Is Seaweed the Future of Biofuel?

Engineerblogger
March 6, 2012

Credit: TAU

As scientists continue the hunt for energy sources that are safer, cleaner alternatives to fossil fuel, an ever-increasing amount of valuable farmland is being used to produce bioethanol, a source of transportation fuel. And while land-bound sources are renewable, economists and ecologists fear that diverting crops to produce fuel will limit food resources and drive up costs.

Now, Prof. Avigdor Abelson of Tel Aviv University's Department of Zoology and the new Renewable Energy Center, and his colleagues Dr. Alvaro Israel of the Israel Oceanography Institute, Prof. Aharon Gedanken of Bar-Ilan University, Dr. Ariel Kushmaro of Ben-Gurion University, and their Ph.D. student Leor Korzen, have gone to the seas in the quest for a renewable energy source that doesn't endanger natural habitats, biodiversity, or human food sources.He says that marine macroalgae — common seaweed — can be grown more quickly than land-based crops and harvested as fuel without sacrificing usable land. It's a promising source of bioethanol that has remained virtually unexplored until now.

The researchers are now developing methods for growing and harvesting seaweed as a source of renewable energy. Not only can the macroalgae be grown unobtrusively along coastlines, Prof. Abelson notes, they can also clear the water of excessive nutrients — caused by human waste or aquaculture — which disturb the marine environment.

A man-made "ecosystem"

While biomasses grown on land have the potential to inflict damage on the environment, the researchers believe that producing biofuel from seaweed-based sources could even solve problems that already exist within the marine environment. Many coastal regions, including the Red Sea in the south of Israel, have suffered from eutrophication — pollution caused by human waste and fish farming, which leads to excessive amounts of nutrients and detrimental algae, ultimately harming endangered coral reefs.

Encouraging the growth of seaweed for eventual conversion into biofuel could solve these environmental problems. The system that the researchers are developing, called the "Combined Aquaculture Multi-Use Systems" (CAMUS), takes into account the realities of the marine environment and human activity in it. Ultimately, all of these factors function together to create a synthetic "man-made ecosystem," explains Prof. Abelson.

Man-made fish feeders, which produce pollution in the form of excess nutrients and are generally considered harmful to the marine environment, would become a positive link in this chain. Used alongside an increased population of filter feeders such as oysters, which suck in extra particles and convert them food that the microalgae can consume, this "pollution" could be used to sustain a much greater yield of seaweed, which is needed for seaweed to become a sustainable source of fuel.

"By employing multiple species, CAMUS can turn waste into productive resources such as biofuel, at the same time reducing pollution's impact on the local ecosystem," he says.

Turning waste into opportunity

The researchers are now working to increase the carbohydrate and sugar contents of the seaweed for efficient fermentation into bioethanol, and they believe that macroalgae will be a major source for biofuel in the future. The CAMUS system could turn seaweed into a sustainable bioethanol source that is productive, efficient, and cost-effective.

Source: Tel Aviv University

National Grid, Advanced Plasma Power and Progressive Energy announce new project to transform waste into Bio Substitute Natural Gas

Engineerblogger
March 1, 2012

Project will deliver an end-to-end process for converting waste to Bio-SNG, using Gasplasma® technology

The first pilot project that demonstrates the use of waste to produce bio-substitute natural gas (Bio-SNG) has today been announced by National Grid, Advanced Plasma Power and Progressive Energy.

The project, which uses waste as a feedstock to produce Bio-SNG, will be based at the Advanced Plasma Power Gasplasma® facility in Swindon, UK. It will demonstrate the technical feasibility and commercial viability of the waste to Bio-SNG process. The three partners will work together to design, install and test the operation of a demonstration plant.

The plant will take the waste-derived and energy rich synthesis gas from the existing Gasplasma® process, and convert it to meet the specification for injecting it into the gas network. Bio-SNG could play a crucial role in the decarbonisation of heating and help reach the UK's binding carbon reduction targets. As part of its work on future energy scenarios, National Grid has forecast that renewable gas could be a vital part of the energy mix in the coming decades.

APP’s process converts commercial waste into high-quality syngas, which can then be converted into methane. Credit: APP

Marcus Stewart, Future Distribution Networks Manager at National Grid said, “This project is a great opportunity to look at the potential of Bio-SNG from both a technical and commercial perspective. The project underlines our commitment to seeking economic and innovative ways to decarbonise energy, while making the best use of the existing network. ”

It is estimated that renewable gas, of which Bio-SNG may be a major source, could account for as much as one fifth of the UK’s heat requirement by 2050.

Rolf Stein, Chief Executive, Advanced Plasma Power said, “The development and implementation of a process to derive Bio-SNG from waste using our unique Gasplasma® process has significant global implications for sustainable waste management and low carbon energy solutions. We look forward to demonstrating the process on our plant in Swindon.”

Phillip Cozens, Progressive Energy said, “"This project is a significant step towards greater resource efficiency in our economy, exploiting the capacity of the existing gas infrastructure and demonstrating the potential to deliver renewable heat at a cost that is competitive with other renewable heat options. The partnership has put together a strong project execution team to deliver a practical demonstration of Bio-SNG production from residual wastes. Successful demonstration would provide a blue-print for general deployment.”

National Grid:
National Grid is an electricity and gas company that connects consumers to energy sources through its networks. The company is at the heart of one of the greatest challenges facing our society - to create new, sustainable energy solutions for the future and developing an energy system that underpins economic prosperity in the 21st century. National Grid holds a vital position at the centre of the energy system and we ‘join everything up’. In Britain, we run the gas and electricity systems that our society is built on, delivering gas and electricity across the country. In the North Eastern US, we connect more than seven million gas and electric customers to vital energy sources, essential for our modern lifestyles.

Advanced Plasma Power:
Advanced Plasma Power Limited (APP) is a leading technology provider for advanced waste to energy plants, showcasing its globally patented Gasplasma® technology. After the removal of valuable recyclates, the Gasplasma® process treats a wide range of feedstocks including residual municipal solid waste and commercial/industrial waste converting it all into two high value outputs: a clean, high quality, energy rich synthesis gas (syngas) and a solid, vitrified product each with multiple applications. The syngas can be used to generate electricity directly in gas engines, gas turbines and fuel cells or it can be converted to Bio-SNG or liquid fuels. The solid product, Plasmarok®, has a variety of valuable end uses, for instance, as a building material. The process is clean, modular and scalable, delivering high efficiency and maximising landfill diversion whilst minimising visual and environmental impact.

Progressive Energy:
Progressive Energy is a market leading project development company, specialising in clean energy and carbon abatement in the energy sector through the deployment of carbon capture and storage and renewable energy technologies. 

Source: National Grid

Fuel from market waste

Engineerblogger
Feb 1, 2012

This plant in Stuttgart makes biogas out of waste from wholesale markets.  © Fraunhofer IGB

Mushy tomatoes, brown bananas and overripe cherries – to date, waste from wholesale markets has ended up on the compost heap at best. In future it will be put to better use: Researchers have developed a new facility that ferments this waste to make methane, which can be used to power vehicles.

Drivers who fill up with natural gas instead of gasoline or diesel spend less on fuel and are more environmentally friendly. Natural gas is kinder on the wallet, and the exhaust emissions it produces contain less carbon dioxide and almost no soot particles. As a result, more and more motorists are converting their gasoline engines to run on natural gas. But just like oil, natural gas is also a fossil fuel, and reserves are limited. Researchers at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart have now developed an alternative: They have found a way to obtain this fuel not from the Earth’s precious reserves of raw materials, but from fruit and vegetable waste generated by wholesale markets, university cafeterias and canteens. Fermenting this food waste produces methane, also known as biogas, which can be compressed into high-pressure cylinders and used as fuel.

In early 2012, the researchers will begin operating a pilot plant adjacent to Stuttgart’s wholesale market. The facility uses various microorganisms to generate sought-after methane from the food waste in a two-stage digestion process that lasts just a few days. “The waste contains a lot of water and has a very low lignocellulose content, so it’s highly suitable for rapid fermentation,” says Dr.-Ing. Ursula Schließmann, head of department at the IGB. But it still presents a challenge, because its precise composition varies every day. Sometimes it has a high proportion of citrus fruits, while other times there are more cherries, plums and lettuce. On days with a higher citrus fruit content, the researchers have to adjust the pH value through substrate management, because these fruits are very acidic. “We hold the waste in several storage tanks, where a number of parameters are automatically calculated – including the pH value. The specially designed management system determines exactly how many liters of waste from which containers should be mixed together and fed to the microorganisms,” explains Schließmann. It is vital that a correct balance be maintained in the plant at all times, because the various microorganisms require constant environmental conditions to do their job.

Another advantage of the new plant lies in the fact that absolutely everything it generates can be utilized; the biogas, the liquid filtrate, and even the sludgy residue that cannot be broken down any further. A second sub-project in Reutlingen comes into its own here, involving the cultivation of algae. When the algae in question are provided with an adequate culture medium, as well as carbon dioxide and sunlight, they produce oil in their cells that can be used to power diesel engines. The filtrate water from the biogas plant in Stuttgart contains sufficient nitrogen and phosphorus to be used as a culture medium for these algae, and the reactor facility also provides the researchers with the carbon dioxide that the algae need in order to grow; while the desired methane makes up around two thirds of the biogas produced there, some 30 percent of it is carbon dioxide. With these products put to good use, all that is left of the original market waste is the sludgy fermentation residue, which is itself converted into methane by colleagues at the Paul Scherrer Institute in Switzerland and at the Karlsruhe Institute of Technology.

Others involved in this network project, which goes by the name of ETAMAX, include energy company EnBW Energie Baden-Württemberg and Daimler AG. The former uses membranes to process the biogas generated in the market-place plant, while the latter supplies a number of experimental vehicles designed to run on natural gas. The five-year project is funded to the tune of six million euros by the German Federal Ministry of Education and Research (BMBF). If all the different components mesh together as intended, it is possible that similar plants could in future spring up wherever large quantities of organic waste are to be found. Other project partners are the Fraunhofer Institute for Process Engineering and Packaging IVV in Freising, FairEnergie GmbH, Netzsch Mohnopumpen GmbH, Stulz Wasser- und Prozesstechnik GmbH, Subitec GmbH und the town Stuttgart.

Source: Fraunhofer-Gesellschaft

New uses for diesel by-products

Engineerblogger
Jan 27, 2012

A new catalytic process discovered by the Cardiff Catalysis Institute could unleash a range of useful new by-products from diesel fuel production.

More sustainable production of sulphur-free diesel from natural gas and biomass is increasing. However the by-products, hydrocarbons like decane and other low value alkanes have little practical use.

Now a discovery by the Institute, part of the School of Chemistry, has found a potential route for upgrading these by-products into more useful chemicals.

In the past, synthetic reactions starting from alkanes like decane have been fraught with difficulty. They tend either to over-dehydrogenate or to combust, depending on whether oxygen is present in the reaction. Now a Cardiff Catalysis Institute team has reported the use of a mixed-metal catalyst to convert decane to a range of oxygenated aromatics.

The breakthrough, published in Nature Chemistry, came when the team fed a gas mixture of decane and air through an iron molybdate catalyst. At higher temperatures, the reaction formed water and decene, which is used in the production of detergents. At lower temperatures, however, the reaction took a different route to create oxygenated aromatic molecules. These included phthalic anhydride, used in the dyeing industry, and coumarin which helps in the production of anti-coagulant drugs.

Professor Stan Golunski, a member of the Institute team behind the discovery said: "This discovery breaks new ground as it implies the involvement of oxygen that has not yet made the full transition from its molecular form to its ionic form. This overturns a widely-held view that this type of oxygen was too reactive to form anything other than carbon monoxide and carbon dioxide in reactions with hydrocarbons."

"While the increased production of sulphur-free diesel has been a positive move, the glut of low value by-products will become a problem. We hope our new process will lead to less waste and the creation of more useful chemicals for a range of industries."

Source: Cardiff University

Waste not: Cooking oil great energy source

Engineerblogger
Jan 27, 2012

At one time, Richard Varano, the proprietor of Billy’s Chowder House in Wells, ME, contracted with a local waste disposal firm to haul away his used cooking oil, paying $65 a month for the service.

These days, Varano puts the oil into a device called the Vegawatt, which burns the waste product and sends the heat back into the restaurant to produce hot water for use in the dishwashers and other kitchen facilities. “I’m saving the $65 in waste removal fees, and on top of that about $500 each month in energy costs,” says Varano.

And he is helping the environment. That’s because vegetable oil, a completely renewable biofuel, burns more cleanly than fossil fuel while producing no adverse impact on global warming and supporting worldwide initiatives to reduce carbon-based energy generation.

Beginnings in Transportation

The use of vegetable oil as a fuel dates back to 1898, when the German inventor Rudolph Diesel developed a new type of internal combustion engine that used oil derived from peanuts. Vegetable oil would continue to be used in diesel engines in the early years following the turn of the century.

A hundred years later, vegetable oil is attracting a renewed interest, with the focus shifting from transportation to stationary power generation. According to the University of Minnesota, the U.S. produces roughly 2.7 billion pounds of yellow and brown grease a year, the byproducts of restaurant kitchens and various industrial processes. For proponents of alternative energy, this grease is a precious commodity, an available fuel source that can run a diesel engine to produce heat and electrical generation.

Developmental programs have been underway to optimize processed waste vegetable oil and test its efficiency and practicality in power generation. The Biofuels Power Corp. in Spring, TX, recently announced plans to come online with a 9-megawatt generator that runs on refined waste vegetable oils. The plan is for the generator to be connected to a gas turbine to provide grid power to homes and business in the Houston area.
But it is not large-scale municipal power generation that is creating a market for biodiesel. Plant-derived fuel sources, energy experts believe, can contribute only about 1-2% of the energy needs in the United States.

 

Image courtesy of Vegawatt.

Market Niche

Where vegetable oil is finding a market is in distributed generation applications, in which a power system is configured to provide supplemental heat or electricity to a single home or business. Restaurants, with their continuous supply of waste oil from food preparation, are an ideal market, according to James Peret, founder and chief executive officer of Owl Power Company, maker of the Vegawatt systems.

Richard Varano purchased a 12-kW Vegawatt from Owl. Each year, the chowder house produces about 5,000 gallons of used vegetable oil from its kitchen deep fryers. Once the cooking life of the oil is depleted, Varano’s staff deposits the waste product into storage tanks, from where it is pumped into the Vegawatt. There, a diesel engine consumes the vegetable oil to produce hot water and electricity.

Varano estimates that the system provides about 25% of the restaurant’s electricity and 80% of the hot water.

Owl, located in Boylston, MA, has sold 21 systems since the company started in 2007. Larry Fogarty, the owner of Fogarty’s bakery and restaurant in South Berwick, ME, purchased a 5-kW system from Owl in July 2011 to provide electricity and hot water. “A friend and engineer from the local area, who used vegetable oil in automobile engines, encouraged me to consider the generator,” says Fogarty. “The system has performed well and I’m thinking about expanding its capabilities.”

At $32,000, the unit was a significant business expense; however, Fogarty received a grant from the state of Maine. Peret estimates that a restaurant with an installed Vegawatt can realize a 25-50% reduction in energy costs each year, which can justify the up-front cost of the system and help a client recoup the investment.

The increasing interest in using vegetable oil as fuel, coupled with worldwide initiatives to reduce carbon dioxide emissions, have spawned a global industry. Large and small companies from the U.S. to Spain and from Germany to China design and manufacture vegetable oil generators and peripheral equipment like diesel conversion kits and oil filtration systems. Organic Mechanic distributes an oil press along with a line of generators.

“Farmers can press oil from avocado, soybean, sunflower, or other types of plants and use it to fuel tractors and other farm equipment,” says Christopher Kindig, founder of the six-year old Organic Mechanic.

Paper at 2011 ASME Congress

The primary obstacle to a more widespread use of vegetable oil is availability. Three researchers at the University of Roma in Italy have carried out a comprehensive analysis of power generation using palm oil in a marine diesel, assessing a range of economic and technology factors. Their system performed acceptably in the areas of emissions and heat value. The problem was the lack of biofuel availability, which forced the researchers to import other types of fuel to operate the system, driving up costs.

“Our results show how the fuel cost can decisively affect the feasibility of the power plant,” explained Roberto Capata, a member of the research team, who lectured at the 2011 ASME International Mechanical Engineering Congress and Exposition in Denver, CO. “This highlights the special attention to be paid in searching for suppliers that are able to ensure affordable and stable oil purchase conditions over a long period.”

In the meantime, vegetable oil enjoys success in the retail power market, where restaurant owners, farmers, and other users are contributing to a clean environment—and saving money in the process.

Source:  American Society of Mechanical Engineers (ASME)

Photosynthesis Fuel Company Gets a Large Investment

Technology Review
Jan 19, 2012

Green tea: Joule Energy's SolarConverter turns carbon dioxide and sunlight into ethanol fuel at a pilot plant in Leander, Texas. Credit: Joule Unlimited

Joule Unlimited, a startup based in Bedford, Massachusetts, has received $70 million to commercialize technology that uses microörganisms to turn sunlight and carbon dioxide into liquid fuel.

The company claims that its genetically engineered bacteria will eventually be able to produce ethanol for as little as $1.23 a gallon or diesel fuel for $1.19 a gallon, less than half the current cost of both fossil fuels and existing biofuels.

The new funding comes from undisclosed investors and will allow the company to expand from an existing pilot plant to its first small-scale production facility, in Hobbs, New Mexico.

Joule Unlimited has designed a device it calls the SolarConverter, in which thin, clear panels circulate brackish water and a nitrogen-based growth medium bubbling with carbon dioxide. Inside the converter, the engineered microörganisms use energy from the sun to convert the water and gas into ethanol or paraffinic hydrocarbons, the primary component of diesel fuel.

Enclosed solar conversion systems are expensive and difficult to manage. But Joule Unlimited's technology could prove practical because its microbes produce fuel continuously and efficiently.

The company, formerly known as Joule Biotechnologies, claimed in 2009 that its organisms could in theory produce as much as 20,000 gallons of ethanol on an acre of land in single year. Company officials now say their target is 25,000 gallons per acre, and that efficiencies they have already demonstrated take them 60 percent of the way to that goal.
To read more click here...

Want Cheap Biofuel? A Startup Makes It with Natural Gas

Technology Review
Jan 17, 2012

Fast fuel: Virent’s 100-liter-per-day pilot plant, shown here, produces fuel for Formula 1 race cars. Credit: Virent

Virent, a biofuels company based in Madison, Wisconsin, has developed a potentially inexpensive way to make gasoline and other valuable chemicals out of grass and wood chips. Its approach reduces costs by simplifying or eliminating expensive processing steps, and by using natural gas to increase the amount of fuel that can be made from a given amount of biomass.

In some ways, the process is similar to the one used to refine oil. Virent has demonstrated that it can use it to make gasoline, diesel, and jet fuel, and its 100-liter-per-day gasoline pilot plant makes fuel that's used in Formula 1 racing.

As with many other biofuels companies, Virent's first large-scale product may not be fuel at all. It recently announced a development agreement with Coca-Cola to produce a chemical that can be used to make plastic soda bottles, and is hoping to build a plant for this purpose in 2015.

The company's technology addresses one of the big challenges with making advanced biofuels. This is that making hydrocarbon fuels from grass requires breaking down the long cellulose molecules that make up the bulk of the raw material. Breaking the biomass down is expensive, and is normally done with enzymes that produce sugar, or using high temperatures and pressures to turn it into carbon monoxide and hydrogen gas. Virent's process produces intermediate-sized molecules known as oligomers that require less processing. Its core technology is a way to transform those oligomers into fuel.

Making hydrocarbons from biomass requires first removing the oxygen. Virent has also developed inorganic catalysts that remove most of the oxygen from the molecules it produces. It then uses a series of chemical reactions to remove the remaining oxygen and reconfigure the molecules to take on the properties needed to make in fuels like gasoline or chemicals for making plastic bottles.
To read more click here...

Algae for your fuel tank: New process for producing biodiesel from microalgae oil

Engineerblogger
Jan 13, 2012

Prof. Lercher with a scientist of his team - Photo: Battenberg/TUM

 The available amount of fossil fuels is limited and their combustion in vehicle motors increases atmospheric CO2 levels. The generation of fuels from biomass as an alternative is on the rise. In the journal Angewandte Chemie, Johannes A. Lercher and his team at the Technische Universitaet Muenchen have now introduced a new catalytic process that allows the effective conversion of biopetroleum from microalgae into diesel fuels.

Plant oils from sources such as soybean and rapeseed are promising starting materials for the production of biofuels. Microalgae are an interesting alternative to these conventional oil-containing crops. Microalgae are individual cells or short chains of cells from algae freely moving through water. They occur in nearly any pool of water and can readily be cultivated. “They have a number of advantages over oil-containing agricultural products,” explains Lercher. “They grow significantly faster than land-based biomass, have a high triglyceride content, and, unlike the terrestrial cultivation of oilseed plants, their use for fuel production does not compete with food production.”

Previously known methods for refining oil from microalgae suffer from various disadvantages. The resulting fuel either has too high an oxygen content and poor flow at low temperatures, or a sulfur-containing catalyst may contaminate the product. However, other catalysts are still not efficient enough. The Munich scientists now propose a new process, for which they have developed a novel catalyst: nickel on a porous support made of zeolite HBeta. They have used this to achieve the conversion of raw, untreated algae oil under mild conditions (260 °C, 40 bar hydrogen pressure). Says Lercher: “The products are diesel-range saturated hydrocarbons that are suitable for use as high-grade fuels for vehicles.”

The oil produced by the microalgae is mainly composed of neutral lipids, such as mono-, di-, and triglycerides with unsaturated C18 fatty acids as the primary component (88 %). After an eight-hour reaction, the researchers obtain 78 % liquid alkanes with octadecane (C18) as the primary component. The main gas-phase side products are propane and methane.

Analysis of the reaction mechanism shows that this is a cascade reaction. First the double bonds of the unsaturated fatty acid chains of the triglycerides are saturated by hydrogen. Then, the now saturated fatty acids take up hydrogen and are split from their glycerin component, which reacts to form propane. In the final step, the acid groups in the fatty acids are reduced stepwise to the corresponding alkane.

Source:   Technische Universitaet Muenchen 

Additional Information:

• Towards Quantitative Conversion of Microalgae Oil to Diesel-Range Alkanes with Bifunctional Catalysts, B. Peng, Y. Yao, C. Zhao und J.A. Lercher,  Angewandte Chemie, 2011 – Doi: 10.1002/ange.201106243

Renewable Energy: Clearing a Potential Road Block to Bisabolane

Engineerblogger
Jan 11, 2012

JBEI researchers determined the structure of the AgBIS enzyme and found it to consist of three helical domains, the first three-domain structure ever found in a synthase of sesquiterpenes. This discovery holds importance for advanced biofuels and other applications. Credit: Lawrence Berkeley National Laboratory

The recent discovery that bisabolane, a member of the terpene class of chemical compounds used in fragrances and flavorings, holds high promise as a biosynthetic alternative to D2 diesel fuel has generated keen interest in the green energy community and the trucking industry. Now a second team of researchers with the U.S Department of Energy (DOE)’s Joint BioEnergy Institute (JBEI) has determined the three-dimensional crystal structure of a protein that is key to boosting the microbial-based production of bisabolane as an advanced biofuel.

The JBEI research team, led by bioengineers Paul Adams and Jay Keasling, solved the protein crystal structure of an enzyme in the Grand fir (Abies grandis) that synthesizes bisabolene, the immediate terpene precursor to bisabolane. The performance of this enzyme – the Abies grandis α-bisabolene synthase (AgBIS) – when engineered into microbes, has resulted in a bottleneck that hampers the conversion by the microbes of simple sugars into bisabolene.

“Our high resolution structure of AgBIS should make it possible to design changes in the enzyme that will enable microbes to make bisabolene faster,” says Adams, a leading authority on x-ray crystallography. “It should also enable us to engineer out inhibition effects that slow throughput, and perhaps also engineer the enzyme to produce other kinds of fuels similar to bisabolane.”

Adams, who heads JBEI’s Technologies Division, is the corresponding author of a paper describing this work in the Cell Press journal Structure. The paper is titled “Structure of a Three-Domain Sesquiterpene Synthase: A Prospective Target for Advanced Biofuels Production.” Co-authoring it with Adams and Keasling were Ryan McAndrew, Pamela Peralta-Yahya, Andy DeGiovanni, Jose Pereira and Masood Hadi.

JBEI is one of three DOE Bioenergy Research Centers established by DOE’s Office of Science to advance the technology for the commercial production of advanced biofuels. It is a multi-institutional partnership led by the Lawrence Berkeley National Laboratory (Berkeley Lab) and headquartered in Emeryville, CA.

This past fall, JBEI researchers identified bisabolane as a potential new advanced biofuel that could replace D2 diesel, today’s standard fuel for diesel engines, with a clean, green, renewable alternative that’s produced in the United States. Using the tools of synthetic biology, the researchers engineered strains of bacteria and yeast to produce bisabolene from simple sugars, which was then hydrogenated into bisabolane. While showing much promise, the yields of bisabolene have to be improved for microbial-based production of bisabolane fuel to be commercially viable.

“The inefficient terpene synthase enzyme is one of the bottlenecks in the metabolic pathway used by the engineered microbes,” says Peralta-Yahya, a lead member of the earlier JBEI team as well as the current team. “Knowing the AgBIS crystal structure will guide us in engineering it for improved catalytic efficiency and stability, which should bring our bisabolene yields closer to economic competitiveness.”

Peralta-Yahya and her colleagues determined that the AgBIS enzyme consists of three helical domains, the first three-domain structure ever found in a synthase of sesquiterpenes – terpene compounds that contain 15 carbon atoms. The discovery of this unique structure holds importance on several fronts, as co-lead author of the Structure paper McAndrew explains.

“That we found the structure of AgBIS to be more similar to diterpene (20 carbon terpene compounds) synthases not only provides us with insight into the function of these less well characterized enzymes, it also provides us with clues to the evolutionary heritage as the archetypal three-domain terpenoid synthases became two-domain sesquiterpene synthases in plants. Furthering our knowledge of the structures and functions of terpenoid synthases may prove to have abundant practical applications aside from advanced biofuels because these enzymes produce a wide variety of specialized chemicals.”

Solving the three-dimensional crystal structure of AgBIS was made possible by the protein crystallography capabilities of Berkeley Lab’s Advanced Light Source (ALS), a DOE Office of Science national user facility for synchrotron radiation, and the first of the world’s third generation light sources. For this work, the JBEI team used three of the five protein crystallography beamlines operated by the Berkeley Center for Structural Biology (BCSB) – beamlines 8.2.1, 8.2.2, and 5.0.3.

“We needed to use multiple beamlines because we collected data on several crystals – the protein by itself, and the protein with different inhibitors/cofactors,” says Adams, who headed the BCSB from 2004 to 2011. “Also, the approach we used to solve the AgBIS structure required high flux tunable x-rays such as those provided at 8.2.1 and 8.2.2, which are superbend beamlines.”

This research was supported by the DOE Office of Science.

Source: Lawrence Berkeley National Laboratory

Powering insect cyborgs with an implantable biofuel cell

Engineerblogger
Jan 9, 2012

Researchers have developed a biofuel cell to enable the development of 'insect cyborgs' Image: Shutterstock

Research into developing insect cyborgs for use as first responders or super stealthy spies has been going on for a while now. Most research has focused on using batteries, tiny solar cells or piezoelectric generators to harvest kinetic energy from the movement of an insect's wings to power the electronics attached to the insects. Now a group of researchers at Case Western Reserve University have created a power supply that relies just on the insect's normal feeding.

Recognizing that using a real insect is much easier than starting from scratch to create a device that works like an insect, Case Western Reserve chemistry professor teamed up with graduate student Michelle Rasmussen, biology professor Roy E. Ritzmann, chemistry professor Irene Lee and biology research assistant Alan J. Pollack to develop an implantable biofuel cell to provide usable power for the various sensors, recording devices, or electronics used to control an insect cyborg.

To convert chemical energy harvested from the insect and turn it into electricity, the team used two enzymes in series to create the anode. The first enzyme breaks down the sugar trehalose, which a cockroach constantly produces from its food, into two simpler sugars, called monosaccarides, while the second enzyme oxidizes the monosaccarides to release electrons. A current them flows as the electrons are drawn to the cathode, where oxygen from air takes up the electrons and is reduced to water.

After testing the system using trehalose solution, the team inserted prototype electrodes in a blood sinus away from critical organs in the abdomen of a female cockroach. The cockroaches suffered no long-term damage, which the researchers say bodes well for long-term use.

"Insects have an open circulatory system so the blood is not under much pressure," Ritzmann explained. "So, unlike say a vertebrate, where if you pushed a probe into a vein or worse an artery (which is very high pressure) blood does not come out at any pressure. So, basically, this is really pretty benign. In fact, it is not unusual for the insect to right itself and walk or run away afterward."

Using an instrument called a potentiostat, the team determined the maximum power density of the fuel cell reached nearly 100 microwatts per square centimeter at 0.2 volts, with a maximum current density of about 450 microamps per square centimeter.

The researchers are now working to miniaturize the fuel cell so that it can be fully implanted into an insect while still allowing it to run or fly normally and examining which materials might last for a long time inside an insect. They are also working with other researchers to develop a signal transmitter that can run on little energy and also exploring how to add a lightweight rechargeable battery to the system.

"It's possible the system could be used intermittently," Scherson said. "An insect equipped with a sensor could measure the amount of noxious gas in a room, broadcast the finding, shut down and recharge for an hour, then take a new measurement and broadcast again."

The Case Western Reserve University team's work was published last week in the Journal of the American Chemical Society.


Source: Gizmag

Biofuels from Switchgrass: Researchers Boost Switchgrass Biofuels Potential by Adding a Maize Gene to Switchgrass

Engineerblogger
Nov 21, 2011

Introducing a maize gene into switchgrass substantially boosted the potential of the switchgrass biomass as an advanced biofuel feedstock. (Photo courtesy of USDA/ARS)

Many experts believe that advanced biofuels made from cellulosic biomass are the most promising alternative to petroleum-based liquid fuels for a renewable, clean, green, domestic source of transportation energy. Nature, however, does not make it easy. Unlike the starch sugars in grains, the complex polysaccharides in the cellulose of plant cell walls are locked within a tough woody material called lignin. For advanced biofuels to be economically competitive, scientists must find inexpensive ways to release these polysaccharides from their bindings and reduce them to fermentable sugars that can be synthesized into fuels.

An important step towards achieving this goal has been taken by researchers with the U.S. Department of Energy (DOE)’s Joint BioEnergy Institute (JBEI), a DOE Bioenergy Research Center led by the Lawrence Berkeley National Laboratory (Berkeley Lab).

A team of JBEI researchers, working with researchers at the U.S. Department of Agriculture’s Agricultural Research Service (ARS), has demonstrated that introducing a maize (corn) gene into switchgrass, a highly touted potential feedstock for advanced biofuels, more than doubles (250 percent) the amount of starch in the plant’s cell walls and makes it much easier to extract polysaccharides and convert them into fermentable sugars. The gene, a variant of the maize gene known as Corngrass1 (Cg1), holds the switchgrass in the juvenile phase of development, preventing it from advancing to the adult phase.

“We show that Cg1 switchgrass biomass is easier for enzymes to break down and also releases more glucose during saccharification,” says Blake Simmons, a chemical engineer who heads JBEI’s Deconstruction Division and was one of the principal investigators for this research. “Cg1 switchgrass contains decreased amounts of lignin and increased levels of glucose and other sugars compared with wild switchgrass, which enhances the plant’s potential as a feedstock for advanced biofuels.”

The results of this research are described in a paper published in the Proceedings of the National Academy of Sciences (PNAS) titled “Overexpression of the maize Corngrass1 microRNA prevents flowering, improves digestibility, and increases starch content of switchgrass.”

Lignocellulosic biomass is the most abundant organic material on earth. Studies have consistently shown that biofuels derived from lignocellulosic biomass could be produced in the United States in a sustainable fashion and could replace today’s gasoline, diesel and jet fuels on a gallon-for-gallon basis. Unlike ethanol made from grains, such fuels could be used in today’s engines and infrastructures and would be carbon-neutral, meaning the use of these fuels would not exacerbate global climate change. Among potential crop feedstocks for advanced biofuels, switchgrass offers a number of advantages. As a perennial grass that is both salt- and drought-tolerant, switchgrass can flourish on marginal cropland, does not compete with food crops, and requires little fertilization. A key to its use in biofuels is making it more digestible to fermentation microbes.

“The original Cg1 was isolated in maize about 80 years ago. We cloned the gene in 2007 and engineered it into other plants, including switchgrass, so that these plants would replicate what was found in maize,” says George Chuck, lead author of the PNAS paper and a plant molecular geneticist who holds joint appointments at the Plant Gene Expression Center with ARS and the University of California (UC) Berkeley. “The natural function of Cg1 is to hold pants in the juvenile phase of development for a short time to induce more branching. Our Cg1 variant is special because it is always turned on, which means the plants always think they are juveniles.”

Chuck and his colleague Sarah Hake, another co-author of the PNAS paper and director of the Plant Gene Expression Center, proposed that since juvenile biomass is less lignified, it should be easier to break down into fermentable sugars. Also, since juvenile plants don’t make seed, more starch should be available for making biofuels. To test this hypothesis, they collaborated with Simmons and his colleagues at JBEI to determine the impact of introducing the Cg1 gene into switchgrass.

In addition to reducing the lignin and boosting the amount of starch in the switchgrass, the introduction and overexpression of the maize Cg1 gene also prevented the switchgrass from flowering even after more than two years of growth, an unexpected but advantageous result.

“The lack of flowering limits the risk of the genetically modified switchgrass from spreading genes into the wild population,” says Chuck.

The results of this research offer a promising new approach for the improvement of dedicated bioenergy crops, but there are questions to be answered. For example, the Cg1 switchgrass biomass still required a pre-treatment to efficiently liberate fermentable sugars.

Overxpression of the Cg1 gene in switchgrass (left) compared to Wild-type of switchgrass of the same age and grown under the same conditions. (Photo courtesy of USDA/ARS)

“The alteration of the switchgrass does allow us to use less energy in our pre-treatments to achieve high sugar yields as compared to the energy required to convert the wild type plants,” Simmons says. “The results of this research set the stage for an expanded suite of pretreatment and saccharification approaches at JBEI and elsewhere that will be used to generate hydrolysates for characterization and fuel production.”

Another question to be answered pertains to the mechanism by which Cg1 is able to keep switchgrass and other plants in the juvenile phase.

“We know that Cg1 is controlling an entire family of transcription factor genes,” Chuck says, “but we have no idea how these genes function in the context of plant aging. It will probably take a few years to figure this out.”

Source: Lawrence Berkeley National Laboratory

Researchers develop ‘super’ yeast that turns pine into ethanol

Engineerblogger
Nov 21, 2011



Researchers at the University of Georgia have developed a "super strain" of yeast that can efficiently ferment ethanol from pretreated pine-one of the most common species of trees in Georgia and the U.S. Their research could help biofuels replace gasoline as a transportation fuel.

"Companies are interested in producing ethanol from woody biomass such as pine, but it is a notoriously difficult material for fermentations," said Joy Doran-Peterson, associate professor of microbiology in the Franklin College of Arts and Sciences.

"The big plus for softwoods, including pine, is that they have a lot of sugar that yeast can use," she said. "Yeast are currently used in ethanol production from corn or sugarcane, which are much easier materials for fermentation; our process increases the amount of ethanol that can be obtained from pine."

Before the pinewood is fermented with yeast, however, it is pre-treated with heat and chemicals, which help open the wood for enzymes to break the cellulose down into sugars. Once sugars are released, the yeast will convert them to ethanol, but compounds produced during pretreatment tend to kill even the hardiest industrial strains of yeast, making ethanol production difficult.

Doran-Peterson, along with doctoral candidate G. Matt Hawkins, used directed evolution and adaptation of Saccharomyces cerevisiae, a species of yeast used commonly in industry for production of corn ethanol, to generate the "super" yeast.

Their research, published online in Biotechnology for Biofuels, shows that the pine fermented with the new yeast can successfully withstand the toxic compounds and produce ethanol from higher concentrations of pretreated pine than previously published.

"Others before us had suggested that Saccharomyces could adapt to harsh conditions. But no one had published softwood fermentation studies in which the yeast were pushed as hard as we pushed them," said Doran-Peterson.

During a two-year period, Doran-Peterson and Hawkins grew the yeast in increasingly inhospitable environments. The end result was a strain of yeast capable of producing ethanol in fermentations of pretreated wood containing as much as 17.5 percent solid biomass. Previously, researchers were only able to produce ethanol in the presence of 5 to 8 percent solids. Studies at 12 percent solids showed a substantial decrease in ethanol production.

This is important, said Doran-Peterson, because the greater the percentage of solids in wood, the more ethanol that can be produced. However, a high percentage of solids also places stress on the yeast.

"Couple that stress with the increase in toxic compounds, and the fermentation usually does not proceed very well," she said.

Pine is an ideal substrate for biofuels not only because of its high sugar content, but also because of its sustainability. While pine plantations account for only 15 percent of Georgia's trees, they provide 50 percent of harvested timber, according to Dale Greene, professor of forest operations in UGA's Warnell School of Forestry and Natural Resources. The loblolly pine that Doran-Peterson and Hawkins used for their research is among the fastest growing trees in the American South.

"We're talking about using forestry residues, waste and unsalable timber," said Peterson, "Alternatively, pine forests are managed for timber and paper manufacturing, so there is an existing infrastructure to handle tree-farming, harvest and transportation for processing. "The basic idea is that we're trying to get the yeast to make as much ethanol as it can, as fast as it can, while minimizing costs associated with cleaning or washing the pretreated pine. With our process, no additional clean-up steps are required before the pine is fermented," she said.

Source: University of Georgia