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Showing posts with label Clean coal. Show all posts
Showing posts with label Clean coal. Show all posts

Tuesday, July 1, 2008

Energy security – ‘Clean Coal’ has potential to change the world from pariah to paragon of virtue in high oil price regime.



Energy security – ‘Clean Coal’ has potential to change the world from pariah to paragon of virtue in high oil price regime.


A. The thirst of populous emerging economies for energy and the industrial countries’ sustained need for energy will ensure a further rise in demand. However, it looks as if the supply of oil, and later also natural gas, will not keep pace with this demand. Only by leveraging every possible means will it be possible to compensate the imbalances emerging on the horizon. However, during the transition to the renewable sources of energy such as wind and solar age, an energy gap will have to be filled.


B. With oil currently trading at around USD 140/bbl, coal-to-liquid technology is already an interesting alternative from a purely commercial point of view. Coal offers great potential as a substitute for oil and natural gas in the medium term, but so far its versatility has been underestimated. Going forward, coal could attract more attention in all three major energy sectors – power generation, the heating market and transport – provided that the right technologies delivering higher efficiency and lower environmental burdens take root. Environmental risks emphasize need for “clean coal”. Global warming is one of the biggest dangers facing human existence on earth, and combating this danger is therefore one of the greatest challenges. Since coal causes 40% of global CO2 emissions, only advanced technology can pave the way to a better future. The required quantum leaps in technology could, however, open the doors to the global mass markets. The need for investment is very high not only in emerging economies like China and India but also in US and Europe. CO2-free coal-fired power plants could become a milestone on the way to a better energy future in spite of their additional fuel consumption.


C. Worldwide prospects for energy is actually quite good, but only if all possible levers are used. These include steps – apart from urgently needed conservation and efficiency-enhancing strategies – to diversify the range of energy carriers with an even greater drive to mobilize renewable energies and to continue developing potential alternative technologies. In public debate about our energy options after the petroleum age virtually no consideration is given to coal or else it gets very bad reviews. In the developed countries, coal is usually considered synonymous with a dangerous climate killer; in the developing countries, for inhuman labor conditions in the mining industry, the talk is of ‘blood coal’. At best, coal is given credit for its valuable contribution to energy security during the industrialization era.


D. Today, coal is used in the industrial countries above all as a source of fuel for generating electricity, for the heating market and for metal production. In some of the emerging economies, coal is still used in some places to fire steam engines. Going forward, coal could attract much more attention in all three major energy sectors – power generation, heating and transport – provided that the right technologies with higher efficiency levels and a low environmental impact take root. In this sense, the versatility of coal has been underestimated. As a substitute for the hydrocarbon fuels oil and natural gas, which will become increasingly scarce in the relatively near future, coal offers considerable potential for improving our energy structures in future. However, only advanced technologies and innovations will be able to pave the way for coal into a better future.


E. As mentioned above, environmental risk emphasizes need for “clean coal”. Global warming is one of the biggest dangers facing human existence on earth, and combating this danger is therefore one of the greatest challenges facing mankind. Fossil fuels, especially those that pose the greatest threat to the earth’s climate, will only have a future if they can be reinvented from an ecological standpoint. Coal accounts for 40% of global output of carbon dioxide (CO2). The ‘bridge to the future’ must therefore lead to ‘clean coal’, which if possible has to be climate neutral and thus acceptable to the public at large. If ‘King Coal’, the mythical figure of the coalmining saga, stops wearing a black robe in future and instead dons an environmentally-friendly white robe, his days will not be numbered and he may go on to prosper the second time round. Until renewable sources of energy are finally mature and established enough to shoulder the burden of the world energy supply largely on their own, the purified ‘clean coal’ may develop into one of the biggest sources of hope for a more secure energy supply.


F. One advantage of coal is that it offers the greatest range of global reserves among the fossil fuels. Plenty of coal reserve, up to about more than 200 years worth, is readily available, almost all over the world. By contrast, the ranges for oil (42 years) and natural gas (63 years) are much smaller.


G. The search for alternatives to conventional fuels did not seem to be an urgent task in late 1998 when a barrel of oil cost less than USD 10. Not quite 10 years later, with oil going for an annual average price of USD 65 in 2006. The most prominent participants in the contest for the fuels of the future are:

(i) First-generation bio-fuels are increasing in popularity in the most diverse countries of the world, such as Brazil, the US and Germany. In Brazil, they have long since become commercially competitive. Research on the second generation, the synthetic bio-fuels (biomass-to-liquids, or BTL), is continuing briskly.

(ii) Natural gas has been a common fuel in some countries for years. More appears to be possible if the catalytic conversion of natural gas proves able to secure the availability of a synthetic fuel, so called GTL (gas-to-liquids), on an industrial scale. GTL and BTL will mean fewer emissions and higher efficiency.

(iii) By means of liquefaction (coal-to-liquids, CTL), coal may directly replace oil even as a fuel. Thanks to higher reserve and resource ranges, coal as a substitute would clearly have an advantage over fuels based on natural gas.

(iv) Nuclear energy will be one of the major contributors to the world energy sources. Although, there is furious opposition against nuclear energy in some part of the world, the advantage of its potential of delivery of clean energy is the major plus point makes it better option.


H. A total of USD 10 trillion is expected to be invested in power generating plants around the globe up to 2030, with over USD 2 trillion being invested in China alone. The need for investment is very high all over the world. For investments, not only the direct costs but also the implications for the world climate will increasingly gain importance. This holds all the more so as over the past 30 years the share of CO2 emissions from coal has risen from 35% to 40% – with total emissions rising by 70% globally. One much more revolutionary project is a plan to develop emission-free coal-fired generating plants. Upstream and downstream CO2 sequestration, for which there are several different methods, aims for climate conservation. Thus, new power generation technology for fewer emissions will become the backbone of industrialization.

Wednesday, June 25, 2008

Green coal for power - To take care of post-Kyoto issues from energy security point-of-view:


Green coal for power - To take care of post-Kyoto issues from energy security point-of-view:

a. Coal is the world’s most abundant and important source of primary energy. Turning a potential pollutant into a clean, green fuel for economical power production has become a matter for concern on a global scale. Coal continues to dominate the energy industries as the single most important and widely-used fuel. Delivering around 27 per cent of the world’s consumption of primary energy, almost half of which is used for electricity generation; reserves of coal are spread worldwide throughout some 100 developed and developing countries, sufficient to meet global needs for the next 250 years.

b. Although a combination of economic and environmental pressures has forced the closure of older, inefficient, fossil fuelled thermal stations, the massive growth in power demand on a world scale will continue to be met predominantly by coal-fired plant for the foreseeable future. In many of the rapidly developing and industrializing regions of the world the rate of consumption of coal as a primary fuel for electricity generation is actually increasing. In energy-hungry India alone, coal-burn for power generation is forecast to more than double in the next few years to 350 million tonnes per year. Annual coal production in China, the world’s largest producer, has rocketed to over 1,500 million tonnes. Nevertheless, post-Kyoto issues have heightened environmental awareness, forcing the pace of technological change in the use of this abundant but potentially polluting fuel for power generation. The environmental threat posed by the release of even more millions of tonnes of toxic pollutants, acidic and greenhouse gases from both new and existing coal-burning power stations is widely accepted. Currently, signatories to the Kyoto Protocol are focusing on solutions to the problem of global warming, including the reduction of CO2 and other ‘greenhouse’ gases. In many other non- signatory countries, major programmes have been implemented by utilities and power producers to reduce SOx, NOx and CO2 emissions. Additional environmental concerns have also emerged, including the potential health impacts of trace emissions of mercury and the effects of particulate matter on people with respiratory problems.

c. In contrast with both natural gas and LPG, hard coal can contain a wide range of compounds including sulfur in addition to useful hydrocarbons. The percentage of sulfur can vary widely, with relatively low concentrations in the highest quality anthracite and very high amounts in lignite, generating large volumes of SOx. As well as the need to treat the fuel prior to firing and control closely the combustion process itself to limit the production of nitrogen oxides, coal-fired stations based on conventional pulverized coal technology can only reduce SOx emissions through the use of post-combustion treatments. Further problems still remain through the safe disposal of fly ash which can contain high levels of toxic compounds including heavy metals.

d. Enormous environmental problems faced by operators of older, coal-fired generating plants all over the world, plants were forced to take drastic action after various public protests about the deadly effects of SOx emissions and other emissions. Emissions from coal and lignite-fired units at various power generating stations caused widespread damage, killing livestock and crops downwind of the plant and causing respiratory illness in the population in many countries. The plants were forced to cut output. This tends to place an unacceptably high strain on the commercial viability of an existing power station in many of the developing nations and represents a completely uneconomic option for the majority of obsolescent installations. Power producers in industrialized developed countries are therefore adopting a variety of leading-edge clean-coal technologies for electricity generation.

e. New clean coal technologies are providing an attractive and economically viable option to post-combustion systems. Applying the latest combustion, steam and process technologies in new power plant or upgrading existing coal-fired generating facilities provides significant improvements in thermal efficiency, reducing environmental impact and energy costs to the consumer. At the same time, higher thermal efficiencies result directly in reduced fuel costs, improving profitability and market position for the independent power producer.

(i) For new and smaller coal-fuelled generating plant, boilers using well-proven circulating fluidized-bed CFB technology provide a cost-effective and efficient system capable of meeting current and future environmental standards. They are now being widely used and successfully operated in coal-fired generating units, burning a very wide range of coal and other fuels with widely differing heat values and mineral content. These can typically include anthracite, semi-anthracite, bituminous and sub-bituminous coal, lignite and even ‘gob’ – a form of high-ash bituminous coal waste.

(ii) As an alternative to direct combustion based systems, coal gasification is becoming increasingly attractive, with Integrated Gasification Combined Cycle (IGCC) technology offering one of the best ‘clean’ options for effective power production. Gasification systems use steam and controlled amounts of air or oxygen under high temperatures and pressures to react with coal to form clean synthetic gas or ‘syngas’. Current systems provide efficient clean-up of the gas-stream to produce a mixture of carbon monoxide and hydrogen which can be used subsequently as a ‘clean’ fuel or a basic feedstock for liquefaction.

f. Used as a fuel for power generation in a typical IGCC generating plant, a syngas-fired gas turbine drives a generator, with exhaust heat from the gas turbine recovered to produce steam to power a steam turbine in conventional ‘combined cycle’. IGCC power generating systems are presently being developed and operated in Europe and the US, with commercial systems capable of operating at thermal efficiencies approaching 50 per cent. NOx and Sox emissions levels are minimized with the potential for carbon-capture and sequestration of the CO in the sysngas stream being actively researched as design strategies for near-term and future coal-based IGCC plants. Elemental sulfur is removed from the syngas before combustion and is a highly saleable commercial byproduct. If the gasifier is fed with oxygen rather than air, the flue gas contains highly concentrated CO2 which can readily be captured, at about half the cost of that from conventional plants.

g. As an alternative to the direct use of syngas as a fuel for electricity generation, it can also be processed using modern gas-to-liquids (GTL) technologies to produce a wide range of liquid hydrocarbon fuels such as gasoline and diesel oil. Coal-to-oil is a long-established technology in coal-rich South Africa.

h. Nevertheless, clean coal technology is moving very rapidly in the direction of coal gasification, with a second stage designed to produce a concentrated and pressurized carbon dioxide stream followed by separation and geological storage. This has the potential to provide extremely low emissions of conventional coal pollutants, and as low-as-engineered carbon dioxide emissions – a vital step in the fight to prevent irreversible climate change.

Sunday, June 15, 2008

Coal is Essential for Energy Security for many – Strategies to enlarge supply base and reduce environmental impacts are the prerequisites:




Coal is Essential for Energy Security for many – Strategies to enlarge supply base and reduce environmental impacts are the prerequisites:

A. More and more frequent environmental problems and disasters – floods, forest fires, tornados, air pollution in big cities – cause growing concerns everywhere. Energy harvesting, conversion, production and use contribute to these environmental burdens.

Hence, improving the environmental performance of the energy sector is of paramount importance. Thus, wider application of cleaner fuels and conversion technologies is a key element in the strategy to improve the environmental performance of the energy sector. Further, the lower price of coal as compare to petroleum based fuels; the interest in coal is renewed because of the more even geopolitical distribution of coal reserves and of larger supply bases of coal allover the world.

In fact, the environmental concerns about coal are not associated with coal itself, but with its utilization in different stages of the energy chain. Novel and more environmentally friendly technologies for coal utilization, commonly known as “Clean Coal Technologies” (CCT), are believed to be able to bring coal back into the picture. Hence, CCT recently enjoy a growing interest almost all parts of the world. At present, this interest mostly focuses on cleaner coal conversion through increased efficiency and CO2 capture technologies, for which large R&D efforts are ongoing worldwide.

B. Market implementation of CCT is expected to cause an increase in coal use. Coal demand could also rise significantly because the recent sharp increase in oil prices has a lower impact on coal than on gas prices. This is explained by the more favorable geopolitical distribution of coal reserves compared to that of gas. As a result, coal has become cheaper in relative terms than oil and gas. All in all, in a scenario of soaring oil & gas prices, coal is predicted to be the energy source with the fastest growing demand. The expected increase in coal demand for power generation raises the question of its secure availability in the future. Thus, enlargement of the coal supply base is essential throughout the world, with adoption of cleaner technology.

C. The enlargement of the coal supply base can take place in four main directions:

(a) More powerful mapping techniques for coal reserves - Modern geophysics and seismic techniques, improve mine planning and exploitation by reducing geological uncertainties and increasing extraction efficiencies. At the same time, they can reduce environmental externalities and energy use for coal extraction.

(b) Improvement of existing under-ground mining technologies - Underground (deep) coal mining accounts for about 60% of world coal production. Current best coal recovery rates for underground mining are 50-60% for the “room-and-pillar” technology and about 75% for “longwall” mining. The implementation of modern automated and computerized mining technologies can increase these recovery rates.

(c) Research and development for underground coal gasification - Underground gasification of coal deposits which are not technically or economically exploitable (anymore) with conventional mining technologies, can add enormous coal supply potential in Europe and worldwide. At present underground coal gasification is at an experimental stage. Significant further efforts are necessary to make it technically and economically viable. In many of the countries like India etc., commercialization of underground gasification technologies may reduce the energy import dependence and enhance energy security scenario, apart from creating new employment.

(d) Utilization of coalmine methane (CMM) gas - Methane gas, released from coalmines, has always raised serious safety and environmental concerns. Methane is highly explosive when accumulated in confined areas. It is also a powerful greenhouse gas with 20- times stronger global warming potential than carbon dioxide. On the other hand, CMM, which consists mainly of natural gas, is a suitable clean fuel. The capture and useful utilization of CMM can bring important synergy benefits in terms of enhanced security of supply and better environmental and safety performance of coal mining.

D. Therefore, for realizing the full potential of CCT, coal is sufficiently

(a) Abundant… only if we keep working on the enhancement of coal reserves,

(b) Cheap… as long as the supply continues to match the demand,

(c) Reliable… as long as the supplies are diversified.

To reach market maturity, clean coal technologies, covering extraction, preparation and conversion, need a long term vision and investment security. In the present pre-commercial stage they need firm political commitment and further R&D support.

Thursday, May 22, 2008

Clean coal technology (CCT) – To mitigate Global warming and climate change - A discussion



Clean coal technology (CCT) – To mitigate Global warming and climate change - A discussion

Coal when burned is the dirtiest of all fossil fuels. A range of technologies are being used and developed to reduce the environmental impact of coal-fired power stations. Thus, clean coal technology (CCT) is the name attributed to coal chemically washed of minerals and impurities, sometimes gasified, burned and the resulting flue gases treated with steam with the purpose of removing sulfur dioxide, and reburned so as to make the carbon dioxide in the flue gas economically recoverable.

A. It is a known fact that, the burning of coal, a fossil fuel, is the principal causes of anthropogenic climate change and global warming. In fact, the byproducts of coal combustion are very hazardous to the environment if not properly contained. This is seen to be the technology's largest challenge, both from the practical and public relations perspectives. While it is possible to remove most of the sulfur dioxide (SO2), nitrogen oxides (NOx) and particulate (PM) emissions from the coal-burning process, carbon dioxide (CO2) emissions will be more difficult to address. Therefore, fact regarding the coal remains:

(a) Coal is a vital fuel in most parts of the world.

(b) Burning coal without adding to global carbon dioxide levels is a major technological challenge which is being addressed.

(c) The most promising "clean coal" technology involves using the coal to make hydrogen from water, then burying the resultant carbon dioxide by-product and burning the hydrogen.

(d) The greatest challenge is bringing the cost of this down sufficiently for "clean coal" to compete with nuclear power on the basis of near-zero emissions for base-load power.

B. In relation to clean coal technology, a terminology ‘carbon capture and storage’ (CCS) is being discussed. CCS is nothing but method of capturing the carbon dioxide, preventing the greenhouse gas entering the atmosphere, and storing it deep underground by various ways, such as

(a) CO2 pumped into disused coal fields displaces methane which can be used as fuel,

(b) CO2 may be pumped into and stored safely in saline aquifers, or

(c) CO2 pumped into oil fields helps maintain pressure, making extraction easier.

A range of approaches of CCS have been developed and have proved to be technically feasible. They have yet to be made available on a large-scale commercial basis because of the costs involved.

C. Clean coal technologies are continually developing. Today, efficiencies of 46% can be achieved by implementing the best available technology. With further research into techniques such as Ultra-supercritical combustion, efficiencies above 50% are envisaged in the near future. Work is underway to exploit the opportunities of capturing and storing CO2, which is an inevitable by-product of the thermal use of all fossil fuels. Coupled with integrated gasification, coal could in this way provide a source of low-carbon hydrogen for fuelling transport without producing local emissions. There will be challenges in bringing these technologies to market, but with the right mix of research investment and market incentives, coal may stake a place in a sustainable and secure energy future.

D. To summarise, burning coal, such as for power generation, gives rise to a variety of wastes which must be controlled or at least accounted for. So-called "clean coal" technologies are a variety of evolving responses to late 20th century environmental concerns, including that of global warming due to carbon dioxide releases to the atmosphere. However, many of the elements have in fact been applied for many years, and they will be only briefly mentioned here:

(i) Coal cleaning by 'washing' has been standard practice in developed countries for some time. It reduces emissions of ash and sulfur dioxide when the coal is burned.

(ii) Electrostatic precipitators and fabric filters can remove 99% of the fly ash from the flue gases - these technologies are in widespread use.

(iii) Flue gas desulfurisation reduces the output of sulfur dioxide to the atmosphere by up to 97%, the task depending on the level of sulfur in the coal and the extent of the reduction. It is widely used where needed in developed countries.

(iv) Low-NOx burners allow coal-fired plants to reduce nitrogen oxide emissions by up to 40%. Coupled with re-burning techniques NOx can be reduced 70% and selective catalytic reduction can clean up 90% of NOx emissions.

(v) Increased efficiency of plant - up to 45% thermal efficiency now (and 50% expected in future) means that newer plants create less emissions per kWh than older ones.

(vi) Advanced technologies such as Integrated Gasification Combined Cycle (IGCC) and Pressurised Fluidised Bed Combustion (PFBC) will enable higher thermal efficiencies still - up to 50% in the future.

(vii) Ultra-clean coal from new processing technologies which reduce ash below 0.25% and sulfur to very low levels mean that pulverised coal might be fed directly into gas turbines with combined cycle and burned at high thermal efficiency.

(viii) Gasification, including underground gasification in situ, uses steam and oxygen to turn the coal into carbon monoxide and hydrogen.

(ix) Sequestration refers to disposal of liquid carbon dioxide, once captured, into deep geological strata.

E. Discussion - Many experts think, the concept of clean coal is said to be a solution to climate change and global warming. Whereas, environmental groups believe it is nothing but another way of making everybody fool, in other words, it is ‘green-wash’. Environmentalists say, with this technology emission and wastes are not avoided, but are transferred from one waste stream to another. They opine that, coal can never be clean. Critics of the planned power plants assert that there is no such thing as "clean coal" and that the plant will still release large amounts of pollutants compared to renewable energy sources such as wind power and solar power. A good deal of investment in research and development and also in implementation of pollutant free renewable energy (such as wind power and solar power) has to augmented, to make the world very clean, to make the required electricity generation fully green.