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Thursday, April 27, 2017
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Monday, April 9, 2012
Bioethanol has successfully substituted Gasoline as a fuel for cars both in the form of blends with Gasoline or individually as an Anhydrous Ethanol. This successful demonstration by Brazil opens up new generation of cars called flex-fuel cars that allow usage of various blends of Ethanol and Gasoline.Bioethanol can also be used to generate Hydrogen onsite by steam reformation so that even Fuel cell cars such as Honda FCX can be felled by Bioethanol.This makes Bioethanol unique as an alternative fuel for transportation. It also facilitates onsite power generation using Fuel cell, replacing diesel engines. Substitution of Gasoline by Bioethanol has several advantages over other alternative fuels. The biggest advantage with Bioethanol is, it is renewable and it allows reduction of greenhouse gases from the atmosphere and it will be eligible for Carbon credit. It can be produced by both developing as well as developed countries using locally available agriculture produces such as cane sugar, corn, tapiaco, sorghum etc. Hydrogen generated from Bioethanol is also free from Sulfur compounds normally associated with natural gas, making it an ideal fuel for Fuel cell application in cars, as well as for power generation using SOFC (solid oxide Fuel cell) or PAFC (Phosphoric acid Fuel cell).The resulting high purity Hydrogen 99.99% can be used as fuel for all type of transportation including Fuel cell Buses, scooters and even boats. The stoichometric reaction of steam reformation in presence of catalyst can be represented by the following chemical reaction: C2H5OH + 3 H2O---------- 6H2 + 2 CO2 The Ethanol and water mixture is preheated and the vaporized mixture is fed into a catalytic reactor. The resulting Hydrogen is contaminated with carbon monoxide. This gas mixture is separated using membrane such as Palladium to get Hydrogen with less than 50ppm CO as contaminant. Such purity is acceptable by Fuel cell such as SOFC as well as PAFC.In future a small micro-reactor for on-board reformation may be possible making Fuel cell cars with onboard liquid fuel storage. Commercial reformers consumes about 0.88 lits of Bioethanol of 96% purity to generate 1 Nm3 of Hydrogen with 60% conversion. This translates to $ 5.90 per Kg of Hydrogen. Fuel cell cars offer a mileage of 240 from 1 kg Hydrogen costing only $5.90. For onsite power generation 1 kg Hydrogen generates as much as 15Kw electricity and 20Kw heat .Onsite Hydrogen generation with steam reformation also facilitates using SOFC and PAFC for high temperature power generation applications. They are ideal for CHP (combined heat and power) applications for 24x7 operations like hospitals, hotels and super markets. These fuel cells are silent in operation without any emissions except water vapor. Governments should encourage Bioethanol production and distribution for both transportation and power generation. There is a fear that Ethanol could be diverted for potable purposes illegally depriving Governments of potential reveneues.But this can be solved by denaturing Bioethanol and making it unsuitable for potable purposes. Denaturants such Pyridine has no effect on steam reformation and number of denaturants are available. Such policies will allow transition from fossil fuels to Hydrogen or Bioethanol.This is a simple and straight forward step any Government can take irrespective of the size or type of a nation. But it requires political will, determination and leadership. Developing countries need not wait for big greenhouse emitters such as US, China and India to make a decision on their Carbon emissions but start introducing Bioethanol as fuel locally.
Monday, March 19, 2012
There is a general opinion that Hydrogen is dangerous or explosive; people are often reminded of Hindenburg accident or Hydrogen bombs. Hydrogen is as safe as Gasoline or Butane gas. It should be handled with care like any combustible material. We have used Hydrogen in industries for so many decades and transported by pipelines across thousands of kilometers; the methods and procedures of handling Hydrogen is well established. It is a very light, colorless and odorless gas and it can easily escape into the atmosphere. Hydrogenation of vegetable oils for production of certain Margarines is one of the classical industrial examples of Hydrogen usage. When 100m3 Hydrogen is compressed to 10,000psi pressure, it is reduced to just 0.163 m3 by vlume.That is how the Hydrogen storage space is reduced in passenger cars. This volume of gas can give a mileage of 652 miles using Fuel cell power. The only emission is just pure water vapor! No noise, no smoke and it is entirely a new experience driving a Hydrogen Fuel cell car. Powering your home with Hydrogen or fuelling your Fuel cell car is not very difficult. It is expensive compared to grid power for two simple reasons. Grid power is generated by power generation companies somewhere else using coal, oil or gas and transmitted across to millions of people.Therefore investment on power generation is shared by millions of people through their monthly energy bills. When you use the grid power, you do not pay any large sum except, a small deposit of few hundred dollars towards connection fee, and you pay your bills based on your monthly electricity usage. But when you try to generate your own power using a solar panel or Fuel cell then you have to make an investment fully upfront. Of course your bank can help financing the system. However, when you calculate the energy cost over the life period of 25 years, you can clearly see the value of such investment. The grid power cost will only increase and never decrease while your generation cost will decrease as the time passes. The future energy cost is likely to increase substantially due to various factors. You can export surplus power to the grid and your payback time will be reduced as the energy cost increases. The first step in powering your home is to calculate your power requirements accurately in terms of watt.hrs.How many appliances you will be using and how many hours you will using each of these appliances per day. Suppose you estimate 15,000 watt.hrs/day or 15kwhrs/day of power, and then a small Fuel cell consuming 1 Kg/day of Hydrogen or 30 kgs/month of Hydrogen will be sufficient to meet your power demands. Similarly you can calculate the amount of Hydrogen you will be using as a fuel for your Fuel cell car. For example if you will be driving your Fuel cell car for 1000 miles per month, then your Hydrogen requirement will be about 14 kgs/month. Your Hydrogen requirement per month for both power and car together will be 44 kgs only. Your total power requirement to generate the above Hydrogen will be 2464 kwhrs/month costing less than $250 per month for both power and fuel. Of course, you need to calculate other fixed costs on the investment. You can export your solar power at a higher tariff to the Government and import your power requirement from the grid during off-peak season at a lower tariff and generate Hydrogen and store it. You can generate your power as and when you need, and you are in complete control of your situation, even if there is a blackout due to grid failure!
Monday, February 27, 2012
Water constitutes 71% of the planet earth and it is the most potential energy source of the future. Water is a product of combustion between Hydrogen and Oxygen, two most abundantly available elements and vital for life on earth. The bondage between Hydrogen and Oxygen is so strong that it requires certain amount of energy to separate them. Separation of Hydrogen and Oxygen using the process of Electrolysis is a well known technology. Separation of water by high temperature using Thermolysis has also been studied. In both the processes the separation of Hydrogen and Oxygen after decomposition is a key step because of the strong affinity between the two elements. Hydrogen has to be separated in a pure form without any trace of Oxygen. Currently most of Hydrogen is generated commercially by steam reforming natural gas because of its easy availability as piped gas in many developed countries. Moreover steam reforming is a well established commercial technology that has been used for decades in chemical process industries. The hydrogen resulting from steam reforming is acceptable for combusting in Hydrogen internal combustion engines but not pure enough for a Fuel cell car. Any trace of impurity from natural gas such as Sulfur or mercaptans can potentially poison the catalyst used in fuel cell which is very expensive. Hydrogen with purity less than 99.99% is not recommended for Fuel cell applications. Currently there are few issues to be addressed before Hydrogen becoming a commercial fuel. The energy required to separate Hydrogen from water by commercial electrolysis is about 6Kws (kilowatts) to generate 1 m3 (cubic meter) of Hydrogen. Two key factors for electrolysis are purity of water and DC power source. Water of certain purity is a critical component for Hydrogen generation. Deionized water with electrical conductivity less than 0.10 micro Siemens/cm is required. Normal drinking water conductivity is less than 100micro Siemens/cm. The potable water can be deionized with reverse osmosis system to get necessary quality. In fact both high purity water and direct current are not commercially available. A renewable energy sources such as solar or wind that generates direct current can be used for electrolysis. This will eliminate batteries and rectifiers that we normally use in renewable energy systems. The generated Hydrogen can be stored in cylinders under high pressure. The stored hydrogen is the stored energy that can be used as and when required. We can use the stored Hydrogen to generate electricity to meet our power requirement whether it is a home or business or industry. The major advantage with this system is that we can generate power whenever we need and we don’t have to depend on the grid power. We can also export surplus power to the grid. In fact all DC appliances can be connected with DC power from Fuel cell and operated to improve the efficiency. Such a system is ideal for remote locations without any grid supply such as remote villages or islands. The same stored Hydrogen can also be used as fuel for a car whether it is a combustion engine or a Fuel cell car. Hydrogen can be compressed and stored under high pressure. Alternatively, Hydrogen can be stored using metal hydrides in smaller volumes. Honda introduced the first fuel cell car in the market in 1999. Since then they have made considerable improvements. Honda FCX Clarity, sedan offers a mileage of 270 miles for a single cylinder of Hydrogen at 5000 psi pressure. They are introducing a latest model with Hydrogen pressure at 10,000 psi which will considerably improve the mileage further. Unlike Hybrid cars, Fuel cell cars run silently and experts who have test-driven the car are very much impressed with the performance. Similarly Ford introduced Hydrogen combustion engine 6.8 liters V-10 engine to power E-450 Hydrogen shuttle bus. Ford modified their Gasoline engine to suit Hydrogen fuel. Substituting Gasoline with Hydrogen is no longer a theory but a commercial reality. More and more research is being undertaken to improve the performance. Currently the cost of Hydrogen cars and Hydrogen fuel is expensive, due to lack of infrastructures to manufacture such cars or to distribute Hydrogen. However these cars will soon replace gasoline cars. Similarly individual homes and business can generate their own electricity for their daily use using stored Hydrogen. Water will become the fuel of the future and Hydrogen will clean up the air that has been heavily polluted by fossil fuels for decades.