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Showing posts with label Consequences of global warming. Show all posts
Showing posts with label Consequences of global warming. Show all posts

Tuesday, May 15, 2012

Concentrated solar power - a game changer

We acknowledge that solar energy is a potential renewable energy source of the future. The total energy requirement of the world is projected in the next 40 years to be 30 TW (terra watts) and only solar energy has a potential to meet the above demand. However, harnessing sun’s energy to its fullest potential is still a long way to go. Concentrated solar power (CSP) offers a greater hope to fill this gap. The main reason is the cost advantage of CSP compared to PV solar and energy storage technologies and their costs. The cost of PV solar has steadily decreased in the past few years. Though the cost of solar cell has come down to $0.75 per watt, the overall cost of the PV system is still around $ 3.00 per watt. This is due to the cost of encapsulation; interconnect wiring, mounting of panels, inverters and battery bank. The overall cost of the system will not come down drastically beyond a point. This makes PV solar still more expensive compared to conventional power generation using fossil fuels. People can understand the value of renewable energy and impending dangers of global warming due to greenhouse gases, but the ultimate cost of energy will determine the future of energy sources. In PV solar the sun’s light energy is directly converted into Electricity, but storing such energy using batteries have certain limitations. PV solar is suitable for small scale operations but it may not be cost effective for large scale base load power generation. The best option will be to harness the suns thermal energy and store them and use them to generate power using the conventional and established methods such as steam or gas turbines. Once we generate thermal energy of required capacity then we have number of technologies to harness them into useful forms. As we mentioned earlier, the thermal energy can trigger a chemical reaction such as formation of Ammonia by reaction between Hydrogen and Nitrogen under pressure, which will release a large amount of thermal energy by exothermic reaction. Such heat can be used to generate steam to run a stem turbine to generate power. The resulting ammonia can be split with concentrated solar power (CSP) into Hydrogen and Nitrogen and the above process can be repeated. The same system can also be used to split commercial Ammonia into Hydrogen and Nitrogen. The resulting Hydrogen can be separated and stored under pressure. This Hydrogen can be used to fuel Fuel cell cars such as Honda FXC or to generate small scale power for homes and offices. By using CSP, there is potential of cost savings as much as 70% compared to PV solar system for the same capacity power generation on a larger scale. Focusing sun’s energy using large diameter parabolic troughs and concentrators, one can generate high temperatures. Dishes can typically vary in size and configuration from a small diameter of perhaps 1 meter to much larger structures of a dozen or more meters in diameter. Point focus dish concentrators are mounted on tracking systems that track the sun in two axes, directly pointing at the sun, and the receiver is attached to the dish at the focal point so that as the dish moves, the receiver moves with it. These point focus systems can generate high temperatures exceeding 800ºC and even 1,800ºC. The temperature required to run a steam turbine does not exceed 290C and it is quite possible to store thermal energy using mixture of molten salts with high Eutectic points and use them to generate steam. Such large scale energy storage using lead-acid batteries and power generation using PV solar may not be economical. But it will be economical and technically feasible to harness solar thermal energy using CSP for large scale base load power generation. It is estimated that the cost of such CSP will compete with traditional power generation using coal or oil in the near future.CSP has potential to generate cost effective clean power as well as a fuel for transportation.

Thursday, March 8, 2012

Hydrogen from Coal

Coal is an important fuel that helped industrial revolution. It is still a predominant fuel for power generation in many parts of the world. It is also an important raw material for number of chemicals and they directly compete with Hydrocarbons such as Naptha.It is abundantly available and it is cheap. We are still able to generate electricity at 5 cents per kwhr using coal. But, now we are entering into a new phase of energy generation and distribution, due to changing environmental and climatic issues of the twenty first century. We require completely a new fuel to address these issues; a fuel that has a higher heat content, which can generate more power per unit value of fuel, and yet, generates no pollution. It is a challenging job and the world is gearing up to meet these challenges. They affect the whole world because any issues concerning energy impacts each and every one of us. Many industrialized countries around the world are reluctant to sign an agreement that compels them to reduce their greenhouse emission to an acceptable level set by UN panel of scientists. Governments such as US, China and India are reluctant to sign such an agreement because their economy and growth depends upon cheap energy, made from coal. Such an agreement will be detrimental to their progress, and the leaders of these nations are not prepared to sign such an agreement. They also understand that world cannot afford to continue to use coal as they have used in the past. It is simply unsustainable. It is a precarious situation and they need to carefully plan their path forward. On one hand, they need to maintain their industrial and economical growth, and on the other hand they need to reduce their emissions and save the world, from catastrophic consequences of global warming. A simple analysis of the fuel will indicate that Hydrogen is a potential energy source for the future. It has energy content at least five times more than a coal for a unit value. Coal has an average heat content of 5000 kcal /kg while Hydrogen has an average heat content of 39,000 kcal/kg. Coal has a number of impurities such as ash, sulfur, phosphorous, other than carbon. Burning coal will emit greenhouse gases with toxic fumes that have to be removed. Therefore, these industrialized countries are now looking ways to generate Hydrogen from coal; that too at a cost which will be comparable to other current fuels such as natural gas. It is not an easy task because natural gas is formed by Mother Nature over several hundred thousand years. It is readily available and there is no manufacturing cost except processing cost. We are used to free energy from Mother Nature. This is the crux of the issue. Hydrogen is the most abundantly available element on earth; yet it is not available in a free form. It is available as a compound, for example, joined with oxygen forming water H2O molecule; or joined with Carbon forming Methane CH4 molecule.This Hydrogen should be separated in a free form, and this separation requires energy. How can coal, which is just a Carbon, generate Hydrogen? It requires an addition of water in the form of steam. When coal is gasified with air and steam, a mixture of Hydrogen and Carbon dioxide is generated, known as Syngas (synthesis gas). 2C + H2O+O2 ------- 2H2 +2 CO2 The syngas is separated into Hydrogen and carbon dioxide using various methods using their difference in densities. The Hydrogen can be stored under pressure for further use. Research work is currently under way to capture carbon dioxide for sequestering. Carbon sequestration is a method of capturing carbon dioxide and storing it in a place where it cannot enter the atmosphere. But the technical feasibility and economic viability of such a system is yet to be established. Carbon sequestration is a new concept and the cost of sequestration can potentially increase the cost of energy derived from Hydrogen despite the fact, Hydrogen has energy content five times more the carbon. However, there is no quick fix for our energy problems, and we have to reconcile to the fact that the energy cost will increase in the future but eventually reduce the greenhouse emissions. These developed countries should at least disclose to the rest of the world, how they plan to reduce their emissions and their action plans; such disclosure should be subject to inspection by UN panel. In the absence of any concrete mechanism, it will be impossible to stop the global warming in the stipulated time frame considering the fact that a number of coal/oil/gas fired power plants are already under implementation.

Tuesday, March 6, 2012

Hydrogen assisted combustion

We have been using fossil fuels like diesel, petrol and natural gas for power generation and transportation from the time of industrial revolution. The basic fuel and the combustion technology are practically the same with efficiencies less than 40%. In fact we have become very complacent with both the fuel and the combustion technology and there were no major research and development on both the above issues. In fact we became completely dependent on these two issues and there was no substantial breakthrough either in substituting the fossil fuel or in the combustion technology. The basic reason behind this situation can be attributed to the discovery of electromagnestism, which opened the way for electricity generation as well as transportation. In both these industries, the key component is the motor which provided a rotary motion. This rotary motion generates electricity in turbines and such motion is created by combustion of a fuel, which is invariably a fossil fuel. We have been carrying on this for few decades before the emission of greenhouse started rising abnormally and became an issue. We are now at cross roads wondering what the future holds for the world. Is it possible to carry on the business as usual or look for an alternative source of energy? We started looking at various sources of energy as an alternative. Any alternative energy source should meet two critical parameters namely the lower or no carbon emission and sustainability. Low carbon can be achieved by few methods. The immediate option is to maximize the energy efficiency of existing systems so that for the given input of fuel the output is much higher than what we have achieved all these years. But this increase in efficiency should be substantial in order to achieve the emission levels of greenhouse suggested by the UN panel on climate change. The second option will be to switch over to different fuels with less carbon emission e.g., coal fired power plants switching over to gas fired power plants using combined cycle. Retrofitting organic Rankin cycle as a bottoming for steam turbines to squeeze out some extra energy. Decentralizing the power plants in a phased manner in favor of distributed energy systems where gas, instead of electricity, can be supplied to individual industries, to generate their own power using CHP process. All these measures can help reduce the emission level but our dependency on fossil fuel will still continue. W can look at a completely different fuel source and new technology for power generation and transportation. If we examine carefully there are not many alternative fuel sources except Hydrogen that could meet these parameters. We are also trying to develop bio fuels. But biofuels are also organic chemicals with carbon backbone which will generate greenhouse emission. Moreover bio fuel sources such as palm oil, corn are also food sources. There is an indiscriminate deforestation and plantation of palm trees in tropical countries like Malaysis, Indonesia and PNG. The focus is now shifting to carbon based organic compounds like biofuel and biogas. This will create a situation where food crops will be substituted with energy crops creating food shortage.But the carbon dioxide level in the atmosphere may not be reduced drastically by these methods. We need to develop an energy source which does not emit any carbon emission and at the same time we should be able to use existing technology to the possible extent. Only Hydrogen can meet these requirements. In the current situation it is impossible to substitute fossil fuels in a short span of time. We can reduce fossil fuels by blending with Hydrogen to the maximum extent possible so that we can achieve two objectives. We can reduce the carbon emission and at the same we can deploy Hydrogen as a blended fuel with fossil fuel rather than pure Hydrogen. Since Hydrogen is a very light gas and readily form an explosive mixture with oxygen, this opens up a new opportunity to develop Hydrogen assisted combustion process in power generation as well as in transportation. It will be easier to handle a mixture of natural gas and Hydrogen for combustion in Gas turbine, or spark ignited reciprocating engines, as well as, gasoline combustion engines in cars. This will also gives us an opportunity to develop advanced and competitive systems like Fuel cell as an alternative technology for combustion process in due course of time. The hydrogen assisted combustion technology is much easier, faster and economical and at the same time reduce the greenhouse emission to an accepted level. But the source of such Hydrogen cannot be natural gas but only renewable sources. The renewable technologies such as solar, wind, geothermal, OTEC (ocean thermal energy conversion) should generate renewable Hydrogen. This is the key for sustainability as well as for greenhouse gas mitigation. These two benefits are too attractive to ignore and it is time we move from total fossil fuel to Hydrogen blended fossil fuel. The blended fuel along with the energy efficiency measures suggested above should go hand in hand, so that we may get over this turbulent period of financial crisis and global warming. It is also possible that Hydrogen assisted combustion be adopted for coal fired power plants by simply firing coal slurry, finely powdered coal blended with water and conveyed pneumatically for firing boilers and also for gasification process to generate syngas for IGCC (Integrated gasification and combined cycle) applications. Syngas production will be critical in the near future for a smoother transition from fossil economy to Hydrogen economy irrespective of the route we adopt.

Saturday, February 25, 2012

Global warming- a Mayan prophesy?

Globe is warming at an unprecedented rate since industrial revolution due to the effect of greenhouse gases in the atmosphere; according to a panel of scientists in IPCC (Intergovernmental Panel on Climate Change).Thousands of scientists from 30 countries formed IPCC under United Nation to study the problem of global warming and reported to the world. IPCC published a detailed report and it gave an apocalyptic scenario about global warming. They warned that the carbon dioxide level in the atmospheres has increased from 316ppm in 1959 (13% higher than preindustrial level) to current level of 380ppm in 2005, which is 35% above preindustrial level. This dramatic increase in the level of CO2 is due to the human activities. The major contributing gases are Carbon dioxide, Methane, Oxides of Nitrogen, CFC (Chlorofluorocarbons) and Ozone present in the atmosphere. Bulk of the emissions is from power plants and automobiles using fossil fuels. Other process industries like cement plants are also major contributors of greenhouse gases. The enhanced effect of global warming is due to the absorption of invisible infrared radiation coming from the warm surface of the earth. On an average, sun’s light reaches the earth at the rate of 343W/m2 and about 30% of this value is reflected and about 70% is absorbed. The amount of invisible infrared radiation absorbed depends on the concentration of greenhouse gases present in the atmosphere. According to IPCC their findings on global warming are unequivocal, and if the world does not act now, then, we will be facing dire consequences in the near future. Doubling CO2 emission will increase the global temperature from 2-4.5C. But many skeptics say the IPCC report is apocryphal and they have their own theories to support their skepticism. Many climate models proposed by various international institutions projects an average temperature rise of 3.4C above year 2000 level if we do nothing and carry on the “business as usual”. The consequences of global warming are far reaching. An increase of 3C rise in temperature will result in sea level rise up to 4 to 6 mts in the next few thousand years. About 10% of the world population lives in less than 10 mts above sea level and majority of population lives within 10km of sea level. We have already witnessed few islands in pacific (example, Bougainvillea, Sulawesi) inundated with seawater. Maldives and Bangladesh are good examples. They predict shortage of fresh water in many parts of the world and severe draught and flooding in other parts of the world. We have already witnessed these incidents in Northern Queensland in Australia and in Europe, and prolonged draught in Texas, bushfires in Australia and in Russia. Majority of Indian subcontinent is suffering from lack of drinking water. Unscrupulous exploitation of ground water for agriculture purpose has made the situation worse. Many plants, animals and species will face greater risk of extinction. An increasing acidity in seawater due to excess absorption of carbon dioxide will affect aquatic organisms such as shell, coral and shellfish. We are already witnessing bleaching of corals at Great Barrier Reef in Australia. Global warming will displace millions of people due to draught and flooding and consequently leave millions of children malnourished. Water born diseases and infectious diseases will affect many people. Tropical diseases such as dengue and malaria will be widespread. These consequences are real, if the world does not act on greenhouse emissions. One need not be a rocket scientist to understand that human behavior and activity has caused irreversible damage to the plant earth for several decades. We unearthed fossil fuels and converted them into plastics and dumped them in every water ways, parks and beaches. The exponential growth in population and industries has driven many animals, tropical forests into extinction. Each and every one of us who are 50 years and above would have witnessed the unfolding consequences of environmental degradation in our life time. What kind of plant earth we will be leaving behind for our future generations? Every religion on earth has predicted the future of humanity and the final days and hours with deadly consequences for their actions. All native people whether they are Indians from Americas, Aborigines of Australia or Shamans of Indonesia or Natives of Alaska, have time and again raised their voice against indiscriminate destruction of land, water and air in the name of science and industrial growth. But no Government listened to their voice and we are here still struggling with unemployment and poverty. Mayan civilization is a well known civilization in ancient world and their seven prophesies are matters of great debate in the recent past. Their prophecy is ominously similar to what IPCC panel predicts except the “end of the world in Dec 2012”. I quote third, fourth and fifth prophesy out of seven Mayan prophecies here, which are relevant to global warming: “The third prophecy states that there will be change in temperature, producing climatic, geological and social changes in magnitude without patterns and at astonishing speed. One of them will be generated by man in his lack of conscience to care for and protect natural resources of the planet and other generated by sun, which will increase its activity due to increasing vibrations.” “The fourth prophecy says that anti-ecological conduct of man and greater activity by sun will cause melting of ice in the poles. It will allow the earth to clean itself and green itself again, producing changes in the physical composition of the continents of the planet. The Mayans left a register in the Desdre codices that for every 117 spins of Venus, the Sun suffers new alterations and huge spots or solar eruption appears”. “The fifth prophecy says that all systems based on fear, on which the civilization based on, will suffer simultaneously with the planet and man will make a transformation to give way to new harmonic reality. The system will fail and man will face himself and in this need to recognize society and continue down the path of evolution that will bring him to understand creation. Only one common spiritual world for all humanity that will end all limits established among many ways to look at God will emerge”. Perhaps, Jesus too expressed his displeasure with human behavior according to the Gospel of Thomas: Jesus said, "Perhaps people think that I have come to cast peace upon the world. They do not know that I have come to cast conflicts upon the earth: fire, sword, war. For there will be five in a house: there'll be three against two and two against three, father against son and son against father, and they will stand alone."