20th World Energy Congress - Rome 2007
"Energy Future in an Interdependent World"
in the Worldwide Power Sector:
The Assets of Thermal Power
Michel Molière, Amélie Girardot, Robert M Jones
In forthcoming decades we will see major changes in the landscape of the worldwide power
sector as CO management and incipient hydrocarbon scarcity exert their increasing influence. 2
The power generation community must be prepared to satisfy a particularly complex and
challenging set of requirements. These issues include curbing CO emissions, coping with 2
surging primary energy prices, and compliance with regional and local emissions
requirements such as SOand NO—while maintaining maximum efficiency. x x
In this context, as confirmed by International Energy Agency forecasts, thermal power will
maintain a prominent position in overall power generation since it enables the large capacity
additions required in emerging countries. Thanks to their reliable assets (such as energy
efficiency and environment) gas turbine-based power systems, including Gas Turbine
Combined Cycles (GTCC) and Combined Heat & Power (CHP), will continue to be major
contributors to worldwide power generation. However, evolving changes in the spectrum of
fuels will create an additional challenge for power generation equipment manufacturers—
requiring innovative technologies in fuel processing, combustion, and emission controls to
address these needs.
This paper reviews the factors underlining the changing power generation environment
worldwide, including the increasing scarcity of conventional fuels and the growing interest in
biofuels and hydrogen. Insights will be offered into various technologies needed to support
the growing need for increased fuel flexibility.
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In the coming decades the energy landscape will experience major changes for which the
world community must prepare. Past decades have seen a period of low cost energy and
sustained growth that has benefited the power market, with ample movement for new plant
erection worldwide. Electrification has gained ground in developing countries while aging
power plants have been replaced with more efficient units. Gas Turbine Combined Cycle and
Cogeneration (GTCC) Units have demonstrated their potential in a number of regions where
natural gas (NG) and gas turbines have acquired the lion’s share of the market within a win-win game. This accelerated growth has allowed decisive progress in gas turbine technology,
with the typical efficiency of GTCC climbing from 50% to 56%+ over this period.
The way ahead seemed straightforward, driven by a quest for higher efficiency and lower
emissions targets. However, awareness of the fragility of the gas market remained a constant
backdrop—and this threat was amplified by some worldwide events during the 90s. At the
same time the harmful effect of greenhouse gases on the global climate was gaining credence
in scientific circles, resulting in the Kyoto protocol being adopted under the “principle of precaution.” Nevertheless, increasing energy conversion efficiency was still considered as the
only means of keeping the CO
issue under control. Today both the geopolitical issues posed 2
by primary energy supply—and the global challenge created by climate changes—are not only recognized by experts, but also perceived as realities by the public at large; addressing
them is a must for both political and economical factors.
On one hand, the price of natural gas is surging, with a coupling mechanism between the
three main fossil energies. On the other hand, conversion efficiency is no longer considered
sufficient to curb the deleterious effects on climate—while the ability to capture CO
become a must. This has prompted a number of countries to promote measures that
encouraged the use of biomass, the adoption of “Energy Trading Schemes,” and the
implementation of Renewable Obligation Certificates (ROCS).
In the increasingly complex and changing world of the power community, all stakeholders of
the energy world need to seriously consider the power systems of tomorrow—in which
primary energy considerations and environmental concerns will become critical. In this
context, there is no doubt that the quest for alternative energy sources will be a key necessity.
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This paper offers a preliminary analysis of the factors shaping the world power scene of
tomorrow, while emphasizing the assets of the next generation of thermal power plants.
I. THE EQUATIONS OF TOMORROW’S POWER SECTOR
Energy and power are strongly interrelated worlds. In the near future, both the power and
energy scenes are expected to experience major changes due to a number of internal and
external constraints (Figure 1). This creates a vital need to identify the traits that future power
generation plants must acquire in order to “survive the game.”
? GENERAL ELECTRIC COMPANY
Figure 1. The Hexagon of Constraints
1. A Carbon-Constrained World
The world is commencing an irreversible move towards an increasing scarcity of fossil
energy as a result of the aggravating imbalance between limited supply and rising demand.
The International Energy Agency (IEA, World Energy Outlook 2006) forecasts that in the
next decades, fossils fuels will remain indispensable to fulfill power-generation demand,
before they are partly displaced by non-fossil sources. This revolution, never experienced
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before, will cause a regular increase in energy prices. This will combine with fast-paced
developments occurring in some emerging countries that still have highly energy-intensive
economies. Such unprecedented accelerations of demand will in turn foster an increasingly
volatile energy market. Not only oil, but all fossil energies (including natural gas and to a
lesser extent, coal) will actually experience this pressure. This presents a challenge to all
strategic projections for the security of supply and worldwide economic competitiveness.
2. Climate Change
A second overwhelming constraint is represented by the global climate changes that are
increasingly recognized as a major challenge by the scientific community. International
organizations are prompting initiatives such as the Kyoto protocol and the Emission Trading
System (ETS). While these measures to curb CO
emissions generate new regulatory 2
constraints, they also create new opportunities for power generators. These two major
constraints will converge to create a carbon-constrained environment.
3. Globalization of the Energy Market
A third factor is related to the globalization process. Where energy and power are concerned,
globalization means the liberalization of trade and transportation of electricity and fuels.
Where the natural gas market is concerned, a harmonization effort is required to create a
“uniform, single specification commodity” with large composition specifications that can be
used for cross-border trading between delocalized suppliers and large GTCC owners. This
generates an unprecedented fuel flexibility constraint.
4. Economy’s Competitiveness
In every country, the economy has a vital need for competitiveness. Both large manufacturing
industries and small/medium enterprises want reliable and low cost kWh, which tends to
prolong the use of ageing, paid-off power units or promote new ones that must successfully
compete with the former to carve out their place. As is often the case, a combination of
innovative and proven technology features can result in a strategic breakthrough.
5. The Weight of Public Opinion
As a fifth important effect, public opinion plays a major role in energy policies—influencing
site selection and permitting for new power plants, while increasingly determining the
preferred power technologies of the future.
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6. Air Quality: Non-CO Emissions 2
The control of non-CO emissions is another challenge that must be overcome. In many 2
urbanized places, there is a need to improve the quality of the air along with a need to keep
pristine areas under protection. This requires controlling local emissions such as UHC, VOC,
ozone, Poly-Aromatic Hydrocarbons (PAH) and Particulate Matters (PMs) that act
synergistically as allergenic and carcinogenic compounds. Long distance, cross-border
pollutants such as SO and NO that are responsible for the acid rains must also be reduced. xxTherefore, the control of noxious emissions will remain as a major battlefield.
7. Winners’ Profile
Which strategy is inspired by the “hexagon of constraints?” Tomorrow’s successful power
generation schemes will be the ones that best accommodate the complex, often conflicting set
of requirements previously described. To cope with the overwhelming limitations created by
a carbon-constrained market and a volatile energy market, the competing technologies will
have to reach new heights of efficiency and flexibility. In this regard, the word “flexibility”
(often used as a mere synonym for flexible operation) must be understood as a many-faceted
concept that prevails throughout all project phases and over the product life. In thermal plants,
fuel flexibility is a major dimension of flexibility and it is in this area that gas turbine-based
generation (CHP and GTCC) can bring a prominent contribution. To fully understand the
stakes of fuel flexibility in thermal generation, an insight into the cluster of primary energies
is a necessity.
II. THE PRIMARY ENERGIES OF TOMORROW : AN OVERVIEW
As previously emphasized, fossil fuels will remain essential contributors to the cluster of
primary energies for power generation in the next two decades. It is therefore of prime
interest to first summarize the prospects offered by conventional energies—and then to
analyze their respective benefits and limitations—before looking at the possible substitutions.
1. Outlook for Conventional Primary Energies Natural gas has achieved a major penetration in the power market. The strong match between
cleaner attributes of natural gas and the inherent qualities of advanced gas turbines account
for the unrivalled performance demonstrated by GTCC plants in terms of efficiency,
Reliability-Availability-Maintainability (RAM) and emissions. On a global scale this success
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is expected to continue to a large extent into the forthcoming decades. However, the rush
towards natural gas that was experienced worldwide during the 90s—and in the US during
the early 2000s—has placed considerable pressure on the supply side; and the threat of
uncontrolled volatile pricing or excessive energy dependency causes increasing concerns
First, natural gas resources are unequally distributed: for instance, Asia, which is expected to
be responsible for 50% of the increase in energy consumption through the year 2020, has
access to only 7% of the global gas resources. Many world consumers have a strong
dependence upon their suppliers. Therefore, despite the intense development of liquefied
natural gas (LNG) facilities in the Middle East and erection of LNG terminals in the US, EU,
Japan and recently in China, this energy source is unlikely to meet all demand forecasts.
Additionally, with the prospect of an increasing paucity of carbon and the rising
interrelationship observed between the oil and gas markets, there is a growing impression that
the success of natural gas is not sustainable.
Finally, despite its numerous advantages, by itself natural gas does not fulfill zero-CO
emission and requires CO capture, as do the other primary energies. 2
As far as the oil sector is concerned, a real decline in the weight of petroleum products in power generation has already been observed. This is because this market is increasingly
driven by a “huge transportation sector” with most domestic refining facilities struggling to
match the strong demands for light/middle automotive distillates. Therefore the precious,
expensive distillates are unlikely to help satisfy a substantial portion of power needs. The
combustion of increasingly difficult heavy oils in thermal plants raises issues primarily
related to emission control. Currently, gasification of residuals or petroleum coke is the sole
technology that is able to convert low or negative-value carbon to cleaner power. This
technology will be further reviewed in Section III.
Coal is the most abundant and traditional fuel worldwide. According to the IEA, fossil carbon
resources such as coal and lignite will be available for a long period of time, in the range of
400 years. In some EU countries such as Germany, the UK, and Poland where it has been a
major natural resource, coal has long been a prominent energy source for power—although it
has recently been dethroned by natural gas in new plants. This contrasts with other world
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regions such as the USA, Australia, China and India where coal is still considered as the
primary contributor for future base-line electricity production. From the prospective of
efficiency and environmental protection, Integrated Gasification Combined Cycle (IGCC)
coal combustion appears as a promising and proven technological solution for long-term
power needs. This point will be discussed further in Section III.
Finally, for several related reasons—public opinion, investment cost and project cycle—the
contribution of nuclear power is expected to increase at a very modest rate in the EU (except
in France where it has gained public acceptance after over three decades of experience. In
light of this short, simplified analysis, resorting to alternative energies appears as an
2. Alternative Fuels
In a changing landscape of energy supply, the power energy community of the future will
increasingly call on alternative fuels, while capitalizing on the experience gained in this field
during the past decade. In particular, gas turbines have demonstrated, as continuous-flow
machines, distinctive capabilities to accept a wide variety of fuel. Indeed, their robust designs
and universal combustion systems enable heavy-duty gas turbines to handle a vast range of
fuels. Consequently, gas turbines that run on alternative fuels and are deployed either in
GTCC or CHP plants, can greatly contribute to large savings of fossil fuels.
Figures 1 to 3 offer synoptic representations of gaseous and liquid alternative fuels—while
showing the vast panorama of alternative fuels that have been successfully explored by
heavy-duty gas turbines.
In this paper, it is indeed important to distinguish three classes of
alternative fuels (see the table in Appendix 1): ? The first category stems from industry process and ultimately derives from the Oil and
Gas or steel sectors; many of these fuels like “fuel gases” cannot be transported or even
stored—and exploiting this fuel vein will be of interest essentially to minimize fuel
supply in industrial plants in the carbon-constrained environment.
? The second category (syngas and synfuels) directly derives from fossil carbon (coal,
lignite, sand shale oil) which is available in abundance and represents a great potential
within the carbon-constrained economy provided they are subjected to carbon capture.
? The third category derives from biomass, which is distributed around the world and is
also of prime interest due to its overall neutral carbon balance.
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For the purpose of developing power at a worldwide scale, the second and third categories
represent a potentially abundant supply and offer the most promising prospects. From a
technical, economical and environmental viewpoint, IGCC technology offers a very
consistent approach to the cleaner conversion of combustible solids into electricity, especially
at a large scale. Gasification is a form of oxidation performed under pressure by a mixture of
an oxidant—and applies not only to coal or lignite but also to viscous residual fuel oils (RFOs), biomass (wood, straw, vegetables), and even to municipal wastes.
III. FOCUS ON GASIFICATION PRODUCTS
In many countries, coal and lignite remain an important portion of their energy portfolio and
will continue to play a crucial role as an energy provider for the foreseeable future.
1. The Power of IGCC The Integrated Gasification Combined Cycle option can fulfill the “equations of tomorrow’s
power generation” previously analyzed. IGCC actually combines:
? Fair conversion efficiency
? Primary energy security (since coal has an even geographic distribution worldwide)
? Cost effectiveness
? Strict control of non-CO
emissions and CO when combined with CCS 22
? Fuel flexibility
IGCC also provides the advantage of a versatile multi-generation capability: power, heat,
hydrogen and carbon-chemistry derivatives such as methanol or synfuels. These advantages
also apply to other, low-valued opportunity fuels such as residual oils—as IGCC has
successfully demonstrated over a wide variety of fuel applications.
IGCC plants with GE gas turbines (operating or under contract) combine for a total of more
than 2,500 MW. Another total of 1,020 MW is operating (or on order), using process fuels
from steel mills. This machine fleet has accumulated a total of more than 850,000 hours of
operation on low-calorific syngas fuels, as well as significant operation with co-firing of
alternative fuels. Several recent refinery-based IGCC projects boast exceptional performance
and fuel flexibility. Current applications include grass roots power and re-powering,
cogeneration, co-production of chemicals and hydrogen, and varying levels of process
integration. Process feedstock includes coal, lignite, petroleum coke, heavy oil, and waste
materials converted by six different gasifier types (see Appendix 2).
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IGCC’s high marks in environmental performance derive from both the fundamental
characteristics of the process and enhancements in gas turbine combustion. Future IGCC
upgrades are ensured by its capability to meet outstanding performance for heavy metals
(including mercury), PAH and particulate removal.
2. Carbon Capture and Storage
Pre-combustion de-carbonization applied to IGGC or natural gas-fired GTCC plants
represents the preferred method for carbon capture and sequestration (CCS), approaching
towards near-zero CO
emission. For natural gas, the approach is methane reforming, 2
followed by a water shift and scrubbing of CO. In IGCCs this approach benefits from a 2
number of advantages as shown in Figure 2:
? Carbon compounds to be captured are in high concentration in the fuel stream
? The fuel already has been substantially reformed (i.e., transformed into CO + H), so that 2
only a water shift (i.e., transformation into CO + H in presence of steam) is necessary 22
prior to acid gas removal
? The syngas volume is reduced due to elevated pressure gasification
Finally, in both cases the combustion of near-pure hydrogen benefits from existing gas
turbine experience on high hydrogen fuel derived from process plant applications.
Figure 2. Pre-combustion CO? GENERAL ELECTRIC COMPANY
Capture 2th20 World Energy Congress – Rome 2007 9