POWER May 2016 - 14

silo and associated coal conveyor system
as well as reinforcing two other coal silos,
Eskom said. That project should be completed
by December 2017.
The company is notably also taking steps
to increase its nuclear capacity. On March
15, it submitted nuclear installation site license
applications for Thyspunt in the Eastern
Cape and Duynefontein in the Western
Cape to South Africa's National Nuclear
Regulator. The Thyspunt site would be located
a few miles west of Cape St. Francis,
while Duynefontein sits some 20 miles
north of Cape Town. Eskom told POWER that
once the nuclear vendor is chosen, a nuclear
installation license application would be
initiated. Several other regulatory permits
are required for " mega build projects " like
these, so it will likely be years before any
physical work begins at either site.
-Sonal Patel, associate editor
A Supercritical CO2-
Cooled Small Modular
Reactor
A small modular reactor (SMR) system
that uses a supercritical carbon dioxide
(CO2
Rankine cycle is under development at the
Korea Advanced Institute of Science and
Technology (KAIST).
The 12-MW Micro-Modular Reactor (MMR)
concept proposed by a research team led
by professors Jeong Ik Lee, Yonghee Kim,
and Yong Hoon Jeong could be transported
by truck and is well suited to remote
areas. It uniquely uses supercritical CO2
as
a coolant as well as a working fluid, and it
can run without refueling for 20 years and
maintain decay heat removal by natural
circulation. Additionally, it uses a nextgeneration
printed circuit heat exchanger
with no joints, welds, or points of failure,
and is small and light because it adopts
the semiconductor manufacturing process,
the researchers said.
The system (Figure 4) integrates the
supercritical CO2 Brayton cycle to keep
the reactor compact, the researchers said.
Supercritical CO2
is an innovative power
generation cycle whose turbomachines are
smaller than those of the steam cycle or
helium cycle, they noted. Meanwhile, a supercritical
CO2
cycle achieves comparable
efficiency with the helium Brayton cycle,
but with a much lower turbine inlet temperature
(550C versus 850C).
Existing small modular reactor designs
typically use water as coolant and oxidized
uranium as fuel. " Although these may be
good choices in making large reactors economical,
there are economical limits when
the capacity is reduced, " KAIST explained
in a statement. That's why it is focusing
current research on developing a reactor
design that uses uranium mono-nitride
fuel and supercritical CO2
as coolant as
) Brayton cycle instead of the steam
well as the working fluid.
Compared to uranium dioxide ceramic
fuel and uranium-zirconium metallic
fuel, enriched uranium nitride fuel has
notable fuel performance properties
such as high melting temperatures and
high thermal conductivity. Significantly,
it can improve safety margins, offer
more flexibility, and provide better fuel
cycle economics.
-Sonal Patel, associate editor
4. The Micro-Modular Reactor (MMR). The 12-MW MMR design concept under
development at the Korea Advanced Institute of Science and Technology (KAIST) is a fast reactor
that uses supercritical CO2 as a coolant and a supercritical CO2 Brayton cycle power generation
system. Courtesy: KAIST
A Breakthrough CarbonCapturing
Algae Project
A research photobioreactor designed to capture
significant amounts of carbon dioxide
(CO2
sity algae cultivation is showing promise.
The bioreactor patented by Californiabased
algal firm PHYCO2 is undergoing a
multi-year trial at Michigan State University's
(MSU's) T.B. Simon Power Plant,
a co-generation plant that provides
steam, heat, and power to the university
and can fire biomass, natural gas,
and coal.
The bioreactor absorbs the CO2
from a
slipstream of the plant's boiler exhaust
(Figure 5). PHYCO2
says its technology
is set apart from other open and closed
photobioreactor systems because it eliminates
all possible contamination from
outside sources, allowing microalgae to
grow indoors 24 hours a day, without
sunlight.
The first two-month period of testing
showed an algae density of 1.7 g/L,
a CO2
absorption rate of 52%, and a productivity
rate of 0.34 g/l solution/day-
" higher than the algae and production
rates found at recently reported studies, "
it explained.
The " pure algae strands " cultivated by
the process can be used in everyday products,
from lipstick to ice cream and gasoline
to animal feed. The team is now preparing
for a second round of testing, which will
focus on doubling their algae density and
reaching a productivity rate that is eight
times the Phase I rate.
-Sonal Patel, associate editor
5. Biological carbon capture. PHYCO2's
patented photobioreactor installed at
Michigan State University's (MSU's) T.B. Simon
Power Plant captures carbon dioxide for
high-density algae cultivation. Courtesy: MSU
) from power plant flue gas for high-den14
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POWER May 2016

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