POWER May 2015 - 55

CARBON CAPTURE AND SEQUESTRATION
2. Freezing out carbon dioxide. The SES process relies on patented heat exchangers
developed by the company. By chilling the flue gas stream to cryogenic temperature, the process
freezes out CO2 (as well as SOx, NOx, and mercury) for separation and removal. Courtesy: SES
free flowing powder. " That powder has been
used in products ranging from " board type
products " to plant holders and benches.
Scale Matters
At both the ARPA-E and MIT events earlier
this year, industry leaders expressed confidence
that CCS is a realistic option for reducing
greenhouse gas emissions. At the MIT
event, for example, Dirk Smit, chief scientist
for Shell Global, said Shell thinks CCS " is
a very viable alternative " when " enabled by
carbon pricing, " which the company is in favor
of. For a sustainable energy system, we
need " affordable carbon capture technology "
but also carbon storage " at scale, " because affordability,
he said, is a scale question.
Scale, many agree, poses the greater chal3.
Cold, hard cash. Especially when factoring in the Cryogenic Carbon Capture process's
ability to capture traditional power plant pollutants, costs compare very favorably to existing
amine-based approaches to carbon dioxide capture. Source: SES
■ $/Metric ton avoided ■ Parasitic load
70
60
50
40
30
20
10
$69
28%
$35
14%
$32
12%
$27 13%
$26
14%
11%
$14
35
30
25
20
15
10
5
CCC-ECL base
case
With steam
cycle integration
SOx capture
offset
environmental unknowns, EPRI is working on a
report that looks at the impact of CO2
on groundwater.
Given the concerns about the effects of
fracking and fluid reinjection on groundwater,
this is a nontrivial consideration.)
Fortunately, that's not stopping researchers
from exploring new options. SES, for example,
says its patented technology can achieve stable
storage in natural saline aquifers of " up to seven
times more CO2
than traditional methods. "
Aside from underground burial of captured
CO2, what other options are there? Several
have been proposed and explored. The most
likely alternatives involve some sort of encapsulation
in a stable (and perhaps even commercially
useful) solid. POWER has covered
several of these projects over the years, including
Skyonic Corp., whose October 2014-dedicated
Capitol SkyMine near San Antonio,
Texas, is designed to mineralize an adjacent
cement plant's CO2
emissions and sell them as
May 2015 | POWER
NOx capture
offset
Cumulative
potential savings
NETL 2013
amine for
comparison
baking soda, bleach, and hydrochloric acid.
Another enterprise, Calera Corp., converts
CO2 into calcium and magnesium carbonates
for use in manufacturing carbon-negative products.
As of March this year, the company says
its pilot plant in Moss Landing, Calif., has been
in operation for approximately two years " and
the calcium carbonate produced from the capture
and conversion of CO2
from the neighboring
gas power plant has been used in a variety
of demonstration and commercial projects. "
Calera's technology uses flue gas directly
from the source, without concentrating or
compressing it, and " has demonstrated the
technology on CO2
from gas power plants and
from coal burning. The flue gas containing
CO2
alkalinity solution that effectively removes the
CO2
is contacted in a scrubber with an aqueous
and then contacted with a calcium source
that results in the formation of the special calcium
carbonate product that is then dried to a
www.powermag.com
lenge. Though Shell is involved with three
carbon capture " demonstration " projects
(Gorgon in Australia, Mongstad in Norway,
and Quest in Canada), Smit noted there is
still " difficult work to be done. " Sequestering
carbon at scale requires using stable reservoirs
that may not always be available, which
means that CCS (at least in its current form)
may be relegated to " isolated projects. "
Speed Matters
Despite the welcome kickstart that ARPA-E
and other funding sources provide to promising
ideas, and despite the number of researchers
working on improved carbon capture and
sequestration schemes, under the current R&D
paradigm, it could easily be a decade or more
before any effective, efficient, and economical
CCS approaches are sufficiently proven to be
widely and swiftly adopted around the world.
For example, that supersonic ICES
method is being " bench-scale " tested, prior
to " potential future pilot-scale testing with
coal-fired flue gas. Achieving this goal, " the
NETL brief says, " will make progress toward
meeting the DOE goal to demonstrate
second-generation technologies that can capture
90 percent of the CO2
at less than $40 per
tonne in the 2020-2025 timeframe. "
Will that be fast enough-especially
considering that power generators dislike
adopting brand-new technologies, and that
developing nations around the world continue
to build new fossil-fueled generation?
For those who support the continued use of
coal and gas-whether because their jobs are
tied to those fuels or because fossil fuels offer
high energy density and dispatchable power-
the ability to use off-the-shelf CCS technology
is likely to offer a far more secure way to
ensure a bright future for fossil fuels globally
than the current political and legal tactics.
Perhaps what CCS needs is the pedal-to-themetal
focus and resources of an Elon Musk. ■
-Gail Reitenbach, PhD is editor of POWER.
55
$/Metric ton avoided
Parasitic load (%)

http://www.powermag.com

POWER May 2015

Table of Contents for the Digital Edition of POWER May 2015