directly
captured CO2 from air. If I plant a tree seed and it grows into a tree I have
directly captured CO2 from air to make biomass. Yet neither of these examples
appear in DAC literature. To qualify as DAC it apparently must be abiotic and
it must result in concentrated molecular CO2 as the end product (but there are
usually other intermediate C compounds formed and reacted to make conc CO2). Of
course you can then feed this to rocks, plants or chemical synthesis to make
whatever C compound you want, but it still has a DAC front end. My question is:
Why do this if you can more cheaply coax rocks, plants and/or chemistry to
directly capture air CO2 and process and store it in other C forms, avoiding
the thermodynamically costly CO2 concentration step? Unless, of course, there
is a hot market or credit for concentrated CO2 that can offset the cost.Greg
From: Andrew Lockley <[email protected]>
To: RAU greg <[email protected]>
Cc: geoengineering <[email protected]>; Christophe Jospe
<[email protected]>
Sent: Wednesday, May 24, 2017 11:37 PM
Subject: Re: [geo] #WhatIsDAC?
Indirect air capture would be when the industrial process doesn't capture CO2,
eg crushing rock, planting seeds, etc.
A
On 25 May 2017 01:25, "Greg Rau" <[email protected]> wrote:
In more that 140 characters: Direct Air Capture has come to mean any abiotic
method of removing CO2 from air in which the end product is concentrated CO2.
It is not an accurate term because any method of capturing CO2 from air is
direct removal - a photosynthesizing plant cell, a pan of concentrated NaOH, a
weathering rock. Or please define for me what Indirect Air Capture is. ;-)Greg
From: Christophe Jospe <[email protected]>
To: geoengineering@googlegroups. com
Sent: Wednesday, May 24, 2017 2:03 PM
Subject: [geo] #WhatIsDAC?
Hi Group,
I'd like to try a social online experiment with this group (against my better
judgement of not wanting to be pigeon-holed into advocating for one specific
geoengineering solution). Sure, it's in part self-motivated because I just
published an article entitled "what is direct air capture? (part 1)" and I plan
on continuing to answer that question in future posts. I always like it when
more people read what I have to say. However, I would much rather increase the
number of people who are asking that question, irrespective of any online
recognition, and pull out of the wood work others who are well positioned to
answer that question.
My personal viewpoint is that direct air capture is NOT a silver bullet to
solving climate change, nor something that will necessarily work at scale, nor
is better positioned than any of the other many concepts presented in this
group. During the few short years when I was working inside that industry for
the Center for Negative Carbon Emissions, I gathered a lot of anecdotal
information and now feel compelled to get it out through the blogging section
on my website. I do think that as an "out there" technology, the approach
provides a unique hook for people who are just beginning to think about carbon
dioxide removal - or geoengineering more broadly and can expand the number of
people who want to engage with this community.
I started a hashtag #WhatIsDAC on twitter. If you have positive, negative, or
inquistive feelings about the topic - please express them in 140 characters.
Let's collectively see where it goes!
Christophe
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Christophe Jospe
LinkedIn
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