BY LOUIS BERGERON AND STEPHANIE KENITZER

Wind farms can be built in mountainous regions, such as in Spain (above), or placed offshore like the one at Middelgrunden (other photo), near Copenhagen, Denmark.

LM Glasfiber

Wind farms can be built in mountainous regions, such as in Spain (other photo), or placed offshore like the one at Middelgrunden, near Copenhagen, Denmark.

Wind power, long considered to be as fickle as wind itself, can be groomed to become a steady, dependable source of electricity and delivered at a lower cost than at present, according to scientists at Stanford University.

The key is connecting wind farms throughout a given geographic area with transmission lines, thus combining the electric outputs of the farms into one powerful energy source. The findings are published in the November issue of the American Meteorological Society’s Journal of Applied Meteorology and Climatology.

Wind is the world’s fastest growing electric energy source, according to the study’s authors, Cristina Archer and Mark Jacobson, who will present their findings Dec. 13 at the annual meeting of the American Geophysical Union in San Francisco. Their talk is titled “Supplying Reliable Electricity and Reducing Transmission Requirements by Interconnecting Wind Farms.”

However, because wind is intermittent, it is not used to supply baseload electric power today. Baseload power is the amount of steady and reliable electric power that is constantly being produced, typically by power plants, regardless of electricity demand. But interconnecting wind farms with a transmission grid reduces the power swings caused by wind variability and makes a significant portion of it just as consistent a power source as a coal power plant.

“This study implies that, if interconnected wind is used on a large scale, a third or more of its energy can be used for reliable electric power, and the remaining intermittent portion can be used for transportation, allowing wind to solve energy, climate and air pollution problems simultaneously,” said Archer, the study’s lead author and a consulting assistant professor in Stanford’s Department of Civil and Environmental Engineering and research associate in the Department of Global Ecology at the Carnegie Institution.

It’s a bit like having a bunch of hamsters generating your power, each in a separate cage with a treadmill. At any given time, some hamsters will be sleeping or eating and some will be running on their treadmill. If you have only one hamster, the treadmill is either turning or it isn’t, so the power’s either on or off. With two hamsters, the odds are better that one will be on a treadmill at any given point in time, and your chances of running, say, your blender, go up. Get enough hamsters together, and the odds are pretty good that at least a few will always be on the treadmill, cranking out the kilowatts.

The combined output of all the hamsters will vary, depending on how many are on treadmills at any one time, but there will be a certain level of power that is always being generated, even as different hamsters hop on or off their individual treadmills. That’s the reliable baseload power.

The connected wind farms would operate the same way.

“The idea is that, while wind speed could be calm at a given location, it could be gusty at others. By linking these locations together we can smooth out the differences and substantially improve the overall performance,” Archer said.

As one might expect, not all locations make sense for wind farms. Only locations with strong winds are economically competitive. In their study, Archer and Jacobson, a professor of civil and environmental engineering at Stanford, evaluated 19 sites in the Midwestern United States with annual average wind speeds greater than 6.9 meters per second at a height of 80 meters above ground, the hub height of modern wind turbines. Modern turbines are 80 to 100 meters high, approximately the height of a 30-story building, and their blades are 70 meters long or more.

The researchers used hourly wind data, collected and quality-controlled by the National Weather Service, for the entire year of 2000 from the 19 sites. They found that an average of 33 percent and a maximum of 47 percent of yearly-averaged wind power from interconnected farms can be used as reliable baseload electric power. These percentages would hold true for any array of 10 or more wind farms, provided it met the minimum wind speed and turbine height criteria used in the study.

Another benefit of connecting multiple wind farms is reducing the total distance that all the power has to travel from the multiple points of origin to the destination point. Interconnecting multiple wind farms to a common point and then connecting that point to a far-away city reduces the cost of transmission.

It’s the same as having lots of streams and creeks join together to form a river that flows out to sea, rather than having each creek flow all the way to the coast by carving out its own little channel.

Another type of cost saving also results when the power combines to flow in a single transmission line. Explains Archer: Suppose a power company wanted to bring power from several independent farms—each with a maximum capacity of, say, 1,500 kilowatts (kW)—from the Midwest to California. Each farm would need a short transmission line of 1,500 kW brought to a common point in the Midwest. Then a larger transmission line would be needed between the common point and California—typically with a total capacity of 1,500 kW multiplied by the number of independent farms connected.

However, with geographically dispersed farms, it is unlikely that they would simultaneously be experiencing strong enough winds to each produce their 1,500 kW maximum output at the same time. Thus, the capacity of the long-distance transmission line could be reduced significantly with only a small loss in overall delivered power.

“Due to the high cost of long-distance transmission, a 20 percent reduction in transmission capacity with little delivered-power loss would notably reduce the cost of wind energy,” added Archer, who calculated the decrease in delivered power to be only about 1.6 percent.

With only one farm, a 20 percent reduction in long-distance transmission capacity would decrease delivered power by 9.8 percent—not a 20 percent reduction, because the farm is not producing its maximum possible output all the time.

Archer said that if the United States and other countries each started to organize the siting and interconnection of new wind farms based on a master plan, the power supply could be smoothed out and transmission requirements could be reduced, decreasing the cost of wind energy. This could result in the large-scale market penetration of wind energy—already the most inexpensive clean renewable electric power source—which could contribute significantly to an eventual solution to global warming, as well as reducing deaths from urban air pollution.

A wind power feasibility study of potential sites along the California coast by Mike Dvorak, a Stanford doctoral student in civil and environmental engineering who is working with Jacobson and Archer, also is being presented during an afternoon poster session at the meeting.

When Stanford students come back to school this month after a hot summer, they’ll be in the ideal frame of mind to consider a new engineering degree that is rare, if not unique, in the United States: the atmosphere and energy major.

The interdisciplinary undergraduate program is being launched as governments and businesses around the world try to reconcile their need for energy with increasing concern about the effects of pollution on human health and the climate.

“The major will create students who will have the skills to do things that are in high demand,” said Mark Jacobson, a professor of civil and environmental engineering. “To come up with creative solutions to global warming and pollution while also addressing energy needs.”

“Problems in the atmosphere are very closely linked to problems with energy,” he added. “Global warming, urban air pollution, acid rain and other atmospheric problems are driven by pollution from energy. Right now there is a big disconnect between understanding these issues and solving them.”

The undergraduate major, new for the 2007-08 academic year, follows in the footsteps of Stanford’s graduate Atmosphere/Energy Program, which has grown quickly since starting in the 2004-05, when 15 students enrolled. The next year, 22 signed up. Applications to the graduate program have grown from 37 three years ago to 70 this year.

Reflecting the interdisciplinary nature of their education, graduates from the master’s program have gone on to jobs at places as diverse as Fortune 500 energy companies and environmentally focused, non-governmental organizations, Jacobson said.

About 60 universities around the country offer majors in atmospheric science, but none of them couple that so strongly with a curriculum in energy, he said. A student in a traditional atmospheric science major may therefore gain a deep understanding of how excessive carbon dioxide influences climate but won’t know as much about what drives people to use the energy sources that emit the gas, or what energy alternatives could satisfy those needs more cleanly.

At Stanford, however, students will not only take classes titled Aerosols, Clouds and Climate Change and Weather and Storms, but also Electric Power: Renewables and Efficiency and Powering the Rim: Energy issues for the Pacific.

One such student will be junior Emily Gorbaty of Baltimore.

“In my future career I would like to work toward mitigating global warming, and I found that no other major addresses this issue as well as atmosphere/energy,” Gorbaty said. “Ultimately I want to help implement renewable energy in developing countries, specifically India, China and Southeast Asia.

Jacobson said about a half-dozen undergraduates also have expressed interest in the new major so far.

Technically, the degree conferred will be “Bachelor of Science with an Individually Designed Major in Engineering: Atmosphere/Energy.” More importantly, Jacobson said, the skills and knowledge conferred will be unique preparation for addressing urgent global problems with meaningful, practical solutions.

read more: http://www.stanford.edu/group/atmosenergy/

Much as human intuition is far better than artificial intelligence in making sense of the world, people are far better at imagining thinking machines than actually making them. Now a large, ambitious team of AI researchers has launched a long-term research campaign to narrow both inequities, aiming unabashedly for a long-imagined grail of robotics: the personal aide.

“This encompasses the idea of broad competence intelligence,” says Andrew Ng, an assistant professor of computer science who is leading the new Stanford Artificial Intelligence Robot (STAIR) project. “The goal is not to engineer one robot to solve a narrowly defined task but to create a single platform to perform a wide variety of tasks.”

The true-life realization of a robot with the intelligence to help around the house could deliver a tremendous benefit to the disabled or the elderly, Ng says. Rather than heading out into a cold, winter afternoon with her walker, an elderly woman could send STAIR to fetch her mail, for example. A STAIR success would also be a very big deal in research circles, because it requires advancing and integrating about a dozen subspecialties (e.g. language processing, machine vision, machine learning, and decision analysis) in the currently fragmented field of AI.

Big goals and baby steps
Take the example of a robot assistant fielding a request to fetch an object from a room in the house, the team’s nearest-term major goal for STAIR. “STAIR!” a future owner might bellow. “Could you bring the ‘I, Robot’ book from my bedroom? I think it’s on the nightstand or maybe the floor.” That simple request would set off a cascade of tasks that are intuitive for people but actually quite complicated if done with the explicit deliberation required in computers.

Here’s a rough idea of how STAIR could handle the question: First it would try to figure out what was asked, perhaps by finding the best match with patterns of stored template questions. Then it would want to recognize through a combination of face and voice recognition, who was asking, because that would dictate which bedroom to search. STAIR would know where itself and the bedroom were, based on its laser and video vision. It would then have to navigate to the bedroom safely, maybe using the lasers and vision sensors to dodge the cat along the way. Then STAIR would have to find an object that matched the appearance of a book (whether or not the suggested locations were correct). Prudent programming would require it to check whether the book it found was the correct one, perhaps by scanning the largest-print text, which is most likely to be the title. Of course, it would have to judge how to safely handle any objects that it wants to pick up and look under during its search.

“By 2008 we hope to have it fetch objects off the top of people’s desks, bookshelves, nightstands, or floors,” Ng says. “Searching under a pile of things to locate a specific object might take a bit longer, maybe five years.”

Leading up to these milestones, the researchers have more modest goals that would each be achievements in their own right. During STAIR’s toddlerhood they hope to enable the robot to go anywhere it pleases in the Gates Information Sciences Building, including opening doors and hitting appropriate elevator buttons. STAIR will then be expected to act as a messenger around the building before earning its promotion to gofer.

In the first few months of work, Ng and his team have built the first version of STAIR’s body (it uses a modified Segway Human Transporter to get around). They have also taught it to recognize and open four doors in the Gates building.

Over the next decade the researchers will strive to have STAIR meet three challenges — in addition to fetching objects — that are similarly mundane, useful and hard:

• Tidying up a living room after a party, including picking up and throwing away trash, and loading the dishwasher.
• Using multiple tools (e.g. a screwdriver, hammer, pliers) to assemble a bookshelf.
• Guiding guests around an active place such as a museum, research lab or other facility that changes daily, answering questions and keeping track of the group.

Read more: http://cs.stanford.edu/group/stair/index.php
Awesome Video Link: STAIR in Action