Certainly adding CO2 to the ocean has been throughly discussed, but curiously
not the safer, more secure and I think cheaper ways of first converting the CO2
to other stable forms like bicarbonates, carbonates, and recalcitrant organics
prior to ocean storage. No need to expensively make and riskily store
concentrated CO2, as in (BE)CCS. As one example: biomass or f fuels ---->
energy + CO2 ---> CO2 + H2O + CaCO3 ----> Ca2+ + 2HCO3- ----> large, secure
ocean C storage + ocean acidity mitigation. Use marine biomass and you
eliminate land, water and nutrient use issues. So rather than circling the
wagons around (BE)CCS and in the interest of maximizing our chances of success,
how about an open and objective solicitation of ideas, policy prescriptions,
and R&D investment that goes beyond land biomass +/- making concentrated CO2,
storing it underground and hoping it: stays there, isn't too expensive, doesn't
cause too many seismic events or contaminates too much ground water. Certainly
any form of CO2 management will have negatives, so let's find out which forms
offer the best benefit/risk and capacity before crowning winners or
losers.Regards,Greg
From: R. T. Pierrehumbert <phys1...@nexus.ox.ac.uk>
To: Greg Rau <gh...@sbcglobal.net>
Cc: "bmer...@mercerenvironment.net" <bmer...@mercerenvironment.net>;
"andrew.lock...@gmail.com" <andrew.lock...@gmail.com>; geoengineering
<geoengineering@googlegroups.com>; Andrew Revkin <rev...@gmail.com>;
"cla...@onid.orst.edu" <cla...@onid.orst.edu>; Oliver Morton
<olivermor...@economist.com>; Oliver Morton <omeconom...@gmail.com>
Sent: Monday, September 5, 2016 4:57 AM
Subject: Re: [geo] Scientists Focused on Geoengineering Challenge the
Inevitability of Multi-Millennial Global Warming
Actually, there has been plenty of discussion of using oceans as a place to
sequester CO2. However, injecting liquid CO2 into the deep ocean does bad
things to bottom ecosystems. One of the more interesting proposals is to
inject the CO2 in pore space in marine sediments. The hold-up there seems to
be lack of knowledge of the amount of pores space available, but I think the
idea is still live. Note that simply injecting CO2 into the deep ocean (as
opposed to sequestering it in sediments) only accelerates the equilibration of
the ocean with the atmosphere. Once you go beyond the equilibrium point, the
ocean will start outgassing CO2 back into the atmosphere, though with a time
lag of several centuries to a millennium.
As for why BECCS gets most of the attention, it’s because it’s the one
technology that has fairly predictable scaling, though even there there’s the
question of how well you can capture the CO2 from the combustion in practice,
which is subject to a lot of the same engineering problems as for coal. They
are solvable problems though, involving engineering of processes that are
basically pretty well understood. The big question about BECCS is how much
biomass you can really spare for BECCS while still feeding everybody (though if
everybody becomes vegetarian that’s less of an issue). BECCS is just a way to
capture CO2 from the air. It does not require that you store the CO2 on land —
you can inject it into the deep ocean or ocean sediments.
The way I look at reforestation is that it gives you a way to “take back” the
part of the carbon budget in the atmosphere/ocean that was due to
deforestation; that’s why, when I think about carbon budgets in the long term,
I usually focus on just the fossil fuel component. Whatever you put into the
atmosphere by deforestation can (in principle) be taken back on a century time
scale by reforestation, if there is political will to do so. Beyond that, it
is extremely dicey to rely on an equilibrium forest to be a carbon sink. There
is very little soil carbon that is truly recalcitrant, and most studies of
average age of soil carbon show rather little that is much older than a
century. This is a rather unsettled area of the carbon cycle, though.
—Ray
On Sep 4, 2016, at 6:18 PM, Greg Rau <gh...@sbcglobal.net> wrote:
Relatedly, how and why did afforestation and BECCS come to dominate the
discussion, and why has 70% of the Earth surface, half of the C cycle and the
vast majority of C storage potential (the ocean) so far been largely ignored
in designing interventions?
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