Charcoal - a value added biomass

One of the methods of value addition of biomass is the production of charcoal for fuel, soil conditioner, water purification and other purposes and at the same time,contributing to carbon sequestration or CO2 emission reductions. Charcoal is usually produced by slow pyrolysis and the resulting soft, brittle, lightweight, black, porous material resembles coal with 85% to 98% carbon and the remainder consisting of volatile chemicals and ash. Charcoal is cleaner, easier and less smoky and smelly than other biomass fuels. Charcoal is a very stable substance and the half-life of charcoal (carbonized in 1000 degree Celsius) is reported to be around one thousand years. Gross heating value is estimated to be within the range of 28-30 MJ/kg. Charcoal carbonized under lower temperature is more stable under the higher concentration of ozone in the air. Charcoal can hold pure carbon inside it for a long time and can be a carbon sink. In the carbonization process (pyrolysis), considerable amount of carbon goes to the air and CO2 emission from charcoal production must be minimized. Burying char, known as black carbon sequestration enhances soils, helping future crops and trees grow even faster, thus absorbing more carbon dioxide in the future. Researchers believe that the char, an inert and highly porous material, plays a key role in helping soil retain water and nutrients, and in sustaining microorganisms that maintain soil fertility. It has been estimated that as much as 9.5 billion tons of carbon which is more than what is currently emitted globally through the burning of fossil fuels could be sequestered annually by the end of this century through the sequestration of char.

Fungus strain for biodiesel production

Biodiesel, also known fatty acid methyl ester (FAME), has become more attractive as an alternative fuel because of its environmental benefits, including low toxicity and favourable emission profile. There are various methods of biodiesel production. Biocatalytic enzymatic method and chemical transesterification are promising methods among others. Biocatalytic enzymatic method offers mild reaction conditions and reduction in chemical wastes. However, biocatalysis of plant derived oil (PDO) feedstocks has relatively high price of pure lipase enzyme for use in the tranesterification reaction and has short operational period. Jeffrey and Ms. Xiao Man of Faculty of Engineering, National University of Singapore have conducted an investigation to undertake fundamental research on the locally isolated strains of fungus to investigate whole-cell performance as a biocatalyst for the conversion of PDOs to FAME. The investigation has yielded a microbial mold isolate (JN7) from the local environment having a high intrinsic lipase production and suitable for use as a whole cell biocatalyst for the transesterification of PDOs. The transesterification reaction resulted in a 86% yield of FAME in 72 hours when immobilized on biological support particles.

Energy funda

Energy is defined as the capacity of doing work. Energy comes in different forms - heat (thermal), light (radiant), mechanical, electrical, chemical, and nuclear energy. The energy of a body due to its position with respect to another body is called its potential energy. It is stated as, E = mgh, where E is the potential energy, m is the mass of the body, g is the acceleration due to gravity and h is the distance through which it has been raised. The energy of a body due to its motion is called its kinetic energy. It is stated as, E = ½ m v sq(2), where E is the kinetic energy, m is the mass of the body and v is its velocity. We can classify energy into high and low grade for practical purposes. High-grade energy like electricity is better used for high grade applications like melting of metals rather than simply heating of water. The energy lost or dissipated is called as low-grade energy. In our day to day work we use terms like thermal energy, mechanical energy, electrical energy, chemical energy, electromagnetic energy, etc. These are useful forms of energy. The origin of these forms may be in potential energy or kinetic energy or both. For example heat (thermal) energy is a form of kinetic energy due to the random motion of the atoms or molecules of solids, liquids or gases. Chemical energy, stored in atoms or molecules, is a form of potential energy. Energy can be converted from one form to another. According to the first law of thermodynamics, in any process of conversion of energy the total quantity of energy does not change. But practical experiences tell us that the useful energy output of an energy converter is always less than its energy input. This is because of some loss of energy during the conversion. The sum of energy loss and useful energy output is equal to energy input. The ratio of useful energy output to energy input is the conversion efficiency. Because of the losses it is always less than 100%. The conversion efficiency, generally expressed as a percentage, is high if the losses are low..

Hydrogen storage using nano pillared graphene

Hydrogen storage using nano pillared graphene Researchers are exploring new ways of using carbon nanotubes (CNTs) to store hydrogen in fuel cell vehicles. A unique hydrogen-storage structure consisting of parallel graphene sheets layers of carbon just one atom thick and stabilized by vertical columns of CNTs added with lithium ions has been suggested as a storage medium. Chemically modified graphene material has been prepared using several types of common electrolytes and graphene-based ultracapacitor cells have been constructed and electrically tested. The amount of electrical charge stored per weight (specific capacitance) of the graphene material has suggests the possibility of doubling the capacity compared to the existing ultracapacitors. The scientists' calculations has shown that the so-called "pillared graphene" could theoretically store up to 41 grams of hydrogen per liter which almost can approach the DOE's target of 45 grams of hydrogen per liter for transportation applications.

Mitsubishi Electric manufactures high efficiency PV cells

Solar power is a clean way to generate electricity that’s not only environmentally friendly, but economical. photovoltaic modules that gather energy from the sun, and release it as electricity that can power home or office to save on energy costs while helping protect the planet and to bring clean, reliable energy to residences, business, power-generation plants, schools, factories and areas without access to electricity, as well as other applications such highway and stadium lighting.
Photovoltaic modules manufactured by Mitsubishi Electric’s utilize polysilicon technology which is known for their high reliability, high-efficiency, and low environmental impact with 25-year limited warranty on power output.Solar cells have separate connecting tab wiring between the front and back sides. This is an effective step toward optimization of connecting conditions, while curving cell warp to support the move toward thinner solar cells.For the silver electrodes formed on the solar cell surface, an exclusive composition and manufacturing process is used by them that excel in environmental resistance and introduced industry-first introduction of mass-produced “solder-coatingless cells”. This removes lead (traditional lead-solder modules use about 860 grams of lead) which is harmful to the human body, while the expanded light reflection effects with the solderless status improve cell efficiency. Mitsubishi Electric has developed fine grid electrodes with an optimal BSF structure and use of anti-reflective coating for the solar cell manufacturing process which has expanded the solar cell light receiving area to realize high-efficiency cells.Solar cell string pitch have been expanded and the high reflectance back film reflects light to raise module efficiency.Use of glass that is cerium-free and high in transmittance has defined a new dimension in high efficiency, free of initial deterioration.

Solid Oxide Fuel Cell Technology

High temperature solid oxide fuel cell (SOFC) uses a hard ceramic electrolyte instead of a liquid and operates at temperatures up to 1,000 degrees C. A mixture of zirconium oxide and calcium oxide form a crystal lattice, though other oxide combinations have also been used as electrolytes. The solid electrolyte is coated on both sides with specialized porous electrode materials. At these high operating temperature, oxygen ions (with a negative charge) migrate through the crystal lattice. When a fuel gas containing hydrogen is passed over the anode, a flow of negatively charged oxygen ions moves across the electrolyte to oxidize the fuel. The oxygen is supplied, usually from air, at the cathode. Electrons generated at the anode travel through an external load to the cathode, completing the circuit and supplying electric power along the way. Generating efficiencies can range up to about 60 percent. In one configuration, the SOFC consists of an array of tubes. Another variation includes a more conventional stack of disks. Since SOFCs operate at such high temperatures, a reformer is not required to extract hydrogen from the fuel. Some demonstration units have capacities up to 100 kilowatts.

Biodiesel

Biodiesel is a mixture of fatty acid alkyl esters made from vegetable oils, animal fats or recycled greases. Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as a petroleum diesel additive to reduce levels of particulates, carbon monoxide, hydrocarbons and air toxics from diesel-powered vehicles.
Key Reaction
The main reaction for converting oil to biodiesel is called transesterification. The transesterification process reacts an alcohol (like methanol) with the triglyceride oils contained in vegetable oils, animal fats, or recycled greases, forming fatty acid alkyl esters (biodiesel) and glycerin. The reaction requires heat and a strong base catalyst, such as sodium hydroxide or potassium hydroxide. The simplified transesterification reaction is shown below.
Base transesterification
Triglycerides + Free Fatty Acids (<4%)> Alkyl esters + glycerin
Pretreatment Reaction
Some feedstocks must be pretreated before they can go through the transesterification process. Feedstocks with less than 4% free fatty acids, which include vegetable oils and some food-grade animal fats, do not require pretreatment. Feedstocks with more than 4% free fatty acids, which include inedible animal fats and recycled greases, must be pretreated in an acid esterification process. In this step, the feedstock is reacted with an alcohol (like methanol) in the presence of a strong acid catalyst (sulfuric acid), converting the free fatty acids into biodiesel. The remaining triglycerides are converted to biodiesel in the transesterification reaction.
Acid transesterification
Triglycerides + Free Fatty Acids (>4%) + Alcohol ——> Alkyl esters + triglycerides

Chemistry of gasification

Gasification is a quite complex thermo-chemical process. Conceptually zones of the gasifier may be divided into different stages viz., drying, pyrolysis, oxidation and reduction. The reactions occur at the same time in different parts of gasifier. The generation of gas occurs in two significant steps. The first step involves exothermic reactions of oxygen in air with the pyrolysis gas under fuel-rich conditions. The second step involves the endothermic reaction of these gases largely CO2 and H2O with hot char leading to product gases namely, CO, H2 and CH4.
Drying
Biomass fuel consists of moisture ranging from 5 to 35% and at the temperature above 100C, the water is removed and converted into steam. In the drying stage, fuels do not experience any kind of decomposition.
Pyrolysis
Pyrolysis is the thermal decomposition of biomass fuel in the absence of oxygen. Pyrolysis involves release of three kinds of products: solid, liquid and gases. The ratio of products is influenced by the chemical composition of biomass fuels and the operating conditions. The heating value of gas produced during the pyrolysis process is low (3.5 - 8.9 MJ/m 3). It is noted that no matter how gasifier is built, there will always be a low temperature zone, where pyrolysis takes place, generating condensable hydrocarbon.
Oxidation
Air is introduced in the oxidation zone contains oxygen, water vapours and inert gases such as nitrogen and argon. These inert gases are considered to be non-reactive with the fuel constituents. Oxidation takes place at 700-2000C temperature. Heterogeneous reaction takes place between oxygen in the air and solid carbonised fuel, producing carbon monoxide. Positive and negative symbol indicate the release and supply of heat energy during the process respectively.
C + O 2 → CO 2 + 406 MJ/kmol
Hydrogen in fuel reacts with oxygen in the air blast, producing steam.
H 2 + ½ O 2 → H 2 O + 242 MJ/kmol
Reduction
In the reduction zone, a number of high temperature chemical reactions take place in the absence of oxygen. The principal reactions that take place in reduction are mentioned below:
Boudouard reaction: CO 2 + C → 2CO - 172.6 MJ/kmol
Water-gas reaction: C + H2 O → CO + H 2 - 131.4 MJ/kmol
Water shift reaction:CO 2 + H 2 → CO + H 2 O + 41.2 MJ/kmol
Methane production reaction:C + 2H 2 → CH 4 + 75 MJ/kmol
Main reactions show that heat is required during the reduction process and hence, the temperature of gas goes down during this stage. If complete gasification takes place, all the carbon is burned or reduced to carbon monoxide, a combustible gas and some other mineral matter is vaporized. The remains are ash and some char (unburned carbon).

Ballard Power Systems Inc. offers Fuel cell-based backup power to India

Fuel cells offer a number of significant advantages over conventional batteries and diesel generators for backup power solutions. These include: greater reliability over a wide range of operating conditions; lower maintenance costs; longer operating life; reduced size, weight, installation footprint; and positive environmental impacts. Hydrogen-powered fuel cells are not only pollution-free, but also can have two to three times the efficiency of traditional combustion technologies. A conventional combustion-based power plant typically generates electricity at efficiencies of 33 to 35 percent, while fuel cell systems can generate electricity at efficiencies up to 60 percent (and even higher with cogeneration). These advantages make fuel cell technology ideal for telecommunications backup applications.

In the telecommunications environment, uninterrupted voice, data and video services are vital to business operation and competitive success. Proton Exchange Membrane (PEM) fuel cell is widely regarded as the most promising for light-duty transportation and stationary operations. In the Proton Exchange Membrane three layers of cathode, electrolyte and anode make up the membrane electrode assembly (MEA) of the proton exchange membrane (PEM) fuel cell. The electrolyte is a thin film, usually a sulfonated, perfluorinated polymer. The catalysed electrodes are porous carbon. The operating temperature is less than 100C. Cell outputs generally range from 50 to 250 kW. The solid flexible electrolyte will not leak or crack but their fuels must be purified, and a platinum catalyst is used on both sides of the membrane which raises the costs.

Principle of operation

The principle is that hydrogen gas flows through channels to the anode, where a catalyst causes the hydrogen molecules to separate into protons and electrons. The membrane allows only the protons to pass through it. The protons are conducted through the membrane to the other side of the cell, where oxygen gas, typically drawn from the outside air, flows through channels to the cathode. The stream of negatively-charged electrons follows an external circuit to the cathode which is electricity. When the electrons return from doing work, they react with oxygen and the hydrogen protons (which have moved through the membrane) at the cathode to form water. This union is an exothermic reaction, generating heat that can be used outside the fuel cell.

Ballard Power Systems Inc., is a world leader in the development, manufacture, sale and servicing of hydrogen fuel cells having headquartered in Burnaby, British Columbia. Ballard provides complete backup power solutions to telecommunications providers. Ballard’s Mark1020 ACS™ fuel cell product provides significant advantages to system integrators, and enables an extremely compact and cost-effective backup power solution in power increments ranging from 300 watts to 5 kilowatts. Fuel cell-based backup power systems are designed to operate for approximately ten years, while incumbent technologies may need total replacement every three to five years. Additionally, fuel cell solutions require only minimal maintenance once every one to three years compared to monthly or quarterly site visits to lead-acid battery installations. Ballard Power Systems offers an air cooled, scalable proton exchange membrane (PEM) fuel cell stack suitable to a wide range of light duty applications where durability, reliability and a simplified balance of plant are key requirements. According to Ballard their PEM (Proton Exchange Membrane) fuel cell stack has advanced open cathode technology and a state of the art self humidifying membrane electrode assemblies (MEAs). These features completely eliminate the need for humidification systems and simplify system integration with no moving parts, high efficiency, and low thermal and acoustic signatures and produces clean DC power. The system start up to rated power 20 seconds has a steady state life 4000 hours and requires hydrogen gas of 99.95% or better. The stack efficiency 47% to 58% LHV and DC voltage range 24 to 30 Volts.

Ballard to supply Backup Power units for Telecom in India

Ballard Power Systems announced that it has entered into a high volume development and supply agreement, with an affiliate of the ACME Group and IdaTech, to supply net 5kW natural gas fuel cell products to India. The systems will be deployed by ACME, primarily for telecom backup power applications in India. ACME who is an infrastructure provider to telecom network operators and IdaTech will enter into an agreement to form a joint venture in India for the manufacture and assembly of this system. Ballard will be the exclusive supplier of fuel cells to this joint venture. This agreement provides a binding commitment for the purchase of approximately 1,000 units in 2009 and 9,000 units in 2010, subject to meeting product design and acceptance specifications. This high volume, binding agreement represents a big step forward for Ballard and the broader fuel cell sector and also popularise and establish the application in India and other developing countries. The ten-thousand unit volume will enable significant cost reductions and this new low cost, natural gas fuel cell product will be an important enabler for the acceleration of product adoption in other stationary power markets.

Gasification & its hystory

Gasification

Gasification is a partial oxidation process whereby a carbon source such as coal, natural gas or biomass, is broken down into carbon monoxide (CO) and Hydrogen (H2) plus carbon dioxide (CO2) and possibly hydrocarbon molecules such as methane (CH4). This mix of gas is known as producer gas and the precise characteristics of the gas will depend on the gasification parameters such as temperature and also the oxidizer used. The oxidizer may be air, in which case the producer gas will also contain Nitrogen (N2), or steam or oxygen.

History of gasification

Gasification is an old technology with a long history of development. The process was mainly used from the mid of 1800’s through the early 1900’s to produce “town gas” from coal for heating and lighting purposes. The subsequent development of natural gas fields soon replaced “town gas." World War II brought a resurgence of gasification when petroleum starved Europeans used wood gas generators to power vehicles. But the need for liquid fuels remained and German engineers devised a way to make synthetic liquid fuel from gasified coal.

The 1970’s brought “The Arab Oil Embargo” and the “energy crisis” which prompted the U.S. government to support industrial scale gasification projects. From this development came the first Integrated Gasification Combined Cycle (IGCC) electric generating plant. Presently, several IGCC power plants are operating throughout the world. Year wise development of the technology is given below:

1969 - Thomas Shirley conducted crude experiments with carbonated hydrogen

1699 - Dean Clayton obtained coal gas from pyrolytic experiment

1788 - Robert Gardner obtained the first patent with regard to gasification

1792 - First confirmed use of producer gas reported, Murdoc used the gas generated from coal to light a room in his house. Since then, for many years coal gas was used for cooking and heating

1801 - Lampodium proved the possibility of using waste gases escaping from charring of wood 1804 - Fourcroy found the water gas by reaction of water with a hot carbon

1812 - Developed first gas producer which uses oil as fuel

1840 - First commercially used gasifier was built in France

1861 - Real breakthrough in technology with introduction of Siemens gasifier. This gasifier is considered to be first successful unit

1878 - Gasifiers were successfully used with engines for power generation

1900 - First 600 hp gasifier was exhibited in Paris. Thereafter, larger engines up to 5400 hp were put into service

1901 - J.W. Parker ran a passenger vehicle with producer gas

1901-1920 - many gasifier-engine systems were sold and used for power and electricity generation

1930 - Nazi Germany accelerated effort to convert existing vehicles to producer gas drive as part of plan for national security and and independence from imported oil

1939 - About 2,50,000 vehicles were registered in the Sweden. Out of them, 90 % were converted to producer gas drive. Almost all of the 20,000 tractors were operated on producer gas, 40 % of the fuel used was wood and remainder charcoal.

After 1945 - After end of Second World War, when plentiful gasoline and diesel were available at cheap cost, gasificaton technology lost glory and importance.

1950 to 1970 - During this decades, gasification was “Forgotten Technology ". Many goverments in europe to felt that consumption of wood at the prevailing rate will reduce the forest, creating several environmental problems.

After 1970 to 1990 - The next stage in the evolution of gasification began after the Arab Oil Embargo of 1973. In reaction to that event and the ensuing “energy crisis,” the U.S. government provided financial support for several proof-of-concept gasification projects, including the world’s first Integrated Gasification Combined Cycle (IGCC) electric powerplant. Another important event during this period was conversion of Eastman Chemical’s flagship manufacturing plant from petroleum to syngas from coal.

1990 to 2000 - The fourth stage of gasification’s development began in the early 1990s when government agencies in the United States and Europe provided financial support to four medium-sized (≈ 250 MWe) projects to further “demonstrate” the feasibility of the IGCC process.

2000 to Present- The current stage in the evolution of gasification began when commercial developers started building IGCC powerplants without government subsidies. These new IGCC facilities (all outside the United States) are adjacent to refineries where petroleum coke and other residual hydrocarbons are readily available.

Direct Ethanol Fuel Cell (DEFC)

One of the major drawbacks of the DMFC is that the low-temperature oxidation of methanol to hydrogen ions and carbon dioxide requires a more active catalyst, which typically means a larger quantity of expensive platinum catalyst is required than in conventional PEMFCs. This increased cost is, however, expected to be more than outweighed by the convenience of using a liquid fuel and the ability to function without a reforming unit. Since methanol is supposed to be toxic some companies have embarked on using ethanol to substitute for methanol. More than 30% of world ethanol production is from corn, the rest is produced from suger based raw material like juices of sugarcane or beet and also their molasses. There are other grains used in the production of ethanol which is rice, wheat, rye, sorghum or tubers like cassava / tapioca. Cellulosic biomass, holds tremendous promise as a feedstock for ethanol production due to its widespread availability and potential for high fuel yields. Examples of sources for celluosic ethanol include corn stover , wheat and barley straw, sugarcane or rice bagasse, sawdust, paper pulp, small diameter trees and dedicated energy crops such as switch grass and other fast growing grasses. Study is still going in making cellulosic ethanol more viable. Hence developing a Direct Ethanol Fuel Cell (DEFC) has gained importance. The performance of the DEFC is currently about half that of the DMFC, but this gap is expected to narrow with further development.

Hydrogen storage by non-metallic solid material

Hydrogen is often spoken as an environmentally-friendly fuel for road vehicles of the future. When consumed in a fuel-cell powered electric car, it produces nothing more than pure water as a by-product. However, many technological challenges remain before it can be used commercially. In particular, hydrogen has a low energy density compared to conventional fuels and therefore it must be stored as a liquid or an extremely high pressure gas to ensure that reasonable distances can be traveled before refueling. Current materials that can easily absorb and discharge hydrogen near room temperature contain transition metals and the storage process must be catalysed by expensive precious metals such as platinum. This makes them too heavy and too expensive for commercial use. But Douglas Stephan and colleagues at the University of Windsor have developed the first non-metallic solid material that can absorb and store hydrogen at room temperature without involving a transition metal. This discovery could lead to the development of low-cost and lightweight materials for the onboard storage of hydrogen fuel in cars. Although the metal-free material offers hope of lighter and cheaper storage materials, it stores less than 0.25% of its weight in hydrogen and researchers say there is still a long way to go.

Ceramic material as membrane

A central component of a solid oxide fuel cell is the electrolyte which consists of an oxygen ion conducting ceramic material. Such ion conducting materials can also be used for membranes. The membrane route has some environmental advantages and has the potential of becoming cost competitive with the existing industrial routes. A specific use of such mixed conducting membranes is in a membrane reactor for production of synthesis gas which is a mixture of CO and H2, which is the source for a number of industrially important syntheses such as methanol and ammonia and has potential use as electrode materials for solid oxide fuel cells. Presently available membranes based on palladium support a high flux of hydrogen, but their mechanical stability is limited and their catalytic properties favor the formation of coke.

Towards 50% efficiency solar cells

Allen Barnett and Christiana Honsberg have a project under DARPA Very High Efficiency Solar Cell (VHESC) program on developing affordable portable solar cell battery chargers. They have integrated the optical design with the solar cell design leading to a new paradigm about how to make solar cells and how to use them. It is claimed that an advance of 2 percentage points is noteworthy in a field where gains of 0.2 percent are the norm and gains of one percent are seen as significant breakthroughs with regard to solar cell efficiency.They aim at a major step toward their goal of 50 percent efficiency of solar cell. The percentage will be a record under any circumstance, but it's particularly noteworthy because it's at low concentration, approximately 20 times magnification. The low profile and lack of moving parts mean that these devices easily could go on a laptop computer or a rooftop.

Improving efficiency of solar cells

Photovoltaic (PV) cells are made of special materials called semiconductors such as silicon, which is currently the most commonly used. When sun light strikes the cell, energy knocks electrons loose and the flow of electrons is a current. By placing metal contacts on the top and bottom of the PV cell, we can draw that current off to use externally. Many factors limit the efficiency of photovoltaic cells. Silicon is cheap, for example, but in converting light to electricity it wastes most of the energy as heat. The most efficient semiconductors in solar cells are alloys made from elements from group III of the periodic table, like aluminum, gallium, and indium, with elements from group V, like nitrogen and arsenic. One of the most fundamental limitations on solar cell efficiency is the band gap of the semiconductor from which the cell is made. The maximum efficiency a solar cell made from a single material can achieve in converting light to electrical power is about 30 percent; the best efficiency actually achieved is about 25 percent.
One way of improving efficiency is to use two or more layers of different materials with different band gaps. The higher band gap material is on the surface, absorbing high-energy photons while allowing lower-energy photons to be absorbed by the lower band gap material beneath. This technique can result in much higher efficiencies. Such cells are called multi-junction cells.
Instead of using a germanium wafer as the bottom junction of the device, the new design uses compositions of gallium indium phosphide and gallium indium arsenide to split the solar spectrum into three equal parts that are absorbed by each of the cell's three junctions for higher potential efficiencies. This is accomplished by growing the solar cell on a gallium arsenide wafer, flipping it over, and then removing the wafer. The resulting device is extremely thin and light and represents a new class of solar cells with advantages in performance, design, operation and cost.
A team led by John Geiszat of the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) have set a world record in solar cell efficiency with a photovoltaic device that converts 40.8 percent of the light that hits it into electricity. This is the highest confirmed efficiency of any photovoltaic device to date.
Presently using a novel technology that adds multiple innovations to a very high-performance crystalline silicon solar cell platform, a consortium led by the University of Delaware (UD) has achieved a record-breaking combined solar cell efficiency of 42.8 percent.

Direct Methanol Fuel Cells (DMFC)

Initially developed in the early 1990s, DMFCs were not embraced because of their low efficiency and power density, as well as other problems. Improvements in catalysts and other recent developments have increased power density 20-fold and the efficiency may eventually reach 40%. The technology behind Direct Methanol Fuel Cells (DMFC) is still in the early stages of development, but it has been successfully demonstrated powering mobile phones and laptop computers potential target end uses in future years. DMFC is similar to the PEMFC in that the electrolyte is a polymer and the charge carrier is the hydrogen ion (proton). However, the liquid methanol (CH3OH) is oxidized in the presence of water at the anode generating CO2, hydrogen ions and the electrons that travel through the external circuit as the electric output of the fuel cell. The hydrogen ions travel through the electrolyte and react with oxygen from the air and the electrons from the external circuit to form water at the anode completing the circuit.

Anode Reaction: CH3OH + H2O => CO2 + 6H+ + 6e-

Cathode Reaction: 3/2 O2 + 6 H+ + 6e- => 3 H2O

Overall Cell Reaction: CH3OH + 3/2 O2 => CO2 + 2 H2O

Low operating temperature and no requirement for a fuel reformer make the DMFC an excellent candidate for very small to mid-sized applications, such as cellular phones and other consumer products, up to automobile power plants.

Biodiesel

Biodiesel is the name for a variety of ester-based oxygenated fuels derived from natural, renewable biological sources such as vegetable oils. Biodiesel operates in compression ignition engines like petroleum diesel thereby requiring no essential engine modifications. Moreover it can maintain the payload capacity and range of conventional diesel. Biodiesel fuel can be made from new or used vegetable oils and animal fats. Unlike fossil diesel, pure biodiesel is biodegradable, nontoxic and essentially free of sulphur and aromatics. The oil extracted from the seeds of Jatropha is mixed with methanol at a proportion under a particular temperature. This solution is continuously stirred for two hours. During the above process, glycerol present in the solution separate out; which when settled can be separated out. Whatever is left after removing the glycerol is the liquid fuel. When the liquid fuel is washed twice, purified biodiesel is obtained. This could be used directly for running the engine. Advantages of biodiesel are:
. Produced from sustainable / renewable biological sources
. Ecofriendly and oxygenated fuel
. Sulphur free, less CO, HC, Particulate matter and aromatic compounds emissions
. Income to rural community
. Reduce the dependency on conventional source
. Fuel properties similar to the conventional fuel
. Used in existing unmodified diesel engines
. Reduce the expenditure on oil imports
. Non toxic, biodegradable and safety to handle
. Reduce the depletion conventional fuel resources

Jatropha seed oil

India imported about 36.5x106of its diesel requirement in the year 2003 and demand for diesel is also increasing every year. Biodiesel is the only fuel to meet out increasing diesel demands. So even mixing of 20 per cent with diesel fuel by biodiesel can help India save 7.3 x 106 tonnes of diesel per year. In India, about more than 14 million hectares land is cultural wasteland while more than 24 million hectare land is fallow land . The use of non edible oils compared to edible oils is very significant because of the increase in demand for edible oils as food and they are too expensive as compared with diesel fuel.

Among the various non edible oil sources, Jatropha curcas oil has added advantages like pleasant smell, odorless and light yellowish colorless and easily mixed with diesel fuel. Jatropha curcas oil cannot be used for food or feed because of its strong purgative effect. The Jatropha plant having advantages namely effectively yields oilseeds from the 3rd year onwards, rapid growth, easy propagation, life span of 40 years and suitable for tropical and subtropical countries like India.

Use of jatropha oil in engine

The direct use of raw jatropha oil in engine by several researchers and they reported formation of carbon deposits, incomplete combustions and results in reducing the life of an engine due to high viscosity of curcas oil. Similar problems reported by many researchers when they using raw vegetable oils as engine fuel. When using refined curcas oil blends in precombustion chamber engine, results for thermal efficiency and emission were fair compared with diesel No.2 diesel. The problems of filter blockage, carbon deposits and oil incompatibility with fuel line materials were also noticed. It is also reported that jatropha oil blending up to 40 to 50 per cent with diesel fuel used in engine without modifications. However, Acrolein is high toxic substance released from the engine due to thermal decomposition of glycerol present in the oils. The problems encountered in raw oils are solved by forming biodiesel, which is non toxic, eco-friendly fuel, and have similar properties of diesel fuel.

Solar power for India

The best form of renewable energy available to the developing countries is the solar energy. This is due to the fast changing world energy scenario, particularly for emerging economies such as India and China on account of the rising costs of oil and coal. India is a small player in the world photovoltaic cells market, yet 69% of its modules are exported. The rest are put to use mainly in telecommunications and lighting homes. Solar PV modules are developed in the industrialised countries despite the fact that their energy efficiency is 15-20% is because of rising fossil fuel costs and the need to contain greenhouse gas emissions. Germany, Spain, Japan, China and the US are the leading PV module makers, with Germany making up almost half the world’s output of about 3,800 MW. China’s PV cell output was 820 MW in 2007, ten times that of India. It is time India broke into the big league, to take advantage of global technological transition. If wind power generation has risen sharply in the last decade to account for 80% of India’s renewable energy output of over 10,000 MW, the next decade could belong to solar. While the installed capacity for wind power is limited close to 8,000 MW, which is little more than 2 MW in the case of grid-connected solar power.

Alkaline Fuel cell

The alkaline fuel cell consists of electrodes and chambers for electrolyte and gas supply. Electrodes viz., anodes and cathodes are for operation with hydrogen and air. Each electrode consisted of 3 layers; a current collecting nickel mesh, a catalytic layer and a hydrophobic gas-porous PTFE (Teflon) layer at the gas side of the electrodes. The catalytic layer is a calendered mixture of platinized carbon particles with PTFE, the only difference between anodes and cathodes is the type of carbon substrate used for the catalyst in order to cope up different electrocatalytic environments such as reduction or oxidation. The carbon substrate used is powdered charcoal. The catalytic loading is 0.3 mg platinum (Pt) per square centimeter of cell area. The electrodes are designed to operate at atmospheric pressure and had a thickness of 0.4 mm. there are several modules and each module has the electrodes combined together using a semi industrial two step manufacturing process. The frames are of thermoplastic material injection moulded and friction welded.

Biomass briquetting

Agricultural or agro-industrial biomass is generally difficult to handle because of its bulky and scattered nature, low thermal efficiency and copious liberation of smoke during burning. Legal and administrative problems are also encountered with agro-industrial biomass. In order to achieve maximum and efficient exploitation of locally available resources, it is essential to compress them into manageable and compact pieces, which have a high thermal value per unit weight. This process is called biomass briquetting or pelleting. Compressed biomass briquettes are usually cylindrical in shape with a diameter between 30 to 90 mm and length varying between 100 to 400 mm. Briquetting consists of applying pressure to a mass of particles with or without a binder and converting it into compact aggregate.
Biomass densification, which is also known as briquetting, has been practiced for many years in several countries. Briquetting is one method, which can take care of pollution problems while using important industrial/ domestic energy resources. Normally bulk density of loose biomass is in the range of 0.05-0.02 g/cm3 and can be densified to briquettes of density 1.1-1.4 g/cm3.

Partial oxidation of biogas

The conversion of gaseous hydrocarbons can be achieved in many ways. Partial oxidation with air is one of the options. In this process methane in the biogas with oxygen in air to form hydrogen in a bed of catalyst.
This commercial process route is basically the result of sequential combustion reactions in which the gas is burnt with deficit oxygen (nearly 30 % of stoichiometric requirement). Depending on the feed -stock the product gas may require purification of sulphur compounds and CO2 removal. The advantage of dispensing with an external heat source favours the partial oxidation step, since the oxidation of CO supplies the necessary heat.
The biogas containing 55-60 % methane , 40 % CO2 and traces of H2 S is first dehydrated and then purified from H2 S. The gas is then sent to the partial oxidizers to form hydrogen. Depending on the composition of the outlet gas from the oxidizer methanation of residual carbon oxides can be incorporated. Finally a Co2 scrubber may be added depending on the type of fuel cell to be used in the power plant.
The process occuring in the partial oxidizer is
CH4 + 0.5 O2 = Co + 2H2
The process requires oxygen, which may be separated and supplied from air and is favoured by moderately high pressure. It is understood that due to residence time limitations, the process approaches equilibrium leaving some residual methane and carbon in the product gas. Hence CO2 needs to be scrubbed and recycled in the plant.

Types of agro residues

Due to growing worldwide concern about the environmental impacts of fossil fuels, particularly global warming and nuclear risks, there is currently a resurgence of interest in biomass energy, since potentially it can satisfy a much larger energy demand. According to a report, under the minimum case scenario, biomass is the most important of the renewable and is projected to account for 45% (243 mtoe) of the contribution by renewable to world energy by 2020 and to about 65% of energy use in developing countries. At present however, the residues are normally under utilized. CO2 emission could be avoided significantly by utilizing normally unused residues in place of fossil fuels, wherever possible.
Biomass residues and by products are available in abundance at the agro-processing centres (rice husk, bagasse, molasses, coconut shell, groundnut shell, maize cobs, potato waste, coffee waste, whey), farms (rice straw, cotton sticks, jute sticks), animals sheds (cow dung, poultry excreta, forests (bark, chips, shavings, sawdust), municipal waste (city refuse, sewage) and industrial waste (distillery effluents/ spent wash, textile waste, plastic waste). The increase in productivity as a result of green revolution has effected not only the production of main products but also the generation of residues. The residues generated by rice, sugarcane, coconut, groundnut, cotton, jute and maize is significantly substantial.

Photovoltaic power

Photovoltaic systems and power plants have emerged as viable power sources for applications such as lighting, water pumping and telecommunications and are being increasingly used for meeting electrical energy needs in remote villages, hamlets, hospitals and households. PV systems, when used on a large scale, can cut down the need for extending the distribution grids in rural areas and the resultant losses in transmission. Solar Photovoltaic (SPV) water pumping systems are technically proven and have potential of replacing diesel pumping systems, commonly used in un electrified locations for lifting water from shallow depths. The pumps can also bring the benefits of irrigation and drinking water supply in backward areas not served by the exiting grid and where supplying diesel is a problem. It is clear that there is a vast potential for the use of solar photovoltaic technology in the developing countries.

Materials aspects of the SOFC

One major difference between the MCFC and SOFC technologies is that the MCFC uses readily available materials and predictable manufacturing technology, particularly in its use of sheet metal parts. In contrast, the prospects for manufacture of the SOFC are not very predictable, since it will require sophisticated ceramic fabrication techniques that go beyond the state of the art for production processes. Two versions of the SOFC technology exist. The first is a conservative version in pre prototype stage, whereas the second is an idea that is only in the design stage. Since the latter is only on the drawing board, any conclusions concerning its fabricability and performance will involve many technological extrapolations.

New ways to use biomass

Presently, cellulose is mainly processed by fermentation. For the fermentation process to take effect yeast must be added to the cellulose, this will allow the sugar to be fermented into ethanol as well as carbon dioxide. The next step is the distillation process which is necessary to remove the alcohol from the solids and the water. However, splitting cellulose into its individual sugar components, which can then be fermented, is a slow and cost-intensive process. The direct conversion of cellulose into useful organic compounds is thus an attractive lternative.Researchers in the USA and China have now developed a new catalyst that directly converts cellulose, the most common form of biomass, into ethylene glycol, an important intermediate product for chemical industry. A team led by Tao Zhang at the Dalian Institute of Chemical Physics, China and Jingguang G. Chen at the University of Delaware, Newark, USA has developed a novel process. In this the catalyst is made of tungsten carbide and deposited on a carbon support with small amounts of nickel added to improve the efficiency and selectivity of the catalyst system. A synergetic effect between the nickel and tungsten carbide not only allows 100 % conversion of cellulose, but also increases the proportion of ethylene glycol in the resulting mixture of polyalcohols to an amazing 61 %. Ethylene glycol is an important intermediate in the chemical industry. For example, in the plastics industry it is needed for the production of polyester fibres and resins, and in the automobile industry it is used as antifreeze.

A simple catalytic process converts plant sugars into fuel

Researchers at the University of Wisconsin-Madison have developed a simple, two-step chemical process to convert plant sugars into hydrocarbon fuels. The compounds created during the process could also be used to make other industrial chemicals and plastics.
The Wisconsin researchers, led by chemical- and biological-engineering professor James Dumesic employ chemical reactions with catalysts at high temperatures to convert glucose into hydrocarbon biofuels in smaller, cheaper reactors. The catalytic process is done in two main steps, which can be integrated and run sequentially with the output from one reactor going to the other in a continuous process with catalyst recycling. In the first reactor has platinum-rhenium catalyst at about 500 K and the second has various solid catalysts such as copper and magnesium-based catalyst. The first reactor creates a mixture of various hydrocarbon compounds, such as alcohols and organic acids which is transferred to the second reactor, where it results in a range of hydrocarbon molecules that make up gasoline, diesel, and jet fuel.
This research can use sugars derived from cellulosic biomass such as agricultural waste and switchgrass instead of using food sources such as corn and sugarcane that are economically competitive with petroleum fuels.

Renewables have a bright future

Norway goes renewable

Norway’s total energy consumption is based on renewable energy. That is far higher than any other European country, except Iceland. The European average is 8.5 per cent. The Norwegian government also gives high priority to promoting new investments in renewable energy and energy efficiency. It has been planned for increasing the production of renewable energy and energy efficiency by 30 terawatt hours by 2016. Norway has already achieved an increase of 10 terawatt hours. Next year Norway will double the capital in the Fund for Renewable Energy from 10 billions kroner to 20 billions.
Hawaiian island goes renewable

Silicon Valley-based Sun Power is the supplier of a new 1.5 MW solar photovoltaic farm for the Hawaiian island of Lanai. The solar farm is spread over 10 acres of the Palawai Basin and the island has 3,000 residents.The Lanai solar farm will supply up to 30% of peak electrical demand on Lanai and is expected to generate 10% of the island's total power needs. This is the largest solar installation in Hawaii and one of the larger systems in the nation. The State wants to achieve its goal of 70% renewable energy by 2030.

Google plans for renewables

Google plan for a more environmentally friendly America with details of a proposal to curtail the use of oil and coal by 2030 by establishing wind, solar and geothermal power plants to largely replace fossil fuels. Hybrid and electric cars would also get a major boost. Google calculates that it will save the United States $1 trillion over the 22-year life of the plan as renewables become cheaper and gasoline gets more expensive.

What is Renewable Energy?

Fossil fuels are the main sources of energy presently used, but there is a fear that they will get exhausted by the next century. Hence other systems based on non-conventional and renewable sources are being attempted and succeeded by many countries. They can come from solar, wind, biomass or other natural sources. These technologies are variedly termed as alternate or appropriate technologies, but the term renewable energy has gained global acceptance.