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MAXIMIZING PERFORMANCE FROM EXISTING COAL-FIRED

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                                               THE FUTURE OF COAL POWER GENERATION
                                                 IN A CARBON CONSTRAINED WORLD

                                                  Authors: Charles SOOTHILL, ALSTOM
                                                     Philippe PAELINCK, ALSTOM




Abstract

Growing awareness of environmental problems at the close of the 20 th century
appeared to spell the end for coal, which could not compete with the cheaper
cleaner energy, provided by gas. However, the escalating price of gas and the
uncertainties over supplies and transport means that coal has returned to the picture.
Global demand for electricity is growing apace; indeed, it will increase 50% by 2030.
Coal already accounts for 40% of power generation worldwide. In Germany, India
and US, coal delivers 50% of electricity needs, in China 80%. According to IEA, coal’s
share in energy production is set to rise substantially in coming decades.

But, of course, there is one major problem associated with the return of coal and we
immediately think of acid rain, pollution and dust which coal inevitably causes when
burnt to produce electricity, so we need the key technology innovations to boost
coal’s energy efficiency and reduce pollutant emissions. Developments in
international regulations, calling for the stabilising of greenhouse gas emissions in the
atmosphere, all demand a reduction in harmful emissions as the way forward to a
cleaner world.

This paper looks at the future of coal power generation in such a world where carbon
emissions are constrained but where the use of clean coal technologies points
towards a strong future for coal as a source of fuel for clean power today and even
cleaner power tomorrow.




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                                               The Future of Coal Per Generation
                                                In a Carbon Constrained World




1- INTRODUCTION
                                                  first focus is therefore on what can      The plants being built are high
Growing levels of CO2 and other                   be done to produce cleaner                efficiency, large pulverised coal
Greenhouse Gases are increasingly                 power in today's coal plants, using       boilers, driving steam turbines. The
contributing to global warming and                advanced but proven                       steam temperature conditions are
to fundamental shifts in the Earth's              technologies. In this respect,            rapidly advancing towards ultra
climate. It is now generally                      retrofitting those existing plants to     super critical conditions that offer,
accepted that a more stringent                    current best available                    in the longer term, the potential for
post-Kyoto reduction in CO2                                                                 50% efficiency from coal. This
emissions will be required for the                technology standards provides for         means a 30% reduction in CO2
world temperature not to exceed 2                 a both immediate and cost                 compared to the average
°C increase over the coming                       effective strategy of carbon              current plant. Best available
decades.                                          avoidance. (ALSTOM has                    technology benchmarks for new
                                                  extensive experience, as leader in        plants are therefore rapidly
Existing power generation accounts                the retrofit market and ALSTOM            becoming a worldwide standard in
for a third of these Greenhouses                  technology is present in 27% of the       government policies for permitting.
Gases. Worldwide demand for                       world’s installed base.)
electricity is expected to grow by
3% a year over the next ten years,                Retrofitting for a better efficiency
even more so in developing                        means a lower rate of fuel used per       4 - PREPARING THE
economies such as China and                       MW of electricity and a substantial
India, increasing needs for energy                reduction in CO2 emissions. For
                                                                                            FUTURE
production. This implies a need for               example, for a 400 MWe coal fired
                                                  power station, a 3% efficiency            Whilst best available technologies,
substantial reduction in CO2
                                                  improvement avoids approximately          retrofit for improved efficiency and
emissions from power generation,
                                                  250 000 tons CO2 emission per year.       biomass co-firing are existing
compared to a "business as usual"
                                                                                            options, they will not of themselves
scenario.
                                                  In addition to improving the              resolve the problem of CO2
                                                  efficiency of pulverized coal plants,     emissions.
Whilst a shift to non-CO2 energy
sources (hydro, nuclear,                          another efficient mitigation solution
                                                  is the co-firing of biomass in coal       Substantial reduction in CO2
renewables) will play a more
                                                  plants. This technical feature can        emissions are required to limit
significant role going forward, such
                                                  be added as a retrofit option or          temperature rise to only 2˚C above
technologies are unlikely to
                                                  build-in for any new plant. In a          the pre-industrial reference. While
displace fossil fuels as a primary
                                                  recent retrofit application, ALSTOM       specific future GHG restrictions are
source of energy. Irrespective of
                                                  has put in service a flexible muti-       uncertain in many regions, capture
price issues, coal in particular is
                                                  biomass fuel co-firing installation in    and storage/sequestration (CCS) of
abundantly available, with over
                                                  the United Kingdom. This facility         CO2 from fossil fuel combustion
160 years of reserves, nearly three
                                                  can fuel up to 20% of biomass in          represents one of several critical
times that of natural gas.
                                                  2x500 MWe coal fired plants,              strategies identified for long-term
The challenge today for power                     resulting in CO2 avoided emissions        GHG reductions. In particular, the
generation from coal is to limit CO2              of 800 000 tons per year.                 capture and the storage of CO2
and other emissions while                                                                   emissions from coal power plants
maintaining plant economics,                      Worldwide government should               will be a sound long term strategy
guaranteeing an ultimately                        address the retrofit of existing plants   to keep coal as a safe and secure
affordable energy price to                        as a primary target for substantial       energy resource while preventing it
consumers.                                        and immediate CO2 emission                from adversely contributing to
                                                  reduction policies. This approach is      climate change.
                                                  both economically sound and is
                                                  possible with existing technologies.      While capture and storage
2 - EXISTING PLANTS                                                                         technologies are rapidly maturing,
                                                                                            newly built plants should be
                                                                                            conceived that are capable of
The main issue today is the CO2                   3 - NEW PLANTS
emitted by existing plants and the

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                                               The Future of Coal Per Generation
                                                In a Carbon Constrained World


integrating those technologies                    makers and other power plant             existing technology. ALSTOM is also
when available.                                   owners.                                  pursuing a very promising new post-
                                                                                           combustion process involving
To address this concern, legislators                                                       chilled ammonia. This technology
and policy makers are creating                                                             has lower energy requirements,
diverse and evolving regulatory
frameworks within which electricity
                                                  5 - THE FUTURE OF                        aiming at a 10% drop in net plant
                                                                                           output, which could significantly
generators must manage their                      COAL POWER                               reduce the cost and impact of CO2
generation portfolios for today’s                                                          capture.
and tomorrow’s requirements.
                                                  GENERATION
                                                                                           Oxy-firing
The European Commission has                       The future of coal power
initiated a review of new fossil fired            generation bears greatly on the          The overall principle of oxy-firing
installations to determine if they are            introduction of CO2 capture              technology is to burn solid fuel with
prepared for later addition of CCS                solution coupled with storage. A         pure oxygen rather than air. The
technologies, termed Carbon                       large set of different technologies is   combustion is controlled with a
Capture Ready (CCR). Similar                      being developed and will be the          recycled stream of CO2. The flue
discussions are occurring at the                  base of a future competitive CCS         gas obtained from oxy-combustion
state/provincial and federal levels               economy.                                 combustion is mainly composed of
in North America.                                                                          water and CO2, the latter being
                                                  There are currently three main lines     easily captured at the back-end by
The author’s company has                          of CO2 capture technologies: post        water separation. Oxy-firing applies
recognised the need to providing                  combustion processes, oxy-firing         to new units but may suit some
the power generation industry with                and pre-combustion capture.              retrofits as well.
flexible solution to provide Clean
Coal Power solutions for today and                                                         The main challenge of oxy-firing
tomorrow. To meet this                                                                     technology lies in the cost of
commitment, we have initiated a                                                            producing oxygen on a large scale
program to ensure that our thermal                Post-combustion capture                  through Air Separation Units, a
power generation plant designs                                                             major reason for the 20-25% drop in
are CO2 capture ready (CCR). To                   Post-combustion capture of CO2           net plant output compared to an
this end, specific features are                   has the advantage of being the           air-fired plant.
integrated in the initial design to               most readily available technology
facilitate the retrofit of capture                today and the most easily
technology at a time of the                       adaptable to the huge installed
owner’s choosing. As new CO2                      base of coal units.                      Major gas specialists who are
capture technologies will continue                                                         working on improving ASU
to reach commercialization, our                   In this technology, the CO2 is           technology and exploring
goal is to provide maximum                        selectively removed from the flue        promising new oxygen-production
flexibility to our customers in the               gas of the power plant through a         techniques are currently addressing
choice of the CO2 capture                         capture unit. The most widely            this issue.
technology eventually                             developed post-combustion
implemented in their plant.                       capture solvent is amine, which has      The authors’ company is playing a
                                                  been used since the 1970's for CO2       key role in developing several oxy-
Inherent in a carbon capture ready                capture in other industries. The         firing techniques and has been
strategy, provisions for                          main challenge of post-combustion        selected to set up the first steam
transportation and conditioning of                capture is its important heat            power demonstration plant using
CO2 for long term storage are part                requirement in the stripping phase       oxygen combustion of brown coal.
of the special features of the CCR                to separate the amine solvent and
concept. It is anticipated that the               CO2, leading to an important drop        It is also investigating breakthrough
storage, siting and planning                      in plant output. Several companies,      technologies such as chemical
process for CO2 storage would be                  including ALSTOM are dedicating          looping. This unique system
integrated with public policy                     an important research and                replaces the traditional boiler with
                                                  development effort in order to           a two-stage chemical conversion
                                                  improve the performance of this



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                                               The Future of Coal Per Generation
                                                In a Carbon Constrained World


process, using an oxygen "carrier"                coal power generation will have a
to transfer oxygen to the fuel. The               clean and zero emission future.
exhaust gas is similar to oxy-firing,
enabling easy CO2 capture.                        As the first successful demonstration
                                                  plants are being started-up it is
Pre-Combustion                                    anticipated that a full
                                                  commercialisation of capture
The principle of IGCC (Integrated                 technologies will be possible as
Gasification Combined Cycle) is to                early as 2015. In order for this
transform a carbon-rich fuel such                 commercialisation to deploy,
as coal or petroleum residues,                    however, massive investments will
through a chemical reaction, into                 also be needed in CO2
syngas (a mixture of CO and H2),                  transportation pipeline systems,
which is then burned in a                         including on and off-shore storage
combined cycle plant.                             facilities. The challenge here is both
                                                  technical and regulatory. World-
IGCC technology is mainly                         wide governmental policies and
destined for new plant                            regulations must be developed at
construction, since re-powering of                an accelerated pace to facilitate
an existing coal plant into an IGCC               the deployment of a CO2
plant is complex and expensive.                   transportation and storage
                                                  network, capable of handling
Pre-combustion CO2 capture is the                 volumes of pressurized CO2
technology adapted to IGCC                        comparable to the current volumes
plants. In pre-combustion capture,                of gas and oil transported in the
carbon is separated right after the               world.
gasification phase, before the
syngas is burnt in the gas turbine.               In conclusion, coal will keep its
This involves a shift reaction from a             leading position to answer the
CO/H2 blend to pure hydrogen,                     world-wide growing need for
followed by CO2 absorption by a                   power, while meeting the
physical solvent.                                 challenge of preserving our planet
                                                  from adverse green house gas
The main challenge with this                      emissions.
technology is the fact that syngas -
after CO2 removal - essentially
contains only hydrogen.



Burning a hydrogen-rich gas raises
significant issues for gas turbines
and is a technological hurdle,
which has yet to be fully overcome.


6-CONCLUSION
All the above technologies are
being developed in parallel. Their
number, their variety and the
dedication that the equipment
suppliers are showing in their rapid
development is the guarantee that




a5591f3a-1900-4cbb-88e9-27ee6a65cb1e.doc                                                 
                                               The Future of Coal Per Generation
                                                In a Carbon Constrained World




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posted:11/22/2011
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