New Rice Plant

This is an interesting revelation. Simply that there are two types of photosynthesis and that rice uses the inferior method. Thus a combination of uncontroversial bioengineering, insect control and the application of biochar practices could increase production a plausible two fold. This is pretty important because this is done without additional inputs like more fertilizer.

What I cannot emphasize enough is that we are living through the first generation of scientific agriculture. Every improvement is often unprecedented. We are often not that satisfied with results but it is an evolutionary process. It will take a couple more generations to all fully mature.

Thus we see rice culture been industrialized and now been reshaped and reengineered. A hundred years from now one will wonder what all the fuss was about.

New Rice Plant Could Ease Threat Of Hunger For The Poor

http://www.agribusinessweek.com/new-rice-plant-could-ease-threat-of-hunger-for-the-poor/

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An ambitiuos project to re-engineer photosynthesis in rice, led by the International Rice Research Institute (IRRI) through a global consortium of scientists, has received a grant of US$11 million over 3 years from the Bill & Melinda Gates Foundation. As a result o research being conducted by this group, rice plants that can produce 50% more grain using less, fertilizer and less water are a step closer to reality.

Currently, more than a billion people worldwide live on less than a dollar a day and nearly one billion live in hunger. Over the next 50 years, the population of the world will increase by about 50% and water scarcity will grow. About half of the world’s population consumes rice as a staple cereal, so boosting its productivity is crucial to achieving long-term food security. IRRI is leading the effort to achieve a major increase in global rice production by using modem molecular tools to develop a more efficient and higher-yielding form of rice.

Photosynthesis, the process by which plants use solar energy to capture carbon dioxide and convert it into the carbohydrates required for growth, is not the same for all plants. Some species, including rice, have a mode of photo-synthesis (known as C3), in which the capture of carbon dioxide is relatively I inefficient. Other plants, such as maize and sorghum, have evolved a much more efficient form of photosynthesis known as C4.

According to IRRI scientist and project leader Dr. John Sheehy, in tropical climates the efficiency of solar energy conversion of crops using the so-called C4 photosynthesis is about 50% higher than that of C3 crops. Given the demands from an increasing population, combined with less available land and water, adequate future supplies of rice will need to come in large part through substantial yield boosts and more efficient use of crop inputs.

“Converting the photosynthesis of rice from the less-efficient C3 form to the C4 form would increase yields by 50%,” ; said Dr. Sheehy, adding that C4 rice would also use water twice as efficiently. In developing tropical countries, where billions of poor people rely on rice as their staple food, “The benefits of such an improvement in the face of increasing world population, increasing food prices, and decreasing natural resources would, be immense,” he added.

“This is a long-term, complex project that will take a decade or more to complete,” said Dr. Sheehy. “The result of this strategic research has the potential to benefit billions of poor people.”

The C4 Rice Consortium combines the strengths of a range of partners, including molecular biologists, geneticists, physiologists, biochemists, and mathematicians, representing leading research , organizations worldwide. Members include Yale, Cornell, Florida, and Washington State universities in the United States; Oxford, Cambridge, Dundee, Nottingham, and Sheffield universities in Britain; the Commonwealth Scientific and Industrial Research Organization (CSIRO), Australian National University, and James Cook University in Australia; Heinrich Heince University and the Institute for Biology in Germany; Jiangsu Academy in China; the University of Toronto in Canada; and the Food and Agriculture Organizations of the United Nations.

Hydrogen Breakthrough

This is a major development in the hydrogen story. Suddenly we can use solar energy to directly produce both hydrogen and oxygen from water while keeping them separate. Plants are unable to do this because they produce the oxygen by consuming the hydrogen. Up to now, when the question of producing hydrogen came up at all we were treated to a hand wave because we had no satisfactory solution protocols that did not entail huge energy expenditures.

This breakthrough needs a quick work up on a practical production tool, just to get a handle on the practical issues involved. It sounds extremely promising at this point.

The light step is using very little energy to succeed in producing free oxygen that can then be removed. The concentrated hydrogen is liberated by the solution been heated to 100C. so the energetics of the system calls for a solution circulating between room temperature and 100C in concert with a heat exchanger while absorbing sunlight to release the oxygen. It is efficient on paper but sounds a lot like refrigeration.

However, it surely will be massively efficient compared to the cost of electrolysis that has crippled the use of hydrogen from the beginning.

Having a simple and cheap mechanism for the production of both hydrogen and oxygen from water is a huge boon to industrial process. Metallurgy particularly will be revolutionized as pure oxygen substitutes the present regimes. We are going to see factories using this technology to produce the two gases on a massive scale.

Even if we never use hydrogen as a transportation fuel and there is good reason not to, we can use massive amounts in industry itself were transporting the cgas is not an issue.

Unique Approach For Splitting Water Into Hydrogen And Oxygen

http://www.energy-daily.com/reports/Unique_Approach_For_Splitting_Water_Into_Hydrogen_And_Oxygen_999.html

http://www.energy-daily.com/images/hydrogen-bonding-water-h2o-molecule-bg.jpg



The new approach that the Weizmann team has recently devised is divided into a sequence of reactions, which leads to the liberation of hydrogen and oxygen in consecutive thermal- and light-driven steps, mediated by a unique ingredient - a special metal complex that Milstein's team designed in previous studies.


by Staff Writers
Rehovot, Israel (SPX) Apr 07, 2009

The design of efficient systems for splitting water into hydrogen and oxygen, driven by sunlight is among the most important challenges facing science today, underpinning the long term potential of hydrogen as a clean, sustainable fuel.

But man-made systems that exist today are very inefficient and often require additional use of sacrificial chemical agents. In this context, it is important to establish new mechanisms by which water splitting can take place.

Now, a unique approach developed by Prof. David Milstein and colleagues of the Weizmann Institute's Organic Chemistry Department, provides important steps in overcoming this challenge. During this work, the team demonstrated a new mode of bond generation between oxygen atoms and even defined the mechanism by which it takes place.

In fact, it is the generation of oxygen gas by the formation of a bond between two oxygen atoms originating from water molecules that proves to be the bottleneck in the water splitting process. Their results have recently been published in Science.

Nature, by taking a different path, has evolved a very efficient process: photosynthesis - carried out by plants - the source of all oxygen on Earth.

Although there has been significant progress towards the understanding of photosynthesis, just how this system functions remains unclear; vast worldwide efforts have been devoted to the development of artificial photosynthetic systems based on metal complexes that serve as catalysts, with little success. (A catalyst is a substance that is able to increase the rate of a chemical reaction without getting used up.)

The new approach that the Weizmann team has recently devised is divided into a sequence of reactions, which leads to the liberation of hydrogen and oxygen in consecutive thermal- and light-driven steps, mediated by a unique ingredient - a special metal complex that Milstein's team designed in previous studies.

Moreover, the one that they designed - a metal complex of the element ruthenium - is a 'smart' complex in which the metal center and the organic part attached to it cooperate in the cleavage of the water molecule.

The team found that upon mixing this complex with water the bonds between the hydrogen and oxygen atoms break, with one hydrogen atom ending up binding to its organic part, while the remaining hydrogen and oxygen atoms (OH group) bind to its metal center.

This modified version of the complex provides the basis for the next stage of the process: the 'heat stage.' When the water solution is heated to 100 degrees C, hydrogen gas is released from the complex - a potential source of clean fuel - and another OH group is added to the metal center.

'But the most interesting part is the third 'light stage,'' says Milstein. 'When we exposed this third complex to light at room temperature, not only was oxygen gas produced, but the metal complex also reverted back to its original state, which could be recycled for use in further reactions.'

These results are even more remarkable considering that the generation of a bond between two oxygen atoms promoted by a man-made metal complex is a very rare event, and it has been unclear how it can take place. Yet Milstein and his team have also succeeded in identifying an unprecedented mechanism for such a process.

Additional experiments have indicated that during the third stage, light provides the energy required to cause the two OH groups to get together to form hydrogen peroxide (H2O2), which quickly breaks up into oxygen and water. 'Because hydrogen peroxide is considered a relatively unstable molecule, scientists have always disregarded this step, deeming it implausible; but we have shown otherwise,' says Milstein.

Moreover, the team has provided evidence showing that the bond between the two oxygen atoms is generated within a single molecule - not between oxygen atoms residing on separate molecules, as commonly believed - and it comes from a single metal center.

Discovery of an efficient artificial catalyst for the sunlight-driven splitting of water into oxygen and hydrogen is a major goal of renewable clean energy research.

So far, Milstein's team has demonstrated a mechanism for the formation of hydrogen and oxygen from water, without the need for sacrificial chemical agents, through individual steps, using light. For their next study, they plan to combine these stages to create an efficient catalytic system, bringing those in the field of alternative energy an important step closer to realizing this goal.

Participating in the research were former postdoctoral student Stephan Kohl, Ph.D. student Leonid Schwartsburd and technician Yehoshoa Ben-David all of the Organic Chemistry Department, together with staff scientists Lev Weiner, Leonid Konstantinovski, Linda Shimon and Mark Iron of the Chemical Research Support Department.

Prof. David Milstein's research is supported by the Mary and Tom Beck-Canadian Center for Alternative Energy Research; and the Helen and Martin Kimmel Center for Molecular Design. Prof. Milstein is the incumbent of the Israel Matz Professorial Chair of Organic Chemistry.

Quantum Dots In Solar Cells

This is another interesting advance in the solar cell story. We are able to sculpt the active layer and use that geometry to control the behavior of the nanodots that are a promising alteration to solar cell design.

It promises an improvement in the theoretical efficiency of silicon based solar cells.

Again, this is an indication of how we are advancing in terms of fabricating devices to the tolerances needed for nano technology. It is not quite like laying down the structure one atomic layer at a time, but we are beginning to see the next best thing.

There are many research groups focused on the area now and they are all attempting different protocols and all seem to be seeing some semblance of success. Yet this is surely only the beginning. I have already described the type of atomic layering preferred for a magnetic exclusion device. We are close enough to see the mountain tops.

Feb 27, 2009

http://physicsworld.com/cws/article/news/38046

http://physicsworld.com/cws/article/news/38046/1/solar

Quantum dots boost solar cell efficiencies

Dots and wells

Scientists in the UK and US have shown how to increase photovoltaic efficiencies by attaching nanocrystal quantum dots to patterned semiconductor layers. The approach exploits the phenomenon of non-radiative energy transfer and could, say the researchers, lead to a new generation of more efficient solar cells.

Semiconductor solar cells work by using the energy of incoming photons to raise electrons from the semiconductor’s valence band to its conduction band. A potential barrier formed at the junction between p-type and n-type regions of the semiconductor forces the pairs to split up, thereby producing a current.

A solar cell’s performance is measured by its efficiency; in other words how much electrical power it generates for a given incident solar power. Cells consisting of a single p–n junction that are made from bulk semiconductor have a maximum theoretical efficiency of 31% — and the best performing affordable commercial devices are about 18% efficient.

Carrier multiplication

One way in which scientists are trying to overcome this limit is to make cells from billions of tiny pieces of semiconductor known as quantum dots, rather than one large piece of semiconductor, because these can harness light more effectively and can also create multiple carriers from each incoming photon — a process known as “carrier multiplication”.

Unfortunately, carriers in quantum dots are not as mobile as in bulk semiconductors and are usually trapped in crystal impurities. In addition, immobile carriers are attracted by neighbouring carriers of opposite charge and by coupling together they annihilate and emit a photon in exactly the reverse process that created the carriers in the first place.

Pavlos Lagoudakis of Southampton University and colleagues say that they can overcome these problems by combining the light-absorption ability of quantum dots with the current-generating capacity of a bulk semiconductor.

To demonstrate this they etched an array of rectangular channels some 500 nm wide into a layered semiconductor structure. The structure comprised a multiple-quantum-well (MQW) layer sandwiched between a p-type layer and an n-type layer. The MQW itself comprised 20 layers of gallium arsenide, each about 7.5 nm thick.

They then deposited a solution of cadmium-selenium quantum dots, each just a few nanometres across, onto the structure.

Inspired by photosynthesis

The idea, says Lagoudakis, is to take advantage of the “non-radiative energy transfer” used in photosynthesis. The photo-generated carriers within the quantum dots, which are confined within the etched channels, are close enough to the quantum wells that they can exchange energy via a dipole–dipole interaction. “Appropriate engineering of the hybrid device allows for the coupling of the electronic properties of the different components in a way that we get the best properties from each system,” he adds.

To prove that their device was enhancing current output via non-radiative transfer, the researchers also deposited quantum dots onto a substrate without channels. They reasoned that this unpatterned device would not support non-radiative transfer because the photo-generated carriers would be too far apart to interact via dipole–dipole interaction, and that it would therefore produce a much smaller current for a given light input than the patterned device. This is what they found: the patterned device, they report, was six times more efficient than the unpatterned one.

Lagoudakis and colleagues are now designing devices that can combine this feature of non-radiative energy transfer with carrier multiplication by appropriate engineering of the p–n junction and choice of materials for the quantum dots. Such devices, he believes, will exceed the 31% efficiency limit. He admits that these devices would cost more than existing silicon solar cells because the “molecular beam epitaxy” technique used to make the layered structure is expensive. However, he maintains that because the biggest cost in manufacturing solar cells is in fact associated with housing the device, an improvement in efficiency, which would reduce the “active area” of the device, could lead to cheaper solar cells overall.

Thinner and cheaper?

Solar cell developer Martin Green of the University of New South Wales in Australia believes that the research by Lagoudakis’ team is interesting because cells made from quantum dots may prove to be thinner and cheaper than traditional cells. But he cautions that the group may not have chosen the ideal reference device to demonstrate increased photocurrent. He says it would have been better to have used as a reference an identical device but with no quantum dots attached as this should also be more efficient than the unpatterned device.

About the author
Edwin Cartlidge is a science writer based in Rome