Clean Technology : Energy & resource efficiencies


Stimuli-Responsive Smart Block Copolymers Improve Dispersion of Titanium Dioxide in Architectural Coatings

An associate professor of materials science and engineering at the University of Wisconsin-Eau Claire has synthesized a series of stimuli-responsive block copolymer dispersants optimized for use in architectural coating applications. These novel polymer dispersants are currently being developed as additives to existing coatings for improved dispersion of TiO2. Dispersant properties are tunable through modification of the polymer composition as a function of pH and temperature. Initial data shows that the addition of these polymers can decrease settling rate, control viscosity, and control interfacial activity, all of which are important for greater dispersant effectiveness and stability over time. These polymers have demonstrated the ability to interface with pigment particles, such as TiO2, resulting in improved dispersion of the pigment. Initial testing shows reduced TiO2 concentration while maintaining zero shear viscosity and shear thinning properties, which prevents drips in the coatings, and is comparable to commercially available formations. These properties are tunable and may be altered to tailor the product for a desired use or environment, or to readjust the properties of an aged existing product. New methods of synthesis to allow for the scaled-up production of these polymer additives are complete and new purification methods are in progress. Further development will also focus on maintaining additional properties like coverage and opacity, and testing of additional polymer compositions and particle surface coatings.

Perovskites for Stable, High Activity Solid Oxide Fuel Cell Cathodes and Related Technologies

Using high-throughput computing and informatics to screen thousands of candidates, UW–Madison researchers have identified doped perovskite compounds that exhibit both high catalytic activity and thermodynamic stability under ORR operating conditions. These improvements are believed to enable lower-temperature operation of SOFCs and improve device lifetime.

In total, approximately 1950 distinct perovskite compositions were simulated. The most active predicted compounds were found to contain alloys of transition metals and redox-inactive dopant elements (ex., Zr, Hf, Nb, Re and Ta) that can enhance stability.

Boron- and Nitride-Containing Catalysts for Oxidative Dehydrogenation of Small Alkanes and Oxidative Coupling of Methane

UW–Madison researchers have developed improved ODH catalysts for converting short chain alkanes to desired olefins (e.g., propane to propene and ethene) with unprecedented selectivity (>90 percent).

The new catalysts contain boron and/or nitride and minimize unwanted byproducts including CO and CO2. They contain no precious metals, reduce the required temperature of the reaction and remain active for extended periods of time with no need for costly regenerative treatment.

In addition to driving ODH reactions, the new catalysts can be used to produce ethane or ethene via oxidative coupling of methane (OCM).

Platinum-Free Catalysts for Fuel Cells

UW–Madison researchers have developed a new scheme to improve the efficiency of oxygen reduction reactions in electrochemical cells. Their method combines a redox catalyst with a charge transfer mediator capable of transferring electrons and protons. Careful redox mediator/redox catalyst pairings avoid the need for expensive metal cathodes (or anodes). Favorable pairings include quinones with cobalt or iron-containing redox catalysts, and nitroxyl-type materials paired with nitric oxide-type redox catalysts.

Phosphine Ligands Made Cheaper, Better

UW–Madison researchers have developed methods for synthesizing novel classes of chiral phosphine ligands via enantioselective copper-catalyzed halogenation. The process is rapid and flexible, and also can be used to streamline the preparation of known phosphines.

The researchers previously described their ‘recycling’ method for use with aromatic compounds. Now, they have rendered the process enantioselective using an asymmetric bidentate phosphine ligand to produce scaffolds with high enantiomeric purity.

In essence, the use of the phosphine ligand helps form a chiral center in a complex product that is otherwise costly or impossible to create.

Environmentally Green Glue

UW–Madison researchers have developed a process to transform soy flour into a strong, environmentally safe wood adhesive.

In the process, a suitable reagent is used to phosphorylate the flour’s lysine amino acid residues. The phosphorylated flour then is mixed with an oxidizing agent that drives the formation of cross-linking bonds. This improves the flour’s adhesive properties. Unwanted salts created in the process can be removed.

Flours of other legumes and/or oil seed crops (e.g., flax, canola) are suitable as well.

Two-Step Process Converts Lignin into Simple Aromatic Compounds

Building on their work, the researchers have now developed a two-step process for selectively converting lignin and lignin-type material into low molecular weight aromatic compounds.

The lignin is first selectively oxidized via the previously described method, then reacted with an organic carboxylic acid, salt or ester (e.g., formic acid) for a time and temperature sufficient to cleave carbon-carbon or carbon-oxygen bonds. The process results in high yields of simple aromatic compounds.

Powering Devices with Piezoelectric ‘Sponge’

UW–Madison researchers have developed a thin piezoelectric film that converts ambient vibrations into electrical energy and can be directly integrated onto the surface of a device.

The film is made by dispersing metal oxide or other nanoparticles into a solution of a piezoelectrically active polymer like PVDF (polyvinylidene fluoride). The solution is allowed to dry into a sponge-like layer. The nanoparticles then are etched away or otherwise removed. This leaves a finely porous matrix that can be sandwiched between electrodes to create a nanogenerator.

Transgenic Lignin Easier to Break Down for Biofuel

UW–Madison researchers and others have developed methods to genetically alter the structure of plant lignin to be less resistant to chemical (mostly alkaline) degradation.

They have identified and isolated nucleic acids from the Angelica sinensis plant that encode feruloyl-CoA:monolignol transferase. This enzyme produces lignin rich in CAFA and similar chemicals, and thus contains ester bonds that cleave under relatively mild conditions.

Plant cells can be modified to contain the enzyme gene sequence using standard genetic techniques. Whole plants (and their seeds) then can be generated from these cells.

Biomass-Derived HMF Using Renewable Solvents

UW–Madison researchers have developed a process to convert biomass-derived sugars into HMF, furfural and other downstream chemicals using an organic solvent. In this way, both the sugars and solvent are sourced from renewable feedstock.

Biomass sugars (mostly fructose and glucose) are reacted in a one- or two-phase reaction solution containing water and the organic solvent. This solvent can comprise lactones, furans and pyrans derived from plant matter like starch and cellulose. The reaction is conducted in the presence of acid and dehydration catalysts. Under suitable conditions, a portion of the sugar is converted to HMF.

Moreover, the HMF may be readily separated and upgraded into other chemicals like FDCA (furandicarboxylic acid), which is used to make fiber and packaging polyesters.

Lignin from Transgenic Poplar Is Easier to Process

UW–Madison researchers and others have developed genetically modified poplars with lignin that is less resistant to alkaline degradation.

Having previously identified and isolated the gene for FMT, the researchers introduced the nucleic acid sequence into poplar tissue. The enzyme produced lignin rich in monolignol ferulates, including coniferyl ferulate and sinapyl ferulate. The transformed lignin thus contained ester bonds that cleaved under relatively mild ammonia conditions.

The poplar cells were modified using standard genetic techniques.

A Method of Modifying Lignin to Improve Biomass Utilization

Wisconsin researchers have developed a method of structurally altering lignin by modifying its monomer complement to allow biomass polysaccharides to be more efficiently and sustainably utilized. The method comprises performing a lignin-producing polymerization reaction in the presence of various gallic acid or flavan-3-ol derivatives. Cell walls containing these modified lignins are inherently more fermentable by rumen microflora and can be more readily delignified by mild pretreatments and enzymatically saccharified to sugars for industrial fermentations.

Method and Electrocatalyst to Efficiently Produce Hydrogen Fuel over a Broad, Acidic pH Range

UW-Madison researchers have developed an improved method for generating oxygen and hydrogen with a cobalt-oxide electrocatalyst that uses fluorophosphate or a similar anion electrolyte as the electrolytic buffer in the electrolysis reaction. Using this method, an anode and a cathode are placed in an aqueous solution containing water, a cobalt cation and the anion electrolyte. Then an external source of energy (potentially derived from solar, wind or other renewable energy) drives the electrolysis reaction to generate oxygen and hydrogen. Alternatively, a catalyst containing cobalt, oxygen and the anion electrolyte can be deposited on the anode of the electrochemical cell prior to electrolysis in cobalt-free conditions.

This cobalt-oxide catalyst enables efficient oxidation of water at room temperature over a more favorable pH range. The reduction in overpotential makes it easier and less expensive to split water into hydrogen and oxygen, while the expanded pH range allows water oxidation to be coupled with desirable reactions such as reduction of carbon dioxide at the cathode. In addition, the electrolyte buffers are compatible with conventional materials used in electrochemical cells. The hydrogen gas output of this process can be collected and used as an alternative fuel source or as feedstock for conversion into other fuels or materials. The oxygen gas can be collected, dried and used for any process requiring pure oxygen.

Improved Heat Transfer Fluid Helps Sun Drive Steam Power Plants

UW-Madison researchers have developed a system and method for transferring heat using a variable composition heat transfer fluid that remains liquid over a wide temperature range, up to 500 ºC or above. Typically, low molecular weight fluids stay fluid at low temperatures but evaporate quickly at high temperatures, while high molecular weight fluids stay liquid at high temperatures but solidify at lower temperatures. This new system and method utilizes a heat exchanging fluid comprised of a mixture of a high boiling point, high molecular weight fluid (H), and a low freezing point, low molecular weight fluid (L).

As the combined fluid mixture heats up during the heat exchange process, L evaporates and the vapor is collected in a tank and condensed back into the liquid phase, leaving the heated fluid comprised mostly of H. As the heated H is cooled after heat exchange, the liquid L is added back into the mixture to prevent H from solidifying as it cools. The high boiling point component of the mixture is useful in increasing the boiling point temperature of the heat transfer fluid and lowering the vapor pressure of the heat transfer fluid at high temperatures. The low freezing point component of the mixture is useful in lowering the freezing point temperature of the heat transfer fluid, ensuring that it does not solidify during the temperature cycle.

The system of the invention includes a vessel for containing the heat transfer fluid, a heat source, an outlet for removing some of L as temperature increases during the cycle and an inlet for re-adding L as temperature decreases during the cycle.

Improving Biomass Conversion Efficiency by Modifying Lignin so Plant Cell Walls Are More Digestible and Fermentable

Wisconsin researchers have demonstrated that lignin may be engineered to be more digestible and fermentable by structurally altering the lignin so its monomer complement incorporates coniferyl and/or sinapyl ferulate. This allows biomass polysaccharides to be utilized more efficiently and sustainably, which should reduce inputs for energy, pressure vessel construction and bleaching during papermaking, and lessen pretreatment and enzyme costs associated with biomass conversion.

Producing Methyl Vinyl Ketone from Levulinic Acid

UW–Madison researchers have developed an efficient method to convert levulinic acid to methyl vinyl ketone. The method involves performing a reaction with an aqueous solution comprising levulinic acid over an acid catalyst, preferably a solid acid catalyst, at a temperature from 500 to about 900 Kelvin and without added molecular hydrogen.  The reaction can be performed in either a batch or continuous reactor, although a continuous reactor is preferred. The reaction produces methyl vinyl ketone at higher yields from less expensive starting material compared to current methods.

Method and Electrocatalyst to Efficiently Produce Hydrogen Fuel for Storage of Renewable Energy

UW-Madison researchers have developed an improved catalytic method for generating hydrogen and oxygen gas via water electrolysis. The method uses novel electrocatalysts formed from cobalt, oxygen and fluoride. These unique catalysts result in an electrolysis reaction with a favorable shift in pH tolerance and altered overpotential, making it easier and less expensive to split water into hydrogen and oxygen and providing a more practical means of storing renewable energy.

To drive the electrolysis reactions, electricity can be generated using a renewable energy source such as a solar cell or wind turbine. The hydrogen gas that results from this process can be collected and used as an alternative fuel source for vehicles or other fuel-dependent applications or as a feedstock for conversion into other fuels or materials. The oxygen gas can be collected and used for any process that requires pure oxygen, such as steelmaking.

Low-Temperature, Corrosion-Resistant Integrated Metal Coatings to Improve Efficiency of Coal Plants

UW-Madison researchers have developed an improved method for the low-temperature synthesis of integrated, corrosion-resistant coatings for metal substrates. The low-temperature process avoids the degradation of substrate mechanical properties that occurs in traditional pack cementation processes. The new method also improves upon previous technologies by widening the scope of its application. For example, synthesis of aluminide coatings on steel alloys via low-temperature pack cementation can enhance oxidation resistance in conditions of extreme temperature and moisture, as in high-temperature operation of steam power generation plants. 

In general, the integrated coating consists of the substrate metal, a diffusion-barrier that hinders diffusion of the coating components into the substrate, a corrosion-resistant layer and an oxidation barrier. Deposition of the integrated structure can be achieved via pack cementation at a temperature lower than 700°C, or by thermal spray, vapor deposition or electrodeposition methods.

The substrate, diffusion layer and corrosion-resistant layer can consist of metals, intermetallic compounds or metalloid alloys, depending on the specific application of the integrated structure. For example, a chromium/molybdenum/steel alloy substrate could be coated with an aluminum/iron/intermetallic diffusion-barrier and an aluminum/iron corrosion-resistant layer for use in coal-fired power plants, in which the integrated coating is in contact with supercritical steam. With these techniques, coal-fired power plants can operate at higher temperatures to exploit supercritical steam properties, improving efficiency and reducing overall emissions.

Efficient Method for Pretreating Lignocellulosic Materials to Produce Paper with Improved Properties

UW-Madison researchers now have improved their previous technology by using derivatives of oxalic acid, preferably diethyloxalate (liquid) and dimethyloxalate (solid). These derivatives work better than oxalic acid in the pulping process.  They can be added to the wood chips as dry components and then treated with steam.

Cost-Effective Synthesis of HMF from Fructose

UW-Madison researchers have developed a method for the selective dehydration of carbohydrates (preferably fructose) to produce furan derivatives (preferably HMF).  This new process provides a cost-effective way for making these valuable chemical intermediates, which could replace key petroleum-based building blocks used in production of plastics, fine chemicals, diesel fuel and fuel additives.

The method is more commercially viable than those previously developed because it yields a higher concentration of HMF and produces HMF in a separation-friendly solvent which does not require difficult extraction processes.  The dehydration process employs a two-phase reactor system in which a reactive aqueous phase containing fructose and a chemically modified acid catalyst is contacted with an organic extracting phase modified with a C1-C12 alcohol (preferably 2-butanol).

Non-Inverter-Based Distributed Energy Resource for Use in a Dynamic Distribution System

UW-Madison researchers have developed a method for effective autonomous control of non-inverter based generation in a system that includes other classes of DER units. The method relies on controllers that use local information to regulate rotation of the shaft of the microsource generator. The controller calculates an operating frequency for the generator based on a comparison between a power set point and a measured power flow. A requested speed for the shaft of the generator (prime mover) is calculated by combining a maximum frequency change, a minimum frequency change and the calculated operating frequency. The system then uses this information to calculate a shaft speed adjustment and implements the change by regulating a fuel command for the prime mover. This keeps the AC output voltage at a desired frequency, eliminating the need for a front-end inverter to couple the DC front end and the remaining AC components.

Multi-Mode Liquid Cooling System for Electronics, Including Computers

By mixing together liquid coolants of different volatilities and boiling points, UW-Madison researchers have devised a means to efficiently remove heat from electronics, while avoiding potentially damaging dry-out conditions. In this system, a more volatile coolant of lower boiling point begins to evaporate as it flows over the hot surface. This phase change from liquid to vapor removes heat much more efficiently than can be achieved through simple heating of the liquid. At the same time, a less volatile component in the mixture remains liquid. This keeps the surfaces of electronic circuitry wet at all times, preventing dry-out and associated temperature fluctuations.

Interface Switch for Distributed Energy Resources

UW-Madison researchers have developed an improved interface switch that seamlessly and automatically connects and disconnects a DER microgrid from a utility grid. The interface switch disconnects the DER from the utility grid for protection and power quality events, allowing the cluster of loads and DER to continue to operate as an island. During island conditions, the frequency of the DER microgrid differs from that of the utility. When the conditions that created the islanding are gone, the interface switch exploits this frequency difference to rapidly and seamlessly reconnect the microgrid to the utility.

Plasma Treatment within Dielectric Fluids

UW–Madison researchers have developed a method for producing a plasma discharge in liquids at low temperatures and atmospheric pressure. It shows particular promise for treating gasoline and other liquid fuels to increase combustion efficiency.

In the method, bubbles of gas or vapor are first created within a liquid through mechanical, chemical or other means. Next, the liquid is subjected to an electric field that generates micro-discharges, and thus a plasma state, within the bubbles. Unlike previous techniques aimed at treating liquids by dielectric barrier discharge (DBD) plasma processes, this method produces a very large plasma/liquid interface per unit volume of liquid. This feature is needed to treat the entire liquid volume without causing heating or other unwanted effects.

Using this process, the researchers have shown that octane can be broken down into lower molecular weight compounds of higher burning efficiency. Thus, this technology could potentially be used for in-line treating of gasoline and diesel fuels prior to fuel injection, to increase combustion efficiency and possibly reduce emissions.

Full Coverage Spray and Drainage System for Orientation-independent Removal of High Heat Flux

UW-Madison researchers have developed an improved spray cooling system and method for cooling electronic circuitry in high-performance computers and other similar systems. The method involves directing a spray of cooling fluid onto the surface of a chip at an angle. The cooling fluid then flows in one direction along the circuitry toward the drainage point(s). Directing the spray along the chip with high momentum allows the system to be portable, because a uniform layer of coolant is maintained even when the orientation of the system varies. The cooling fluid is efficiently delivered by several fan-shaped sprays that are positioned to cover the entire heated surface without allowing interaction between the spray plumes that could otherwise lead to coolant buildup and poor heat transfer.

Control of Small, Distributed Energy Resources

UW-Madison researchers have developed a microsource controller that ensures stable operation of a large number of distributed energy resource generators. This cluster of microsources and loads allows for efficient connection to a power system of small, low cost and reliable distributed generators such as microturbines, fuel cells and photovoltaic cells. The system can include a microsource composed of a prime mover, a DC interface and a voltage source inverter; a means for controlling real and reactive power coupled to the microsource; and a means for regulating voltage through droop control to the microsource. Power electronics provide the control and flexibility to ensure stable operation for large numbers of distributed generators.