Yulia Pushkar, a Purdue assistant professor of physics involved in the research said, “The proteins we study are part of the most efficient system ever built, capable of converting the energy from the sun into chemical energy with an unrivaled 60 percent efficiency. Understanding this system is indispensable for alternative energy research aiming to create artificial photosynthesis.”
The process by which plants convert the sun’s energy into carbohydrates is used to power the cellular processes. During photosynthesis plants use solar energy to convert carbon dioxide and water into hydrogen-storing carbohydrates and oxygen. Artificial photosynthesis could allow for the conversion of solar energy into renewable, environmentally friendly hydrogen-based fuels.
In Pushkar’s laboratory, students extract a protein complex called Photosystem II from spinach they buy at the supermarket. It is a complicated process performed over two days in a specially built room that keeps the spinach samples cold and shielded from light, she said.
Once the proteins have been carefully extracted, the team excites them with a laser and records changes in the electron configuration of their molecules.
“These proteins require light to work, so the laser acts as the sun in this experiment,” Pushkar said. “Once the proteins start working, we use advanced techniques like electron paramagnetic resonance and X-ray spectroscopy to observe how the electronic structure of the molecules change over time as they perform their functions.”
The idea is to figure out how Photosystem II is involved in the photosynthetic mechanism that splits water molecules into oxygen, protons and electrons. During this process a portion of the protein complex, called the oxygen-evolving complex, cycles through five states in which four electrons are extracted from it, Pushkar said.
Petra Fromme, professor of chemistry and biochemistry at Arizona State University, leads the international team that recently revealed the structure of the first and third states at a resolution of 5 and 5.5 Angstroms, respectively, using a new technique called serial femtosecond crystallography. A paper detailing the results was published in Nature and is available online.
In addition to Pushkar, Purdue postdoctoral researcher Lifen Yan and former Purdue graduate student Katherine Davis participated in the study and are paper co-authors.
Fromme explained in a statement, “The trick is to use the world’s most powerful X-ray laser, named LCLS, located at the Department of Energy’s SLAC National Accelerator Laboratory. Extremely fast femtosecond (one-quadrillionth of a second) laser pulses record snapshots of the PSII crystals before they explode in the X-ray beam, a principle called ‘diffraction before destruction.’”
While X-ray crystallography reveals structural changes, it does not provide details of how the electronic configurations evolve over time, which is where the Purdue team’s work came in. The Purdue team mimicked the conditions of the serial femtosecond crystallography experiment, but used electron paramagnetic resonance to reveal the electronic configurations of the molecules, Pushkar said.
“The electronic configurations are used to confirm what stage of the process Photosystem II is in at a given time,” she said. “This information is kind of like a time stamp and without it the team wouldn’t have been able to put the structural changes in context.”
The Arizona State University (ASU) press release hints that the team will get to a moving picture over time. The study that shows the first snapshots of photosynthesis in action as it splits water into protons, electrons and oxygen – the process that maintains Earth’s oxygen atmosphere.
The revealing of the mechanism of this water splitting process is essential for the development of artificial systems that mimic and surpass the efficiency of natural systems. The development of an “artificial leaf” is one of the major goals of the ASU Center for Bio-Inspired Solar Fuel Production, which was the main supporter of this study.
ASU Regents’ Professor Devens Gust in a connected paraphrase sums up, “A crucial problem is discovering an efficient, inexpensive catalyst for oxidizing water to oxygen gas, hydrogen ions and electrons. Photosynthetic organisms already know how to do this, and we need to know the details of how photosynthesis carries out the process using abundant manganese and calcium. The research gives us a look at how the catalyst changes its structure while it is working. Once the mechanism of photosynthetic water oxidation is understood, chemists can begin to design artificial photosynthetic catalysts that will allow them to produce useful fuels using sunlight.”
Its known that in photosynthesis, oxygen is produced at a special metal site containing four manganese atoms and one calcium atom, connected together as a metal cluster. This oxygen-evolving cluster is bound to the protein Photosystem II that catalyzes the light-driven process of water splitting. It requires four light flashes to extract one molecule of oxygen from two water molecules bound to the metal cluster.
The ultimate goal of the work is to record molecular movies of water splitting.
For now the researchers discovered large structural changes of the protein and the metal cluster that catalyzes the reaction. The cluster significantly elongates, thereby making room for a water molecule to move in.
Its a large team that is getting to the point they understand what is happening at the level of atoms inside the molecule. Its only a matter of time until a protein can be made to accomplish the job in an artificial way.
July 23, 2014 | 1 Comment
Shanhui Fan, an electrical engineering professor at Stanford University in California has found a way to let photovoltaic solar cells cool themselves by shepherding away unwanted thermal radiation. By adding a specially patterned layer of silica glass to the surface of ordinary solar cells, a team of researchers may have overcome one of the major hurdles in developing high-efficiency, long-lasting solar cells – keeping them cool, even in the blistering heat of the noonday sun.
Photovoltaic solar cells are among the most promising and widely used renewable energy technologies on the market today. Though readily available and easily manufactured, even the best designs convert only a fraction of the energy they receive from the sun into usable electricity. Part of this loss is the unavoidable consequence of converting sunlight into electricity. A surprisingly vexing amount, however, is due to solar cells overheating.
Under normal operating conditions, solar cells can easily reach temperatures of 130 degrees Fahrenheit (55 degrees Celsius) or more. These harsh conditions quickly sap efficiency and can markedly shorten the lifespan of a solar cell. Actively cooling solar cells, however – either by ventilation or coolants – would be prohibitively expensive and at odds with the need to optimize exposure to the sun.
The newly proposed design avoids these problems by taking a more elegant, passive approach to cooling. By embedding tiny pyramid- and cone-shaped structures on an incredibly thin layer of silica glass, the researchers found a way of redirecting unwanted heat arriving in the form of infrared radiation from the surface of solar cells, through the atmosphere, and back into space.
“Our new approach can lower the operating temperature of solar cells passively, improving energy conversion efficiency significantly and increasing the life expectancy of solar cells,” said Linxiao Zhu, a physicist at Stanford and lead author on the Optica paper. “These two benefits should enable the continued success and adoption of solar cell technology.”
Solar cells work by directly converting the sun’s rays into electrical energy. As photons of light pass into the semiconductor regions of the solar cells, they knock off electrons from the atoms, allowing electricity to flow freely, creating a current. The most successful and widely used designs, silicon semiconductors, however, convert less than 30 percent of the energy they receive from the sun into electricity – even at peak efficiency.
The solar energy that is not converted generates waste heat, which inexorably lessens a solar cell’s performance. For every one-degree Celsius (1.8 degree F) increase in temperature, the efficiency of a solar cell declines by about half a percent.
“That decline is very significant,” said Aaswath Raman, a postdoctoral scholar at Stanford and co-author on the paper. “The solar cell industry invests significant amounts of capital to generate improvements in efficiency. Our method of carefully altering the layers that cover and enclose the solar cell can improve the efficiency of any underlying solar cell. This makes the design particularly relevant and important.”
Additionally, solar cells “age” more rapidly when their temperatures increase, with the rate of aging doubling for every increase of 18 degrees Fahrenheit.
To passively cool the solar cells, allowing them to give off excess heat without spending energy doing so, requires exploiting the basic properties of light as well as a special infrared “window” through Earth’s atmosphere.
Different wavelengths of light interact with solar cells in very different ways – with visible light being the most efficient at generating electricity while infrared is more efficient at carrying heat. Different wavelengths also bend and refract differently, depending on the type and shape of the material they pass through.
The researchers harnessed these basic principles to allow visible light to pass through the added silica layer unimpeded while enhancing the amount of energy that is able to be carried away from the solar cells at thermal wavelengths.
“Silica is transparent to visible light, but it is also possible to fine-tune how it bends and refracts light of very specific wavelengths,” said Fan, who is the corresponding author on the Optica paper. “A carefully designed layer of silica would not degrade the performance of the solar cell but it would enhance radiation at the predetermined thermal wavelengths to send the solar cell’s heat away more effectively.”
To test their idea, the researchers compared two different silica covering designs: one a flat surface approximately 5 millimeters thick and the other a thinner layer covered with pyramids and micro-cones just a few microns (one-thousandth of a millimeter) thick in any dimension. The size of these features was essential. By precisely controlling the width and height of the pyramids and micro-cones, they could be tuned to refract and redirect only the unwanted infrared wavelengths away from the solar cell and back out into space.
“The goal was to lower the operating temperature of the solar cell while maintaining its solar absorption,” said Fan. “We were quite pleased to see that while the flat layer of silica provided some passive cooling, the patterned layer of silica considerably outperforms the 5 mm-thick uniform silica design, and has nearly identical performance as the ideal scheme.”
Zhu and his colleagues are currently fabricating these devices and performing experimental tests on their design. Their next step is to demonstrate radiative cooling of solar cells in an outdoor environment. “We think that this work addresses an important technological problem in the operation and optimization of solar cells,” he concluded, “and thus has substantial commercialization potential.”
This is worthwhile good news. Most photovoltaic buyers aren’t aware of the lifespan of their new cells. If nothing else should this technology get to market the importance of cell longevity will have a more prominent role in photovoltaic selection.
Researchers at the University of Twente have developed a simple new catalyst that improves the quality of bio oil. The bio oil they have in mind comes from wood chips or plant residues, which seldom has the same quality and energy content as fossil sourced crude oil. The new catalyst upgrades the bio oil closer to the crude oil standards for refineries.
The idea in Europe is to source fuel destined bio oil not from fruits or seeds, such as palm or rape seed oil, but from plant residues, pruning waste and wood chips, resulting in no competition with the food supply.
Converting plant residues, which take up a lot of space, into oil simplifies transport considerably and the product can go directly to an oil refinery. Blending with crude oil is already possible. However, the quality of this oil does not yet equal that of crude oil. Residue bio oil has a lower energy content per liter, is acid and still contains too much water.
The catalyst developed by Prof. Leon Lefferts and Prof. Kulathuiyer Seshan’s group Catalytic Processes and Materials (MESA+ Institute for Nanotechnology/Green Energy Initiative) significantly improves the quality and energy content of the oil.
The researchers believe the new bio oil product can be better than crude oil.
The new product is made by heating the oil in nitrogen to 500 degrees Celsius and by applying a simple catalyst: sodium carbonate on a layer of alumina. When using this method, the energy content of the bio oil can be boosted from 20 to 33-37 megajoule per kilogram, which is better than crude oil and approximates the quality of diesel.
The technology, recently defended by PhD candidate Masoud Zabeti, is already being tested by KIOR in Texas, USA, on a small industrial scale, with a production of 4,500 barrels of oil per day. The quality of the oil can be improved even more by adding the material caesium, as well as sodium carbonate. “By doing so, we can, for instance, also reduce the aromatics, which are harmful when inhaled,” says Prof. Seshan.
The technology is currently being further studied, in cooperation with the University of Groningen, the Energy research Centre of the Netherlands (ECN) and Utrecht University, in a new CATCHBIO program of the Netherlands Organization for Scientific Research (NWO). The Netherlands is committed to leading the way in research on technology that will help realize the European 2020 fuel objective.
This is a technology much further along than the press release notes. A pilot demonstration at small commercial scale running 4,500 barrels per day is no small feat in today’s circumstances.
What we don’t know are the costs and processes involved to get the raw materials to an oil product and the kind and condition of the waste materials the process chain produces. But, the dream of oil sourced from current plant growth is alive and the new catalyst looks like a major improvement.
July 17, 2014 | 5 Comments
Dr. Randall Mills of Blacklight Power plans a demonstration a power production device that is expected to produce 10 MW of power in a one cubic foot sized module.
The Blacklight Power announcement hasn’t garnered a huge following, but there is good cause to watch and encourage the enterprise’s continued efforts. Dr. Mills is without doubt an accomplished academic with impressive skills. His curiosity has taken him to highly controversial fields and, if his ideas are taken solemnly, may well introduce us to a new scientific field. His controversy is based in a new form of hydrogen that has been made into “hydrinos”.
By Dr. Mills estimation, the hydrino is a discovery with immense potential for the future. So far, Dr, Mills has managed to involve some power producers and set up some future sales.
In lay terms Dr. Mills is remaking the hydrogen atom into a hydrino and using the hydrino for power production activities. For decades the theory Dr, Mills had worked out has been investigated to seek the engineering means to take what is nearly free, the hydrogen in water and returning a valuable power source.
This year has seen Blacklight post videos that are admittedly deep in expertise that will leave most folks bewildered. The net result to date is Blacklight has figured out how to extract hydrogen, make the hydrinos, create a sold fuel from them and ignite them into a vigorous plasma ball.
The plasma ignition itself offers a considerable blast of energy in heat and light. The Blacklight team has been working at feeding the plasma into a magnetohydrodyamic converter, then directly into electricity, in a clean and safe way. This effort entails some significant challenges that are yet to be fully met.
The Blacklight folks came to realize that the greatest energy output of the process comes in the form of intense light. That adds the potential for using photovoltaic solar cells as a way to harvest the plasma’s energy output. Some of the photovoltaic cell research has been directed to concentrated solar energy where 100s and even 1000s of times the power of the sun are delivered to photocells.
The light to photocell harvest looks like it may be enough to self drive the module with extra energy to use outside the module system. The only input would be water.
Naturally there are estimates and claims, most of which are simply not going to work out. Some will be close, others just left behind. But a few are very interesting.
In the money segment Dr. Mills’ idea might supercede and obsolete nuclear power in both the fission and fusion fields. As well as crush the need for most fuels. If the capital cost estimates are even remotely close, with approximately $100/kW suggested, capital for electrical power would drop by 90%. The price of power at the module would be $0.001 per kwh (10th of a cent per kilowatt hour).
Nothing else comes anywhere close to that.
The mechanical segment looks very challenging. Its an enormous amount of energy in a very small space. Plasma is basically electrons and positively charged ions that is going to dissipate no matter what. Capturing all of it and rendering it to useful power isn’t going to be easy or low cost. Letting it get away uncontrolled would be a serious mechanical problem. It would be like a huge welding arc bouncing around looking for a way to ground out.
On the other hand plasma is rather nice. The energy is in the zone of the infrared that’s useful as heat on up to the ultraviolet in the photovoltaic region. Plasma offers very little harmful radiation and no radioactivity. The determined paranoid folks are going have problems worrying about this kind of technology.
Naturally the main question for now is Blacklight for real? For many in the physics field the answer is no. But Dr. Mills is a formidable intelligence. Much of what he’s offered seems to be coming to fruition. Blacklight is getting funded and you can be sure that the investors are getting an inside view none of us are ever going to see.
With many hours over the years invested in observing and trying to understand what Dr. Mills is proposing your humble writer on principle accepts the hydrino theory subject to experimentation. So far third party experimentation has been lacking. For proprietary reasons and academic intransigence, that is understandable.
That leaves it up to the investors. There has been a lot of money put on the line by no fools. It would be no surprise to see a working device for sale in the coming years.
It will take longer than expected. The device, now named the “SunCell” has some major engineering and design matters to work out.
Blacklight has Dr. Randall Mills leading it and that one fact suggests that someday there will be Blacklight Power units in use.
A University of Wisconsin team led by Professor Rolf Reitz has designed a hybrid fueled engine using both diesel fuel and gasoline that is 59.5% efficient. Chemical efficiency at 59.5% is far better than gasoline engines and 10 to 15% better than the 52% maximum in modern diesel truck engines.
Professor Reitz is one to watch, he wants to push the limits of efficiency. “Our study demonstrated 59.5% efficiency in a truck-size engine. The theoretical efficiency is 64%, so we have reached 95% of the theoretical maximum,” he said. “But why is that theoretical level there? What would it take to make it even higher?”
The one-cylinder test engine in the basement of a University of Wisconsin-Madison lab is connected to a support system of pipes, tubes, ducts and cables. New engine technologies are frequently developed in one-cylinder engines like this one. For now professor Reitz’s team has the most efficient diesel in the engine-research world.
But the test engine is not strictly speaking a diesel engine. Instead, it burns diesel and gasoline in a ratio that is precisely controlled to exploit each fuel’s strong points. Sensors and a computer can vary the mixture with split-second timing, creating an engine that runs much cooler than conventional gas or diesel engines. That temperature reduction is key to efficiency, because less heat is lost to the engine block and the radiator, Reitz said.
He calls the system reactivity controlled compression ignition, or RCCI. A group of students in the Engine Research Center on campus have just installed an engine using these principles into an electric hybrid version of a 2009 Saturn, and have begun road tests.
“Putting this in the test car was a major project. It’s amazing that a bunch of students could do this and make it work,” says Reitz. “I worked for six years at GM, and hundreds of engineers would be needed for a project like this.”
Road tests will expand on results from the lab, he says, adding, “The engine has a lot of controls, so when you put your foot on the gas, we automatically change the amount of diesel and gasoline to optimize the combustion process. We can blend the correct dosage on a cycle-by-cycle basis.”
The engine uses readily available diesel and gasoline, but Reitz’s group has also experimented with additives that bring similar advantages in much smaller quantities. The RCCI technology could be used in a wide range of engines for automobiles, heavy-duty trucks and buses, off-road vehicles, locomotives, generators and even ships. The technology was funded by the Department of Energy and other organizations. Patents have been assigned to the Wisconsin Alumni Research Foundation, which is handling licensing.
It gets better, high efficiency is only one benefit of the RCCI system.
To burn cleanly, conventional diesel engines pressurize the injected fuel up to 3,000 times atmospheric pressure. The RCCI system, working at 300 atmospheres, offers a major cost saving.
The high temperature operation of conventional gasoline and diesel engines forms nitrogen oxides, the key source of smog. “With the low-combustion temperature, we produce insignificant amounts of nitrogen oxides,” Reitz said. “And if you can run with the ideal mix between fuel and air, you don’t have regions in the combustion chamber that make soot. Soot and nitrogen oxides – the two biggest problems for diesel – are eliminated.”
Research in this area has a lot of attention. In an over-the-road truck, an exhaust-treatment system that meets current emissions standards costs as much as the engine itself, he said, explaining, “It’s a complicated system, and it has to work in Alaska and the desert.” Much of that system would be superfluous in the RCCI system.
Pollution reduction, in fact, was the starting point for the discovery of RCCI. In 2007, Reitz began writing computer code to model the many parameters of an internal-combustion engine. “You can change the shape of the combustion chamber, the injection pressure, the number of pulses, how much fuel is in each pulse, the orientation of the injectors, and on and on. The result is a phenomenally complex computation,” he said. “To model the combustion process in a single cycle in one cylinder takes a day on a computer. We use a network of 4,000 computers on campus to run many of these configurations.”
Borrowing a technique from biology, Reitz’s group modifies the best-performing combinations in the constant quest for improvement. “Eventually, what evolves is things your brain could never conceptualize,” he said.
Reitz seems to have a firm grip on reality and a solid sense of how things work in the engine business. Proving that a great idea works will not guarantee its adoption, Reitz realizes, and so he has made the results known to the 30 members of the Direct-Injection Engine Research Consortium. He said continued pressure to reduce fuel usage, greenhouse gases and other pollutants “could lead manufacturers to look at alternative combustion strategies. My approach is to make it as widely known as possible, and see where it goes.”
A little PR work can only help.
Meanwhile, Sage Kokjohn, an assistant professor of mechanical engineering, worked on RCCI as a graduate student under Reitz said that although using two fuels seems revolutionary, it’s an extension of current trends. “We are seeing a merging of gasoline and diesel; gasoline engines now have a higher compression ratio, are direct-injected and are often boosted with a turbocharger – all techniques that have been associated with diesel. And diesel is starting to use a lower compression ratio, more like gasoline. So I think this is a logical step. It’s not a huge change compared to where they are already going.”
The team did a very good job getting the press release written, but leaving virtually all the details out yet leaving readers with the sense they know what is going on. Its a sure thing an engine manufacturer can get explicit information with little effort.
What we know is the RCCI isn’t a fuel blend such as adding ethanol, methanol or even mixing diesel and gasoline. The engine seems to be using two injection sets with sensors and computer programming to precisely fuel the air charge appropriate for the power demand.
Professor Reitz may have broken open a new field. There are a lot of fuels ranging from methanol up to bunker fuel that could be explored. With such high efficiency in gasoline and diesel there is a huge incentive to look at other combinations.