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
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The Future of Coal Per Generation
In a Carbon Constrained World
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