February 2013

Technology, Abengoa Research

Abengoa collaborates with the Helmholtz Dresden-Rossendorf research center
The objective is to improve the efficiency of solar plants

Abengoa has signed a collaboration agreement with the Helmholtz Dresden- Rossendorf research center in Dresden, Germany, to develop materials that increase the efficiency of solar receivers, one of the key components for improving the efficiency of solar plants.

At present, the move towards larger plants and better designed components is leading to higher temperatures in solar receivers. Consequently, the receivers of the future will require materials that are capable of resisting high temperatures, are highly absorbent, and are capable of minimizing any heat loss in order to increase the efficiency of the solar plant.

Abengoa, through its own research center, Abengoa Research, will collaborate with the Helmholtz Dresden-Rossendorf center, specifically with the nanotechnology department of the Institute of Ion Beam Physics and Materials Research, to search for new materials for the covering of solar receivers using multi-layer thin films to enable them to withstand high temperatures.

The research will focus on the use of ion beams to analyze and modify thin films, mainly in carbon and nitrogen based nanocomposites as well as advanced oxides. Furthermore, it has recently acquired some high-tech equipment known as a "cluster tool", which will enable it to prepare thin films using steam deposition techniques, while also measuring the thickness, composition and optical properties of the deposited materials at high temperatures.

Thanks to these innovative techniques and the "in-situ" nature of the work, Abengoa's researchers can study the optimum parameters that enable the maximum amount of thermal solar energy to be absorbed, and to be more stable athigh temperatures, optimizing the efficiency of these components in tower technology plants.

This collaboration will further consolidate Abengoa's commitment to sustainable development and new technologies, demonstrating its dedication to solar energy, as one of the companies that has globally contributed the most to developing new technologies to improve photovoltaic and solar-thermal energy. Innovation has driven the company's development from the outset and has enabled it to maintain a competitive advantage in the sectors in which it operates.

Plasma: an efficient way to adapt surfaces
The scientific community is working to comprehend the fundamental phenomena that govern the interaction of plasma with different materials

The four classical elements of alchemy proposed by Empedocles of Agrigento in 430 BC are earth, water, air and fire. Reinterpreted in the light of new knowledge, they can be identified as the four basic states of matter: solid, liquid, gas and plasma. Fire, frequently associated with magic and witchcraft due to its mysteriousness and different uses – good and bad – is identified with plasma, a quasineutral state of matter, in which atoms are transformed by the loss of electrons, with many becoming positive ions. The plasma becomes a mixture of negative electrons, positive ions and neutral atoms that move like a gas, i.e. with great freedom of particles, but forming a set. As with gas, the higher the temperature the higher the speed of the particles, but in the case of plasma they can collide and produce electrons. Moreover, unlike gas, plasmas are electrically conductive and can be confined or guided by magnetic fields.

Although the plasma state is not abundant on Earth – it is almost reduced to what is created artificially: interior of fluorescent tubes, neon lights, televisions, and screen monitors, etc., - it is the most abundant and common state in the universe: stellar atmospheres where most atoms are in constant ionic state, interplanetary, interstellar and intergalactic matter. In our planet too, the ionosphere, located at an altitude between 80 and 600 km, can be considered "our plasma ceiling" and this layer is precisely what enables the transmission of radio waves, as they rebound off it and are not lost in outer space.

Controlling the unknown is no easy task. However, since the American Irving Langmuir, Nobel Prize for Chemistry in 1932, termed the electrified fluids he was observing in an ionized gas as plasma (possibly due to its similarity to blood plasma that serves to transport white and red blood cells), the control and use of plasmas has been extended to a multitude of applications.

Nowadays, many companies in various sectors (metallurgy, glass, plastic, health, or energy) utilize plasma surface technology to induce, directly or indirectly, special qualities in different products and services. The scientific community is making a major effort to comprehend the fundamental phenomena that govern the interaction of plasma with different materials with the aim of adapting different properties of surfaces and coatings, and for the development of thin films.

The optimization of surface treatment processes using plasma to obtain multifunctional features is being applied in different fields such as mechanical protection, optics, biomaterials and energy. It is, without doubt, a key technology for our state of wellbeing. In these types of applications, plasma can be used for three purposes: to clean, disinfect or activate surfaces, so that they can be recovered with paints and additives that adhere well, providing new electrical, optical, mechanical strength or corrosion resistant functionalities; and to improve their chemical function so that the surfaces interact or react with other substances.

The benefits of plasma use are to be found everywhere. For example, in dentistry, where atmospheric plasmas are used at body temperature to sterilize areas that in the not too distant past would have been removed through a small hole. Vacuum plasma is mainly used to coat components and devices we use every day, such as computer hard drives, which contain a thin layer of extremely hard diamond-like carbon that protects the information we store and has been subjected to plasma sintering. Razor blades are also protected by a similar layer that reduces friction and enables a close and smooth shave.

Furthermore, there is great potential for plasma technology in the sustainability sector, as it is fundamental for the development of new photovoltaic materials; membrane functionalization for wastewater treatment; and to increase the resistance to corrosion or erosion of any component, among many other applications.

Our future now depends on the use and interaction of Empedocles' four elements and, especially in the 'magic' of plasmas, the development and control of which will enable a host of new high added value products.

Manipulation of fluids at microscale: much more than simple miniaturization
Microfluidics is becoming a consolidated sub-discipline of engineering, and new applications of interest are being developed

Example of a microfluidic device (Lab on a Chip, 2009)

Microfluidics involves the manipulation of fluids at microscopic scale, using ductwork, chambers, valves, actuators, sensors, dispensers, etc. at micrometric sizes and integrated in a single device.

The first microfluidic applications emerged in the 90s, and were the result of prior development of micro-electro-mechanical systems (MEMS), capable of integrating control signals in a single block with micromachines using photolithographic techniques. There was a shift from a technology based predominantly on silicon (microelectronics and MEMS) to another in which polymer materials like PDMS or SU8, which possess the qualities of transparency and biocompatibility that microfluidic applications usually require, dominate.

The integration of complex hydraulic circuits in a single device (Lab on a Chip) has many advantages and numerous parallels to the route taken by electronics. In the same way as the replacement of vacuum tubes by transistors and their integration in a single circuit led to current day compact and powerful chips, many of the functionalities of chemical and biology laboratories can be incorporated in a much more efficient and cheaper manner in centimeter sized devices.

Microfluidics offers numerous advantages associated with miniaturization such as, for example, a more than notable reduction in the amount of reagents, time and cost of each process. In addition, it allows parallelization and simultaneous performing of multiple tests, resulting in high production rates (high-throughputscreening). But as or even more significant is the different behavior of the fluids in the small scale compared to that which they exhibit in the normal macroscopic scale: these differences allow development of a large variety of applications that would be unattainable in the macroscale.

The differences in behavior are the result of the significant variation in magnitude of the different forces that emerge in fluid motion (inertia, viscosity, surface tension, gravity, etc.) when size decreases. The most notable change is that viscous forces dominate those of inertia. To illustrate the difference we can, quite simply, imagine that in microfluidics water behaves as glycerin would at usual macroscopic scales. In terms of application development, this means that the usual turbulence disappears, flows are perfectly predictable, fluid particles follow well defined stream lines, and mixing phenomena are significantly hampered, allowing much more controlled conditions. In addition, surface forces such as surface tension also become much more relevant and new high-precision methods for control and manipulation of fluids are possible.

The advantages of high precision, small volumes and high production rates are used in many applications. For example, in the field of cellular biology, microfluidics allows high-resolution study of cells individually and of their collective behavior, with the possibility of applying experimental conditions that reproduce physiological environments. For the pharmaceutical industry, the possibility of massive simultaneous testing under different conditions (pH, composition and concentration, temperature, etc.) represents extraordinary progress in terms of reduction of costs and time required for intensive scrutiny in the development of new drugs. In the field of energy, fuel cells in which the currents, reducer and oxidant flow in parallel, without the need of a separation membrane, due to conditions in which the viscosity dominates, have been depicted. In other fields of physics and engineering there are also multiple possible applications: for example, the possibility of actively controlling the optical properties of fluids in microchannels allows the creation of adaptable property waveguides. Precision in the handling of multiphase flows enables new production methods for emulsions, polymers or micro- and nano-structured materials. The number of applications is very high and on the increase, and is being accompanied by continuous development of new manufacturing technologies.

In short, microfluidics is gradually becoming a consolidated sub-discipline of engineering, with new applications of interest being developed continuously. The pending mass marketing of these devices is perhaps one of the greatest challenges to be overcome. Given the youth of microfluidics and the time it took for microelectronics to be accepted by the public at large, we can expect a future in which microfluidics integrates naturally into our daily lives.

Abengoa launches a technology development project for catalytic conversion of ethanol to biobutanol
The production of butanol will allow the company to access chemical markets it has not yet operated in

Ethanol to biobutanol reconversion process

Abengoa Bioenergy is engaged in an innovation and technology development project focused on catalytic conversion of the ethanol produced at its plants into biobutanol (n-butanol), which will allow it to diversify its product portfolio.

Butanol is a chemical compound that is used in the chemical industry for different purposes, such as the manufacture of butyl acrylate, butyl acetate, glycols, plasticizers and solvents. Traditionally, it has been produced in two ways: either by fermentation of sugars with Clostridium Acetobutylicum (ABE process) or via the petrochemical process called 'oxo'.

In the first case, the sugars are fermented by the microorganism to produce a mixture of acetone, butanol and ethanol, which is then subjected to a separation process. This process was developed in 1920 but its use gradually petered out due to lack of competitiveness with the 'oxo' process.

In the second case, propylene reacts with synthesis gas (mixture of carbon monoxide and hydrogen) forming butylaldhyde that is subsequently hydrogenated to produce butanol. Propylene is a compound originating from either naphtha cracking or dehydrogenation of propane.

The Abengoa Bioenergy method, which hitherto had not been developed at industrial level, involves catalytic condensation of ethanol to produce butanol through the Guerbet (2CH3-CH2OHCH3- CH2-CH2-CH2OH + H20) reaction. In this process, the company has developed and patented a catalyst that allows attainment of a conversion and a selectivity of ethanol to butanol that enables the manufacture of biobutanol competitively.

Furthermore, Abengoa Bioenergy is developing the chemical process that will allow the ethanol produced at two of its plants to be transformed into butanol. One of the advantages of this technology is that the butanol plant can be built next to the ethanol plant, allowing the production of butanol without having to halt the ethanol production process, that is to say, the conversion of ethanol to butanol is not irreversible as occurs with other technical solutions.

Thus, Abengoa will be able to access higher value added chemical markets in which it has not yet operated and create new opportunities for the establishment of long term relations with butanol users seeking to improve the carbon footprint of their products, as there will now be a product in the market that replaces butanol of fossil origin with another of renewable source.

The "CRS Sales" molten salt power tower plant celebrates six months of uninterrupted operation

It is Abengoa's first molten salt power tower plant and was brought into operation in August 2012

Surface temperature of receiver

 

The Abengoa solar thermal power tower demonstration plant, using molten salts at 565º C as fluid, has been operating uninterruptedly for six months. The plant, which became fully operational in late August 2012, is continuing the program to test operation at different temperatures in a manner similar to that of a commercial plant 7 days a week.

Over the past six months, the different models of efficiency achieved have been validated, experience in operating plants employing this technology has been gained, and work has been conducted on preparing the commercial introduction of several improvements. In addition, it has been found that this technology can offer several advantages in certain geographies with very high energy storage needs.

The plant consists of a receiver, designed exclusively by Abengoa Solar; a steam generator, on whose design Abengoa also participated; and a tank where the salts are stored during operation. The solar field comprises 88 heliostats of 120 m2 each.

The up to 5 MW receiver, manufactured with alloy steel capable of withstanding high concentrated radiation fluxes and temperatures, was designed with the following objectives: first, to allow operation during transient days and, second, to validate its operation for a commercial plant. The design of said receiver has been the subject of a patent application filed by Abengoa Solar.

Another key component of the plant is the steam generator, designed especially to withstand a high temperature gradient in the evaporator. It generates steam at 90 bar pressure and 550º C, which is cooled in an air condenser and returned to the cycle.

Furthermore, new components are being validated, ranging from new types of insulation, high-temperature heat tracing systems, innovative foundations for tanks, and new start-up and preheating procedures for the receiver and control systems.

The next steps for development of this technology will be the upgrading and standardization of the key components, boosting of efficiency of the cycle, and further increasing of the temperature of the heat transfer fluid.

In this regard, the molten salts power tower plant (CRS Sales) is a major milestone for Abengoa Solar, positioning it as a leader in solar thermal power plant technology, where it concentrates its resources and efforts on meeting the challenges the technology presents.


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