By Neil Bowdler, Science reporter, BBC News
23 December 2010 Last updated at 14:11 ETA prototype solar device has been unveiled which mimics plant life, turning the Sun's energy into fuel.
The machine uses the Sun's rays and a metal oxide called ceria to break down carbon dioxide or water into fuels which can be stored and transported.
Conventional photovoltaic panels must use the electricity they generate in situ, and cannot deliver power at night.
Details are published in the journal Science.
The prototype, which was devised by researchers in the US and Switzerland, uses a quartz window and cavity to concentrate sunlight into a cylinder lined with cerium oxide, also known as ceria.
Ceria has a natural propensity to exhale oxygen as it heats up and inhale it as it cools down.
If as in the prototype, carbon dioxide and/or water are pumped into the vessel, the ceria will rapidly strip the oxygen from them as it cools, creating hydrogen and/or carbon monoxide.
Hydrogen produced could be used to fuel hydrogen fuel cells in cars, for example, while a combination of hydrogen and carbon monoxide can be used to create "syngas" for fuel. …
The prototype is grossly inefficient, the fuel created harnessing only between 0.7% and 0.8% of the solar energy taken into the vessel.
Most of the energy is lost through heat loss through the reactor's wall or through the re-radiation of sunlight back through the device's aperture.
But the researchers are confident that efficiency rates of up to 19% can be achieved through better insulation and smaller apertures. Such efficiency rates, they say, could make for a viable commercial device. …
Saturday, December 25, 2010
New solar fuel machine ‘mimics plant life’
Sunday, April 11, 2010
MIT researchers harness viruses to split water
Crucial step toward turning water into hydrogen fuel
CAMBRIDGE, Mass. -- A team of MIT researchers has found a novel way to mimic the process by which plants use the power of sunlight to split water and make chemical fuel to power their growth. In this case, the team used a modified virus as a kind of biological scaffold that can assemble the nanoscale components needed to split a water molecule into hydrogen and oxygen atoms.
Splitting water is one way to solve the basic problem of solar energy: It's only available when the sun shines. By using sunlight to make hydrogen from water, the hydrogen can then be stored and used at any time to generate electricity using a fuel cell, or to make liquid fuels (or be used directly) for cars and trucks.
Other researchers have made systems that use electricity, which can be provided by solar panels, to split water molecules, but the new biologically based system skips the intermediate steps and uses sunlight to power the reaction directly. The advance is described in a paper published on April 11 in Nature Nanotechnology.
The team, led by Angela Belcher, the Germeshausen Professor of Materials Science and Engineering and Biological Engineering, engineered a common, harmless bacterial virus called M13 so that it would attract and bind with molecules of a catalyst (the team used iridium oxide) and a biological pigment (zinc porphyrins). The viruses became wire-like devices that could very efficiently split the oxygen from water molecules.
Over time, however, the virus-wires would clump together and lose their effectiveness, so the researchers added an extra step: encapsulating them in a microgel matrix, so they maintained their uniform arrangement and kept their stability and efficiency.
While hydrogen obtained from water is the gas that would be used as a fuel, the splitting of oxygen from water is the more technically challenging "half-reaction" in the process, Belcher explains, so her team focused on this part. Plants and cyanobacteria (also called blue-green algae), she says, "have evolved highly organized photosynthetic systems for the efficient oxidation of water." Other researchers have tried to use the photosynthetic parts of plants directly for harnessing sunlight, but these materials can have structural stability issues.
Belcher decided that instead of borrowing plants' components, she would borrow their methods. In plant cells, natural pigments are used to absorb sunlight, while catalysts then promote the water-splitting reaction. That's the process Belcher and her team, including doctoral student Yoon Sung Nam, the lead author of the new paper, decided to imitate.
In the team's system, the viruses simply act as a kind of scaffolding, causing the pigments and catalysts to line up with the right kind of spacing to trigger the water-splitting reaction. The role of the pigments is "to act as an antenna to capture the light," Belcher explains, "and then transfer the energy down the length of the virus, like a wire. The virus is a very efficient harvester of light, with these porphyrins attached.
"We use components people have used before," she adds, "but we use biology to organize them for us, so you get better efficiency." …
Thursday, February 11, 2010
Sun-powered water splitter makes hydrogen tirelessly
Nanoscale dots can absorb sunlight and release hydrogen from water, without damage from bleaching
13:59 11 February 2010 by Colin Barras
Sunlight + water = hydrogen gas, in a new technique that can convert 60 per cent of sunlight energy absorbed by an electrode into the inflammable fuel.
To generate the gas Thomas Nann and colleagues at the University of East Anglia in Norwich, UK, dip a gold electrode with a special coating into water and expose it to light. clusters of indium phosphide 5 nanometres wide on its surface absorb incoming photons and pass electrons bearing their energy on to clusters of a sulphurous iron compound.
This material combines those electrons with protons from the water to form gaseous hydrogen. A second electrode – plain platinum this time – is needed to complete the circuit electrochemically.
Organic molecules have been used before to perform the same feat. But they are quickly bleached by the sunlight they are collecting, rendering them inefficient after a few weeks.
The inorganic materials used in the University of East Anglia's system are more resilient. Their first generation proof of concept is "a major breakthrough" in the field, they say, thanks to its efficiency of over 60 per cent and ability to survive sunlight for two weeks without any degradation of performance.
"In fact the 60 per cent figure is probably a worst-case scenario," says Nann. "This is still a preliminary study." …
Wednesday, June 10, 2009
Who killed the hydrogen-powered car?
Energy density or transportation problems didn’t kill hydrogen. What killed it is the deliverable amount of energy to the wheels of a vehicle compared to a battery solution. This is why we won't be seeing hydrogen-powered cars from Toyota (TM), Honda (HMC), or Ford (F).
The table below needs a little explanation. It starts with 100 kilowatts of electricity from renewable sources -- solar or wind for example. It then compares the steps required to get the electrical energy stored on a vehicle as either hydrogen or batteries. During each step, energy is lost -- generally as heat -- until electric power is driving the electric motors on a hydrogen fuel cell vehicle or a battery-powered vehicle. Each step shows the percentage efficiency and the remaining energy left after each step. …
Who Killed the Hydrogen-Powered Car?
Sunday, April 26, 2009
Mazda delivers hydrogen-powered RX-8 RE to Norway
Could That Guy Look Any Less Excited to be Getting a Hydrogen Car?
Mazda has delivered the second hydrogen RX8, but the first one to have Norwegian-specs, to the Norwegian government. 29 others are to follow and will be used in HyNor, a government-backed national hydrogen project. This particular hydrogen RX8 RE will in ceremonies and media events on May 11th when the country's hydrogen refueling stations officially open. Read on for more details on HyNor and Mazda's hydrogen RX8 RE....
Mazda Delivers Hydrogen-Powered RX-8 RE to Norway
Friday, March 27, 2009
MIT Professor: Power your house with 5 liters of water per day
At the Aspen Environment Forum today, MIT professor Dan Nocera gave a revolutionary picture of the new energy economy with an assertion that our homes will be our power plants and our fuel stations, powered by sunlight and water. And it’s not science fiction.
Nocera stated that even if we put all available acreage into fuel crops, all available acreage in wind power, and build a new nuclear power plant every 1.5 days, and we save 100% of our current energy use (yes, you read that correctly), we will still come up short by 2050. His estimate is that we will need 16 TW of energy production by then, and with our current methods, we won’t get there.
But there is a solution. And we don’t need to invent anything new to get from here to there.
Nocera said that MIT will announce its patent next week of a cheap, efficient, manufacturable electrolyzer made from cobalt and potassium phosphate. This technology, powered by a 6 meter by 5 meter photovoltaic array on the roof, is capable of powering an entire house’s power needs plus a fuel cell good for 500 km of travel, with just 5 liters of water. …
MIT Professor: Power Your House With 5 Liters of Water Per Day
Thursday, February 12, 2009
Hydrogen fuel recipe ‘like Prometheus stealing fire’
A group of US researchers say they’ve developed a “one-pot” process for generating hydrogen fuel from cellulosic plant waste, water and a cocktail of enzymes.
The “recipe” produces hydrogen gas that’s pure enough to power a fuel cell, says the team of scientists from Virginia Tech, Oak Ridge National Laboratory (ORNL) and the University of Georgia.
The novel process combines 14 enzymes and one coenzyme with non-food-based plant waste and 32-degree C water. The result: hydrogen production as fast as that yielded by natural hydrogen fermentation and an output of chemical energy that’s actually greater than the chemical energy stored in the plant-based sugars themselves. The combination, the research team says, produces the highest reported hydrogen yield yet from cellulosic materials.
“In addition to converting the chemical energy from the sugar, the process also converts the low-temperature thermal energy into high-quality hydrogen energy — like Prometheus stealing fire,” said Percival Zhang, assistant professor of biological systems engineering in the College of Agriculture and Life Sciences at Virginia Tech. “If a small fraction — 2 or 3 percent — of yearly biomass production were used for sugar-to-hydrogen fuel cells for transportation, we could reach (global) transportation fuel independence.”
Hydrogen fuel recipe ‘like Prometheus stealing fire’
Tuesday, January 6, 2009
Omnivorous fuel cells
A prototype fuel cell runs on a wide range of fuels without turning up the heat.
Fuel cells are the most efficient way to convert chemical energy into electricity. But most either operate at high temperatures or require very pure hydrogen fuel. Superprotonic, a startup company in Pasadena, CA, is developing a fuel cell that can handle dirty hydrogen at relatively low temperatures. It could thus use hydrogen produced from other fuels--such as natural gas or ethanol--by a simple device called a "reformer."
In a fuel cell, an electrolyte is sandwiched between an anode and a cathode. A catalyst at the anode splits hydrogen into electrons and protons. The protons can pass through the electrolyte, but the electrons can't. So in order to reach the cathode, the electrons travel through an external electrical circuit, where they can be used to recharge a battery or power a device. At the cathode, another catalyst helps the protons and electrons combine with oxygen sucked from the air to form water--the fuel cell's only waste product.
Superprotonic's fuel cells rely on a material called a solid acid, first tested as an electrolyte in 2001 by Caltech materials-science and chemical-engineering professor Sossina Haile. "What makes our fuel cell special is the nature of this electrolyte," she says. Solid-acid fuel cells operate at what Haile calls a Goldilocks temperature: not too hot, not too cold.
Omnivorous Fuel Cells
Tue, 06 Jan 2009 05:00:00 GMT
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