Not only does it appear that there is enough latent energy in wind to supply all our needs here on Earth, but our use of wind energy is seen to have no climate consequences. So say climate science researchers from Lawrence Livermore National Laboratory who have studied the impact of wind turbines on the atmosphere. The reason for the study – a previous concern raised by researchers that demonstrated wind turbines could alter local climate.
In their study the Lawrence Livermore team looked at how much power could be theoretically harvested from wind. In addition they looked at deployment of high-altitude wind turbines to see how much additional wind power capacity could be created. They also studied the implications to climate should high-altitude turbines be deployed.
How do wind turbines influence climate? Turbines alter airflow as the wind passes over the spinning blades. This creates drag. Put up enough 30 meter towers and theoretically you could alter wind speeds near the ground and as a result, local climate. The saturation wind power potential point is the moment when turbine capacity begins to degrade wind speeds. It represents the theoretical limit and energy capacity that we can derive from wind.
The Lawrence Livermore researchers calculated total wind energy capacity for the planet at ground level and in the upper atmosphere at 2,200 terawatts, 400 terawatts from ground-level wind and 1,800 terawatts from the upper atmosphere. Compare that to total energy demand of 18 terawatts today and you can see that wind can provide us with more than all of our current and future needs.
A Stanford-University of Delaware study is also shedding light on the theoretical limits of wind turbines. Researchers at these two universities have calculated that 4 million wind turbines, half deployed onshore and the remainder offshore, could supply between 5 and 7.5 terawatts of power with no significant climatic impact. Triple that number and wind could meet the current energy demands of the entire planet with capacity to spare.
Studying the Effect of Wind Turbines
How do researchers study wind turbine interaction with the atmosphere. The National Oceanic and Atmospheric Administration or NOAA in the United States has developed High Resolution Doppler Lidar. Also known as HRDL, the technology produces accurate three-dimensional portraits of atmospheric activity capturing information covering a column of air measuring 1,000 meters (3,280 feet) in height and 7,000 meters (4.3 miles) downwind. This allows researchers to study real-world wake effects from wind turbines. Another technology, a WindCube Lidar, is a ground-based device placed at wind farm locations to capture measurements at various levels in the air column across the entire site. Add wind profiling technology such as the Triton Sodar, a portable, solar-powered device that can be deployed inside a wind farm to study the impact of the rotating blades on the local atmosphere.
Of course the challenge for wind is its variability. But with such large numbers of turbines in play, there would be enough capacity to meet energy demands worldwide even if the wind isn’t blowing at a number of sites.
Where would wind turbines least interfere with existing human populations while taking advantage of the most reliable wind conditions? Researchers suggest locations such as the Gobi Desert of Central Asia, the Sahara Desert of North Africa, and the North American Great Plains. And because a wind turbines footprint on land surfaces is relatively small wherever deployed land use is not restricted. That’s what makes wind such an attractive option to meet worldwide energy demand without burning fossil fuels.
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I’ll grant that the biosphere could withstand all the direct environmental impact of 100-times the present number of wind turbines. Personally I’m hostile to wind turbines for four reasons.
(1) Aesthetics aside, wind turbines generate huge low frequency noise pollution, which carries many miles from the turbine sources, and in principle there is no standard dilution solution. The turbines must be sited far from populations, or the populations must be sited far from the turbines.
(2) The costs are impossible to accurately compute. I don’t know how to discover the true costs, which are quoted by various factions with wide differences. My suspicions are that costs are much higher than generally quoted and believed. There are virtually no major wind farms that operate purely on market economics, with government subsidies nearly always comprising a major component of the economic model.
(3) Money sunk into wind turbines is money that is not available to fund high-energy-density systems such as nuclear reactors, natural gas fired boilers, and combustion turbines. In most regions, wind turbine capacity is parasitical on base load generation, which must lose part of the grid market to non-base load wind when the wind blows at night. Hence the base-load high-capital and high-capacity-factor power plants must yield market share to high-capital low-capacity factor wind turbines. For many locations wind turbine nameplate capacity, which might specify 28 mph wind speed, is 5-times actual average performance. Ultimately the consumer must pay more for his grid power.
(4) Since wind power doesn’t make much economic sense unless the average wind speed is greater than 20 mph and doesn’t vary too much above or below that, the turbines must be sited where the wind blows constantly and strongly, not near the populated markets for power. Hence the power must be transmitted over long distances. That requires big transformers, thousands of miles of large-cross-section transmission cables, and support towers. Should be obvious that each unit of wind power will make greater demands on reserves of copper and steel than will power plants that are sited near markets. The greater demand for copper will certainly raise costs of power tools, electric motors, appliances, and residential wiring.
Eventually, the extensive Danish offshore wind farms might pay out. That’s because the nighttime generation power can travel a relatively short distance over to mountainous Norway, where it drives pumps to replenish many hydroelectric reservoirs. Then during periods of peak loads the impounded water discharges through the hydro-turbines, but the reservoirs are not depleted because wind power from Denmark recharges them every night the wind is blowing.
A similar scheme might work with solar power installed near Hoover Dam/Lake Mead. The Hoover Dam generators must work at a much lower capacity than design because the Colorado River flow cannot maintain constant water level in Lake Mead. Lake level is now down some 120-feet. That means the hydro-turbines have lost some 50-psi penstock pressure. So solar power might be used to restore Lake Mead levels and increase power production at Hoover Dam. If solar isn’t practical to replenish Lake Mead, it probably isn’t practical for anything else. (Las Vegas gets most of its profligately consumed power from Nevada Energy’s NG fired boilers, not from nearby Hoover Dam, but the region can readily consume all the power it can get. If you want to strike an effective blow to lower the US atmospheric carbon contribution, don’t build wind farms, shut down Las Vegas)
As always an insightful comment. Wind needs to be a supplemental power source in my opinion. And it needs to scale down. Just like the windmills that used to operate on farms years ago, wind can serve a great off-the-grid energy source. Combined with better storage technology to harvest the excess energy created when the wind blows, small wind turbines plus rooftop solar arrays could prove to be an excellent adjunct to grid-distributed power.
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The sooner we can shift to widely distributed power sources, the better off we will be. There are a few localities where average wind speeds are high enough to make sense out of private non-grid wind turbines, but they are by far the exception, not the rule. The South Texas/Houston region has about 6-mph average wind speeds (and lower than that if you discount gusts and wind speeds that are too high for wind turbines). Grid power is mostly available for about $0.10 kWh even in remote rural areas. Every decade or so, a powerful storm knocks out grid power, sometimes for as long as 14-days. In low wind-speed areas, the third-power of wind speed law dictates practical economics are such that small rooftop or small farm wind turbines can’t produce power for much less than $1.00 kWh. It’s hard to see how they could ever pay out. Yet every home show has displays hawking roof-mounted wind generators that would make good sense in 20-mph winds, but no sense at all in 6 mph winds (the 20-mph winds would produce 37-times as much power as 6-mph wind, but the system costs are identical).
Solar cells are now cheap enough for off-grid, but the associated energy storage and conversion systems are still way too expensive. In the Houston area, home solar systems can probably produce and store off grid power for about $0.35 kWh; that’s three times grid power costs, but hailstorms that dent automobile sheet-metal are common. Who knows how low cost solar panels would hold up?
Those concerned about losing grid power for days on end should invest $1000-$2000 into a diesel or gasoline generator. I’m on a small ranch that is all electric with 240V AC electric water well. An $800 generator and 55-gallon drum of gasoline will keep me in potable water and hot showers for months. I can cook on my propane grill until grid power and civil order is restored. If grid power should never be restored, then we will likely be in the “Mad Max” world with massive die-off, road warrior pirates, and motorcycle cannibals stalking the land. Then most of the remaining motor fuel would be in service station underground storage tanks, and the only practical way to recover it would be emergency generators with electric pumps.
Len says: “And it needs to scale down. Just like the windmills that used to operate on farms years ago, wind can serve a great off-the-grid energy source.”
The problem with scaling it down is that wind power output is a direct function of the area the blades sweep in rotation. If the blades double in dimension, output power quadruples. The same square function is true in scale-down. If the blades are made half size the power will fall by a factor of four.
But doubling tower height and increasing blade swept area doesn’t raise costs by four times. So to squeeze the most wind power per dollar out of installed costs, the commercial installations, which are always problematic at best, are made as large as technology allows. There is another major factor that encourages larger sizes. The wind speeds are higher as the towers are made taller, and the turbine’s power is a cube function of wind speed. If the tower is made taller to exploit the higher wind speed, it’s rather obvious and nearly irresistible that the blades could be made longer with the same ground clearance. So if the tower is made just 20-feet taller, the swept area can increase another 40-feet in diameter. That can make a huge difference in power output.
So, I’m with you, I would dislike wind turbines much less if they were size limited to say 160-feet diameter and the towers were only 100-feet tall. But that would mean costs per unit of power produced would probably be over five times higher than with 200-foot towers and 360-foot diameter blade swept area. The market is demanding cheaper power, especially with the glut of cheap natural gas, which will likely continue for decades, and that’s in direct conflict with environmental concerns. The concept of inexpensive off-grid power for the masses is highly desirable, but so far also highly elusive.
Cheap natural gas will constrain the development of renewables if price per kilowatt for the latter remains uncompetitive. But I’m not sure that cheap natural gas for the foreseeable future is global in scope. We are certainly seeing it in North America and in Central Asia but in areas of the Developing World, I’m not convinced that is the case. For these parts of our planet we need sustainable energy generating solutions that do not require elaborate infrastructure and that can serve local needs. Power grids based on landlines may not be the best energy technology investment for Developing World countries.
Len says: “But I’m not sure that cheap natural gas for the foreseeable future is global in scope. We are certainly seeing it in North America and in Central Asia but in areas of the Developing World, I’m not convinced that is the case. For these parts of our planet we need sustainable energy generating solutions that do not require elaborate infrastructure and that can serve local needs. Power grids based on landlines may not be the best energy technology investment for Developing World countries.”
Well, the developed world is considered developed mainly because of its high productivity. High productivity depends on a combination of competent work force, capital equipment, good communication, efficient transportation infrastructure, civil order, national security, and adequate energy base. Each factor is essential. Remove any one of them and productivity begins to collapse. Outside capital will shun any “developing” country that lacks the efficient energy base, and internal capital is generally too meager to prime a prosperity pump. In much of the developing world the problems are much, much, deeper than insufficient energy base. Generally there are serious problems in all the essential factors. Unless and until some radical new energy base technology is discovered (such as the mythological E-Cat), the developing world will be stuck with gradually expanding power grid infrastructure.
Looming ominously over all humanity is John Kenneth Galbraith’s deep and wise observation: “For nearly all of human history the world has been overpopulated.” By that he meant that the scale of resource base needed to support a given population depends on the available technology to exploit the resources, and the more advanced the technology the more energy will be required. Throughout most of history growth in population outstripped growth in technology. That meant wars, disease, poverty, famine, and slavery.
Very much dependent on the specfiic engineering of the wind turbine. You are losing energy to friction, so the mechanics of the device are very important. All of that is not a consideration for fossil fuels becase the earth has done most of the conversion already by using gravity (i.e., pressure), which is basically infinitely available. If you are thinking not in terms of energy cost, but financail cost, then you really need to think about the supply chain. A single high-effeicncy wind turbine might cost $5MM to build, but there is operational cost, land cost, distribution and storage costs. All of that is baked into the end user price of a gallon of processed fossil fuels. I don’t know the specfiic numbers, but I do know that none of the wind farms would be profitable without the government subsidies that they are getting ATM.That chart of 1996 California date someone posted showing that wind is the lowest cost seems highly suspect to me at a minimum it is looking at regulatory compliance costs for things like nuclear and fossil feuls, not just the cost of generating and delivering the energy. That is the problem with data “sound bites”, they are a little to easy to quote without thinking about them.
I am in total agreement. Without subsidies today only hydro as a renewable is cost competitive with fossil fuel sources. And considering where fossil fuel prices are headed currently the difference will remain significant for sometime to come.