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Monday, February 20, 2012
Power generation using fossil fuels is a well established technology dating back to 1839, when Michael Faraday invented the principle of Electro-magnetism. There was not much of a change in this technology all these years. But recently greenhouse emission and global warming has become an issue; and the world started looking for an alternative source of energy and method of power generation. However it is not an easy task to develop completely a different technology as well as a fuel in a short span of time, while an unabated man-made greenhouse gas emission continues. Scientists are now warning catastrophic consequences if the greenhouse gas emission is not curtailed with great urgency.Untill now the world was able to avert some of the potentially catastrophic events happening, like ozone layer depletion, pandemic bird flu etc.But global warming is a new thereat that demands an entirely a new solution and a swift action. But majority of countries in the world are not is a position to curtail greenhouse emission gas, simply because there is no alternative fuel known, except fossil fuels. Renewable energy is relatively a new concept. Though solar and wind energy sources were known long time back, they were not persuaded seriously because they could not compete with conventional fossil fuels. But the time has come for new emerging technologies that can not only compete with fossil fuels but also eliminate greenhouse emissions. The world has invested massively on fossil fuel infrastructures and still investing heavily on oil and gas explorations. Obviously there is no end in sight as far as fossil fuels are concerned and the world is carrying on business as usual. Meanwhile a new technology based on fuel cell is emerging as an alternative for power generation. Fuel cell is a known concept and it has been successfully deployed in ‘Apollo space programme in space shuttle. This old version of alkaline fuel cells was replaced with PEM (proton exchange membrane) fuel cell or (PEMF) Polymer electrode membrane fuel cell. This new version was used in Gemini’s space programme in sixties. Fuel cell is an electro chemical devise that uses Hydrogen gas as a fuel and it operates at ambient temperature. It is like a battery cell. The difference between fuel cell and batteries is the Fuel cell will keep generating power as long as fuel is supplied unlike a battery, where energy is stored in the form of chemical energy and converted into electrical energy when used by connecting through a conductor. Battery needs recharging but Fuel cell requires refueling. The fuel used in Fuel cell is invariably Hydrogen. Conventional power generation involves combustion of fossil fuel (heat energy) which drives a turbine (mechanical energy) to run an alternator to generate power (electrical energy).In fuel cell; Hydrogen gas reacts with oxygen from the atmosphere (electrochemically) to generate power. It produces water as by-product. The efficiency of Fuel cell is about 50-60% compared to 35-40% by steam or gas turbine. In regenerative fuel cell, water can be split into Hydrogen and oxygen using same proton exchange membrane elecrolyzer.The resulting Hydrogen can be used as a Fuel to the PEM Fuel cell to generate power, thus recovering water. It is a closed circuit system. There are no mechanical moving parts, no combustion, no smoke or no noise. It is a quiet and clean operation. It is a very promising technology that can revolutionize the way we produce fuel and generate power. The Hydrogen and fuel cell combination is used in cars. Honda FCX (fuel cell model) cars work on the same principle and they are already on roads! One problem with Hydrogen generation is it requires more power to split water, into Hydrogen and oxygen, than the power generated by resulting hydrogen, using Fuel cell. However, this technology will change the future of power generation by eliminating greenhouse emission completely. But how long it will take to become a commercial reality is something to be seen! If political leaders and Governments around the world recognize the potential of this technology and take bold decisions coupled with swift actions, probably our future generation can breathe a clean air.
Monday, February 13, 2012
Why I say “water and clean energy, are two sides of the same coin?” At the outset, it may sound odd, but in reality, these two are closely interconnected. Let us examine, step by step, how they are connected, to each other, and what are the implications, in terms of cost, and environmental issues. Take for example, power generation industries. The two basic materials, any power plant require, are, fuel and water. It does not matter, what kind of fuel is used, whether it is a coal based power plant or liquid fuel based plant like Naphtha, or gas based plants, like piped natural gas or LNG Of course, this statement is applicable only, for existing, conventional power generation technologies, and not for PV solar or wind energy, technologies. Let us consider, only power generation, involving conversion of thermal energy, into electrical energy. Today, more than 80% of power generation in the world, is based on thermal power, including nuclear plants. What is the usage of water in power plants? All thermal power plants use steam, as the prime motive force, to drive the turbines, (gas turbine is an exception, but, even in gas based plants, the secondary motive force, is steam, using waste heat recovery boilers, in combined cycle operations). The quality of water for conversion into steam is of high quality, purer, than our drinking water. The second usage of water is for cooling purpose. The water consumption by power plants, using once through cooling system is 1 lit/kwhr, and by closed circuit cooling tower, it is 1.7lit/kwhr .Only about 40% power plants in Europe, for example, use closed circuit cooling towers, and the rest use only ‘once through’ cooling systems. The total power generated in 2010, by two largest users, namely US and China, were 3792Twhrs and 3715 Twhrs respectively. The total world power production, in 2008 was 20,262 Twhrs, using following methods. Fossil fuel: Coal 41 %, Oil 5.50%, Gas 21%, Nuclear 13% and Hydro 16%. Renewable: PV solar 0.06%, PV thermal 0.004%, Wind 1.1%, Tide 0.003 %, Geothermal 0.3%, Biomass &others 1.30%. (1Twhrs is = 1,000,000,000 kwhrs) The above statistics, gives us an idea, on how much water, is being used, by power generating plants, in the world. Availability of fresh water, on planet earth, is only 2.5% (96. 5% oceans, 1.70% ground water, 1.7% glaciers and ice caps, and 0.001% in the air, as vapor and clouds).The world’s precious water source, is used for power generation, while millions of people, do not have water, to drink. The cost of bottled drinking water is US$ 0.20 /lit, in countries like, India. This situation is simply unsustainable. The prime cause, for this situation, is lack of technology, to produce clean power, without using water. The power technology, we use today, is based on the principle of electromagnetism, invented, by Michael Faraday, in the year 1839. That is why, renewable energy, is becoming critically important, at this juncture, when the world is, at the cross road. In order to overcome, the shortage of fresh water, many countries are now opting, for seawater desalination. Desalination, again, is an energy intensive process. For example 3-4 kwhrs of power is used, to desalinate 1 m3 of water. This power has to come, from fossil fuel fired, thermal power plants, which are often co-located, with desalination plants, so that, all the discharge, from both the plants, can be easily pumped into the sea. Since, the world is running out of fresh water, we have to look for alternative source of water. In countries like India, the ground water is being exploited, for agricultural purpose, and the ground water is getting depleted. Depleting water resources is a threat to agriculture production. It is a vicious circle. That is why, distributed energy systems, using Hydrogen as an alternative fuel, is an important step, towards sustainability. One can generate Hydrogen from water, using renewable energy source, like solar or wind, and store them, for future usage. The stored Hydrogen can be used to generate power, as and when required, at any remote location (even where there is no grid power).The water is regenerated, during this process of power generation using Fuelcell, which can be recycled. There is no large consumption of water, and there is no greenhouse emission. It is a clean and sustainable solution. The same stored Hydrogen can also be used as a fuel for your car! Therefore; one can say “water and clean energy, are two sides of the same coin”. (The above statistics are based on Wikipedia data).