Submersible Robot Runs on Sea's Heat

Submersible Robot Runs on Sea's Heat

Scientists have invented the Prius of ocean-going submersibles — a new "green" robotic glider that runs on energy absorbed from the heat of the sea, rather than batteries.

The new underwater glider can stay at sea at least twice as long as previous submersibles that used battery power. It is the first autonomous underwater vehicle to travel great distances for extended periods running on green energy, according to the Woods Hole Oceanographic Institution (WHOI).

Submersibles gained fame in 1985 when WHOI's remotely-operated underwater vehicle, "Argo," discovered the wreck of the RMS Titanic near Newfoundland.

Built by the Webb Research Corporation in Falmouth, Mass., the new submersible has successfully traveled back and forth between two of the U.S. Virgin Islands, St. Thomas and St. Croix, more than 20 times. WHOI researchers plan to use the data gathered by the craft to study ocean currents in the area.

To power its propulsion, the submersible gathers thermal energy from the ocean. When it moves from cooler water to warmer areas, internal tubes of wax are heated up and expand, pushing out the gas in surrounding tanks and increasing its pressure. The compressed gas stores potential energy, like a squeezed spring, that can be used to power the vehicle.

"This glider allows longer missions than previous [battery-run] versions," said Ben Hodges, a physical oceanographer at WHOI. "It could be out there for a year or two years. None of the old ones could go beyond six months. And producing fewer batteries is good for the environment."

The torpedo-shaped glider moves through the ocean by changing its buoyancy to dive and surface, unlike motorized, propeller-driven undersea vehicles. To rise, oil is pushed from inside the vehicle to external bladders, thus increasing the glider's volume without changing its mass, making it less dense. The oil can be shifted inside to increase the density and sink the vehicle. A vertical tail rudder allows the glider to be steered horizontally.

Technically, the new vehicle is a hybrid, like Toyota's Prius, because it uses a small amount of battery power to run the onboard instruments and to move the rudder.

Gliders of this type are perfect for long-term, long-distance journeys that humans can't make, Hodges said.

"They can be very helpful in getting measurements that would be too expensive to get otherwise — any kind of study that requires long-term measurements from multiple locations," Hodges told LiveScience. "If you had to be there in a ship, it would cost millions of dollars." 

Powering Your Cell Phone Could Be a Walk in the Park

Powering Your Cell Phone Could Be a Walk in the Park

Budding technologies seek to turn kinetic energy created by the human body into electricity for battery-powered devices

 
THE BIOMECHANICAL ENERGY HARVESTER: developed at Simon Fraser University includes an aluminum chassis and generator mounted on a customized orthopedic knee brace, weighing 3.5 pounds (1.6 kilograms).

 
BURNING CALORIES, CREATING ENERGY: The best area to place a device for harnessing human energy is near a joint, because this is where the muscles--the body's power source--work hardest.

 
SELF-POWERED CELL: This illustration shows the inner working of a cell phone that allows the wearer to power for his or her device if it includes a magnet and copper coil that generate energy from motion.

 
THE FUTURE OF BATTERIES: M2E has developed several prototype energy-rechargeable batteries, including "D" cell batteries.

Exercise may soon do more for you than tighten up your sagging muscles. Advances in biomechanical engineering could use energy generated while walking, hiking or running to power any device requiring portable power, including night-vision goggles and other battery-operated devices used by soldiers as well as robotic prosthetic limbs, cell phones and computers in remote locations where no other energy sources are available.

A team of researchers at the Simon Fraser University (S.F.U.) Locomotion Laboratory in Burnaby, British Columbia, are studying the amount of energy that can be generated by 3.5-pound (1.6-kilogram) aluminum and steel knee braces worn while walking or running. Volunteers, wearing a brace strapped on each leg, generated about five watts of electricity per person during a recent experiment, enough power, researchers say, to run 10 cell phones concurrently and twice that needed to keep a computer running (something useful in developing regions of Africa where electricity is scarce). They report that one brace-wearing subject generated 54 watts of power by running in place.

The best area to place a device for harnessing human energy is near a joint, because this is where the muscles—the body's power source—work hardest, says Max Donelan, Locomotion Lab director and an assistant professor at S.F.U.'s School of Kinesiology. "There's a long history of human power generation using hand cranks and bikes, but these require your dedicated attention, so you don't do it for very long." The key to energy harvesting is extracting the energy from the body's natural movement and, aside from breathing, very few unconscious muscle movements are more automatic than the action of walking.

Donelan and his team of researchers targeted a particular part of the stride, halfway through the swing of the lower leg after it has left the ground (when the hamstring comes to life to make sure you don't have uncontrolled extension) through the time the foot returns to the ground. The brace designed to capture this energy features gears, a clutch, a generator and a computerized control system that monitors the knee's angle to determine when to engage and disengage power generation.

The specific amount of energy generated from Donelan's device depends upon the weight of the wearer, the difficulty of the terrain, the speed of the person's gait and how long the device is used. In the prototype, energy generated is dissipated into resistors, although future models could include an onboard battery for energy storage. The researchers hope to be able to test their device within a year on Canadian soldiers at a field site.

Another effort underway to convert motion into energy relies on the Faraday law of induction, named after English chemist and physicist Michael Faraday, which holds that the movement of a conductor (such as a metal wire) through a magnetic field produces a voltage in that conductor proportional to the speed of movement. M2E Power, Inc., in Boise, Idaho, has developed a system of magnets and coils that, when moved, generates energy that can be used to power their host device. M2E's technology originated at the Idaho National Laboratory, a Department of Energy–funded research group.

A good example of this would be walking with a cell phone in your front pocket or attached to your belt. The phone's movement would cause the magnet and coil to generate energy that could be transferred to a bank of ultracapacitors that charge the phone's battery when a certain voltage level is reached. "Think of it as a minigenerator whose power comes from movement," says Regan Warner-Rowe, M2E's director of business development. "Because power management is such a critical issue for cell phones, we have been in discussions with handset companies." (Warner-Rowe declined to name them.)

Another goal of M2E's research and development is to develop technology that could be used by the U.S. military. (The Australian army is working with contractors to develop its own wearable, rechargeable battery system, as well.) Much like Donelan's work, the objective is to eliminate several pounds of weight that soldiers must lug around in the form of spare batteries. M2E has done some work developing prototype energy-rechargeable "D" cell batteries.

Biofuels Are Bad for Feeding People and Combating Climate Change

Biofuels Are Bad for Feeding People and Combating Climate Change

By displacing agriculture for food—and causing more land clearing—biofuels are bad for hungry people and the environment

 
BAD BIOFUEL: Clearing rainforest to plant palms for oil, like the one pictured here, is a major emitter of the greenhouse gases that cause climate change.

Converting corn to ethanol in Iowa not only leads to clearing more of the Amazonian rainforest, researchers report in a pair of new studies in Science, but also would do little to slow global warming—and often make it worse.

"Prior analyses made an accounting error," says one study's lead author, Tim Searchinger, an agricultural expert at Princeton University. "There is a huge imbalance between the carbon lost by plowing up a hectare [2.47 acres] of forest or grassland from the benefit you get from biofuels."

Growing plants store carbon in their roots, shoots and leaves. As a result, the world's plants and the soil in which they grow contain nearly three times as much carbon as the entire atmosphere. "I know when I look at a tree that half the dry weight of it is carbon," says ecologist David Tilman of the University of Minnesota, coauthor of the other study which examined the "carbon debt" embedded in any biofuel. "That's going to end up as carbon dioxide in the atmosphere when you cut it down."

By turning crops such as corn, sugarcane and palm oil into biofuels—whether ethanol, biodiesel, or something else—proponents hope to reap the benefits of the carbon soaked up as the plants grow to offset the carbon dioxide (CO₂) emitted when the resulting fuel is burned. But whether biofuels emit more or less CO₂ than gasoline depends on what the land they were grown on was previously used for, both studies show.

Tilman and his colleagues examined the overall CO₂ released when land use changes occur. Converting the grasslands of the U.S. to grow corn results in excess greenhouse gas emissions of 134 metric tons of CO₂ per hectare—a debt that would take 93 years to repay by replacing gasoline with corn-based ethanol. And converting jungles to palm plantations or tropical rainforest to soy fields would take centuries to pay back their carbon debts. "Any biofuel that causes land clearing is likely to increase global warming," says ecologist Joseph Fargione of The Nature Conservancy, lead author of the second study. "It takes decades to centuries to repay the carbon debt that is created from clearing land."

Diverting food crops into fuel production leads to ever more land clearing as well. Ethanol demand in the U.S., for example, has caused some farmers to plant more corn and less soy. This has driven up soy prices causing farmers in Brazil to clear more Amazon rainforest land to plant valuable soy, Searchinger's study notes. Because a soy field contains far less carbon than a rainforest, the greenhouse gas benefit of the original ethanol is wiped out. "Corn-based ethanol, instead of producing a 20 percent savings [in greenhouse gas emissions], nearly doubles greenhouse emissions over 30 years and increases greenhouse gases for 167 years," the researchers write. "We can't get to a result with corn ethanol where we can generate greenhouse gas benefits," Searchinger adds.

Turning food into fuel also has the unintended consequence of driving up food prices, reducing the access of the neediest populations to grains and meat. "It's equivalent to saying we will try to reduce greenhouse gases by reducing food consumption," Searchinger says. "Unfortunately, a lot of that comes from the world's poorest people."

"We are converting their food into our fuel," Tilman notes. " The typical driver of an SUV spends as much on fuel in a month as the poorer third of the world spend on food."

The studies do find some benefit from biofuels but only when planted on agricultural land too dry or degraded for food production or significant tree or plant growth and only when derived from native plants, such as a mix of prairie grasses in the U.S. Midwest. Or such fuels can be made from waste: corn stalks, leftover wood from timber production or even city garbage.

But that will not slake a significant portion of the growing thirst for transportation fuels. "If we convert every corn kernel grown today in the U.S. to ethanol we offset just 12 percent of our gasoline use," notes ecologist Jason Hill of the University of Minnesota. "The real benefit to these advanced biofuels may not be in displacement of fossil fuels but in the building up of carbon stores in the soil."

Of course, there is another reason for biofuels: energy independence. "Biofuels like ethanol are the only tool readily available that can begin to address the challenge of energy security," Bob Dinneen, president of industry group the Renewable Fuels Association said in a statement. "The alternative is to continue to exploit increasingly costlier fossil fuels for which the environmental price tag will be great."

But the environmental price tag of biofuels now joins the ranks of other, cheaper domestic fuel sources—such as coal-to-liquid fuel—as major sources of globe-warming pollution as well as unintended social consequences. As a result, 10 prominent scientists have written a letter to President Bush and other government leaders urging them to "shape policies to assure that government incentives for biofuels do not increase global warming."

"We shouldn't abandon biofuels," Searchinger says. But "you don't solve global warming by going in the wrong direction."

The Artificial Heart: Not Just a Pump

The Artificial Heart: Not Just a Pump

The goal of building a safe artificial heart has frustrated bioengineers for more than four decades. At last, an end could be in sight

 
AbioCor artificial heart

In the late 1970s American television viewers were captivated by a weekly drama called The Six Million Dollar Man, starring Lee Majors as secret agent Steve Austin. Austin was a cyborg, a flesh-and-blood man brought back from near death and bioengineered to be superhuman in strength, speed and vision. During the series’s five-year run, Austin entered the popular idiom as “the bionic man.”

An era of technological optimism had been gathering momentum since the 1960s, in large part following the stunning successes of the space program. There was a growing confidence that American scientific ingenuity could engineer almost anything—including the human body. Indeed, at the same time that astronauts started flying into space, the government also set its sights on the gold ring of bioengineering: a permanent mechanical replacement for the human heart.

Fast forward to May 1988, when the New York Times dismissed the entire concept of an artificial human heart as the “Dracula of Medical Technology,” a hubristic $240-million boondoggle. The paper’s editorialists opined tersely: “The Federal project to create an implantable artificial heart is dead.”

What happened? How did the grand hopes of bioengineering a human heart turn to such cynicism in just a decade?

There is a long answer and a short answer to that question. The long answer is complex, encompassing several strands of basic science and technology, from materials to batteries to motors and microprocessors, plus a healthy dose of marketing psychology. The Times may have been premature in writing off the whole enterprise, which many believe is more promising today than ever before. Nevertheless, deconstructing the early setbacks offers a useful lens on recent progress and further challenges.

The short answer is Barney Clark.
Clark was a Seattle dentist who, in 1982, became the first recipient of a permanent mechanical heart. “Permanent” is something of a grisly misnomer, because Clark lasted only 112 days. More to the point, they were 112 miserable days for the 61-year-old, who never left the hospital and was tethered the entire time to a refrigerator-size compressor powering his noisy new heart. He suffered convulsions, cognitive problems and kidney failure, then died of massive organ failure.

The mechanical heart that kept Clark alive for those months was the so-called Jarvik-7, named after its inventor, Robert Jarvik. The nation followed Clark’s progress with rapt attention, fueled by daily press conferences, which turned quickly to sympathy and disappointment as the patient deteriorated. The case was a public-relations disaster for the Jarvik-7. The quality of Clark’s life with his new heart was so poor that it turned public opinion sour on the idea for a decade. Four more patients would receive permanent Jarvik-7 hearts over the next few years, and one, William Schroeder, even survived 620 days, but the damage to the dream was done. In 1990 the U.S. Food and Drug Administration withdrew permission to manufacture any more Jarvik-7 hearts.

It’s easy, of course, to second-guess quarter-century-old decisions, but many cardiologists today feel that implanting the Jarvik-7 was a mistake—premature given the primitive state of knowledge at the time. Visionaries were seduced by the simplicity of the natural organ’s design—which really is just a four-chambered pump—and somewhat naive about its dynamic complexity. Says Alfred Bove, vice president of the American College of Cardiology: “The God-given heart is a dynamically balanced, finely tuned organ, with the capacity to generate force, raise and lower pulse. It’s not possible to get that in an artificial heart.”

But it is possible to approximate it. And if nothing else, the Jarvik-7 experiments demonstrated that the basic concept was not flawed: they proved that people could survive for extended periods with a heartlike thing made of plastic and metal. Back then, that demonstration in itself was a dramatic step forward, and it was very good news for the 50,000-plus Americans with heart failure who die every year, some while awaiting one of the meager 2,200 donated hearts available for transplant. All of the work since the mid-1980s has been figuring out the problems with the Jarvik-7 and fixing them.

Robert Kung was still a young graduate student in physical chemistry when the federal government began its pursuit of an artificial heart. The Framingham (Massachusetts) Heart Study, begun in 1948, was yielding its early results on Americans’ high rates of heart disease and mortality, and cardiologists were realizing just how little they understood about either the prevention or treatment of this killer disease. So in a sense, the government’s pursuit of a mechanical heart was inspired by the medical inadequacies of the time.

The early target date for a fully functional artificial heart was 1972—an overly optimistic expectation, says Kung, who has spent his entire career developing a new, improved mechanical heart. He is chief scientific officer at Abiomed, a Danvers, Mass.–based company created specifically to solve the many problems that were glaringly apparent in the Jarvik-7 experiments. Even though flying rockets to the moon seems so much grander a feat, he says, it is actually much simpler because velocities and trajectories can be accurately predicted with the laws of math and physics. The interface between a mechanical heart and human tissue and blood is much more complex and squishy, involving the delicate interplay of blood-flow patterns, clotting agents, and a small army of immunological sentries and soldiers warding off infection. The heart beats, but it’s not like clockwork.

This dynamism was poorly understood a generation ago, resulting in insurmountable problems. The two most daunting threats to the survival of Jarvik-7 recipients were stroke and infection. Kung, in designing a successor to the Jarvik-7 called the AbioCor, has focused on these two problems for most of three decades. The designers of the CardioWest, an iteration of the Jarvik-7 used only as a “bridge to transplant,” have also been working on these problems in different ways. Here is a look at the lessons learned.

“Blood Wants to Move”
William Schroeder, the longest-lived Jarvik-7 recipient, died of a stroke. It was one of the most common risks associated with the early total-heart replacements: fragments of blood cells would stick to the mechanical device, then break off, causing potentially life-threatening clots.

Part of the problem at the time was that medical scientists simply did not understand very well the physics of blood flow and the behavior of circulating platelets. As Kung says, “Blood wants to move. It wants to be in motion all the time.” And when it moves too sluggishly, it will clot. On the other hand, if it moves too fast, cells can be sheared off and broken, producing debris that can glom up arteries and cause blockages.

The Jarvik-7 had a couple of fatal clotting problems that subsequent research appears to have solved. First, the materials used to build the Jarvik-7 were too coarse; they had nicks and gullies that allowed blood cells to cling and later to split off and cause problems. The AbioCor is made from titanium and a polyurethane blend called Angioflex, which is produced by a secret process that Abiomed claims makes it very pure and slick—much less susceptible to clotting.

What’s more, the Jarvik-7 was powered by a large and clumsy pneumatic pump, which ­actually jolted the heart recipients’ bodies as it forced blood through the mechanical chambers. Barney Clark’s 112 days must have been extremely unpleasant, with his body constantly jostled by a clattery machine. That harsh pump has been replaced by a tiny motor-driven hydraulic one, which much more closely approximates the continuous blood flow of the natural heart and circulatory system. The rotary motor pushes hydraulic fluid from one of the AbioCor’s ventricles to the other, back and forth, 100,000 times a day, pumping blood slowly but steadily to the lungs and body. A miniature electronic “controller” adjusts the flow level according to need, keeping the blood flow smooth whether a patient is sleeping or seated or strolling.

The AbioCor was in clinical trials from 2001 to 2004, during which time 14 severely ill patients received the device. All died, but it is important to know that these people were the sickest of the sick, with just weeks to live if they had had no intervention at all. A few did die of stroke, but the average survival time was more than four months, more than quadruple their life expectancy before the trial. One, Kentucky tire dealer Tom Christerson, survived 17 months and actually lived the last nine months at home with his family. Kung says that most of the clotting problems had to do with the cuffs that connect the mechanical heart to the body’s circulatory system. The cuffs have since been redesigned to eliminate the clotting.

The other major killer in the early mechanical-heart trials was infection. All major surgery carries infec­tion risk, of course, and the installation of an artificial heart is a long, complicated operation. But most of the infections that plagued Jarvik-7 recipients came later, as a result of its design. The refrigerator-size pneumatic pump powered the mechanical heart through hoses, which had to run through permanent incisions in the skin. These open incisions were constantly vulnerable to infection, and in fact autopsies revealed considerable bacterial growth in the recipients following death.

The CardioWest still has problems with infection, because like its ancestor it is powered externally through large pneumatic tubes. The risk of infection has been reduced, however, by covering the tubes in a polyester fiber. The recipient’s tissue intertwines itself with the fibrous surface, creating a tight fit that can keep at least some germs out. Even so, more than 70 percent of patients in a large clinical trial of the CardioWest heart did acquire infections.

Fighting Infection
The AbioCor has solved the infection problem even more ingeniously. Instead of a pneumatic pump, the AbioCor uses electrical power, from either a standard outlet, an external battery or a tiny internal battery. But instead of piercing the skin, the heart’s so-called transcutaneous energy transfer system, or TET, sends the energy across the skin in electromagnetic waves, from an external coil to an electromagnetically coupled internal coil, which in turn powers the heart and charges an internal battery. Eliminating the need for skin-piercing tubes has dramatically reduced complications caused by infection. Indeed, none of the 14 patients in the clinical trial died of device-related infections, according to Kung.

The TET power system has an added benefit: improved quality of life. Patients are able to power the heart’s external battery while sleeping or sitting and are free to move about with a small fanny pack for a couple of hours at a time between charges. What’s more, the internal battery can power the heart for about one hour, allowing patients to take showers and so forth without any external attachments. These may sound like small things, but they are a dramatic improvement over the severely restricted lives of Clark and other Jarvik-7 recipients.

The TET power system would not be possible without certain technologies that simply were not available in the early 1980s. For example, the system requires high-capacity lithium ion batteries, which are now ubiquitous in portable electronics but were not commercially available until the 1990s. The TET system also uses a very small microprocessor to regulate the energy flow. The miniaturization of electronics in general has now made this crucial design element possible.

Despite these advances in miniaturization, the AbioCor is far from small. At two pounds, the grapefruit-size device is more than twice the size of the typical human heart. That means it is too big for all children, most women, and even some grown men. Abiomed scientists are currently working on a design called the AbioCor II, which will be 30 percent smaller—small enough even for some children.

Questions remain about how much wear and tear the AbioCor and similar devices can take. No mechanical device lasts forever, and it is fair to ex­pect some parts of this one to wear down. Cardiologist Robert Dowling, writing in the Journal of Thoracic and Cardiovascular Surgery during the clinical trials, estimated the life span of the hydraulic membrane—the part that expands into the ventricles to make them pump—at a year or more. The actual pump and switching valve—the only real moving parts in the heart—could last three to five years, according to Dowling. But the fact is that nobody knows for sure. All that is known is that one AbioCor heart beat inside Christerson’s chest for 17 months without breakdown.

The biggest question, not only about the AbioCor but also about the larger enterprise, is how much need there is for a permanent mechanical heart. According to Timothy Baldwin of the National Heart, Blood and Lung Institute—the major funder of mechanical-heart development over the decades—government scientists gradually revised their view of heart technologies over time. While funding research on artificial replacements for full hearts, the institute was double-tracking research on various ventricular-assist devices, or VADs—devices that support left ventricle function only. The left ventricle is the strongest muscle in the heart, responsible for pumping blood throughout the body. (The right ventricle merely pumps blood to the lungs for reoxygenation.) But it is also more prone to problems. Many people suffer only left ventricular failure; their right ventricles remain healthy. With the clinical successes of the simpler devices in the 1990s, it became apparent that many people with heart failure could get by with VADs alone. But the jury is still out on this: a fair number of patients with VADs later require right ventricular support as well. Some believe that a total heart replacement, because it is better at controlling overall circulation, will lead to less kidney and liver failure.

The incidence of heart failure is on the rise, in part the result of the aging of the baby boomer generation. The national supply of human hearts for transplants appears to be stuck at about 2,200—not even 5 percent of what the population with heart failure needs. The bottom line is that for some patients, a permanent mechanical heart literally means life or death. Last fall, after the clinical trial of AbioCor, the FDA approved the mechanical heart for marketing under a special humanitarian ruling. This category of approval is reserved for devices and drugs that have proved beneficial, albeit for a very small number of patients—no more than 4,000 a year. Tom Christerson would have qualified. For him, the 17-month reprieve meant witnessing the birth of his great-granddaughter, 

"Clean" Coal Power Plant Canceled--Hydrogen Economy, Too

"Clean" Coal Power Plant Canceled--Hydrogen Economy, Too

The FutureGen coal-fired power plant would not only have captured greenhouse gas emissions, it also would have produced hydrogen

 
FUTURE CANCELED?: The FutureGen power plant, depicted here in an artist's rendering, would have captured and stored all the greenhouse gases associated with burning coal to produce electricity--as well as produce hydrogen fuel.

The U.S. government—and major U.S. banks—seem to have lost their appetite for coal. After spending five years and approximately $50 million on preliminary studies as well as selecting a proposed site in Mattoon, Ill., the U.S. Department of Energy (DOE) has scuttled plans to build the so-called FutureGen power plant. The facility would have captured the greenhouse gas carbon dioxide (CO₂) that is emitted when coal is burned for electricity generation. Instead, the DOE hopes to help industry add carbon-capture-and-storage capability to advanced coal plants already in the works.

"This restructured FutureGen approach is an all-around better investment for Americans," Energy Secretary Samuel Bodman said in a statement announcing the change. The DOE is asking Congress for $407 million to research how to burn coal most efficiently, along with $241 million to demonstrate such carbon capture and storage (CCS) technologies—at least $900 million less than DOE said it would have cost to complete FutureGen.

Still up in the air is which power plants will be used to demonstrate CCS; few now employ the required integrated gasification and combined cycle (IGCC) technology capable of turning coal into gaseous form and removing pollutants, among them CO₂, before the gas is burned. Further, only a handful are planned, because of the rising costs of cement, steel and other materials as well as the additional cost of the technology.

"IGCC is not advancing very well," notes principal research engineer Howard Herzog at the Massachusetts Institute of Technology's (M.I.T.) Laboratory for Energy and the Environment. "There may be one commercial IGCC plant coming, the Duke Energy plant in Indiana, and there's the Southern Company's [demonstration] plant. Beyond that, I don't really see a lot."

He notes that canceling FutureGen will slow the pace of developing this technology, which may prove crucial in demonstrating that coal can be burned without emitting massive amounts of CO₂ and other pollutants. "There is no way we will get anything before 2012 on the same type of scale and I'm not convinced that anybody's going to be able to do it cheaper than FutureGen," Herzog says. Either "we have to see the coal industry dwindle and disappear or sit back and see what impacts we get from climate change, both of which are not good alternatives."

The U.N. Intergovernmental Panel on Climate Change (IPCC) identified carbon capture and storage as a critical technology for reducing emissions, not only from power plants but also from industries that manufacture cement, chemicals and steel. Given the scale of the climate change problem—and the relatively short window of time left to address it—delays in demonstrating the feasibility of such technology will be difficult to overcome, notes M.I.T. physicist Ernest Moniz, who co-chaired a recent report on the future of coal. "Gasification looks today to be the lowest cost option with carbon capture," he says.

Although there have been a few demonstrations that it is possible to store relatively small amounts of CO₂ deep below the ground—largely to push more oil and natural gas to the surface—there is no commercial-scale power plant that both captures and stores greenhouse gases, Moniz adds. Without such technology, it may prove difficult to get any coal-fired power plants built at all. Investment banks such as Citi, JPMorgan Chase and Morgan Stanley, for example, have drawn up funding guidelines that would preclude capital for new power plants that lack the ability to adapt to future CO₂ regulations.

But coal provides more than half of the electricity used by the U.S., and China builds the equivalent of two 500-megawatt coal-fired power plants each week, helping keep these nations at the top of the list of the world's biggest greenhouse gas emitters. "Since the transition away from fossil fuels is likely to take a very long time, we foresee a long-term need to deal with coal-based emissions and, therefore, the sooner we begin to develop [carbon capture and storage] technology, the better," Austin-based energy policy specialist Scott Anderson of Environmental Defense told a Senate panel earlier this year during a hearing on CCS technology. "We aren't champions of coal, but we are realists."

Research into other ways to avoid greenhouse gas emissions from burning coal continues, particularly into so-called post-combustion capture, which captures the CO₂ after the coal has been burned. This leads to cheaper electricity prices because it skips the coal-to-gas step, but it is more technically difficult to extract the diffuse greenhouse gas in the smokestack. "If we have a breakthrough in post-combustion capture it would really be a game-changer," Herzog says.

Meanwhile, the FutureGen Alliance—a consortium of 14 of the world's largest coal producers and coal burners behind the proposed plant—plans to continue to pursue the facility, but not without some form of government assistance. One option would be to convince Congress to fund the project directly, Herzog says.

There are also similar efforts underway elsewhere in the world, such as China's GreenGen initiative. More are needed, Herzog says, if catastrophic climate change is to be avoided while coal continues to be a major fuel. "There should be about 10 large demonstrations worldwide, and at least three of them should be in the U.S.," he adds. "How can we expect to build hundreds of these plants when we're having so much trouble building the first one?"

In addition to imperiling efforts to combat climate change, canceling FutureGen also sets back plans for a so-called "hydrogen economy." As originally proposed, the plant would have produced both electricity and "clean" hydrogen from coal, as the CO₂ would be captured and stored. No such hydrogen production is planned at any existing or planned IGCC plants. "Why was this such a great idea even a few months ago, let alone five years ago when it was announced?" Herzog asks. "The best way to proceed would be to keep FutureGen alive."