NAABB Chooses Harvesting and Extraction Technologies

May 24, 2012 AlgaeIndustryMagazine.com (Editor’s note: This story replaces one posted 5-22-12) The National Alliance for Advanced Biofuels and Bioproducts (NAABB) has selected three harvesting and one extraction technology for Phase II scale up development. The three harvesting technologies include an electrolytic flocculation system from Texas AgriLife Research (Texas A&M), new cross-flow membrane technologies from Pacific Northwest National Laboratory (PNNL), and the ultrasonic algal biofuel harvester from Los Alamos National Laboratory (LANL). The selected extraction technology is a specialized mesoporous nanomaterial technology for extraction of high value lipids, e.g., tocopherol, being developed by Iowa State University (ISU). The electrolytic flocculation system utilizes technology developed for the wastewater treatment industry. It is therefore the most advanced of the selected technologies and has been demonstrated, by Texas AgriLife Research, for algal culture processing at scales of ~600 L/hr. The cross-flow membrane technologies utilize the well-known concept of cross-flow filtration to minimize surface fouling and cleaning issues. The PNNL technology utilizes a new class of thin porous metal flat sheet membranes, recently invented, with uniform pores effective in capturing the small algae cells that are encountered in common biofuels systems, along with membrane materials and surfaces that are very promising in addressing common fouling problems caused by algae adhesion and/or bio-film growth. The LANL technology is based on LANL’s R&D 100 Award-winning Ultrasonic Algal Biofuel Harvester. The ultrasonic harvester utilizes sound waves to concentrate and cause flocculation of the algae into a separate concentrated flowing stream. The mesoporous nanoparticle technologies from ISU utilize nanomaterials with a selective binding agent that can efficiently bind specific molecules within the algal oils for extraction and has been demonstrated in the extraction of tocopherol from algal oil. All of these technologies have demonstrated high efficiency and energy minimization when compared to traditional technologies currently in the market. The NAABB selected these four harvesting and extraction technologies for scale-up following a rigorous review. Five harvesting technologies and four extraction technologies being developed within the NAABB program were compared to each other and to market benchmarks for projected operational costs and energy consumption for this down select process.

Low-Cost Nanosheet Catalyst Discovered to Split Hydrogen from Water

ScienceDaily (May 11, 2012) — Hydrogen gas offers one of the most promising sustainable energy alternatives to limited fossil fuels. But traditional methods of producing pure hydrogen face significant challenges in unlocking its full potential, either by releasing harmful carbon dioxide into the atmosphere or requiring rare and expensive chemical elements such as platinum. Now, scientists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory have developed a new electrocatalyst that addresses one of these problems by generating hydrogen gas from water cleanly and with much more affordable materials. The novel form of catalytic nickel-molybdenum-nitride -- described in a paper published online May 8, 2012 in the journal Angewandte Chemie International Edition -- surprised scientists with its high-performing nanosheet structure, introducing a new model for effective hydrogen catalysis. "We wanted to design an optimal catalyst with high activity and low costs that could generate hydrogen as a high-density, clean energy source," said Brookhaven Lab chemist Kotaro Sasaki, who first conceived the idea for this research. "We discovered this exciting compound that actually outperformed our expectations." Goldilocks chemistry Water provides an ideal source of pure hydrogen -- abundant and free of harmful greenhouse gas byproducts. The electrolysis of water, or splitting water (H2O) into oxygen (O2) and hydrogen (H2), requires external electricity and an efficient catalyst to break chemical bonds while shifting around protons and electrons. To justify the effort, the amount of energy put into the reaction must be as small as possible while still exceeding the minimum required by thermodynamics, a figure associated with what is called overpotential. For a catalyst to facilitate an efficient reaction, it must combine high durability, high catalytic activity, and high surface area. The strength of an element's bond to hydrogen determines its reaction level -- too weak, and there's no activity; too strong, and the initial activity poisons the catalyst. "We needed to create high, stable activity by combining one non-noble element that binds hydrogen too weakly with another that binds too strongly," said James Muckerman, the senior chemist who led the project. "The result becomes this well-balanced Goldilocks compound -- just right." Unfortunately, the strongest traditional candidate for an electrocatlytic Goldilocks comes with a prohibitive price tag. Problems with platinum Platinum is the gold standard for electrocatalysis, combining low overpotential with high activity for the chemical reactions in water-splitting. But with rapidly rising costs -- already hovering around $50,000 per kilogram -- platinum and other noble metals discourage widespread investment. "People love platinum, but the limited global supply not only drives up price, but casts doubts on its long-term viability," Muckerman said. "There may not be enough of it to support a global hydrogen economy." In contrast, the principal metals in the new compound developed by the Brookhaven team are both abundant and cheap: $20 per kilogram for nickel and $32 per kilogram for molybdenum. Combined, that's 1000 times less expensive than platinum. But with energy sources, performance is often a more important consideration than price. Turning nickel into platinum In this new catalyst, nickel takes the reactive place of platinum, but it lacks a comparable electron density. The scientists needed to identify complementary elements to make nickel a viable substitute, and they introduced metallic molybdenum to enhance its reactivity. While effective, it still couldn't match the performance levels of platinum. "We needed to introduce another element to alter the electronic states of the nickel-molybdenum, and we knew that nitrogen had been used for bulk materials, or objects larger than one micrometer," said research associate Wei-Fu Chen, the paper's lead author. "But this was difficult for nanoscale materials, with dimensions measuring billionths of a meter." The scientists expected the applied nitrogen to modify the structure of the nickel-molybdenum, producing discrete, sphere-like nanoparticles. But they discovered something else. Subjecting the compound to a high-temperature ammonia environment infused the nickel-molybdenum with nitrogen, but it also transformed the particles into unexpected two-dimensional nanosheets. The nanosheet structures offer highly accessible reactive sites -- consider the surface area difference between bed sheets laid out flat and those crumpled up into balls -- and therefore more reaction potential. Using a high-resolution transmission microscope in Brookhaven Lab's Condensed Matter Physics and Materials Science Department, as well as x-ray probes at the National Synchrotron Light Source, the scientists determined the material's 2D structure and probed its local electronic configurations. "Despite the fact that metal nitrides have been extensively used, this is the first example of one forming a nanosheet," Chen said. "Nitrogen made a huge difference -- it expanded the lattice of nickel-molybdenum, increased its electron density, made an electronic structure approaching that of noble metals, and prevented corrosion." Hydrogen future The new catalyst performs nearly as well as platinum, achieving electrocatalytic activity and stability unmatched by any other non-noble metal compounds. "The production process is both simple and scalable," Muckerman said, "making nickel-molybdenum-nitride appropriate for wide industrial applications." While this catalyst does not represent a complete solution to the challenge of creating affordable hydrogen gas, it does offer a major reduction in the cost of essential equipment. The team emphasized that the breakthrough emerged through fundamental exploration, which allowed for the surprising discovery of the nanosheet structure. "Brookhaven Lab has a very active fuel cell and electrocatalysis group," Muckerman said. "We needed to figure out fundamental approaches that could potentially be game-changing, and that's the spirit in which we're doing this work. It's about coming up with a new paradigm that will guide future research." Additional collaborators on this research were: Anatoly Frenkel of Yeshiva University, Nebojsa Marinkovic of the University of Delaware, and Chao Ma, Yimei Zhu and Radoslav Adzic of Brookhaven Lab. The research was funded by Brookhaven's Laboratory Directed Research and Development (LDRD) Program. The National Sychrotron Light Source and other Brookhaven user facilities are supported by the DOE Office of Science.