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.

‘FutureGen’ project - to design, build and operate a nearly emission-free coal-based electricity and hydrogen:

‘FutureGen’ project - to design, build and operate a nearly emission-free coal-based electricity and hydrogen:

The clean coal technology field is moving very rapidly in the direction of coal gasification with a second stage so as to produce a concentrated and pressurised carbon dioxide stream followed by its separation and geological storage. At present the high cost of carbon capture and storage renders the option uneconomic. But a lot of work is being done by many of the research institutes, to improve the economic viability of this system.

More recently department of energy (DOE) of Federal Govt. of the USA has announced ‘FutureGen’ project to design, build and operate a nearly emission-free coal-based electricity and hydrogen production plant. It will use cutting-edge technologies to generate electricity while capturing and permanently storing carbon dioxide deep beneath the earth. The integration of these technologies is what makes FutureGen unique. Researchers and industry have made great progress advancing technologies for coal gasification, electricity generation, emissions control, carbon dioxide capture and storage, and hydrogen production. But these technologies have yet to be put together and tested at a single plant - an essential step for technical and commercial viability.

Therefore, the FutureGen initiative would have comprised a coal gasification plant with additional water-shift reactor, to produce hydrogen and carbon dioxide. About one million tones of CO₂ would then be separated by membrane technology and sequestered geologically. The hydrogen would have been be burned in a power generating plant and in fuel cells. The project was designed to validate the technical feasibility and economic viability of near-zero emission coal-based generation. Construction of FutureGen was due to start in 2009, for operation in 2012.

Coal gasification processes –

(a) In conventional plants coal, often pulverised, is burned with excess air (to give complete combustion), resulting in very dilute carbon dioxide at the rate of 800 to 1200 g/kWh.

(b) Gasification converts the coal to burnable gas with the maximum amount of potential energy from the coal being in the gas.

(c) In Integrated Gasification Combined Cycle (IGCC) the first gasification step is pyrolysis, from 400°C up, where the coal in the absence of oxygen rapidly gives carbon-rich char and hydrogen-rich volatiles.

(d) In the second step the char is gasified from 700°C up to yield gas, leaving ash. With oxygen feed, the gas is not diluted with nitrogen.

(e) The key reactions today are C + O₂ to CO, and the water gas reaction: C + H₂O (steam) to CO & H₂ - syngas, which reaction is endothermic.

(f) In gasification, including that using oxygen, the O₂ supply is much less than required for full combustion, so as to yield CO and H₂.

(g) The hydrogen has a heat value of 121 MJ/kg - about five times that of the coal, so it is a very energy-dense fuel.

(h) However, the air separation plant to produce oxygen consumes up to 20% of the gross power of the whole IGCC plant system.

(i) This syngas can then be burned in a gas turbine, the exhaust gas from which can then be used to raise steam for a steam turbine, hence the "combined cycle" in IGCC.

(j) To achieve a much fuller clean coal technology in the future, the water-shift reaction will become a key part of the process so that:

(i) C + O₂ gives CO, and

(ii) C + H₂O gives CO & H₂, then the

(iii) CO + H₂O gives CO₂ & H₂ (the water-shift reaction).

(k) The products are then concentrated CO₂ which can be captured, and hydrogen. (There is also some hydrogen from the coal pyrolysis), which is the final fuel for the gas turbine.

(k) Overall thermal efficiency for oxygen-blown coal gasification, including carbon dioxide capture and sequestration, is about 73%.

(l) Using the hydrogen in a gas turbine for electricity generation is efficient, so the overall system has long-term potential to achieve an efficiency of up to 60%.