Archive for the ‘Express 104’ Category

Electrified Plants from Stanford; Grid-scale Batteries from MIT

Posted by admin on April 14, 2010
Posted under Express 104

Electrified Plants from Stanford; Grid-scale Batteries from MIT

In an electrifying first, Stanford scientists have plugged into algae cells to harness a tiny electric current that could be a first step toward generating “high efficiency” bioelectricity that doesn’t give off CO2 as a by product, while at MIT researchers have come up with a battery able to match the output of those used in cellphones from 1/20th of their electrode area. Its inventors hope it will provide much-needed storage capacity for electricity grids.

Released by Stanford University (13 April 2010):

Stanford researchers find electrical current stemming from plants

In an electrifying first, Stanford scientists have plugged in to algae cells and harnessed a tiny electric current. They found it at the very source of energy production – photosynthesis, a plant’s method of converting sunlight to chemical energy. It may be a first step toward generating “high efficiency” bioelectricity that doesn’t give off carbon dioxide as a byproduct, the researchers say.

“We believe we are the first to extract electrons out of living plant cells,” said WonHyoung Ryu, the lead author of the paper published in the March issue of Nano Letters. Ryu conducted the experiments while he was a research associate for mechanical engineering professor Fritz Prinz.

The Stanford research team developed a unique, ultra-sharp nanoelectrode made of gold, specially designed for probing inside cells. They gently pushed it through the algal cell membranes, which sealed around it, and the cell stayed alive. From the photosynthesizing cells, the electrode collected electrons that had been energized by light and the researchers generated a tiny electric current.

“We’re still in the scientific stages of the research,” said Ryu. “We were dealing with single cells to prove we can harvest the electrons.”

Plants use photosynthesis to convert light energy to chemical energy, which is stored in the bonds of sugars they use for food. The process takes place in chloroplasts, the cellular powerhouses that make sugars and give leaves and algae their green color. In the chloroplasts, water is split into oxygen, protons and electrons. Sunlight penetrates the chloroplast and zaps the electrons to a high energy level, and a protein promptly grabs them. The electrons are passed down a series of proteins, which successively capture more and more of the electrons’ energy to synthesize sugars until all the electron’s energy is spent.

In this experiment, the researchers intercepted the electrons just after they had been excited by light and were at their highest energy levels. They placed the gold electrodes in the chloroplasts of algae cells, and siphoned off the electrons to generate the tiny electrical current.

The result, the researchers say, is electricity production that doesn’t release carbon into the atmosphere. The only byproducts of photosynthesis are protons and oxygen.

“This is potentially one of the cleanest energy sources for energy generation,” Ryu said. “But the question is, is it economically feasible?”

Ryu said they were able to draw from each cell just one picoampere, an amount of electricity so tiny that they would need a trillion cells photosynthesizing for one hour just to equal the amount of energy stored in a AA battery. In addition, the cells die after an hour. Ryu said tiny leaks in the membrane around the electrode could be killing the cells, or they may be dying because they’re losing out on energy they would normally use for their own life processes. One of the next steps would be to tweak the design of the electrode to extend the life of the cell, Ryu said.

Harvesting electrons this way would be more efficient than burning biofuels, as most plants that are burned for fuel ultimately store only about 3 to 6 percent of available solar energy, Ryu said. His process bypasses the need for combustion, which only harnesses a portion of a plant’s stored energy. Electron harvesting in this study was about 20 percent efficient. Ryu said it could theoretically reach 100 percent efficiency one day. (Photovoltaic solar cells are currently about 20-40-percent efficient.)

Possible next steps would be to use a plant with larger chloroplasts for a larger collecting area, and a bigger electrode that could capture more electrons. With a longer-lived plant and better collecting ability, they could scale up the process, Ryu said. Ryu is now a professor at Yonsei University in Seoul, South Korea.

Other authors of the paper are Prinz, the senior author,; Seoung-Jai Bai, Tibor Fabian, Rainer J. Fasching, Joong Sun Park, and Zubin Huang, all researchers in the Rapid Protoyping Laboratory at Stanford University; and Jeffrey Moseley and Arthur Grossman, both researchers in the Department of Plant Biology at the Carnegie Institution and Department of Biological Sciences.


By David C. Holzman in New Scientist (9 April 2010):

A BATTERY able to match the output of those used in cellphones from 1/20th of their electrode area may have you dreaming of more talk time.

But putting it in your pocket would be a bad idea – it’s full of molten metal. Instead, its inventors hope it will provide much-needed storage capacity for electricity grids.

Grid-scale batteries would boost efficiency by allowing solar energy to be used at night, for example, or excess power from a nuclear plant to be stored for later.

Engineers led by Donald Sadoway at the Massachusetts Institute of Technology were inspired by the way aluminium is smelted using electricity. They created a similar but reversible process that can either consume or release energy.

Their batteries are simply tanks filled with three separate layers of liquid at 700 °C that float on top of one another: the top one is molten magnesium, the bottom antimony and the one in between a salt containing magnesium antimonide, a dissolved compound of the two metals.

When the battery is being charged, magnesium antimonide in the middle layer breaks down into the pure elements and so the upper and lower layers deepen. Discharging the battery reverses the process and releases electrons to provide power. Once heated up to its operating temperature, the battery generates enough heat on its own to keep the liquids molten.

A small prototype provided up to 20 times as much current as a lithium-ion battery – the kind used in portable devices and electric cars – from the same area of electrode, says team member Luis Ortiz. The materials used are much cheaper than lithium, making scaling to up to grid scale feasible, he says.

“Cost-effective storage is the holy grail of the electricity grid,” says Matthew Nordan, a specialist in clean technology at venture-capital firm Venrock in Cambridge, Massachusetts, who has not invested in the technology.

The MIT team calculates that a battery the size of a shipping container could deliver a megawatt of electricity – enough to power 10,000 100-watt light bulbs – for several hours.

A battery the size of a shipping container could deliver a megawatt of electricity.


“Lead in Your Pencil” Could Provide Cheaper Solar Solution

Posted by admin on April 14, 2010
Posted under Express 104

 “Lead in Your Pencil” Could Provide Cheaper Solar Solution

Carbon, in the form of a graphene – a thin version of graphite – shows promise as an effective, cheap-to-produce, and less toxic alternative to other materials, currently used in solar cells. The Scientists at Indiana University are in the process of redesigning the graphene sheets with sticky ends that bind to titanium dioxide, which will improve the efficiency of the solar cells.

From Indiana University (9 April 2010):

Closing in on a carbon-based solar cell

BLOOMINGTON, Ind. — To make large sheets of carbon available for light collection, Indiana University Bloomington chemists have devised an unusual solution — attach what amounts to a 3-D bramble patch to each side of the carbon sheet. Using that method, the scientists say they were able to dissolve sheets containing as many as 168 carbon atoms, a first.

The scientists’ report, online today (April 9), will appear in a future issue of Nano Letters, an American Chemical Society journal.

“Our interest stems from wanting to find an alternative, readily available material that can efficiently absorb sunlight,” said chemist Liang-shi Li, who led the research. “At the moment the most common materials for absorbing light in solar cells are silicon and compounds containing ruthenium. Each has disadvantages.”

Their main disadvantage is cost and long-term availability. Ruthenium-based solar cells can potentially be cheaper than silicon-based ones, but ruthenium is a rare metal on Earth, as rare as platinum, and will run out quickly when the demand increases.

Carbon is cheap and abundant, and in the form of graphene, capable of absorbing a wide range of light frequencies. Graphene is essentially the same stuff as graphite (pencil lead), except graphene is a single sheet of carbon, one atom thick. Graphene shows promise as an effective, cheap-to-produce, and less toxic alternative to other materials currently used in solar cells. But it has also vexed scientists.

For a sheet of graphene to be of any use in collecting photons of light, the sheet must be big. To use the absorbed solar energy for electricity, however, the sheet can’t be too big. Unfortunately, scientists find large sheets of graphene difficult to work with, and their sizes even harder to control. The bigger the graphene sheet, the stickier it is, making it more likely to attract and glom onto other graphene sheets. Multiple layers of graphene may be good for taking notes, but they also prevent electricity.

Chemists and engineers experimenting with graphene have come up with a whole host of strategies for keeping single graphene sheets separate. The most effective solution prior to the Nano Letters paper has been breaking up graphite (top-down) into sheets and wrap polymers around them to make them isolated from one another. But this makes graphene sheets with random sizes that are too large for light absorption for solar cells.

Li and his collaborators tried a different idea. By attaching a semi-rigid, semi-flexible, three-dimensional sidegroup to the sides of the graphene, they were able to keep graphene sheets as big as 168 carbon atoms from adhering to one another. With this method, they could make the graphene sheets from smaller molecules (bottom-up) so that they are uniform in size. To the scientists’ knowledge, it is the biggest stable graphene sheet ever made with the bottom-up approach.

The sidegroup consists of a hexagonal carbon ring and three long, barbed tails made of carbon and hydrogen. Because the graphene sheet is rigid, the sidegroup ring is forced to rotate about 90 degrees relative to the plane of the graphene. The three brambly tails are free to whip about, but two of them will tend to enclose the graphene sheet to which they are attached.

The tails don’t merely act as a cage, however. They also serve as a handle for the organic solvent so that the entire structure can be dissolved. Li and his colleagues were able to dissolve 30 mg of the species per 30 mL of solvent.

“In this paper, we found a new way to make graphene soluble,” Li said. “This is just as important as the relatively large size of the graphene itself.”

To test the effectiveness of their graphene light acceptor, the scientists constructed rudimentary solar cells using titanium dioxide as an electron acceptor. The scientists were able to achieve a 200-microampere-per-square-cm current density and an open-circuit voltage of 0.48 volts. The graphene sheets absorbed a significant amount of light in the visible to near-infrared range (200 to 900 nm or so) with peak absorption occurring at 591 nm.

The scientists are in the process of redesigning the graphene sheets with sticky ends that bind to titanium dioxide, which will improve the efficiency of the solar cells.

“Harvesting energy from the sun is a prerequisite step,” Li said. “How to turn the energy into electricity is the next. We think we have a good start.”

PhD students Xin Yan and Xiao Cui and postdoctoral fellow Binsong Li also contributed to this research. It was funded by grants from the National Science Foundation and the American Chemical Society Petroleum Research Fund.


Lucky Last – Addicted to the End?

Posted by admin on April 14, 2010
Posted under Express 104

Lucky Last – Addicted to the End?

Is the Sun Finally Setting on Climate Change Scepticism? We would like to think so and so would Todd Tanner, who writes about conservation and the outdoors from his home in Montana’s Flathead Valley. Maybe that is too much to expect. But when Todd describes climate change deniers (not sceptics) as addicts, he says “they’re addicted to fossil fuels. Of course they’re going to deny that they–or we–have a problem. That’s what addicts do.”

By Todd Turner on        

Over the last few years I’ve noticed something interesting about our ongoing climate change discussions. It used to be that logic and knowledge were the keys. We looked at the best available science, weighed the predicted costs of action versus the predicted costs of inaction, and then considered the most appropriate alternatives. Businesses use this kind of approach all the time. It’s called a “cost-benefit analysis.”

Recently, though, our climate discussions have slowed and even stalled. Not because of the science, which remains irrefutable, or because of the proposed solutions, which are generally still feasible, but because so-called climate sceptics are doing their best to muddy the water and raise doubts about the issue.

Let’s be clear. By its very nature, scepticism implies a reliance on reason, logic and empirical data. A true sceptic will say, “I’m not sure you’re right, so show me why I should believe you.” That’s not cynicism or negativity, that’s a healthy approach to most any controversial issue.

As Congressman Willard Vandiver of Missouri said all the way back in 1899, “I come from a country that raises corn and cotton, cockleburs and Democrats, and frothy eloquence neither convinces nor satisfies me. I’m from Missouri, and you have got to show me.”

You can’t argue with that kind of statement. It makes too much sense.

But what doesn’t make sense–not even for a second–is when climate skeptics refuse to accept the overwhelming preponderance of scientific evidence. That isn’t scepticism; it’s denial. And it’s the same kind of response we hear time and again from people who’ve fallen into alcoholism or drug addiction.

“No way. I don’t have a problem.”

Or in the case of the climate deniers, “No way. We don’t have a problem.”

Here’s an interesting anecdote. Not long ago a bright, well-informed “sceptic” e-mailed me an essay that disputed conventional climate science. When I responded, I told him that my opinion wasn’t set in stone and that I’d be happy to alter my views–just as soon as the scientists modified theirs. Then I asked him two simple questions: What would it take for him to change his mind?  What would have to happen before he’d agree that we have a major problem on our hands?

You’d think he’d be able to offer a reasonable answer, something centered on a near-unanimous scientific consensus, or dramatic new empirical evidence, or people he trusted changing their views. Nope. Nothing. He has gone radio silent. As best as I can tell, he’s simply not open to anything except denial.

Nor are most other “sceptics.” They’re past the point where scientists can convince them or where logical arguments can persuade them. They’ve become ideologues, and whether they’re driven by religion or politics or their distrust of the science is ultimately irrelevant. They’ve hardened into intransigence and their scepticism is nothing more than a thin veneer of respectability plastered over an otherwise indefensible position.

Not that we can fault them. They rely on fossil fuels. They’re addicted to fossil fuels. Of course they’re going to deny that they–or we–have a problem. That’s what addicts do.

But we need to realize that this isn’t a normal case of addiction. There’s more than one life, or one family’s well-being, at stake.  Our collective future is on the line. Our kids and our grandkids will live well, or poorly, or not at all, because of the decisions we make over the next year or two. Which means it’s our responsibility to make the best possible choices about climate and energy legislation.

Here’s what we need to know. The science is clear and unequivocal. We are dumping huge amounts of carbon into the atmosphere, and all that carbon is warming the planet and making our oceans more acidic. Our dependence on fossil fuels has created a worldwide crisis that threatens every single aspect of our lives.

Fortunately, there’s hope on the horizon. Green energy development (such as wind and solar) has the potential to drive our economy and create millions of high-quality jobs–jobs that can’t be shipped overseas. Energy conservation can cut our carbon emissions while it saves us money on our utility bills and at the gas pumps. And if we stop sending our petro-dollars to the Mid-East, we can stop funding rogue regimes who promote international terrorism. It’s a win/ win for America. We have the ability to strengthen our economy at the same time we protect our security–but only if we pass strong climate and energy legislation.

Real skeptics figured this out a long time ago. And now they agree with the 97 percent of climate scientists who insist that climate change is a real threat. They agree with the 76 percent of Americans who are worried about global warming and want the federal government to address the problem. They agree with the 55 percent of Americans who want the USA to sign a binding global treaty that would require significant reductions in greenhouse gas emissions.

In short, they side with the science–and with common sense.

As for the climate change deniers who are shouting down the experts and telling us not to believe our own eyes, well, they’re addicts. And we all know what that means.

Todd Tanner writes about conservation and the outdoors from his home in Montana’s Flathead Valley.

This article first appeared on New West, a next-generation media company dedicated to the culture, economy, politics, environment and lifestyle of the Rocky Mountain West. Its core mission is to serve the Rockies with innovative, participatory journalism and to promote conversation that helps us understand and make the most of the dramatic changes sweeping our region. New West Publishing LLC, headquartered in Missoula, Montana, was founded in 2005 by Jonathan Weber.


For those who would like a chat or buy a book, author/publisher of “The ABC of Carbon” will be back (by popular demand) at Angus & Robertson, Toowong Village this Saturday 17 April from 11.30am to 2.30pm. On Sunday 18 April, you’ll find the undersigned at the University of Queensland’s centenary day at St Lucia where the focus of attention will be on the Global Change Institute series of talks in the Abel Smith Lecture Theatre from 9am to 4.30pm.