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Cornell University professors, from left, Zellman Warhaft, Francis Vanek and Alan Zehnder have been closely studying wind power and what needs to be done to get the U.S. to reach its target of 20 percent of electrical energy produced by wind by 2030. (Photo by Taryn Thompson) |
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Cornell professors: Marginal wind in Tompkins County
Taryn Thompson
Reporter
In order to mitigate the impact of electricity generation on global climate change and to reduce the nation's dependence on fossil fuels, the U.S. Department of Energy suggested a scenario in which 20 percent of the nation's electricity will be supplied by wind power by the year 2030.
In June, Cornell University professors David Caughy, Zellman Warhaft and Alan Zehnder hosted a weekend workshop to address the issues associated with the extended use of wind power to generate electricity in the United State. The workshops united world-renowned experts in the field of wind power to consult with the university faculty and discuss critical research issues that must be resolved in order to meet the U.S. DOE's goal.
Reaching the goal would entail a nearly thirty-fold increase over today's wind power electricity production. Many other countries are proposing even greater investments in wind power. While the cost of wind power is competitive with hydrocarbon power production, there are many issues and obstacles that need addressing. These include the effects of variable wind loading, materials and drive train durability, effects on birds and bats, noise, aesthetics, cost and the overhaul of the national power grid.
One obstacle recently investigated in the Ithaca Times focuses on the fact that wind itself is so intermittent. Wind power opponents argue that using wind power would raise the need for more reserve power, and that it would therefore require other power plants to run non-stop, essentially using more energy than what's saved.
However, the utility industry doesn't work that way, according to Francis Vanek, a visiting lecturer in the Civil and Environmental Engineering and Mechanical and Aerospace Engineering departments at Cornell University.
"Electricity is always being demanded in some amount every hour of every day of the year," Vanek said.
He explained that the electric companies can divide the demand between base-load plants - which they know will be needed to meet a given amount of demand, since there is a minimum at all times - and load-following plants that can adjust their output as load changes.
"What wind energy does is to reduce the demand," said Vanek, who's also writing his second text book on the subject. "Wind and other renewable [sources of energy] meet as much demand as they can, and then the load-following plants must meet the remaining amount, [or] the original demand minus the amount that the renewables met."
The way the grid works, wind energy comes into the grid and is mixed in with all other forms of energy. In fact, the intermittency of wind is irrelevant, according to the American Wind Energy Association. Wind energy simply takes its place as part of the mix.
"The fluctuations in wind plant output change more slowly than do the changes in customer demand that a utility must adjust to throughout the day," said Donald Furman, AWEA's senior vice president for Development, Transmission and Policy. "Studies indicate that for a 100-megawatt wind plant, only about two megawatts of conventional capacity is needed to compensate for changes in wind plant output."
Therefore, Vanek said, the question of whether the operation of a wind energy facility generates more carbon dioxide than it saves is extraneous.
"The effect of wind is almost negligible," Vanek said, noting a report by the New York State Energy and Research Development Authority.
"The savings you get from using wind is exactly the amount of carbon that's reduced by displacing fossil with wind energy," he added. "There's some kind of small penalty associated with the fact that it's intermittent and you have to back it up with fossil fuel, but it's much more reasonable than the argument that wind would actually end up generating more carbon dioxide than it saves."
The NYSERDA report from 2005 titled The Effects of Integrating Wind Power on Transmission System Planning, Reliability, and Operations states that when wind is added to a utility system, no new backup is required to maintain system reliability.
The report, conducted by the firm GE Energy Consulting and lead by project manager Richard Piwko, states that "the system operating strategy strives to make best use of all elements of the overall system, taking into account the operating characteristics of each generating unit and planning for contingencies such as plant or transmission line outages."
The utility system is also designed to accommodate load fluctuations, which occur continuously. This feature also facilitates accommodation of wind plant output fluctuations, the report noted.
"Right now there's a small percentage of wind-generated electricity nationwide, but 20 percent is enough such that there will have to be some big-scale decisions about reserve power plants," Warhaft said.
"You'd probably have baseline plants running at their steady load and then gas turbine-powered plants to take up the reserve load," he said. "They can come up to speed fairly quickly."
Warhaft added that natural gas-burning plants are pretty clean compared to coal, and since gas turbine-powered plants are the fastest, the DOE is talking about new fossil fuel plants being mostly natural gas-fired as opposed to coal.
The claim is sometimes made that manufacturing wind turbines and building wind plants creates large emissions of carbon dioxide, but according to AWEA, this is false.
"Studies have found that even when these operations are included, wind energy's carbon dioxide emissions are quite small - on the order of one percent of coal or two percent of natural gas per unit of electricity generated," Furman said.
In other words, using wind instead of coal reduces carbon dioxide emissions by 99 percent, using wind instead of gas by 98 percent.
Warhaft said the storage of power is important, too, but this aspect has yet to be developed.
"It's not a finally configured system and part of the whole development of the DOE is to look at not only wind mill citing, but also the power infrastructure," Warhaft said. "The way the grid is constructed will have to be largely re-designed and control systems will be put into place."
The grid already has different kinds of units on standby, Vanek added.
"Some of them are called spinning reserve, so literally the shaft of the turbine is spinning and pretty much instantaneously can be called upon to start generating electricity," he said.
"But when there's no load on that spinning reserve, it doesn't use very much energy," Vanek added. "The amount of energy it uses increases greatly when you actually call on it to start making electricity."
Then there are the other load-following plants on conventional standby.
"We know how to do those things, we probably would need more of them," Vanek said. "Suppose wind energy by itself reduces 100 percent of carbon dioxide just coming from the turbine, but maybe there's a 20 percent penalty because you had to have these back-up units that are either standing by; or, you have to call on them.
"You've still cut your carbon dioxide emissions by 80 percent," he added.
And, considering the inevitable fact that the reserve of fossil fuels throughout the world will eventually dry up, the very distant future poses a convincing argument that research into renewable energy sources is simply imperative.
"We're left with either renewables or nuclear," Vanek said, adding that there are reasons why improving nuclear energy is less transparent.
"You have to figure out breeder reactors and make them work reliably, [and] you'd have to figure out what to do with the waste on a much larger scale than what we're doing now," he added. "Or you'd have to figure out nuclear fusion, and all of those things, to me, seem difficult enough that renewables are the more likely outcome."
A few years ago, NYSERDA set a state-wide goal to employ renewable energy sources to the point where, collectively, the state would get 30 percent of its electrical energy needs from renewable sources by 2015 - six years from now.
This percentage includes hydraulic energy, and estimates 10 percent coming from wind energy. That's why NYSERDA guarantees that wind farm developers will be able to sell power to the state. But wind power is not the only option.
Warhaft said discussions on alternative sources of energy should be predicated on the over-arching importance of using non-fossil fuels.
He added that the average U.S. citizen is accountable for consuming10 kilowatts of power - constantly. That's 90 megawatt-hours per year of energy that every American citizen is using.
"Every one of us is equivalent to 10 electric radiators running full time, and the average U.S. citizen is using five times the power of the average person in the world," Warhaft said. "It's an unsustainable situation, not only because of global warming but because of the sheer need of resources."
In addition to weaning the country's dependence off fossil fuels and foreign sources of oil - in the name of economic and environmental insecurity, to name just a few issues - Warhaft suggested that a true paradigm shift is also necessary. He said conservation efforts are just as important.
"Unless we reduce carbon emissions, we're going to have really severe effects of global climate change," Warhaft said.
"There are a lot of different estimates of how much we have to reduce the burning of fossil fuels," he added, "but some estimates suggest that the world has got to install around 10 or more terawatts of fossil fuel-free energy, or green energy that doesn't use fossil fuels, by 2050."
That number, Warhaft said, is as much power as the world is using at the moment, directly from fossil fuels.
"We've got to really work toward replacing our whole infrastructure that's using fossil fuels by one that is not using fossil fuels," he said. "So it's a daunting task."
Scientists argue that there have to be a lot of different pieces to the puzzle: conservation plus wind energy, nuclear energy, and energy from the sun - known as photovoltaic.
According to the federal Department of Energy, the United States could potentially have 20 percent of its electrical energy produced by wind by 2030. It's called the 20/30 Plan and it entails putting in 300 gigawatts of wind power by that time.
"At the moment we're producing less than one-tenth of that," Warhaft said. "So we're going to have to increase wind power by over twenty-fold, just to get 20 percent of all the electrical energy from wind."
At peak development, that would involve erecting 5,000 large wind turbines per year across the country in the late teens and early 20s. To bring it locally, there are only marginal wind sites around Ithaca for commercial purposes.
"The best locations for New York are around the Great Lakes and possibly in the Great Lakes, and also off Long Island," Warhaft said.
"One way of citing is to localize two or three wind turbines in a particular position [in] little clusters," he added, "or having very large wind farms."
But a successful large wind farm requires an excellent source of wind. The threshold for making wind energy viable economically is class three wind, reaching speeds of 14 to 15.5 miles per hour at the tower height, which is around 200 feet for utility-scale, land-based turbines. Class four or five would be even better, but such winds in New York State are only available off shore, Zehnder said.
"You can site wind turbines - one, two or three - in rather localized areas," he said. "In either case, you've got to be really careful. Meteorological measurements often take at least a year to decide on a particular site."
At Ithaca College, NYSERDA funded a wind feasibility study that enabled the college to have a permit for a meteorological tower on campus. The met tower was erected in summer 2008 and has recently been dismantled.
Beth Ellen Clark Joseph, the chair of the physics department at IC, said the college contracted the feasibility study to Sustainable Energy Developments, Inc.
"They're still wrapping up the results for us," she said, adding that IC hopes to see those results soon.
Under the American Colleges and Universities Presidents Climate Commitment project, 650 campuses nationwide are creating climate action plans. Clark Joseph was member of IC's commitment team.
"We worked very hard to come up over the past few years with a climate action plan," Clark Joseph said. "The proposal for our wind project is wrapped up in the climate action plan, and that needs to be discussed by the college board of trustees."
Warhaft said it's important to have a global vision.
"My view is that you can't think completely locally," he said. "You've got to think in the broader context. You've got to think about Tompkins County, New York State, the United States, and the whole world. In the end, these are very delicate issues."
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Suicide has recently come to Ithaca in a very public, and at times controversial, way. This past academic year, after three years with no suicides, Cornell experienced what is known in the scientific community as a "suicide cluster." OK, so maybe you're like me and you thought this whole JetBlue flight attendant story was good for maybe one news cycle.  |
