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Friday, August 31, 2012

Indian black out and aftermath


The largest power outage that affected 650 million people in India recently was a major news around the world. Power outage is common in many countries including industrialized countries during the times of natural disasters such as cyclones, typhoons and flooding. But the power outage that happened in India was purely man-made. It was not just an accident but a culmination of series of failures as the result of many years of negligence, incompetency and wrong policies. Supplying an uninterrupted power for a democratic country like India with 1.2 billion people with 5-8% annual economic growth, mostly run by Governments of various political parties in various states is by no means an easy task. While one can understand the complexities of the problems involved in power generation and distribution, there are certain fundamental rules that can be followed to avoid such recurrence. The supply and demand gap for power in India is increasing at an accelerated rate due to economic growth but the power generation and distribution capacity do not match this growth. Most of the power infrastructures in India are owned by Governments who control the power generation, distribution, operation and maintenance, financing power projects, supplying power generation equipments, supplying consumables, supplying fuel, transportation of fuel and revenue collection. The entire system is based on the policy of ‘socialistic democracy’, after the independence from the British, though economic liberalization and globalization is relatively a new phenomenon in India. Since every department of power infrastructure is controlled by Government, there is a lack of accountability and competition. Many private companies and foreign companies do not participate in tendering process because it is a futile exercise. Some smart multinational companies set up their manufacturing facilities in India, often in collaboration with Governments in order to get an entry into one of the largest market in the world. Indigenous Coal is the dominant fuel widely used for power generation though the quality of coal is very low, with ash content as high as 30%.The calorific value of such coal hardly exceeds 3000 kcal/kg, which means more quantity of coal is required than any other fuel to generate same amount of power. Such coal generates not only low power but also generates huge amount of ‘fly ash’ (the ash content is the coal comes out as fly ash) causing pollution and waste disposal problems. Large piles of fly ash and age old cooling towers with a large pool of stagnant water are common sights in many power plants in India. Such low cost coal does not make any economic sense when considering the amount of fly ash disposal cost and environmental damages. Thanks to research institutions that have developed methods to utilize fly ash in production of Portland cement. The indigenous low grade coal is the fuel of choice by Indian power industries, though many plants have started importing coal recently from Indonesia and South Africa. Indigenous low grade coal and cooling water from rivers and underground sources are two major pollutants in India. Water is allocated for power plants at the cost of agriculture. There is a shortage of drinking water in many cities as well as irrigation water for agriculture. Since most of the power infrastructures are owned by Governments there is a tendency to adopt populace policies such as power subsidies, free water and power for farmers, low power tariffs etc, making such projects economically unviable in the long run. Most of the State Electricity boards in India are running at a loss and such accumulated losses amount to staggering figures. The Central electricity authority regulates the power tariff. They calculate the cost of power generation based on specific fuel and fix the power tariff that companies can charge their consumers even before the plant is set up. Most of such tariffs are based on their past experience using indigenous low grade coal and transport cost which are often impractical. Such low power tariffs are not remunerative for private companies and many foreign companies do not invest in large capital intensive power projects in India for the same reason. The best option for the Governments to solve energy problems in India will be to open to foreign investments and allow latest technologies in power generation and distribution. It is up to the investing companies to decide the right type of fuel, right type of equipments, source and procurement, power technology to be adopted and finally the tariff. India has come a long way since independence and Governments should focus on Governing rather than managing and controlling infrastructure projects. The latest scam widely debated in Indian media is 'Coal scam’. It is time India moves away from fossil fuel and allow foreign investments and technologies in renewable energy projects freely without any interference. India needs large investments in building power and water infrastructures and it will be possible to attract foreign investment only by infusing confidence in investing companies. It is not just the size of the market that is to be attractive for investors but they also need a conducive, fair and friendly environment for such investment.

Sunday, August 19, 2012

Colloidal Coal Water Fuel by Nanotechnology for power generation


Coal is still the dominant fuel used for power generation due to its low cost and abundant availability despite its emission problems and global warming issues. Companies around the world are trying to improve the efficiency of coal fired power plants and reduce emissions by various methods. The idea is to prepare an ultra clean coal with very low ash content in the form of coal-water slurry that can be directly injected into a diesel engine. Direct firing of coal requires micronising to less than 20-30 microns for diesel engine and less than 10 microns for turbines and producing a coal water slurry with at least 50% w/w coal content. The thermal and combustion efficiency of coal water fuel seems to be matching to that diesel engine at up to 1900rpm according to literatures. Still more research is required on engine modification and engine nozzle to handle coal water slurry because of its abrasive nature. If coal can be converted into a fluid like a diesel or Fuel oil then it can substitute diesel at reduced cost. However the Carbon problem needs to be addressed by ongoing research on sequestration. Nanotechnology is an emerging field that offers hope to produce Colloidal coal water fuel that resembles fuel oil that may be suitable for direct injection into diesel engine with little modifications. The colloidal suspensions of coal in water (CCW) are produced using a proprietary wet-combination device. These suspensions are a new material with new properties. “First, the colloidal fraction plus water is a pseudo fluid good for transport, handling and suspension of large particles. Second, the surface area per unit volume of coal available for chemical reaction and burning is greatly increased and finally, CCW may be milled with a third fluid, seeding the mixture with submicron coal. The colloidal nature of the majority of particles provides for very good features such as outstanding long-term stability, in contrast to regular coal water slurries (CWS) which rapidly sediment under storage. Moreover, the very small particles create an increased reactivity to combustion because small particles with large surface area react faster than large particles with the same volume.” A company based in Panama has conducted experiments using colloidal coal water fuel and published the following information. CCW suspension preparation and properties Characterization “The colloidal dispersions are prepared in two stages: first by a bench mill and then by our wet- comminuting device. The bench mill was manufactured by IKA®- Group. After grinding, samples were sieved using mesh size sieves 40 (400 μm), 70 (212 μm) or 140- (106 μm) and the passing particles were retained and used to prepare coal suspensions with various water contents (30 to 50 %), surfactants and other type of additives. These mesh sizes are not foreign to coal fired power plants. It is noteworthy that a preliminary formulation study is first necessary in order to determine the type and concentration of additives that are best suited to improve coal particle wetting and reduce viscosity. The additives were mostly surfactants and viscosity controlling agents and every type of coal tested usually required a specific formulation. In general, it was found that nonionic surfactants were good wetting agents, in concentrations varying from 0.1 to 0.6 w/w %. Some of the additives used to reduce viscosity by decreasing particle interactions, before or after the wet comminuting process, were amines. The suspension formulation previous to the wet-comminuting instance was very simple since what was basically required was a good wetting agent or a combination of two wetting agents. The idea was to have a uniform mixture with as low viscosity as possible. Particle size of coal samples was determined by direct observation in an optical microscope, or by sieving using five or six different sieves ranging from 20 to 400 μm, or using a laser diffraction apparatus made by Microtrac Corporation, Nanotrac model, having a measurement range from 8 nm to 6.5 μm. Neither of these methods was sufficient to obtain a complete characterization of the particle size distributions, but a combination of the three allowed for a good assessment of what really was in the suspension, before and after the wet-comminuting process. In our study, the percentage of mass passing the 635 mesh size sieve (< 20 μm) was used as an indicator of wet-comminuting process efficiency (generation of colloidal particles), given that microscopic observations generally showed that particles between 8 to 20 μm were very scarce. The preparation of the colloidal suspension of coal was centered in a technology that is totally based on fluid mechanics principles. As mentioned above, a preliminary suspension was prepared in a tank with low agitation and the appropriate water and surfactant contents. This suspension is then fed into a device that spins a film of the fluid to the walls of a cylindrical vessel at very high speed and under cavitations free conditions. The resulting flow field induces a “particle trap” region where coal particles are locally concentrated above their nominal value and under very high shear. Particles are then milled to very small sizes by a wet-comminuting mechanism. Friction heating is controlled by a chilled water jacket around the vessel.
A schematic view of the set up is shown in the attached figure. The energy consumed by the wet-comminuting device was evaluated by monitoring the power (voltage and amperage) during the process. The latter has two components, the power required to drive the motor shaft and mechanical seal, and the net power consumed by the fluid during comminuting. It was found that the net power divided by the mass flow rate, in terms of kWH/ton depended on coal content and viscosity of the preliminary slurry, exhibiting values of 30 to 80 kWh/ton. The energy consumed by the motor shaft and seal would account for 50 to 80 % of the total power consumed. Using the method described above, 100 gallons of CCW were prepared, using an Eastern bituminous coal that was previously grinded to 200 mesh. Several properties of this sample were characterized.” Colloidal coal water fuel has certain distinct advantages over conventional coal water slurry for power generation using conventional diesel engine and turbines. Further research and development work is needed before it can be expanded for large scale production. But it offers a hope to improve the efficiency of existing coal fired power plants and reduces emissions.