Scientists create 'nano-reactor' for the production of hydrogen biofuel

Combining bacterial genes and virus shell creates a highly efficient, renewable material used in generating power from water

Scientists at Indiana University have created a highly efficient biomaterial that catalyzes the formation of hydrogen -- one half of the "holy grail" of splitting H2O to make hydrogen and oxygen for fueling cheap and efficient cars that run on water.

A modified enzyme that gains strength from being protected within the protein shell -- or "capsid" -- of a bacterial virus, this new material is 150 times more efficient than the unaltered form of the enzyme.

The process of creating the material was recently reported in "Self-assembling biomolecular catalysts for hydrogen production" in the journal Nature Chemistry.

"Essentially, we've taken a virus's ability to self-assemble myriad genetic building blocks and incorporated a very fragile and sensitive enzyme with the remarkable property of taking in protons and spitting out hydrogen gas," said Trevor Douglas, the Earl Blough Professor of Chemistry in the IU Bloomington College of Arts and Sciences' Department of Chemistry, who led the study. "The end result is a virus-like particle that behaves the same as a highly sophisticated material that catalyzes the production of hydrogen."

Other IU scientists who contributed to the research were Megan C. Thielges, an assistant professor of chemistry; Ethan J. Edwards, a Ph.D. student; and Paul C. Jordan, a postdoctoral researcher at Alios BioPharma, who was an IU Ph.D. student at the time of the study.

The genetic material used to create the enzyme, hydrogenase, is produced by two genes from the common bacteria Escherichia coli, inserted inside the protective capsid using methods previously developed by these IU scientists. The genes, hyaA and hyaB, are two genes in E. coli that encode key subunits of the hydrogenase enzyme. The capsid comes from the bacterial virus known as bacteriophage P22. 

The resulting biomaterial, called "P22-Hyd," is not only more efficient than the unaltered enzyme but also is produced through a simple fermentation process at room temperature.

The material is potentially far less expensive and more environmentally friendly to produce than other materials currently used to create fuel cells. The costly and rare metal platinum, for example, is commonly used to catalyze hydrogen as fuel in products such as high-end concept cars.

"This material is comparable to platinum, except it's truly renewable," Douglas said. "You don't need to mine it; you can create it at room temperature on a massive scale using fermentation technology; it's biodegradable. It's a very green process to make a very high-end sustainable material."

In addition, P22-Hyd both breaks the chemical bonds of water to create hydrogen and also works in reverse to recombine hydrogen and oxygen to generate power. "The reaction runs both ways -- it can be used either as a hydrogen production catalyst or as a fuel cell catalyst," Douglas said.

The form of hydrogenase is one of three occurring in nature: di-iron (FeFe)-, iron-only (Fe-only)- and nitrogen-iron (NiFe)-hydrogenase. The third form was selected for the new material due to its ability to easily integrate into biomaterials and tolerate exposure to oxygen.

NiFe-hydrogenase also gains significantly greater resistance upon encapsulation to breakdown from chemicals in the environment, and it retains the ability to catalyze at room temperature.

Unaltered NiFe-hydrogenase, by contrast, is highly susceptible to destruction from chemicals in the environment and breaks down at temperatures above room temperature -- both of which make the unprotected enzyme a poor choice for use in manufacturing and commercial products such as cars.

These sensitivities are "some of the key reasons enzymes haven't previously lived up to their promise in technology," Douglas said. Another is their difficulty to produce.

"No one's ever had a way to create a large enough amount of this hydrogenase despite its incredible potential for biofuel production. But now we've got a method to stabilize and produce high quantities of the material -- and enormous increases in efficiency," he said.

The development is highly significant according to Seung-Wuk Lee, professor of bioengineering at the University of California-Berkeley, who was not a part of the study.

"Douglas' group has been leading protein- or virus-based nanomaterial development for the last two decades. This is a new pioneering work to produce green and clean fuels to tackle the real-world energy problem that we face today and make an immediate impact in our life in the near future,” said Lee, whose work has been cited in a U.S. Congressional report on the use of viruses in manufacturing.

Beyond the new study, Douglas and his colleagues continue to craft P22-Hyd into an ideal ingredient for hydrogen power by investigating ways to activate a catalytic reaction with sunlight, as opposed to introducing elections using laboratory methods.

"Incorporating this material into a solar-powered system is the next step," Douglas said.

Indiana University

Nanotechnology World Association

Boosting Bioenergy

Computer simulations are revealing the biological barriers that prevent the conversion of biomass into energy.

A team led by Oak Ridge National Laboratory’s Jeremy Smith, the director of ORNL’s Center for Molecular Biophysics and a Governor’s Chair at the University of Tennessee, has uncovered information that could help others harvest energy from plant mass. The team’s conclusion—that less ordered cellulose fibers bind less lignin—was published in the August edition of Biomacromolecules.

The team used simulations on the Oak Ridge Leadership Computing Facility’s Jaguar supercomputer—a 2.3-petaflop machine that in 2012 morphed into Titan, which is a more than 27-petaflop supercomputer—along with neutron scattering to seek ways to make ethanol as cheap as gasoline at the pump.

“We are trying to figure out how to effectively break down plant materials like grass or wood chips cheaply enough to make biofuels economically viable,” said Loukas Petridis, a researcher in the Biosciences Division. “We are investigating the two main features that make biomass recalcitrant, or resistant to breakdown—the presence of lignin and the tightly ordered structure of cellulose.”

Lignin’s legacy

All plants contain a sticky molecule called lignin that intertwines with cellulose and hemicellulose in their cell walls. This substance is one of the major roadblocks preventing the cost-effective production of cellulosic ethanol.

Lignin is a plant cell’s first defense against man and beast. It provides strength to the stalks of plants so that these organisms can stand. But a plant’s best friend is a bioenergy researcher’s worst nightmare. During biofuel production—a process that converts plant mass into alcohol—lignin blocks enzymes from breaking down cellulose into the sugars necessary for fermentation.

Petridis works with ORNL’s Biofuels Science Focus Area, a multidisciplinary research group with experts in math, computer science, physics, chemistry, and biology who are working on the lignin problem. By studying lignin–cellulose and lignin–lignin interactions, the scientists have learned more about the physical processes that occur during biomass pretreatment, which is an expensive process that opens plant cell walls and helps enzymes break down plant mass.

“The process is very effective,” Petridis said. “Without it you wouldn’t be able to produce biofuels, but we want to improve it further so that the production of biofuels becomes cheaper and more efficient. In order to do this, we have to understand what is taking place during pretreatment on a molecular level.”

Combining the powers of neutrons and simulations

Neutron imaging and supercomputer simulation allow scientists to resolve the structure of lignin aggregates down to 1 angstrom, about 1 million times smaller than what the naked eye can see.

A previous simulation on Jaguar showed how different pretreatment temperatures change lignin’s structure, causing it to either aggregate or expand. Petridis’s study builds on this finding.

Using neutron beams at ORNL’s High Flux Isotope Reactor, researchers have discovered that cellulose fibers that are less organized, or noncrystalline, are easier for enzymes to break down. Simulations run on Jaguar helped explain this phenomenon.

“Jaguar has shown us that not only is noncrystalline cellulose more easily broken down, but it also associates less with lignin,” Petridis said. “This was the first simulation that has looked at the interaction of lignin with specific types of cellulose.”

But researchers often want to learn why a process is occurring on a more fundamental level. Fortunately computer models also reveal the reason behind lignin’s preference for crystalline cellulose.

“It is harder for lignin to associate with the noncrystalline cellulose because this cellulose interacts very strongly with water,” Petridis said. “To see this we needed Jaguar’s enormous supercomputing power to simulate 3 million lignin, cellulose, and water molecules.”

Interaction between cellulose fibril (blue) and lignin (pink) molecules. Visualization by Jamison Daniel (ORNL)

Accelerating scientific discovery

Smaller supercomputers can simulate a cellulose fiber and one lignin molecule, but they often miss many of the molecular interactions that ORNL supercomputers like Jaguar or Titan can capture.

Smith’s team was awarded 23 million processor hours on Jaguar in 2012 through the Innovative and Novel Computational Impact on Theory and Experiment, or INCITE, program.

Under the INCITE allocation, the team ran a classic molecular dynamics simulation with a code called GROMACS (for Groningen Machine for Chemical Simulations). The code monitored 3 million atoms and used 30,000 of Jaguar’s cores, which means that each core was responsible for 100 atoms. The application provides information on the interaction of water with the cellulose, degree of lignin aggregation, shapes of lignin molecules, diffusion constants, etc.

The researchers received another 78 million INCITE hours this year to run an adapted version of GROMACS that can take advantage of Titan’s speedy GPUs, making the updated application 10 times bigger and much faster than the one run on Jaguar.

The Titan supercomputer is capable of more than 27,000 trillion calculations per second, and is the fastest open-science supercomputer in America. OLCF’s hybrid machine includes CPUs and NVIDIA GPUs, which are computational accelerators originally found in gaming systems. The GPUs provide the processing power needed to simulate larger and more realistic systems and accelerate scientific discovery.

Current simulations track around 30 million atoms, which include crystalline and noncrystalline cellulose, lignin, enzymes and water molecules. The models also account for the long-range interactions that lignin molecules experience with other surrounding molecules. These interactions make the code especially difficult to scale because the processors have to exchange information very frequently to monitor the position of every atom every fraction of a second.

“If you compare our 3-million-atom simulation to our 30-million-atom simulation, you can guess that we’ll eventually be able to simulate a billion atoms, which is the size of a living cell,” said Smith. “Our simulations could even include the microbes that eat the biomass.”

The team is now studying how lignin behaves in different types of biomass, which will help the researchers identify the plant characteristics best suited for biofuel production.

“The scientific insights we gain help improve the biofuel production process,” Petridis said. “We give engineers hints about how the production process works, which we hope will allow them to design new pretreatment methods and engineer different types of biomass and enzymes that can harvest more energy from plant materials.”

Bigger, faster supercomputers

As supercomputing power increases, Petridis’s team will be able to simulate longer biological processes in greater detail. The simulations they run are already high resolution, but they can simulate only processes that happen within milliseconds.

“We can simulate lignin aggregation because it takes place in a millisecond, but there are other interesting biological processes that take much longer than 1 millisecond,” Petridis said. “The future of supercomputing is being able to access time and length scales that are currently accessible only through neutron scattering experiments.” —Jennifer Brouner

Source: https://www.olcf.ornl.gov/2014/01/02/boosting-bioenergy/

Algae to crude oil: Million-year natural process takes minutes in the lab

Process simplifies transformation of algae to oil, water and usable byproducts

Engineers have created a continuous chemical process that produces useful crude oil minutes after they pour in harvested algae — a verdant green paste with the consistency of pea soup.

The research by engineers at the Department of Energy's Pacific Northwest National Laboratory was reported recently in the journalAlgal Research. A biofuels company, Utah-based Genifuel Corp., has licensed the technology and is working with an industrial partner to build a pilot plant using the technology.

In the PNNL process, a slurry of wet algae is pumped into the front end of a chemical reactor. Once the system is up and running, out comes crude oil in less than an hour, along with water and a byproduct stream of material containing phosphorus that can be recycled to grow more algae.

With additional conventional refining, the crude algae oil is converted into aviation fuel, gasoline or diesel fuel. And the waste water is processed further, yielding burnable gas and substances like potassium and nitrogen, which, along with the cleansed water, can also be recycled to grow more algae.

While algae has long been considered a potential source of biofuel, and several companies have produced algae-based fuels on a research scale, the fuel is projected to be expensive. The PNNL technology harnesses algae's energy potential efficiently and incorporates a number of methods to reduce the cost of producing algae fuel.

"Cost is the big roadblock for algae-based fuel," said Douglas Elliott, the laboratory fellow who led the PNNL team's research. "We believe that the process we've created will help make algae biofuels much more economical."

PNNL scientists and engineers simplified the production of crude oil from algae by combining several chemical steps into one continuous process. The most important cost-saving step is that the process works with wet algae. Most current processes require the algae to be dried — a process that takes a lot of energy and is expensive. The new process works with an algae slurry that contains as much as 80 to 90 percent water.

"Not having to dry the algae is a big win in this process; that cuts the cost a great deal," said Elliott. "Then there are bonuses, like being able to extract usable gas from the water and then recycle the remaining water and nutrients to help grow more algae, which further reduces costs."

While a few other groups have tested similar processes to create biofuel from wet algae, most of that work is done one batch at a time. The PNNL system runs continuously, processing about 1.5 liters of algae slurry in the research reactor per hour. While that doesn't seem like much, it's much closer to the type of continuous system required for large-scale commercial production.

The PNNL system also eliminates another step required in today's most common algae-processing method: the need for complex processing with solvents like hexane to extract the energy-rich oils from the rest of the algae. Instead, the PNNL team works with the whole algae, subjecting it to very hot water under high pressure to tear apart the substance, converting most of the biomass into liquid and gas fuels.

The system runs at around 350 degrees Celsius (662 degrees Fahrenheit) at a pressure of around 3,000 PSI, combining processes known as hydrothermal liquefaction and catalytic hydrothermal gasification. Elliott says such a high-pressure system is not easy or cheap to build, which is one drawback to the technology, though the cost savings on the back end more than makes up for the investment.

"It's a bit like using a pressure cooker, only the pressures and temperatures we use are much higher," said Elliott. "In a sense, we are duplicating the process in the Earth that converted algae into oil over the course of millions of years. We're just doing it much, much faster."

The products of the process are:

• Crude oil, which can be converted to aviation fuel, gasoline or diesel fuel. In the team's experiments, generally more than 50 percent of the algae's carbon is converted to energy in crude oil — sometimes as much as 70 percent.
• Clean water, which can be re-used to grow more algae.
• Fuel gas, which can be burned to make electricity or cleaned to make natural gas for vehicle fuel in the form of compressed natural gas.
• Nutrients such as nitrogen, phosphorus, and potassium — the key nutrients for growing algae.

Elliott has worked on hydrothermal technology for nearly 40 years, applying it to a variety of substances, including wood chips and other substances. Because of the mix of earthy materials in his laboratory, and the constant chemical processing, he jokes that his laboratory sometimes smells "like a mix of dirty socks, rotten eggs and wood smoke" — an accurate assessment.

Genifuel Corp. has worked closely with Elliott's team since 2008, licensing the technology and working initially with PNNL through DOE's Technology Assistance Program to assess the technology.

"This has really been a fruitful collaboration for both Genifuel and PNNL," said James Oyler, president of Genifuel. "The hydrothermal liquefaction process that PNNL developed for biomass makes the conversion of algae to biofuel much more economical. Genifuel has been a partner to improve the technology and make it feasible for use in a commercial system.

"It's a formidable challenge, to make a biofuel that is cost-competitive with established petroleum-based fuels," Oyler added. "This is a huge step in the right direction."

The recent work is part of DOE's National Alliance for Advanced Biofuels & Bioproducts, or NAABB. This project was funded with American Recovery and Reinvestment Act funds by DOE's Office of Energy Efficiency and Renewable Energy. Both PNNL and Genifuel have been partners in the NAABB program.

In addition to Elliott, authors of the paper include Todd R. Hart, Andrew J. Schmidt, Gary G. Neuenschwander, Leslie J. Rotness, Mariefel V. Olarte, Alan H. Zacher, Karl O. Albrecht, Richard T. Hallen and Johnathan E. Holladay, all at PNNL.

Reference: Douglas C. Elliott, Todd R. Hart, Andrew J. Schmidt, Gary G. Neuenschwander, Leslie J. Rotness, Mariefel V. Olarte, Alan H. Zacher, Karl O. Albrecht, Richard T. Hallen and Johnathan E. Holladay, Process development for hydrothermal liquefaction of algae feedstocks in a continuous-flow reactor, Algal Research, Sept. 29, 2013, DOI: 10.1016/j.algal.2013.08.005.

Source: http://www.pnnl.gov/news/release.aspx?id=1029