There is enough energy in high altitude winds to power civilization 100 times over; and sooner or later, we’re going to learn to tap into the power of wind and use it to run civilization.
— Ken Caldeira, Carnegie Institution for Science
Energy dependence
Work, power, and energy are three words that invoke modernity. Without energy, we’d have no way to do the work that we need to survive: building shelter, staying warm, gathering and cooking food, obtaining and purifying water, and so on. Doing those things by hand, or even with the help of animals, condemns people to short and precarious lives, dependent on nature’s whims. By replacing human and animal muscles with machines, the industrial revolution made it possible for billions of people to live long lives of relative comfort.
Danger ahead
But our modern lifestyle may be living on borrowed time. After all, most of the power supplying our farms, cars, and factories comes from burning fossil fuels—and fossil fuels contain solar energy that took millions of years to store. Scientists disagree on how much coal, oil, and natural gas remains, but at some point—possibly during your lifetime—we will need to use more energy to obtain these resources than they give back.
Problems with fossil fuels
Furthermore, fossil fuels are bound by the laws of thermodynamics: Most of the heat they make goes straight into the environment without doing any useful work. (No vehicle, even an electric car, can work for long without somehow getting rid of this thermal energy.) Even worse, one unavoidable byproduct of burning fossil fuels is carbon dioxide—a greenhouse gas that traps heat from the Earth’s surface. Many scientists blame recent droughts, heat waves, and storms on the atmosphere’s increasingly high levels of greenhouse gases.
Advantages of wind power
The vital yet controversial role that energy plays in our lives underlies the passion with which people pursue renewable energy—energy from natural processes that can be harnessed to power our modern lifestyle without being destroyed, disrupted, or depleted. Renewable energy sources include sunlight, wind, geothermal energy (hot springs and geysers), and moving water (waterfalls, rivers, ocean waves, and tides). Of these, wind holds much promise in the eyes of many conservationists: It poses relatively few hazards; it is abundant; and it can be harvested on many scales, from tiny backyard windmills to enormous offshore turbines.
Limitations of wind power
Windmills have been used for centuries to mill grain and pump water, as exemplified by the dike system in the Netherlands. Windmills have dotted the landscape for generations. But that, say some, is part of the problem. Modern wind turbines are as tall as a football field is long. Many find them rather noisy. They may pose a significant hazard, some say, to birds and bats. But worst of all, they’re inefficient. Wind turbines typically operate at full power only 10% or 20% of the time; in other words, they have a low duty cycle. Even at an altitude of 100 m above the ground, wind loses lots of energy to friction with the ground. And, as sailors know well, low-altitude winds often stop blowing altogether.
Test your knowledge
List two advantages and two disadvantages of modern wind turbines.
Advantages: relatively few hazards (to people); abundant (found in many settings worldwide). Disadvantages: may be harmful to birds and bats; inefficient, because wind does not always blow at any particular location, and when it does it loses some energy to friction with the ground.
Work, power, and energy are three words that invoke modernity. Without energy, we’d have no way to do the work that we need to survive: building shelter, staying warm, gathering and cooking food, obtaining and purifying water, and so on. Doing those things by hand, or even with the help of animals, condemns people to short and precarious lives, dependent on nature’s whims. By replacing human and animal muscles with machines, the industrial revolution made it possible for billions of people to live long lives of relative comfort. 
The vital yet controversial role that energy plays in our lives underlies the passion with which people pursue 
