Page 64 - New Trends In Coal Conversion

32 New Trends in Coal Conversion

use, the world continues to be heavily dependent on coal, which is mainly used for
electricity generation and, to a lesser extent, for the production of steel, cement, liquid
fuels, and chemicals. The future of coal utilization in a sustainable development sce-
nario depends on the capacity of reducing the associated CO 2 emissions through the
construction of advanced coal power plants and improved industrial processes with
higher efficiencies and through the implementation of carbon capture, use, and storage
(CCUS) technologies.
In the 2 C scenario developed by the International Energy Agency (2DS), unabated

coal-fired power generation starts declining from 2020 and is virtually phased out by
2050. The vast majority of the mitigation effort for the power sector will come from
coal-fired power plants, which will account for 40 Gt or 80% of total CO 2 captured
in the sector through 2050 in the 2DS. In 2050, 570 GW of coal-fired capacity will
be equipped with CCUS, representing 75% of the coal fleet and 8% global power gen-
eration (IEA, 2016). The use of coal in combination with biomass in co-combustion or
co-gasification processes can also contribute to reduce emissions from coal utilities,
reaching even negative emissions if CCUS technologies are applied to these facilities.
In the 2DS, by 2050, 30 GW of biomass capacity will be equipped with CCUS. Going

to below 2 C infers that CCUS will be even more urgent. Negative emissions technol-
ogies will be required in the second half of the century to make up for delayed action
(Rocha et al., 2016).
There is a portfolio of CO 2 capture technologies that can be used to mitigate coal-
related emissions (see Table 2.1). In the power sector, these can be divided into three
broad categories, post-combustion capture (POSTCC), oxy-combustion capture
(OXYCC), and pre-combustion capture (PRECC) (IPCC, 2005). The cost range of
first-generation technologies for POSTCC, PRECC, and OXYCC overlap, although
supercritical pulverized coal power plants with POSTCC present advantage in the
low end (GCCSI, 2017).

2.2 Post-combustion CO capture in coal-fired power
2
plants

POSTCC refers to the separation of CO 2 from the flue gases produced by the combus-
tion of fossil fuels and biomass in air (IPCC, 2005). In the absence of specific regula-
tion or economic incentives, the flue gas is discharged directly to the atmosphere. On
the other hand, in a power plant equipped with POSTCC, the flue gas is passed through
a unit that captures most of the CO 2 and sends decarbonized flue gas to the stack.
Captured CO 2 can be used for industrial applications, such as enhanced oil recovery
(EOR), or stored in a geologic reservoir.
Existing and under-construction coal-fired power generation accounts for 2200 GW
with additional 1000 GW in the planning stage. It is unlikely that these utilities will
shut down within a time frame consistent with climate targets: POSTCC retrofitting
is the only mitigation option for these sources (IEA, 2016).
POSTCC presents an optimal and flexible solution, with a significant capital cost
advantage for environmental compliance compared with PRECC and OXYCC, which