New Power Plant Aims to Help Coal Clean Up

New Power Plant Aims to Help Coal Clean Up

A "clean coal" power plant is set to be built in Illinois in 2009; if it works, it could help avoid catastrophic global warming 

 
CLEAN COAL: By gasifying coal, stripping it of pollution, such as globe-warming carbon dioxide, and then burying that pollution, the FutureGen power plant would make coal clean.

Burning coal provides half the electricity in the U.S. and one third of greenhouse gas emissions worldwide. Capturing that carbon dioxide and storing it will be essential if climate change induced by such pollution is to be averted, according to reports from the U.N. Intergovernmental Panel on Climate Change and the Massachusetts Institute of Technology. Dubbed carbon capture and storage (or carbon sequestration), such technology will be fully demonstrated for the first time near Mattoon in southeastern Illinois, the FutureGen Alliance (a public–private partnership to build a prototype clean-coal plant) announced.

"[Mattoon] has a reliable and assured water source. It has excellent geologic structure and conditions for carbon sequestration," says Lawrence Pacheco, a spokesman for the alliance of 14 of the largest coal burners and miners in the world, including American Electric Power in Columbus, Ohio, Australia-based BHP Billiton and China Huaneng Group headquartered in Beijing. "The goal is to break ground in 2009 and be operational in 2012."

The $1.5 billion power plant is expected to produce 275 megawatts of electricity by turning coal into gas, thereby removing impurities including CO₂, and burning the resulting pure gas to turn turbines to produce power. Some of the power generated would be used to compress the CO₂ and pump it deep underground to be permanently stored in saline aquifers. "It will never come out," says geologist Susan Hovorka of the University of Texas at Austin, who has been conducting carbon sequestration feasibility experiments. "It's moving through the tiny pores between the sand grains and it gets smeared, like grease on a tie."

Hovorka's initial experiments at an oil field northeast of Houston have shown that the CO₂ behaves as expected, remaining trapped in the geologic formation. But it does have impacts, such as leaching out minerals in the rocks and corroding well equipment. "If you put undiluted weak acid into your plumbing, it will eat holes in it," Hovorka notes. "We observed that and it's not unexpected."

But despite some commercial demonstrations of such carbon sequestration technology, largely to help recover more oil from depleted fields, none have approached anywhere near the scale necessary to significantly impact the 9.3 billion metric tons of CO₂—and rising—emitted every year from burning coal. The largest such project, the Sleipner West gas field under the North Sea, injects roughly one million metric tons of CO₂ per year. "The issue on the sequestration side is making sure one can do it on a very large scale," says M.I.T. physicist Ernest Moniz. "Gasification looks today to be the lowest-cost option with carbon capture [but] there is no plant that integrates gasification with capture and sequestration."

The FutureGen power plant aims to fill that hole but has struggled with delays and mounting costs as the materials to build such a power plant become more expensive. The FutureGen Alliance therefore decided to announce the siting of the proposed plant over the objections of its primary government backer, the U.S. Department of Energy (DOE), which concurrently announced plans to demonstrate the feasibility of carbon sequestration in the deep geology of the region by injecting one million metric tons of CO₂. "As the [DOE] has discussed with the FutureGen Alliance for the past several months, projected cost overruns require a reassessment of FutureGen's design," James Slutz, DOE's acting principal deputy assistant security for fossil energy, said in a statement.

"The Alliance has been sticking to a very aggressive schedule and timeline. They wanted to stick to that," Pacheco says. "They felt it was appropriate and important to make this announcement."

Given the scope of the climate change challenge, moving forward quickly is key. "Unless we get confidence for large-scale sequestration in a decade, it's going to be extremely difficult to get what we need by mid-century," Moniz says. "It's like a mortgage. It gets us out of the problem in the 21st century."

A Better Mosquito Net

A Better Mosquito Net

Fighting malaria will require more innovative defenses

Malaria remains one of the world’s great scourges, striking more than 500 million people every year. The groups most at risk are pregnant women and children younger than five years old. In sub-Saharan Africa, 20 percent of all childhood deaths are from malaria. Pregnant women who contract the mosquito-borne disease can develop severe anemia and give birth to underweight babies. The World Health Organization estimates that 10,000 pregnant woman and 200,000 infants in Africa die from malarial infections every year.

To combat the disease, many development agencies have focused on distributing mosquito nets that would protect Africans from being bitten while they sleep. This strategy has resulted in a huge upsurge in the number of bed nets supplied to the population as a whole and particularly to pregnant women and young children. The widespread distribution, however, has not resulted in a significant decrease in malaria. Many doctors in sub-Saharan Africa attribute the failure to an overreliance on nets in lieu of other interventions, such as the indoor spraying of dwellings with insecticide. Other experts say the problem is the misuse of mosquito nets; there is anecdotal evidence that some people have employed the nets as wedding veils or fishing aids. Some economists argue that charging a small fee for the nets would increase the likelihood that they would be used appropriately. Others claim such a fee would prevent a large part of the population from receiving nets. These are valuable debates. Before delving into behavioral economics, though, it might be useful to consider a more basic problem: the mosquito nets are poorly designed.

The bed nets distributed by governments and international organizations have one of two basic designs: circular or rectangular. The circular design hangs from the ceiling by one string, with the net fanning out from a ring at the top and tucked tightly under the mattress on all sides. The rectangular design ties to the ceiling with four strings and hangs straight down on all sides of the bed, with the fringes again tucked under the mattress. Both designs work well for middle-class homes with flat ceilings and a bed for every member of the family. But most of the poor in sub-Saharan Africa, especially in rural areas, live in mud huts, often with thatched roofs.

Hanging mosquito nets is very difficult in these homes, and most people prefer the circular nets because they are easier to hang. Although the rectangular nets can be used without a bed, the circular nets cannot, because they have to be tucked under the mattress to fan out. In many African communities, most children younger than five sleep on the floor, so only the rectangular nets would be effective. But the rectangular nets take up quite a bit of room in a mud hut and have to be taken down and rehung every night for the hut to be of use during the day. Given the difficulty of hanging the nets, it is unreasonable to expect people to follow this routine.

A design more suited to the needs of young children would be a net that does not hang at all. One possibility would be a collapsible, tentlike structure, very similar to the crawl-through children’s toys that clutter so many playrooms in the U.S. The challenge would be to make the structure both affordable to produce and durable enough to be used daily for years. In addition to being user-friendly, this free-standing mosquito net would have to be sized for children to ensure that it is used by the intended recipients rather than older, hardier members of the family.

Mosquito nets have been changed before to meet user needs. Several companies have recently introduced nets that are impregnated with long-lasting insecticide, eliminating the need for people to continually apply fresh coatings of chemicals to the nets. Companies must continue to improve mosquito nets if progress is to be made in combating malaria. And once better nets are available, researchers will be able to objectively judge the effectiveness of the distribution programs.

Self-Powered Nanotech

Self-Powered Nanotech

Nanosize machines need still tinier power plants 

 
Powered by a nano?generator (foreground) that draws energy from the ambient environment, a sensor measures blood glucose or pressure in this conceptual image.

• Nano­technology has huge potential—but those minuscule devices will need a power source that is better than a battery.
• Waste energy, in the form of vibrations or even the human pulse, could provide sufficient power to run such tiny gadgets.
• Arrays of piezoelectric nano­wires could capture and transmit that waste energy to nano­devices.
• Medical devices will likely be a major application. A pacemaker’s battery could be charged so it would not need replacing, or implanted wireless nano­sensors could monitor blood glucose for diabetics.

The watchmaker in the 1920s who de­vised the self-winding wristwatch was on to a great idea: mechanically harvesting energy from the wearer’s moving arm and putting it to work rewinding the watch spring.

Today we are beginning to create extremely small energy harvesters that can supply electrical power to the tiny world of nano­scale devices, where things are measured in billionths of a meter. We call these power plants nano­generators. The ability to make power on a minuscule scale allows us to think of implantable biosensors that can continuously monitor a patient’s blood glucose level, or autonomous strain sensors for structures such as bridges, or environmental sensors for detecting toxins—all running without the need for replacement batteries. Energy sources are desperately needed for nano­robotics, microelectromechanical systems (MEMS), homeland security and even portable personal electronics. It is hard to imagine all the uses such infinitesimal generators may eventually find.

Signaling Neurons Make Neighbor Cells "Want In"

Signaling Neurons Make Neighbor Cells "Want In"

Synapses are primed to strengthen (and thus enable learning) if a neighbor has just been stimulated 

 
HELP THY NEIGHBOR: When an electrical signal crosses a synapse, the spines strengthen, enabling better communication. A residual effect, however, has now been found to aid in strengthening neighboring synapses, as well.

A new discovery about the function of neurons could help scientists understand how the brain assembles information during learning and memory formation.

Scientists have found that when electrical impulses are passed from one neuron to another, they not only strengthen the synapse (connection) between them, but they also give a boost to neighboring synapses, priming them to learn more quickly and easily. Researchers report in Nature that the extra kick, which lasts from five to 10 minutes, may be key to memory formation.

The residual effect "had been predicted based on so-called classic models of plasticity"—the ability of the brain to adapt by strengthening or weakening connections between neurons—but had not previously been proved, says study co-author Karel Svoboda, a biophysics group leader at the Howard Hughes Medical Institute's Janelia Farm Research Campus in Ashburn, Va. "You'd like to have clustered plasticity of this sort" to keep memories grouped together.

Neurons, or nerve cells, each have a pair of projections—the axon and the dendrite, which transmit and receive impulses, respectively. The dendrite, a treelike structure, has several branches dotted with hundreds synaptic receiving terminals called "spines," each connected to the axons of scores of other neurons. When one of these spines receives stimulation (through the synapse it creates with another cell's axonal projection), the spine expands into the synapse, strengthening the link between its neuron and the other cell. This process of enhanced communication through a synapse is called long-term potentiation (LTP) and is thought to be the basis of learning.

Previous attempts to identify this process were stymied by inexact methods. Researchers primarily used electrical impulses, which do not allow for good spatial observation. Svoboda and study co-author Christopher Harvey, a graduate student in Svoboda's lab, used a more precise technique. They attached a light-absorbing chemical group to the neurotransmitter glutamate (an excitatory chemical messenger in the brain) at a particular synapse in a slice of a rat's hippocampus, the brain region responsible for short-term memory. When they trained a laser on the glutamate, it was freed from its light-absorbing molecular captor and thereby able to resume its function; it went to the dendritic spine in the synapse, allowing ions to enter the cell and an electrical signal to be generated.

As a result of this stimulation, the spine stretched farther into the synapse. Researchers did not find any evidence that neighboring spines had also expanded, but they did find that it took less stimulation—only 20 percent of the original prodding—to prompt any of the 20 spines within 10 microns (around four ten-thousandths of an inch) to undergo LTP. This effect appeared to last for five to 10 minutes, the scientists report.

Svoboda says that this cooperative activity may underlie how information is integrated when, for instance, an individual enters a new environment and looks around making associations of different cues within that space. "People didn't know how these associations over the course of 10 minutes or so could be coded in neurons," he says. "It provides a possible mechanism for associations over minutes."

In an editorial accompanying the article, Bernardo Sabatini, an assistant professor of neurobiology at Harvard Medical School, says that Harvey and Svoboda's work introduces new complexity into the brain's neuronal wiring.

"[For] some forms of activity-dependent plasticity in the hippocampus, the fundamental unit of regulation might be larger than an individual synapse," he wrote, "and, rather, a physically clustered cohort of synapses with similar firing patterns, whose spatial arrangement on dendrites arises naturally follow mutually reinforcing interactions between synapses."

Evonomics

Evonomics

Evolution and economics are both examples of a larger mysterious phenomenon

Living along the Orinoco River that borders Brazil and Venezuela are the Yanomamö people, hunter-gatherers whose average annual income has been estimated at the equivalent of $90 per person per year. Living along the Hudson River that borders New York State and New Jersey are the Manhattan people, consumer-traders whose average annual income has been estimated at $36,000 per person per year. That dramatic difference of 400 times, however, pales in comparison to the differences in Stock Keeping Units (SKUs, a measure of the number of types of retail products available), which has been estimated at 300 for the Yanomamö and 10 billion for the Manhattans, a difference of 33 million times! How did this happen? According to economist Eric D. Beinhocker, who published these calculations in his revelatory work The Origin of Wealth (Harvard Business School Press, 2006), the explanation is to be found in complexity theory. Evolution and economics are not just analogous to each other, but they are actually two forms of a larger phenomenon called complex adaptive systems, in which individual elements, parts or agents interact, then process information and adapt their behavior to changing conditions. Immune systems, ecosystems, language, the law and the Internet are all examples of complex adaptive systems.

In biological evolution, nature selects from the variation produced by random genetic mutations and the mixing of parental genes. Out of that process of cumulative selection emerges complexity and diversity. In economic evolution, our material economy proceeds through the production and selection of numerous permutations of countless products. Those 10 billion products in the Manhattan village represent only those variations that made it to market, after which there is a cumulative selection by consumers in the marketplace for those deemed most useful: VHS over Betamax, DVDs over VHS, CDs over vinyl records, flip phones over brick phones, computers over typewriters, Google over Altavista, SUVs over station wagons, paper books over e-books (still), and Internet news over network news (soon). Those that are purchased “survive” and “reproduce” into the future through repetitive use and remanufacturing.

As with living organisms and ecosystems, the economy looks designed—so just as humans naturally deduce the existence of a top-down intelligent designer, humans also (understandably) infer that a top-down government designer is needed in nearly every aspect of the economy. But just as living organisms are shaped from the bottom up by natural selection, the economy is molded from the bottom up by the invisible hand.

The correspondence between evolution and economics is not perfect, because some top-down institutional rules and laws are needed to provide a structure within which free and fair trade can occur. But too much top-down interference into the marketplace makes trade neither free nor fair. When such attempts have been made in the past, they have failed—because markets are far too complex, interactive and autocatalytic to be designed from the top down. In his 1922 book, Socialism, Ludwig von Mises spelled out the reasons why, most notably the problem of “economic calculation” in a planned socialist economy. In capitalism, prices are in constant and rapid flux and are determined from below by individuals freely exchanging in the marketplace. Money is a means of exchange, and prices are the information people use to guide their choices. Von Mises demonstrated that socialist economies depend on capitalist economies to determine what prices should be assigned to goods and services. And they do so cumbersomely and inefficiently. Relatively free markets are, ultimately, the only way to find out what buyers are willing to pay and what sellers are willing to accept.

Evonomics helps to explain how Yanomamö-like hunter-gatherers evolved into Manhattan-like consumer-traders. Nineteenth-century French economist Frédéric Bastiat well captured the principle: “Where goods do not cross frontiers, armies will.” In addition to being fierce warriors, the Yanomamö are also sophisticated traders, and the more they trade the less they fight. The reason is that trade is a powerful social adhesive that creates political alliances. One village cannot go to another village and announce that they are worried about being conquered by a third, more powerful village—that would reveal weakness. Instead they mask the real motives for alliance through trade and reciprocal feasting. And, as a result, not only gain military protection but also initiate a system of trade that—in the long run—leads to an increase in both wealth and SKUs.