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Every 24 hours, wind generates enough kinetic energy to produce roughly 35 times more electricity than humanity uses each day.
每24小时，风所产生的动能大约是全人类每日用电量的35倍。
And unlike coal or oil, this resource is totally renewed each day.
与煤炭或石油不同，这种资源每天都会完全更新。
So how can we harness this incredible amount of energy, and is it possible to create a world powered entirely by wind?
那么，我们能如何驾驭如此大量的能源，是否能让世界完全由风力供能？
The basic principle of wind energy is simple.
风能的基本原则很简单。
A series of sails or blades mounted around a rotor catch the wind and translate its kinetic energy into rotational energy.
风吹动一系列叶片，转动转子，把风的动能转换为旋转能。
Traditional windmills use that rotational energy to grind wheat or pump water. But in modern wind turbines, it turns a generator that creates electricity.
传统的风车用旋转能磨麦或抽水。但现代的风力涡轮机转动发电机来产生电力。
This conversion from wind to rotational energy to electricity has defined wind turbines since their invention in the late 19th century.
自从19世纪后期发明以来，这种从风到旋转能再到电力的转换就定义了风力涡轮机。
And there are three primary factors that determine just how much energy they can produce:
有三个主要因素决定它们能够产生多少能量：
the size and orientation of the blades, the blade's aerodynamic design, and the amount of wind turning the rotor.
叶片的大小和方向，叶片的空气动力学设计，以及转动转子的风量。
First up, blade orientation. Wind turbines can be designed with their rotor on a vertical axis or a horizontal axis.
首先是叶片的方向。风力涡轮机的转子可设计在垂直轴或水平轴上。
Vertical blades can pick up wind coming from any direction, but with much less efficiency than horizontal axis rotors.
垂直叶片能捕获任何方向的风，但效率比水平轴转子要低得多。
Horizontal designs allow blades to capture the wind's full force by tracking the wind's direction and turning to face it.
水平设计能让叶片追踪并正对来风的方向，从而捕获全部风力。
This turning process is called yawing, and older windmills achieved it through manual monitoring.
这种转向的过程称为偏航，旧式风车需通过人工监控进行调整。
Today, wind sensors and computer systems automatically adjust the blades with expert precision to capture as much energy as possible.
如今，风传感器和计算机系统能以专业精度自动调整叶片，以捕获尽可能多的能量。
Outside rotor orientation, the blades themselves need to be shaped to maximize efficiency.
除了转子的方向，叶片本身也要做成能把效率最大化的形状。
While early designs used flat blades, modern blades are curved like airplane wings.
早期的叶片采用平板设计，现代的叶片则像飞机机翼一样弯曲。
Wind travels faster over the curved surface, creating a low-pressure pocket above the blade that forces it upwards.
弯曲的上表面能提高风速，在叶片上方产生低压区，迫使叶片上抬。
Since the amount of lift depends on the angle at which the wind is moving relative to the blade,
由于升力大小取决于风相对于叶片的移动角度，
modern blades also incorporate a twist, optimizing how much of the blade can cut into the wind.
现代的叶片还加入了扭力，能优化叶片切入风的程度。
Made of fiberglass and resin layers, these blades are strong enough to operate through rain, lightning, and blistering sunlight for over 20 years.
这些由玻璃纤维和树脂层制成的叶片足够牢固，能在雨中、闪电里和烈日下运作超过20年。
Even with aerodynamic blades and a horizontal rotor, a wind turbine can only capture wind if it's in a windy environment.
即使有空气动力学叶片和水平转子，风力涡轮机也只能在风大的环境中捕获风能。
Wind speeds typically increase the higher into the atmosphere you travel.
一般来说，在大气层中越高，风速就越大。
So today, most turbines are well over 100 meters tall, with equally large rotor diameters.
所以当今大多数涡轮机都超过100米高，转子直径同样也很大。
A turbine of this height and size can capture a huge amount of wind, generating enough electricity every year to power 750 American homes.
一座这种高度和尺寸的涡轮机能捕获大量的风，每年产生的电力足够为750户美国家庭供电。
A wind farm of 200 similarly sized turbines could power over 150,000 American homes -- or twice as many European homes -- for an entire year.
一个风力发电厂配备200组类似大小的涡轮机，就能为超过15万户美国家庭--或超过30万户欧洲家庭--提供一整年的用电。
Offshore wind farms contain an even greater number of even larger turbines.
离岸风力发电厂配备的涡轮机数量与尺寸还要更大。
In 2019, the largest wind turbine ever built began operating off the coast of the Netherlands.
2019年，有史以来最大的风力发电机开始在荷兰沿海地区投入使用。
With a rotor diameter of 220 meters, just one of these turbines can meet the annual power needs of 16,000 European households.
它的转子直径为220米，仅一台这样的涡轮机就足以供应16000户欧洲家庭一年的用电。
Despite its amazing potential, wind energy still faces challenges.
尽管具有巨大的潜力，风能仍面临着挑战。
Wind may be a free and unlimited fuel, but no matter how large or efficient a turbine is there's a mathematical limit to how much wind it can convert into electricity.
虽然风能免费且取之不尽，但不管涡轮有多大、效率有多高，可转化为电力的风能仍存在数学上限。
German physicist Albert Betz calculated that since some wind must remain to keep the blades spinning, a turbine can only ever capture 59.3% of the wind's energy.
德国物理学家阿尔伯特·贝茨算出由于必须留出风力让叶片保持旋转，涡轮机最多只能捕获59.3%的风能。
Additionally, some people feel turbines disrupt natural scenery, and wind energy's intermittent availability can make it difficult to integrate into electrical grids.
此外，有些人认为涡轮机破坏了自然风光，加上风能只是间歇性可用，使其难以被整合进电网。
But even with these challenges, modern wind turbines have made wind energy the most efficient and inexpensive source of electricity.
但即使有这些挑战，现代风力涡轮机已使风能成为了最高效、最便宜的电力来源。
Wind turbines already provide essential energy for communities around the world.
风力涡轮机已为世界各地的社区提供了必不可少的能源。
And for many farmers, hosting a wind turbine can be a reliable source of additional income.
对于许多农民来说，在耕地上架设风力发电机是可靠的额外收入来源。
With continued improvements in wind forecasting, electrical grid infrastructure and energy storage, wind power might blow away all our energy problems.
随着风预报、电网基础设施和储能技术不断改进，风能或许可以吹散我们所有的能源问题。
