VATIS Update Non-conventional Energy . Nov-Dec 2009

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New and Renewable Energy Nov-Dec 2009

ISSN: 0971-5630

VATIS Update New and Renewable Energy (formerly Non Conventional Energy)* is published 4 times a year to keep the readers up to date of most of the relevant and latest technological developments and events in the field of New and Renewable Energy. The Update is tailored to policy-makers, industries and technology transfer intermediaries.

* This update has been renamed as 'VATIS Update: New and Renewable Energy' from Jan-Mar 2015 onwards.

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From pond scum to jet fuel: algal biofuels

In the United States, several companies are venturing into the field of algal biofuels. Algae have indisputable advantages as a biofuel feedstock. Of all the green fuel options, algae alone seem to possess the potential to provide renewable oil in quantities adequately large to substantially displace petroleum-based fuels, say experts. Large-scale production of algal biofuels is still 5-10 years away, say officials from Exxon Mobil, which is in partnership with Synthetic Genomics to produce algae-based biofuels.

Microscopic algae yield up to 100 times more oil per acre than soybeans and other common biodiesel feedstock, according to Ms. Mary Rosenthal, Executive Director of Algal Biomass Organization. Microalgae can be up to 80 per cent oil by dry weight, although that number is for wild strains that are slow growers, according to Dr. Margaret McCormick of the technology company Targeted Growth. Genetically engineered microalgae, such as those created by Targeted Growth, approach 35-45 per cent oil by dry weight, but achieve dense cultures in one day.

Microalgae grown photosynthetically represent a two-for-one environmental benefit carbon dioxide (CO2) mitigation plus a renewable source of energy. Microalgae can capture sunlight 20-40 times more efficiently than plants, and unlike corn- or soy-based feedstock, they do not create a food or fuel dilemma. Some can even be cultured using seawater. While more than 40,000 wild algal species are in existence, algal biofuel leaders like Solazyme Inc. and Sapphire Energy employ genetically selected or engineered microalgal strains for oil production.

In addition to growing photosynthetically, with sunlight as an energy source and CO2 as carbon source, microalgae can be grown heterotrophically, using sugar, glycerol or cellulosic biomass for energy and carbon. Solazyme uses the latter technique, which gives up the solar advantage in exchange for faster growth, a higher culture density for easier harvesting and a process that fits the existing industrial fermentation infrastructure. Heterotrophic cultivation requires growth in a bioreactor. Other companies such as Sapphire Energy and Solix Biofuels grow microalgae photosynthetically: Solix in photobioreactors and Sapphire Energy in ponds on non-arable land.

Once the microalgae are cultivated, biofuel manufacturers are faced with two main technical hurdles: harvesting and dewatering. Microalgae cultures can be up to 80-90 per cent water and so, the cells must be collected by settling, which is time-consuming, although this can be hastened with flocculating agents that cause cells to clump and pre-cipitate. More high-tech methods like centrifugation and filtering are faster, but are more costly in both money and energy. Once harvested, the cells may be air- or sun-dried, requiring a large surface area and significant time, or they can be dried using heat or a vacuum, again increasing the cost while reducing energy efficiency.

Extracting the oils is another challenge. Options include extraction with solvents like hexane, enzymatic digestion of cell walls, or physical disruption using ultrasonic sound waves or microwaves.

The Exxon-Synthetic Genomics partnership genetically engineers strains to secrete oil continuously. Oil obtained from microalgae can be used as a straight oil fuel, but this needs a modified engine, which hardly anyone wants to do commercially at present. On the other hand, biodiesel can be used in existing diesel engines alone or in a blend, as it has the characteristics of petroleum diesel. The big pay-off in algae biofuels, therefore, will be as drop-in replacements for petrol or jet fuel. Successful test flights have already been run on mixtures of petroleum and algal-based jet fuels, although cost-effectiveness remains an issue.

New microbe improves economics of ethanol production

TMO Renewables Ltd., the United Kingdom, has developed a novel fermentation process using certain microorganisms that enables part of the waste derived from maize-based production of ethanol for use in making more biofuel. Thermophilic microorganism is the bacterial ethanologen at the core of TMOs process. This organism can exist at high temperatures and can digest a wide range of feedstock very quickly. The new process exploits these talents to produce ethanol from any cellulose-based material, most notably maize (corn), domestic waste (paper, food) and second-generation feedstock, such as leftovers from agriculture and industry.

The conventional method widely employed to produce ethanol from corn is energy-intensive since the material requires significant cooling from the high temperature of the pre-treatment process to the low temperature of the fermentation, and then re-heating for the subsequent distillation process. This traditional approach remains uneconomical when used to make ethanol from cellulosic biomass because of the costs and time involved in preparing and pre-treating the feedstock, the energy consumed and the capital costs involved in using exotic metallurgy to build large batch reactors.

In contrast, TMOs new solution offers both short and longer-term benefits for biofuel production. The immediate application of TMOs new technology is that it can be bolted on to an existing corn ethanol plant at nominal cost. Secondly, the technology delivers massive energy savings since the process requires a wet feedstock, which eliminates the cost of drying the dried distillers grains with solubles (DDGS), which are the co-product of the conventional corn ethanol process and in themselves a valuable source of ethanol. TMO has proved that it could deliver lower energy consumption, lower costs and higher output, thus producing a 70 per cent improvement in margin.

The TMO process exploits two innate properties of the organism. Firstly, by exploiting the high temperature that the organism favours, fermentation can be performed at temperatures in excess of 60C. Secondly, the organism prefers consuming the longer chain sugars that derive from the break-up of biomass. This brings a very significant benefit in that a very large portion of the work and cost required to break down biomass to simple sugars, such as glucose, is removed. By changing the starting point for the fermentation of ethanol, the methods of feedstock preparation, pre-treatment and sugar release are all simplified to a point where the whole process emerges as economically viable.

The speed of the fermentation is rapid so vessels can also be reduced in size, further driving down capital costs. Almost al the components at TMOs demonstration plant are off-the-shelf equipment, common in many chemical processes. Contact: TMO Renewables Ltd., 40 Alan Turing Road, Surrey Research Park, Guildford GU2 7YF, United Kingdom. Tel: +44 (1483) 303 305; E-mail: info@tmo-group. com.
Source: www.

A commercial algae bioreactor

W2 Energy Inc., a green energy equipment developer in the United States, is working to have its patented algae bioreactor up and running. The company will then begin selling its bio-oil and searching for partners to help commercialize the bioreactor itself.

The Sunfilter bioreactor will grow algae to produce bio-oil for biofuels and will be employed to sequester carbon dioxide from the companys waste-to-energy processes. It also can be sold separately to algae producers, biodiesel producers, labs, aquaculture companies, and coal and petroleum plants, according to W2 Energy.

In the bioreactor, low-power ultraviolet lights, in combination with the gases, feed the algae so that they grow and fill the tubes with blooms. When the blooms have reached an appropriate density, a set of magnetic rings inside the tubes scrapes the blooms clean and pushes the algae to the upper manifold, where compressed air pushes it out. The algae are then compressed, dried and then gasified or fed into a biodiesel reactor to produce biodiesel. Contact: W2 Energy Inc., 711 S Suite, #4 Carson Street, Carson City, NV 87901, United States of America.

Add hydrogen to make better biofuels

Scientists at Idaho National Laboratory (INL), the United States, are working on a process to convert biomass, such straw or crop residue, into liquid fuels at a far higher efficiency than existing cellulosic ethanol technologies. Rather than one single development, the bio-syntrolysis technology ties together multiple processes, with electrolysis at is starting point. When combined with a carbon-free electricity source, the approach could deliver a carbon-neutral biofuel, according to models done at INL.

Bio-syntrolysis is one of several technologies being developed with the hope of replacing petrol, even though none has been successful at scale. INL researchers recognize the technical barriers, but their recent computer models show that the technique has better potential than todays biofuel processes. The key advantage, is that the process would extract far more energy from available biomass than existing methods, said Dr. Grant Hawkes. Bio-syntrolysis would convert more than 90 per cent of the carbon into a fuel, as compared with the 35 per cent that most of the traditional techniques used in ethanol-making offer.

This is the only process available that will give us all the liquid fuel we currently need that is carbon-neutral with the all the biomass that is available, Dr. Hawkes said. While it is a compelling vision, there are a number of technical hurdles to making bio-syntrolysis commercially viable and environmentally beneficial. For instance, to reduce carbon emissions significantly over other biomass-to-liquid processes, the process requires a lot of carbon-free electricity 1,000 MW of electricity would yield 25,000 barrels of fuel a day, enough for almost one million people, according to INL models. Only a full-size nuclear reactor could produce 1,000 MW. Further, the approach also relies on tying together different technologies, some of which are relatively immature in terms of commercial deployment.

In bio-syntrolysis, a high-temperature electrolyser would split steam into oxygen and hydrogen. Oxygen would be fed to a biomass gasifier to produce synthesis gas, a combination of carbon monoxide and hydrogen. That synthesis gas, along with the hydrogen from the electrolyser, would be fed to a refiner to make liquid fuels that could replace petrol, diesel or jet fuel. Thehigh-temperature electrolysis is the biggest technology breakthrough in this design.

So far, INL researchers have done experiments using available commercial products, and they have modelled the overall efficiency on computer. To build a high-temperature electrolyser, they have modified commercial fuels cells to work in reverse, producing hydrogen and oxygen from electricity. The projected cost of the fuel would be about US$0.65 a litre to produce, which is not cheaper than petrol. But the primary advantages are that the fuel is domestically sourced, low-carbon and available at a predictable price.

Rechargeable batteries from algae

Algae are not just a fossil fuel replacement in the form of biodiesel, but have been made into extraordinary rechargeable batteries. Scientists at Uppsala University in Sweden were looking for a way to turn deadly blooming algae found in oceans and seas into something useful. Rather than go the biofuel route, as so many have done, the scientists decided to try something different.

Combining the expertise found in the departments of Nanotechnology and Functional Materials, Engineering Sciences, and Materials Chemistry at the ngstrom Laboratory at the University, a new type of lightweight battery was created. This battery is composed of taking cellulose fibres from algae and coating them with a 50 nm thin layer of polypyrrole.

Batteries made this way have charging capacities of between 25 and 33 mAh/g or 38-50 mAh/g by weight of the active material. These batteries can be charged with currents as high as 600 mA/cm2. They will only lose 6 per cent of their charging capacity after 100 charges. In laymans terms, these batteries are extremely light and can be charged in 11.3 seconds at 320 mA. The algae batteries tested were not optimally packaged, but the laboratory is working on that issue now. So far, they have created a battery that was capable of taking 1,000 charges.

Demonstration plant for cellulosic bioethanol production

In Japan, a cellulosic bioethanol demonstration plant constructed by Mitsubishi Heavy Industries Ltd. (MHI), Hakutsuru Sake Brewing Co. and Kansai Chemical Engineering Co. is about to launch continuous operation. The new facility, located at the Futami Plant of MHIs Kobe Shipyard & Machinery Works, will produce ethanol for automobile fuel from soft cellulose plant residues such as rice and wheat straw. It will be Japans first biofuel production plant with continuous preprocessing.

For preprocessing and saccharification, MHI adopted a method that combines hydrothermal treatment and enzymatic saccharification technologies the company developed jointly with the New Energy and Industrial Technology Development Organization (NEDO). The new method permits the input of several kinds of soft cellulose feedstock into a reactor at moderate temperature and pressure. The reactor output is separated into carbon and sugar portions on a continuous basis. The separated carbon and portions are saccharified by different enzymes. As only hot water is added during preprocessing, influence of the fermentation inhibitor is minimal and waste utilization is possible, as preliminary verification has already executed. Employing this method will result in significant cost reduction as well as enhanced operational safety because of reduced use of water and heat in the preprocessing reactor.


Bacteria can help convert waste to power

At the University of Massachusetts (UM), the United States, scientists have isolated bacteria with large numbers of tiny projections called pili, which transfer electrons to generate power in fuel cells more efficiently than their counterparts with a smooth surface. The researchers isolated a Geobacter sulfurreducens strain, which they called KN400, that multiplied prolifically on the graphite anodes of fuel cells. The bacteria formed a thick bio-film on the anode surface, which conducted electricity.

The researchers found large quantities of pilin, a protein that makes the tiny fibres that conduct electricity through the sticky bio-film. The filaments form microscopic projections called pili that act as microbial nanowires, said Prof. Derek Lovley. Using this bacterial strain in a fuel cell to generate electricity would greatly increase the cells power output. Microbial fuel cells can be used in monitoring devices in environments where it is difficult to replace batteries if they fail. To be successful, however, they must have an efficient and long-lasting source of power.

A liquid design for cheaper fuel cells

Platinum remains the best material for speeding chemical reactions in hydrogen fuel cells, although the scarcity and cost of this element keep fuel cells from becoming more affordable and practical. Most alternative approaches involve simply replacing the electrodes platinum. Instead, ACAL Energy Ltd. from the United Kingdom has overhauled the fuel cell design to reduce the quantity of platinum used by 80 per cent.

In a conventional fuel cell, platinum is embedded in porous carbon electrodes. ACALs design replaces this with a solution containing low-cost molybdenum and vanadium as the catalyst. The resulting fuel cell works as well as a conventional one but should cost 40 per cent less, the company claims.

ACAL says its design gives power densities of 600 mW/cm2 at 0.6 V. The benchmark value for automotive fuel cells is 900 mW/cm2. ACAL also claims that its fuel cell works unpressurized, and adding pressure would increase the power density further. The ACAL systems power density could reach 1.5 W/cm2, says Mr. Andrew Creeth, co-founder and Chief Technology Officer of ACAL. Contact: ACAL Energy Ltd., The Heath Business and Technical Park, Runcorn, Cheshire, WA7 4QX, United Kingdom. Tel: +44 (1928) 511581; Fax: +44 (1928) 511582; E-mail:

Hydrogen fuel cell powers generator

The hydrogen fuel cell-powered generator, from the Dutch firm Bredenoord, provides 4 kW of clean, quiet power. The companys Purity generator has an output of 4 kW, It is mobile, and does not emit damaging emissions such as carbon dioxide, particulate matter, soot or nitrogen oxides. It is also as quiet as a laptop, and can run for 30 hours on a single set of hydrogen tanks.

The generator incorporates a stack of 60 fuel cells that are 0.5 cm thick. Through an electrochemical reaction between hydrogen and oxygen from the air, the fuel cells produce electricity, heat and water. The company is working with a consortium that is developing a bigger prototype called the Uniflex, which can use both hydrogen and bio-ethanol as fuel.

New alkaline membrane for cheaper fuel cells

A new type of fuel cell membrane made from quaternary phosphonium-based polymers could allow for the production of cheaper fuel cells that do not require the use of expensive precious metal catalysts. Prof. Yushan Yan at the University of California-Riverside, the United States, and his team developed an alkaline membrane, which contains the polymeric ionomer TPQPOH with a tris(2,4,6-trimethoxyphenyl)phosphonium unit. TPQPOH is highly soluble in low-temperature water-soluble solvents, and also has high ionic conductivity as well as alkaline stability. The membrane works on the basis of hydroxide ion exchange rather than hydrogen ion exchange.

In a basic environment created by the hydroxide ions, the over-potential of cathode oxygen reduction can be greatly reduced, which increases the efficiency. It is also possible to use a wide range of fuels including hydrogen, methanol, ethanol and ethylene glycol. Fuel cells containing the alkaline membrane have already been shown to be durable and have high energy and power density. Prof. Yan achieved a power density of 250 mW/cm2 with the membrane. Non-precious metals such as iron, cobalt, nickel and silver can be used as catalysts, instead of the expensive platinum or palladium.

Fuel cell that makes electricity from carbohydrates

Researchers at Brigham Young University (BYU), the United States, have developed a fuel cell that harvests electricity from glucose and other sugars known as carbohydrates. Carbohydrates are very energy-rich, said Professor Gerald Watt. What we needed was a catalyst that would extract the electrons from glucose and transfer them onto an electrode.

The surprising solution turned out to be a common weed killer, report Prof. Watt and his colleagues. The effectiveness of this abundant and cheap herbicide is a boon to carbohydrate-based fuel cells. Most of the hydrogen-based fuel cells require costly platinum as a catalyst. The next step for the BYU team is to ramp up the power through design improvements. The researchers have reported experiments that yielded a 29 per cent conversion rate, or the transfer of 7 of the 24 available electrons per glucose molecule.

New ceramic material for fuel cells

In the United States, Georgia Institute of Technology researchers have developed a new ceramic material that they think could help expand applications for solid oxide fuels cells (SOFCs). The research team thinks its new mixed ion conductor material could address two problems associated with the cells: it resists sulphur poisoning and coking (the build-up of carbon). The material could also allow the fuel cellsto work at lower temperatures, which could reduce material and fabrication costs.

The development of this material suggests that we could have a much less expensive solid oxide fuel cell, and that it could be more compact, which would increase the range of potential applications, said Prof. Meilin Liu, leader of the research effort. The new material could allow fuel cells to run with dirty hydrocarbon fuels without the need to clean them and provide water. However, researchers said that the long-term durability of the material is still to be proved.

A long-lasting fuel cell

Germany-based SFC Smart Fuel Cell has unveiled its Emily 2200 fuel cell, a direct methanol fuel cell (DMFC) that is durable and offers reliable power supply for on-and-off vehicle applications. Integrated into tactical vehicles or in the field, the fuel cell operates as a rugged fuel cell power generator.

As an auxiliary power unit onboard military vehicles, the Emily 2200 fuel cell keeps vehicle batteries charged automatically, reliably, quietly and virtually emission-free. It delivers power for devices ranging from radios and other communication equipment to night-vision goggles, navigation devices and computers. In operation, the DMFC is undetectable by sound or smell, and generates power almost imperceptibly eliminating the need to start the vehicle engine to charge batteries.

Off-vehicle, the fuel cell can supply power for both mobile and stationary military applications. It is being used in unmanned applications as well as a field-based charging station for batteries. It also can be combined with other alternative power sources like solar or wind. The Emily 2200 could produce electrical power for several weeks without maintenance. For operation, the DMFC uses a fuel cartridge, such as a 10 l cartridge weighing 8kg and has enough capacity for more than 10kWh. This fuel cartridge is sufficient to power devices for more than 100hours.


Enzymes inspire new catalyst design

A new enzyme-based catalyst developed byresearchers in the United Kingdom and the United States is hinting at novel ways of designing catalysts for the water-gas shift reaction, an important industrial reaction in the production of high grade hydrogen. The water-gas shift, which uses carbon monoxide (CO) and water to produce carbon dioxide (CO2) and hydrogen, has been used in industry since the 1940s. Various metal catalysts are used, including copper and platinum. Dr. Fraser Armstrong at theUniversity ofOxford did better: his team created an unusual catalyst in which two different bacterial enzymes are stuck to tiny pieces of graphite.

One enzyme, CO dehydrogenase, churns out CO2, releasing electrons in the process. These electrons pass via the graphite support to a [NiFe]-hydrogenase, which uses them to turn hydrogen ions into hydrogen gas (H2). Armstrongs team has calculated that their catalyst beats industry catalysts with ease. Besides working at a higher turnover frequency, it does it in ambient conditions, whereas industrial catalysts for the reaction operate at around 200C.

Although Dr. Armstrongs enzymes are too fragile for industrial scale up, he believes they provide a totally fresh design for a catalyst, where the two different halves of the reaction are catalysed by two different components and connected by an electrically conducting particle a two-site system, each with a well defined role. There are, however, issues of scalability and of designing a solid catalyst with two parts that are not physically connected, say some experts in the field.

Recycling hydrogen fuel

Chemical hydrides form a class of materials that can store and release hydrogen and be potentially used to run a fuel cell. Ammonia borane is a good prospect, because its hydrogen storage capacity nears a high 20 per cent by weight. The problem, though, has been the lack of energy-efficient ways to reintroduce hydrogen back into the spent fuel once it has been released: it cannot be adequately recycled.

A new method for recycling fuel materials containing hydrogen can make hydrogen-based vehicles more economically viable. In the United States, Los Alamos National Laboratory and University of Alabama researchers, working for the Chemical Hydrogen Storage Centre of Excellence, have been focusing on this. The research team has discovered that a specific form of dehydrogenated fuel, called polyborazylene, could be recycled relatively easily without much energy input. It is a significant step towards using ammonia borane as a possible energy carrier for transportation purposes.

The chemistry is new and innovative, and has significant practical applications, said Dr. Gene Peterson, leader of the Chemistry Division at Los Alamos. The team is now working with Dow Chemical Company to improve overall chemical efficiencies and move toward large-scale implementation of hydrogen-based fuels.

Carbon-free hydrogen fuel source

Scientists from RoseStreet Labs Energy (RSLE), the United States, announced a leap forward in generating hydrogen gas directly from sunlight by a photoelectrochemical cell (PEC). The hydrogen fuel is generated spontaneously in a single device without external power and without petroleum products such as natural gas. The discovery is linked with RSLEs Full Spectrum photovoltaic technology, which is primarily based on nitride thin-film semiconductors that have excellent robustness to extreme environments including solar radiation, heat and corrosive environments. Mr. Bob Forcier, CEO of RSLE, stated, We are excited about this new development in capturing the full spectrum of the sun for not only instantaneous power generation, but also for energy storage via liquefied hydrogen or to assist the emerging biofuel and biodiesel efforts.

Hydrogen-powered three-wheeler

Tractor maker Sonalika Group, India, says it has developed a pollution-free three-wheeler that will run on hydrogen and emit only vapour. The engine has been developed in technical collaboration with Banaras Hindu University. Around 20 scientists and engineers from Sonalika Group and Banaras Hindu University have worked for seven years to make the project viable, the company said. As the engine will be powered by hydrogen, fuel efficiency is expected to increase by 25 per cent, said Mr. Deepak Mittal, the companys Managing Director. The vehicle can reach a speed of 70 km per hour and function even in sub-zero temperatures, he said, adding that the test ride had been conducted before scientists and automobile experts. The project was co-funded by the Ministry of New and Renewable Energy, Government of India.


ADB supports waste-to-energy project in China

The Asian Development Bank (ADB) recently signed an agreement to lend up to US$200 million to China Everbright International Ltd. to develop waste-to-energy plants in secondary cities across China. This will mark ADBs first private-sector municipal solid waste management project.

Effective disposal of municipal solid waste is a serious environmental challenge in China, which has become the worlds largest producer of such waste, generating around 148 million tonnes per annum and growing at 8-10 per cent annually. Nearly half of this waste is untreated and dumped in unsuitable landfills meaning many urban poor, especially those living near the landfills, are exposed to severe air and water pollution, as well as to the threat of infectious diseases.

The project financing is in the form of a direct US$100 million A-loan and a complementary B-loan of up to US $100 million, funded by commercial lenders with ADB acting as lender of record. The loans will have a maturity of up to 10 years with a three-year grace period. ADB will also provide a technical assistance grant of up to US$653,000 from its Clean Energy Fund to evaluate the performance of the plants and communicate the lessons learned to municipal governments in China and to other ADB developing member countries.

IFC pushes for green energy finance in Bangladesh

The International Finance Corporation (IFC), a wing of the World Bank Group, is persuading Bangladeshs financial institutions to roll out easy funds for businesses to produce energy-efficient products for sustainable development. As part of the move, IFC took top bankers from the country on a tour to China to inform them on the best practices there in sustainable energy finance and to expose them to real life cases, as well as allow them to meet relevant stakeholders in Chinas sustainable energy finance programme, said Ms. Afifa Raihana, a coordinator of IFCs South Asia Enterprise Development Facility (SEDF).

Sustainable energy or efficiency in energy use is a novel concept in Bangladesh. There are no guidelines from the regulator, nor do banks have the capacity to evaluate green projects. However, SEDF has joined hands with Bangladesh Bank to develop an environmental risk management guideline for the financial sector in the country, Ms. Raihana said. An international firm has been hired for the work. The guideline will be complemented by a 10 sector specific due diligence checklist and relevant training programmes so that financial institutions could adopt it. However, it will be non-binding and maintained by the central bank, Ms. Raihana said.

Indonesia ready to develop solar energy

Indonesia is ready to develop power plants that utilize solar energy on a large scale as one way to develop renewable energy sources and to fulfil electricity needs in remote areas. Indonesian President Mr. Susilo Bambang Yudhoyono has asked PT LEN Industri (Persero) to design a master plan for developing solar energy. PT LEN is located in Bandung, and focuses on producing electronic infrastructure as well as developing sources of renewable energy, such as solar cells. So far, it has built a capacity of 6 MW in solar energy power plants, but this is far from the market needs, as the governments spending alone can reach 10 MW per year.

Reviving an old energy technology

A century-old technology that was widely used during the World War II to power vehicles in Europe and had subsequently disappeared is now drawing the attention of 21st century investors, thanks to the persistent research efforts of scientists from the Indian Institute of Science (IISc), and other institutions across the world. Biomass gasification, which gained popularity before and during World War II, had almost become obsolete when IISc scientists started showing interest in the technology. A team of IISc scientists tweaked the process of gasification to such an extent that it has now become a highly lucrative energy production method, says Dr. S. Dasappa, who has been associated with the project for long.

The technology has now found renewable energy investors like the Singapore-based All Green Energy Pvt. Ltd. The company will launch 10 biomass-based renewable energy projects in India in the next two to three years, investing about Rs 5 billion (US$110 million). According to Mr. Anil Lala, Director, All Green Energy India Pvt. Ltd., the process is highly profitable as even the by-products (like activated carbon) have high market value.

The company plans to generate Rs 250-300 million (US$5.5-6.6 million) per plant per annum, of which 70 per cent will be through electricity sales, 15-20 per cent through activated carbon sales, 5 per cent from cold storage facilities and 5-10 per cent from carbon credits. We use IISc technology, which is proven and has been deployed in over 50 units in India and abroad, said Mr. Lala.

Pakistan to support manufacture of solar water heaters

The Government of Pakistan would extend all possible support for the production and promotion of solar water heaters, which will drastically reduce gas consumption in the country, affirmed Mr. Raja Pervez Ashraf, Water & Power Minister and Chairman Alternative Energy Development Board (AEDB). Mr. Raja, chairing an AEDB Board meeting recently, directed AEDB to help build a market for solar water heaters and take all steps to promote their use. Mr. Pervaiz Ashraf urged public sector organizations to take lead in switching over to solar water heating system.

The Minister informed that a private sector power generation company, Green Power, will soon start setting up wind farm in Jhimpir. It will be the countrys second wind farm after the one set up by Zorlu Enerji in last April. The new project expected to be launched in mid-2010 will comprise 33 wind turbine generators, each with an installed capacity of 1.5 MW wind turbine generator, with aggregate capacity to generate 50 MW of electricity.

China launches differentiated wind energy tariffs

China has instituted a new system of differentiated wind energy tariffs based on four wind energy zones. The move is the first in Asia since the Republic of Korea implemented a feed-in tariff programme in 2005. China is the first jurisdiction outside Europe to implement wind energy tariffs differentiated by geographic location. Costs of the wind feed-in tariff programme above the cost of coal-fired generation will be split between provincial grid operators and the central government as in current policy. The new programme by Chinas National Development and Reform Committee was issued on 20 July 2009.

The wind feed-in tariffs themselves are less than those in Germany and France and less than those proposed in Ontario, Canada. The Chinese feed-in tariffs are said to be based on the differences in the wind resource across the country, and it may represent an innovative hybrid between the graduated wind energy tariffs in Germany or France and the single-value tariffs in Ontario in Canada, and Vermont and California in the United States. The magazine Power Engineering has reported that China is about to announce feed-in tariffs for solar pho-tovoltaic (PV). It quoted Suntech Chairman Mr. Zheng-rong Shi as suggesting the tariff for large-scale solar PV plants could be equivalent to US$0.22/kWh. Whether these tariffs also include access to state subsidies is unknown.

More energy project investment in Republic of Korea

The government of the Republic of Korea plans to spend 13.5 billion won (US$11 million) three times more than this years budget for a global joint development projects on energy next year. Of the total, 10.5 billion won (US$8.6 million) will be invested in projects targeted at enhancing energy efficiency and renewable energy technology development, the Ministry of Knowledge Economy said.

Research institutes or international organizations on energy around the world can sign up for the governments support programme through the website of Korea Institute of Energy Technology Evaluation and Planning. In a related development, the Ministry would be announcing a comprehensive plan to form international joint projects on developing energy technology.

Philippines approves wind, ocean energy projects

The Department of Energy (DoE) of the Philippines has approved the conversion and awarding of pre-development service contracts (PDSC) to nine wind and ocean thermal renewable energy projects to keep up with the provisions of the law. The conversion into PDSC was from pre-commercial contract (PCC), which was the prevailing award type for resource assessment prior to the passage of the Renewable Energy Law or Republic Act (RA) 9513. After resource assessment, the project proponents may move forward to development, after another round of approval by DoE.

The wind projects ready for PSDC awarding are those of: Energy Development Corporation, PetroEnergy Resources Corporation and Northern Luzon UPC Asia Corporation. The projects with PCCs for conversion into PDSC include those of Energy Logistics Philippines Inc. and Alternergy Philippine Holdings Corporation. For ocean thermal energy, the PDSC will be awarded to Deep Ocean Power Philippines Inc. The Deep Ocean project proposal covers 910 blocks in Luzon, Visayas and Mindanao, covering 73,710 ha.

Future Energy Prize honours innovators

Abu Dhabis Zayed Future Energy Prize, which awarded its first prize in 2009, is unique among its peers in that anyone can enter or be nominated, making the Prize the most equitable and non-partisan award in the renewable energy field. The Prize, which recognizes innovation, long-term vision and leadership in renewable energy technologies, is worth US$2.2 million in total, with US$1.5 million going to the winner and US$350,000 each for up to two finalists. The Prize is supported by Masdar, a global cooperative platform for open engagement in the search for solutions to some of humankinds most pressing issues: energy security, climate change and the development of human expertise in sustainability.

The award is open to any individual, company or non-governmental organization that can demonstrate a tangible clean energy solution. Any party can be nominated or enter directly by visiting the website, www. Once a nomination is received, the organizers of the Future Energy Prize will invite the nominee to submit a formal entry according to specific criteria.

Last year, the Zayed Future Energy Prize attracted 204 nominations and 150 submissions from more than 50 countries. This year, over 350 nominations from more than 60 countries have been received eight weeks before the closing date of 16 October 2009.

Private sector invited to join village energy programmes

Indonesias central government has invited the countrys private sector and local governments to participate more in helping villages reach energy self-sufficiency, as it does not have adequate funds to run such programmes alone. Since 2007, 633 villages have reached energy self-sufficiency under the central governments energy self-sufficiency villages programme (DME) at the cost of about US$97.6 million, according to Mr. Bayu Krisnamurthi, a Deputy to the Coordinating Minister for the Economy.

Of about 70,000 villages in Indonesia, between 3,000 and 4,000 need to reach energy self-sufficiency, and this could cost up to US$545 million, while only about US$8.2 million has been invested this year, Mr. Krisnamurthi said. The government expects all of the 4,000 villages targeted would reach energy self-sufficiency by 2014, revealed Ms. Musdhalifah Machmud, Coordinator of the programme. The DME programme is aimed at increasing the opportunities for and productivity of economic activities in villages. It is also expected to become a tool to help bridge the gap between rich-resource areas and poor-resources ones.

China plans to spur renewable energy

Chinas top legislature has turned its attention to the creation of specific plans for the generation of more renewable energy, such as nuclear, wind and solar power. A draft amendment to the renewable energy law was submitted for first reading to the Standing Committee of the National Peoples Congress (NPC), in a bid to remove the power transmission bottleneck that hinders industrial development. The draft requires related ministries to map out definite plans for meeting the nations long- and medium-term renewable energy targets, based on the overall national energy strategy and available technologies.

Chinas power grid development plan is falling behind that of the renewable energy, becoming a major block for reaching the countrys renewable energy target, said Mr. Wang Guangtao, Director of NPCs Environment and Resource Protection Committee. For instance, areas rich in wind power resources are concentrated in the remote northwest, northeast and southeast, where the power transmission network is poorly constructed, he said. More than 20 per cent of the countrys wind power machines did not generate any electricity last year because the equipment was not yet connected to the grid, according to officials of the China Wind Energy Association. The draft law hence stipulates the setting of a nationwide annual purchase quota for renewable energy sources to protect the interests of renewable energy enterprises.


Solar Energy Engineering: Processes and Systems

Solar Energy Engineering: Processes and Systems covers all areas of solar energy engineering. All subjects are presented from the fundamental level to the highest level of current research. The book includes topics such as energy-related environmental problems, solar collectors, solar space heating and cooling, solar water heating, industrial process heat, solar desalination, photovoltaics, solar thermal power systems and modelling of solar systems including the use of artificial intelligence systems in solar energy systems modelling and performance prediction.

Contact: Customer Service Department, Elsevier B.V., 3 Killiney Road #08-01, Winsland House, Singapore 239519. Tel: +65 6349 0222; Fax: +65 6733 1510; E-mail:

Indian Wind Energy Outlook 2009

Indian Wind Energy Outlook 2009 examines the wind power potential in India up to the year 2030. The study found that the technology, re-powering, untapped off-shore potential and furthering wind resource assessment could play a key part in the nations effort to provide energy to meet its ever-growing demand. It explains how wind energy can provide up to 24 per cent of the Indias power needs by 2030, while saving a total of 5.5 billion tonnes of carbon dioxide in that timeframe.

Contact: Indian Wind Turbine Manufacturers Association, Suite A2, OPG Towers, No. 74, Santhome High Road, Chennai 600 004, India. Tel: +91 (44) 2462 0227; Fax: +91 (44) 4210 0139; E-mail: secretary@

Solid Oxide Fuel Cells: Materials Properties and Performance

The book provides state-of-the-art information for the selection and development of materials for improved solid oxide fuel cells (SOFCs) performance. Summarizing progress in the field thus far, it describes current materials, future advances in materials, and significant unresolved technical problems. It shows how the performance of SOFCs can be improved through new materials and methods.

Contact: CRC Press, United Kingdom. Tel: +44 (1235) 400524; Fax: +44 (1235) 400525; E-mail: book.orders


Solar cells that could be printed or painted

Solar cells could soon be produced more cheaply using nanoparticle inks that allow them to be printed like newspaper or painted onto the sides of buildings or rooftops to absorb electricity-producing sunlight. Dr. Brian Korgel, a chemical engineer at University of Texas, Austin, the United States, is hoping to cut costs to one-tenth of their current price by using a new manufacturing process for solar cells gas-phase deposition in a vacuum chamber, which requires high temperatures and is relatively expensive.

The inks that Dr. Korgels team developed could be printed on a plastic substrate or stainless steel using a roll-to-roll printing process. The prospect of being able to paint the inks onto a rooftop or building is not far-fetched, as Dr. Korgel says: This is one step in the direction towards paintable solar cells.

Dr. Korgel uses the light-absorbing nanomaterials, as their microscopic size permits for new physical properties that can help enable higher-efficiency devices. Dr. Korgels team uses copper-indium-gallium selenide (CIGS), which is cheaper as well as environmentally friendly. As CIGS is a direct band gap semiconductor, much less material is required to make a solar cell, Dr. Korgel says. His team has developed solar-cell prototypes with efficiencies at one per cent; however, they need to be about 10 per cent. Dr. Korgel said that the semi-transparent inks could help realize the prospect of having windows that double as solar cells. Contact: Dr. Brian Korgel, Chemical Engineering Department, Cockrell School of Engineering, 1 University Station C0400, Austin, Texas, TX 78712, United States. Tel: +1 (512) 471 56 33; E-mail: korgel@mail.

Nanospears raise solar cell efficiency

Researchers at the Missouri University of Science and Technology, the United States, have devised a method to make more efficient solar cells. Prof. Jay Switzer and his colleagues have developed a simple, inexpensive process for growing and precisely aligning nano-size, spear-shaped zinc oxide (ZnO) crystals on the surface of single-crystal silicon. The scientists likened the process to growing rock candy crystals on a string. Prof. Switzers team grows ZnO nanospears on the single-crystal silicon placed in an alkaline solution saturated with zinc ions. The process yields tilted, single-crystal, spear-shaped rods growing out of the silicon surface, like tiny spikes. The spears are about 100-200 nm in diameter and about 1 m in length.

ZnO is a semiconductor that has some unusual physical properties, Prof. Switzer informs. The material both absorbs and emits light, and so it could be used in solar cells to absorb sunshine as well as in lasers or solid-state lighting as an emitter of light. Silicon also is a semiconductor, but it absorbs light at a different part of the spectrum than zinc oxide. By growing ZnO on top of the silicon, the spectrum from which a solar cell could draw light is widened, Prof. Switzer says.

Previous attempts to align the two materials epitaxially or perfectly one on top of the other have been unsuccessful until now. By tilting the nanospears 51, Prof. Switzer and his team have reduced the mismatch from 40 per cent to just 0.2 per cent, a near-perfect alignment. Aligning ZnO and silicon epitaxially is important for higher efficiency.

Carbon nanotubes for efficient solar cells

Researchers at Cornell University, the United States, have used a carbon nanotube instead of traditional silicon to create the basic elements of a solar cell that hopefully would lead to much more efficient ways of converting light to electricity than now used in calculators and on rooftops. The researchers led by Dr. Paul McEuen and Dr. Jiwoong Park fabricated, tested and measured a simple solar cell called a photodiode. Their device, formed from a carbon nanotube, converts light to electricity in an extremely efficient process that multiplies the amount of electrical current that flows.

The researchers employed a single-walled carbon nanotube, essentially a rolled-up sheet of graphene, to create their solar cell. The nanotube, about the size of a DNA molecule, was wired between two electrical contacts and close to two electrical gates, one negatively and the other positively charged. Their work was inspired in part by previous work in which scientists created a diode using a single-walled nanotube. The Cornell team wanted to see what would happen if they built something similar and shined light on it.

Shining lasers of different colours onto different areas of the nanotube, they found that higher levels of photon energy had a multiplying effect on how much electrical current was produced. Further study revealed that the narrow, cylindrical structure of the nanotube caused the electrons to be neatly squeezed through one by one. The electrons moving through the nanotube became excited and produced new electrons that continued to flow: a nearly ideal photovoltaic cell.

Photovoltaic metallization for thin film technologies

DuPont Microcircuit Materials has introduced Solamet PV412 photovoltaic (PV) metallization paste, the latest in a line of silver conductor materials specifically developed for thin film PV technologies. DuPont collaborated with Ascent Solar Technologies Inc. (ASTI), a developer of flexible thin-film solar modules, as it developed Solamet PV412.

DuPont Solamet PV412 metallization paste is designed for use on PV devices wherein a transparent conductive oxide is used. It is ideal for use with copper-indium-gallium selenide (CIGS), amorphous silicon (a-Si) on flexible substrates, and heterojunction with intrinsic thin layers (HIT) PV cells, and is also suitable for any PV application that requires a low temperature curing conductor. Key features include fine line printing down to 80 m resolution, long screen residence time for robust printer operation, low contact and gridline resistances, high adhesion to indium-tin oxide, and strong compatibility with most of the transparent conductive oxides. Thin film PV is said to be the fastest-growing segment of the solar module industry, primarily because of its potential to reduce the cost of producing solar-derived energy.

Solar car with triple-junction compound solar cells

Tokai University, Japan, has developed a solar car fitted with triple-junction compound solar cells. The cells use indium-gallium phosphide (InGaP), indium-gallium arsenide (InGaAs) and germanium (Ge) for top, middle and bottom cells, respectively. Made by Sharp, the cells are originally space cells and have a cell conversion efficiency of 30 per cent.

Totally, 2,176 cells each measuring 77 39 mm were installed on the top surface of the vehicle. The cells are sealed with a film so that they can be mounted on a curved surface and the total weight of the solar car can be reduced. The total area of the solar cells is 6 m2, and the total output is 1.8 kW. The electricity generated drives a brushless DC direct drive motor. A lithium ion secondary battery (5.6 kWh) is employed to store electricity.

A new record for solar cell efficiency

An international team of scientists has set a new solar cell record when their five-cell array achieved an efficiency of 43 per cent beating the previous record by 0.3 per cent. Prof. Martin Green and his colleague Dr. Anita Ho-Baillie from the University of New South Wales (UNSW), Australia, led the team that developed a silicon cell optimized to capture light at the red and near-infrared parts of the spectrum. That cell was able to convert up to 46 per cent of light into electricity. Together with four other cells, each optimized for different regions of the solar spectrum, the five-cell combination was able to convert 43 per cent of the sunlight into electricity. Besides the UNSW PERL ZT-1-4E cell, the unit consisted of cells from Emcore as well as the National Renewable Energy Laboratory (NREL) in the United States.

Thin films show promise for solar applications

In Israel, researchers at Ben-Gurion University (BGU), Negev, have developed thin films that exhibit carrier multiplication. This development is of importance for future solar cells. The films were synthesized by Prof. Yuval Golan and his doctoral student Ms. Anna Osherov, with assistance from the Ilse Katz Institute for Nanoscale Science and Technology.

One of the major factors limiting solar-cell efficiency is that incident photons create only one electron-hole pair, irrespective of the photon energy. Any excess photon energy is lost as heat. Carrier multiplication (CM) has been thought to be enhanced greatly in nanocrystalline materials such as quantum dots, owing to their discrete energy levels and increased Coulomb interactions. The BGU team demonstrated that, contrary to this expectation, for a given photon energy, CM takes place more efficiently in bulk lead sulphide and lead selenide films than in nanocrystalline films of the same materials.

Notably, the films were made using chemical solution deposition, an attractive, inexpensive technique for which the Prof. Golans group has received considerable recognition. The research work was carried out as part of an international collaboration with counterparts in France and the Netherlands.


In-stream tidal turbine

Nova Scotia Power of Canada and its technology partner OpenHydro of Ireland have unveiled a 1 MW tidal turbine, which they have deployed in the Bay of Fundy, Canada, as part of Nova Scotias tidal power test facility. The Open-Centre Turbine was manufactured by OpenHydro. The turbine rests directly on the ocean floor using a sub-sea gravity base, fabricated in Dartmouth by Cherubini Metal Works.

The 10 m turbine will be under testing for up to two years. Operational data will be collected and shared by Nova Scotia Power and OpenHydro to determine the environmental performance and feasibility of tidal power in the Bay of Fundy. The testing will focus on the robustness of the turbine in the harsh environment, any environmental impacts of the turbine, and the energy production capability of the technology.

Sea Snake leads marine power race

A Sea Snake is being prepared to harness the waves of Britains northern islands to generate electric power. Scheduled for installation next spring at the European Marine Energy Centre (EMEC) in Orkney, northern Scotland, the train-sized wave power generator is being built for German power company E.ON. The Sea Snake system, known as P2, is being developed by Pelamis Wave Power Ltd., Scotland, the United Kingdom. E.ON reportedly examined more than 100 devices since 2001 before opting for Sea Snake for its first ocean project, a three-year testing. A single Sea Snake has a capacity of 750 kW. By around 2015, Pelamis hopes that each unit would have capacity of 20 MW, or enough to power about 30,000 homes.

Innovative ocean wave energy device

Green Ocean Energy Ltd., the United Kingdom, has produced an innovative device called Ocean Treader, which moves up and down on the ocean surface, generating power. It is estimated that each machine will produce around 500 kW of electricity. This power can be transported to the shore with the aid of underwater cables, to electrify about 125 homes. The company is currently producing a full size machine for offshore testing.

Ocean Treader is a floating device, and will be deployed at 1.5-3 km offshore in ocean wave systems that will not pose any obstruction on the shoreline. The theory has been put to test in wave tank. Green Ocean Energy has also developed another device, the Wave Treader, which grew out of the work with Ocean Treader. Wave Treader uses arms and sponsons, and is mounted on the base of a static offshore structure, which could be a wind turbine or tidal turbine. By sharing the high infrastructure costs with another device, such as the foundation costs and cabling costs, the economics of both devices are enhanced and the energy yield for a given sea area greatly improved.

Big wave energy project on the anvil

Investigations are currently under way to determine the viability of constructing a 770 MW ocean wave energy project in the Western Cape, South Africa. The project is being developed by Wave Energy Generation, a company based in Darling, South Africa. The country has a vast wave energy resource available for energy conversion with an annual average deep-sea wave power of about 42 kW/m, dropping to 39 kW/m near shore. Mr. Hermann Oelsner of Wave Energy Generation says the project uses the Stellenbosch Wave Energy Converter (SWEC) designed by Stellenbosch University and further developed by Ocean Energy Research Group.

SWEC consists of two submerged collectors (arms) in a V-formation, coupled to an air turbine and generator mounted above the water level in a tower at the apex of the V. Each arm consists of 12 oscillating water column chambers, where water level oscillations displace air through inlet and outlet valves to low- and high- pressure manifold systems connected to the air turbine in the tower.

This is a near-shore system fixed on the seabed, which eliminates the need for complex mooring systems. A number of submerged V-shaped collector arms along 40 km of the Western Cape coast can generate 770 MW. Each V-shape will have the capability of generating 5 MW.


Worlds first semi-direct drive wind turbine

In China, Shenzhen Fengfa Technology has rolled out the worlds first semi-direct drive wind turbine at the megawatt level. Many years of research and several proprietary innovations, including switched reluctance motor, by researchers at Fengfa Technology have gone into developing the new wind turbine. The new wind turbine weighs 24 tonnes, or half the weight of other similar turbines.

The researchers worked out an array of technical innovations, allowing the turbine to operate in a wider wind range. As a semi-direct drive model, the new turbine enjoys enhanced power generation efficiency (exceeding 92 per cent) and transmission efficiency. It produces direct current, making a conversion process unnecessary. Improved stability and duration allow the wind turbine to work for more than 3,000 hours a year, directly reducing the unit cost for producing electricity. The new system has other advantageous technical features, including super overloading capacity, enhanced safety brought by the strong vane made of composite materials, and suspension arm structures. It also features greatly reduced total cost, construction cost and maintenance cost.

Japan field-tests floating wind turbine

In Japan, the Kyoto University and three manufacturers Toda Corp., Sasebo Heavy Industries Co. and Nippon Hume Corp. announced that they have jointly developed the worlds first hybrid spar-type platform consisting of steel and pre-stressed concrete for floating wind turbines. They field-tested the platform with a prototype floating wind turbine, which is 12.5 m tall (5.5 m are above the surface), in Sasebo, Nagasaki Prefecture.

The idea behind the floating turbine is to avoid the high costs involved in fixing wind turbines to the seabed. One area where the turbines could be put to good use, according to the scientists, is out in the ocean, simply because of the strong winds to be found there. The researchers are hoping to achieve 2,000 kW for the finished version. It will be ten times larger, and the technology is supposed to be commercially available by 2012 or 2013.

New offshore wind turbine model

Denmark-based Vestas has developed a new turbine specifically for the offshore wind industry. The new model, V112-3.0 MW Offshore, is specifically designed to handle very rough conditions at sea and still maintain optimal energy generation and reliability. The turbine is capable of harnessing more wind energy than any other offshore turbine in the 3.0 MW class, according to Vestas.

The unit can operate at a greater efficiency using rotor-to-generator technology, as well as work under all conditions of weather including wind speeds up to 9.5 m/s.The new nacelle design on the V112-3.0 MW Offshore allows the power converter to be integrated into the nacelle floor, which provides more working space and makes it easier to service the components.

With the groundbreaking 54.6 m blades, the V112-3.0 MW makes optimum use of aerodynamics. Although these blades have the same width as Vestas 44 m blades, they sweep an area that is 55 per cent greater to deliver much higher output. The turbine is claimed to come with significant innovations in areas such as blade and nacelle design, load-optimized operation and cooling systems. It is designed around a large number of standard components that several suppliers can provide.

A novel single-blade wind turbine

After years of research and development, the Spanish engineering firm Aplicaciones de Energas Sustitutivas S.L. (ADES) has entered the wind turbine manufacturing sector, launching its innovative pendular wind turbine with adjusted motor torque. The ADES wind turbine includes three passive mechanical systems: a swivelling single-blade rotor, a pendulum power train and a self-steering nacelle. The design compensates, accumulates and reinstates wind speed variations, preventing them from affecting the evenness of generator rotation and subsequently diminishing structural overload and power peaks caused by wind gusts.

The present models have power outputs of 100 and 250 kW, while ADES plans on releasing a 1.3 MW turbine of similar design in 2012. According to ADES, the turbine can be utilized in new plants, in limited and off-grid areas, in conjunction with other forms of energy generation, and in the re-powering of wind farms using the existing infrastructure. Contact: ADES Aplicaciones de Energas Sustitutivas S.L., C/ La Sabina N13, 50171 Poligono Malpica-Alfinden, Zaragoza, Spain. Tel: +34 (976) 571 193; Fax: +34 (976) 571 155; E-mail: ades@

Wind turbine with a 120 m rotor diameter

Siemens, based in Germany, has released a 3.6 MW wind turbine featuring a 120 m rotor diameter. The SWT-3.6-120 turbine is based on the proven technology of the SWT-3.6-107 claimed to be the worlds most popular offshore wind turbine. The new machine will be fitted with 58.5 m long rotor blades. The turbine has a swept area of 11,300 sq. m, which is equivalent to almost two soccer fields. The SWT-3.6-120 extends the performance of the proven Siemens 3.6 MW turbine type, a popular offshore turbine type in the multi-megawatt class. Siemens has installed 100 of its 3.6 MW wind turbines and has another 700 turbines on order.

Saw teeth make wind turbines quieter

It is possible to halve the sound wind turbines make without any energy loss by placing saw teeth on the blades of wind turbines. The saw teeth are designed in the Netherlands by Mr. Stefan Oerlemans of the University of Twente and the National Aerospace Laboratory. Mr. Oerlemans first studied the sounds wind turbines made and then used this knowledge to design the saw teeth and halve the noise. Rotating wind turbine blades make a characteristic whooshing sound. As this noise often annoys those living nearby, wind turbines are not always allowed to operate at full capacity and plans for new wind turbines are often rejected. Mr. Oerlemans, a Ph.D. candidate at the University of Twente and an employee of the National Aerospace Laboratory, hence created a solution to halve the noise without loss of energy.

To diminish the sound of wind turbines, Mr. Oerlemans investigated what caused the noise and how it was produced. For this, he utilized an acoustic antenna system that employs a large number of microphones mounted on flat surfaces. By measuring and comparing the separate times that a sound takes to reach the different microphones, the precise origin of a sound can be calculated. These calculations showed that the wind turbines noise is mostly created by airflow through the blades, and the actual sounds caused by the mechanical components of wind turbineare minimal. Specifically it also revealed that the majority of the noise came from the outer parts of the blades while the blades moved downwards, due to turbulent eddies around the blades. However, Mr. Oerlemans found that when saw teeth were placed on the blades rear edges, the sound was halved.

Scalable wind turbine

Mr. Doug Selsam, an entrepreneur from California, the United States, has invented a new wind turbine design that is smaller, scalable and could potentially fit on the roofs of homes like a long satellite antenna. Rather than one giant rotor with 50 feet long blades, Mr. Selsams Sky Serpent design uses several small rotors attached to a single shaft. By placing the rotors in precise positions and angles, each rotor can harvest its own wind. The entire turbine is hooked up to a generator, which produces about the same amount of power as a turbine that uses ten times as much blade material, Mr. Selsam says.

The shaft that holds the rotors can vary in length, and use any number and size of rotors, depending on its application. The rotors can even be mounted on poles light enough to be hand-held or attached to the roof of a house. Using ten 18 inch rotors, for example, one Sky Serpent can generate between 100 W and 400 W, depending on wind speed. Mr. Selsam has built a seven-rotor turbine that can generate 3,000 W, and a dual-rotor turbine that generates 2,000 W. Another 3,000 W prototype uses 25 rotors. In another concept, the wind turbine can float near the surface of water, its shaft and propellers extended in the air over the open ocean.


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