Un hongo de la madera que produce electricidad/A tree fungus that produces electricity

The white-rot fungus T. versicolor. Photograph by Martina Berg

Sabine Sané, estudiante de doctorado del grupo de investigación Micro Energy Harvesting del Departamento de Ingeniería de Microsistemas (IMTEK) de la Universidad de Friburgo, ha encontrado la forma de que una especie de hongo de la madera sirva para producir electricidad.
Este nuevo concepto de conversión energética es el tema de portada de ChemSusChem, una revista científica sobre química, sostenibilidad, energía y materiales. La investigación fue apoyada por científicos del grupo de investigación dirigido por el Dr. Sven Kerzenmacher en el Laboratorio del Prof. Dr. Roland Zengerle para aplicaciones de MEMS (sistemas microelectromecánicos).
Las células de biocombustible producen electricidad, por ejemplo de desechos orgánicos, de una forma sostenible y que preserva recursos. Pueden emplear enzimas como catalizadores que permiten que se produzcan reacciones electroquímicas que generan electricidad. En contraste con los catalizadores basados en metales preciosos que se utilizan en las células de combustible convencionales, estas enzimas se pueden obtener a bajo coste a partir de materias primas renovables. Sin embargo, su vida es demasiado corta para algunas aplicaciones.
El nuevo concepto desarrollado por los científicos de Freiburg resuelve este problema asegurando que la célula de combustible se alimenta continuamente con el biocatalizador. El proveedor de la célula de combustible es Trametes versicolor, un hongo de la madera, que se encuentra en climas templados: libera la enzima fúngica Laccasa (una enzima oxidasa que contiene cobre) en la disolución que baña el cátodo - polo positivo de la célula – lo que permite la conversión electroquímica de oxígeno.
Los experimentos llevados a cabo por los investigadores han demostrado que este método puede alargar la vida útil de los cátodos hasta 120 días, y parece probable que se pueden lograr tiempos de vida considerablemente más largos. En comparación, los cátodos sólo tienen una vida útil de 14 días si no se les suministra más enzima. Dado que la solución enzimática se puede suministrar directamente a la pila de combustible sin necesidad de un costosa y larga purificación, los costes se reducen a un mínimo.
Las potenciales aplicaciones de este concepto incluyen células de combustible microbianas que generan electricidad a partir de aguas residuales, una tecnología que también está desarrollando el grupo de investigación de Kerzenmacher

The tricopper site found in many laccases. Each copper center is bound to the imidazole sidechains of histidine (color code: copper is brown, nitrogen is blue).

Sabine Sané, doctoral candidate in the Micro Energy Harvesting research group at the Department of Microsystems Engineering (IMTEK) of the University of Freiburg, has found a way to make a species of tree fungus useful for the production of electricity.
The new energy conversion concept was chosen as the cover story of ChemSusChem, a scientific journal for chemistry, sustainability, energy, and materials. The research was supported by scientists from a research group led by Dr. Sven Kerzenmacher at Prof. Dr. Roland Zengerle’s Laboratory for MEMS Applications.
Biofuel cells produce electricity that is environmentally friendly and conserves resources, for instance from organic waste material. They can use enzymes as catalysts to enable electrochemical reactions that generate electricity. In contrast to precious metal catalysts in conventional fuel cells, these enzymes can be obtained at low cost from renewable raw materials. For many technical applications, however, their lifetime is too short.
The new concept developed by the Freiburg scientists solves this problem by ensuring that the fuel cell is continually resupplied with the biocatalyst. The supplier of the fuel cell is Trametes versicolor, a tree fungus that is also found in temperate climates: It releases the fungal enzyme Laccase (a copper-containing oxidase enzyme) into a solution surrounding the cathode – the positive pole of the cell – where it enables the electrochemical conversion of oxygen.
Experiments conducted by the researchers demonstrate that this method can be used to extend the lifetime of the cathodes to as much as 120 days, and even considerably longer lifetimes seem possible. By comparison, the cathodes only have a lifetime of 14 days if they are not supplied with more of the enzymes. Since the enzymatic solution can be supplied directly to the fuel cell without time-consuming and expensive purification, the costs are reduced to a minimum.
Potential applications for the concept include microbial fuel cells that generate electricity from wastewater, a technology Kerzenmacher’s research group is also developing.

Tomado de/Taken from University of Freiburg
Overcoming Bottlenecks of Enzymatic Biofuel Cell Cathodes: Crude Fungal Culture Supernatant Can Help to Extend Lifetime and Reduce Cost S. Sané, C. Jolivalt, G. Mittler, P.J. Nielsen, S. Rubenwolf, R. Zengerle, S. Kerzenmacher (2013) ChemSusChem 6 p. 1209-1215. DOI: 10.1002/cssc.201300205
Available online without a subscription until 17 July 2013 at: http://onlinelibrary.wiley.com/doi/10.1002/cssc.201300205/abstract
Abstract
Enzymatic biofuel cells (BFCs) show great potential for the direct conversion of biochemically stored energy from renewable biomass resources into electricity. However, enzyme purification is time-consuming and expensive. Furthermore, the long-term use of enzymatic BFCs is hindered by enzyme degradation, which limits their lifetime to only a few weeks. We show, for the first time, that crude culture supernatant from enzyme-secreting microorganisms (Trametes versicolor) can be used without further treatment to supply the enzyme laccase to the cathode of a mediatorless BFC. Polarization curves show that there is no significant difference in the cathode performance when using crude supernatant that contains laccase compared to purified laccase in culture medium or buffer solution. Furthermore, we demonstrate that the oxygen reduction activity of this enzymatic cathode can be sustained over a period of at least 120 days by periodic resupply of crude culture supernatant. This is more than five times longer than control cathodes without the resupply of culture supernatant. During the operation period of 120 days, no progressive loss of potential is observed, which suggests that significantly longer lifetimes than shown in this work may be possible. Our results demonstrate the possibility to establish simple, cost efficient, and mediatorless enzymatic BFC cathodes that do not require expensive enzyme purification procedures. Furthermore, they show the feasibility of an enzymatic BFC with an extended lifetime, in which self-replicating microorganisms provide the electrode with catalytically active enzymes in a continuous or periodic manner

Plumas carbonizadas de gallina para almacenar hidrógeno/Carbonized chicken feathers for hydrogen storing

Científicos de Delaware afirman que han desarrollado un nuevo método para almacenar hidrógeno usando fibras de plumas carbonizadas de gallina, que pueden contener grandes cantidades del gas, una fuente muy prometedora y con un coste mucho más bajo que otros sistemas.
Según P. Wool, Ph.D., Profesor de Ingeniería Química en la Universidad de Delaware in Newark, "Las fibras carbonizadas de pluma de gallina tienen potencial para mejorar de forma dramática los rendimientos de otros métodos de almacenamineto de hidrogeno, y quizás puedan facilitar el camino para el desarrollo práctico de una economía basada en el hidrógeno"
Las fibras de pluma de gallina están compuestas mayoritariamente por queratina, una proteína natural que forma tubos huecos y muy robustos. Al calentarla, la proteína se entrecruza reforzando su estructura, y se vuelve más porosa aumentando su área superficial. El resultado final son fibras carbonizadas de plumas de gallina, que pueden absorber tanto o más hidrógeno que los nanotubos de carbono o los hidruros metálicos, los otros dos materiales que se están estudiando por su potencial para almacenar hidrógeno.
Según Wool, la utilización de estas plumas carbonizadas solo añadiría 140 € al precio de un coche. A modo de comparación, un tanque de combustible de 20 galones (75 litros) de hidrógeno hecho con nanotubos de carbono, costaría 3.800.000 €, mientras que uno con hidruros metálicos costaría 21.000 €.

Scientists in Delaware say they have developed a new hydrogen storage method — carbonized chicken feather fibers — that can hold vast amounts of hydrogen, a promising but difficult to corral fuel source, and do it at a far lower cost than other hydrogen storage systems under consideration.
"Carbonized chicken feather fibers have the potential to dramatically improve upon existing methods of hydrogen storage and perhaps pave the way for the practical development of a truly hydrogen-based energy economy," says Richard P. Wool, Ph.D., professor of chemical engineering at the University of Delaware in Newark.
Chicken feather fibers are mostly composed of keratin, a natural protein that forms strong, hollow tubes. When heated, this protein creates crosslinks, which strengthen its structure, and becomes more porous, increasing its surface area. The net result is carbonized chicken feather fibers, which can absorb as much or perhaps more hydrogen than carbon nanotubes or metal hydrides, two other materials being studied for their hydrogen storage potential.
Using carbonized chicken feathers would only add about $200 to the price of a car, according to Wool. By comparison, making a 20-gallon hydrogen fuel tank that uses carbon nanotubes could cost $5.5 million; one that uses metal hydrides could cost up to $30,000, Wool says.

Tomado de/Taken from Eureka Alert

Resumen de la Comunicación/Summary of the Communication
13th Annual green Chemistry & Engineering Conference
Erman Şenöz , Chemical Engineering Department, University of Delaware, Newark, DE
Richard P. Wool , Chemical Engineering Department, University of Delaware, Newark, DE
The biggest obstacles to a hydrogen powered energy economy are the production and storage of hydrogen. The Department of Energy’s (DOE) 2010 and 2015 hydrogen storage targets are quite challenging in terms of gravimetric capacity (6 wt% and 9 wt% respectively), volumetric capacity (45 and 81 grams H2 per L) and storage cost ($4 and $2 per kWh respectively). In order to solve the H2 storage problem, various kinds of nano-structured materials have been investigated and produced, none of which could fulfill these targets entirely. Their disposal methods and degradability are still a big question mark. Additionally, the prices of these materials are extremely expensive. It is crucial that the material that will serve as a hydrogen adsorbent in fuel cell vehicles is cheap and is environmentally.
The goal of this project is to develop new low cost hydrogen storage substrates from a waste material (6 billion lbs/yr in U.S.) —chicken feathers. The results showed that carbonized chicken feathers (CCFF) have the potential to meet the DOE requirements for H2 storage and are competitive with carbon nanotubes and metal hydrides at a tiny fraction of the cost. When keratin based chicken feathers are heat treated by controlled pyrolysis, hollow carbon microtubes are formed with nanoporous walls. Their specific surface area increases up to 450 m2/g by the formation of fractals and micropores thus enabling more hydrogen adsorption than raw (untreated) feather fibers. Experimental hydrogen storage optimization results and surface characterization of CCFF by SEM, XPS and N2 adsorption will be demonstrated. Furthermore, recent findings on heat treatment of chicken feather fibers by thermal analysis techniques will be discussed in detail.

El coste escondido de los bio-combustibles/ The hidden cost of biofuels

Los combustibles biológicos podrían perder su tono verde si se producen a expensas de los bosques tropicales.
Los científicos advierten de que la demanda de bio-combustibles líquidos podría originar una enorme tala de árboles, que liberaría más carbono a la atmósfera que el ahorrado por el cambio a combustibles más verdes.
Holly Gibbs, investigadora en la Universidad de Stanford que presentó el 14 de febrero su informe sobre el uso del territorio y la producción de bio-diesel, durante la reunión anual de la Asociación Americana para el Avance de la Ciencia, afirma que “la letra pequeña es que los combustibles biológicos basados en productos agrícolas van a aumentar las emisiones de gases de efecto invernadero si continúan siendo producidos de la manera en que se está haciendo hoy”
La demanda creciente de combustibles basados en productos agrícolas, por ejemplo maíz, aceite de la soja, de mandioca y de palma tiene efectos devastadores. La mayoría de los países industrializados que pretenden substituir los combustibles fósiles por combustibles biológicos, no tienen regiones agrícolas para producirlos. Y además, muchas de las plantas más prometedoras, tales la caña de azúcar y la palma, se adaptan mejor a las zonas tropicales, por lo que es preciso quemar el bosque tropical para despejar el terreno en que deben plantarse.
Gibbs considera que los biocombustibles se ajustan a las ecuaciones energéticas del futuro, pero que "ningún biocombustible va a poder satisfacer todas nuestras necesidades energéticas, por lo que necesitamos una cartera variada". Se necesitan políticas e incentivos para que se usen tierras previamente degradadas, una empresa que es actualmente de alto coste y de bajo beneficio.

Biofuels could lose their green sheen if they are grown at the expense of tropical forests.
Demand for the liquid fuels could lead to severe deforestation, researchers warn, which would release far more carbon into the atmosphere than that saved by switching to the greener fuels.
“The bottom line is that crop-based biofuels are going to increase greenhouse gas emissions if they continue to be produced the way they are today” says Holly Gibbs, a research fellow at Stanford University, who presented a new assessment of land use and biofuel production February 14 at the annual meeting of the American Association for the Advancement of Science.
Increased demand for biofuel crops such as corn, soybean, cassava and palm oil has ripple effects, Gibbs says. Most industrialized countries aiming to replace fossil fuels with biofuels don’t have the agricultural land to grow these fuels. And many of the most promising plants, such as sugarcane and palm oil, are better suited to the tropics anyway. The primary source of new cropland to grow these plants is cleared and burned tropical forest.
Gibbs is certain that biofuels fit into the energy equations of the future. But “no single biofuel is going to be able to fulfill our energy needs. We need a diversified portfolio,” she says. Policy and market incentives are needed to use already degraded land for crops, an endeavor that is currently high cost, low profit.

Tomado de/Taken from Science News