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While the weather in Iceland is often cold, wet, and windy, a nearly endless supply of heat bubbles away below the surface.
虽然冰岛的天气总是寒冷、潮湿又多风，但在地表之下，几乎无穷无尽的热量在蒸发。
In fact, almost every building in the country is heated by geothermal energy, in a process with virtually no carbon emissions.
事实上，这个国家几乎所有建筑的供暖都来自于地热能，这个过程中几乎没有任何碳排放。
So how exactly does this renewable energy work?
那么，这种可再生能源到底是怎么回事呢？
Between the Earth's core and its crust is a mixed layer of solid and partially molten rock called the mantle.
在地核和地壳之间，是一个由固态和部分熔融的岩石组成的混合层，称为地幔。
Temperatures here range from 1,000 to 3,500 degrees Celsius. Some of this heat comes from the radioactive decay of metals.
这里的温度在1000到3500摄氏度之间。其中一些热量来自金属的放射性衰变。
But much of it comes from Earth's core, which has been radiating energy since the planet formed over four billion years ago.
但很大一部分来自地核，自从地球在40多亿年前形成，地核就不断地在辐射能量。
While the mantle moves slowly, circulating roughly 40 kilometers below the Earth's crust, there are places where it surges closer to the surface.
虽然地幔活动缓慢，在地壳约40公里之下循环，但在有些地方，它会涌向地表。
Here, the magma forms pockets and veins in the ground, heating underground rivers and pools to temperatures reaching 300 degrees.
在这里，岩浆在地面中形成囊和脉，将地下河流和水池加热到300摄氏度。
Controlling heated water is at the heart of harnessing geothermal energy, and there are two primary models for how to do it.
控制这些热水是利用地热能的核心，而有两种主要方法能做到这一点。
One is to build a geothermal power plant which uses these hot, deep pools to produce electricity.
其中一种是建造地热发电厂，利用这些热的深水池发电。
First, engineers drill a well several kilometers into permeable rock like sandstone or basalt.
首先，工程师会在砂岩或者玄武岩这样的可渗透岩石上钻一口数公里的井。
As the hot, highly pressurized groundwater flows into the well, the rapid change in pressure and temperature produces huge amounts of steam.
随着高温高压的地下水流入井中，迅速变化的压力和温度产生大量的蒸汽。
This steam then turns the blades of a turbine to generate electricity.
然后，这些蒸汽将带动涡轮机的叶片发电。
Finally, the remaining cooled water and condensed steam are injected back into the ground to create an open loop that provides electricity without losing water.
最后，剩余的冷却水和冷凝蒸汽被注入地下，形成一个开环，在不失水的情况下提供电力。
However, we don't have to drill this deep to take advantage of the planet's heat.
然而，我们不需要钻这么深的孔来利用地球的热量。
Thanks to solar radiation, dirt just 1.5 meters deep can reach temperatures over 20 degrees Celsius.
多亏了太阳辐射，仅有1.5米深的泥土就可达到20摄氏度以上。
Geothermal heat pumps pipe water or antifreeze liquid through this layer of earth to siphon its energy.
地热热泵将水或者防冻液体通过管道在这层泥土里抽取能量。
These liquids are then pumped through local infrastructure, dispersing their heat before moving back through the ground to absorb more energy.
然后，这些液体被泵送到当地的基础设施中，扩散它们的热量，之后再次在地面中穿梭吸收更多的能量。
While external electricity is needed to operate the pumps,
尽管运作泵需要外部电力，
the energy provided is far greater than the energy used, meaning this process is also a sustainable loop.
但从中提供的能量远远超过消耗的，这代表这个过程也是一个可持续的循环。
In fact, geothermal heat pumps are both cheaper to operate and at least two times more energy efficient than fossil fuel equivalents.
事实上，地热泵不仅运行成本低，它的节能性是化石燃料的两倍。
Whether geothermal energy is radiating just below our feet, or heating water several kilometers deep, the planet is constantly radiating heat.
无论地热能是在我们脚下放射，还是在几公里之下加热水，地球都不断地辐射能量。
Averaged across one year, Earth gives off roughly three times more energy than humanity consumes.
平均一年，地球释放的能量大约是人类消耗的三倍。
So why does geothermal only account for 0.2% of humanity's energy production? The answer has to do with heat, location, and cost.
那么，为何地热能只占人类能源生产的0.2%呢？答案和热量、地点和成本有关。
Since geothermal heat pumps rely on the consistent heat found in shallow earth, they can be implemented almost anywhere.
由于地热热泵依赖来自于浅地层的持续热量，它们几乎可以在任何地方使用。
But geothermal power plants require tapping into high-temperature geothermal fields;
但是，地热发电厂需要利用高温地热田；
regions hotter than 180 degrees and typically several kilometres underground.
温度超过180度的地区，也通常在地下几公里。
These high temperature zones are hard to find, and drilling this deep for just one of the several wells a plant will need can cost up to $20 million.
这些高温地区很难找到，而钻这么深仅仅为了一个工厂需要的几口井中的其中一口，就需要花费2000万美元。
There are regions with shallower geothermal fields.
有些地区的地热田较浅。
Iceland and Japan are near active volcanoes and tectonic plate boundaries, where magma rises up through the crust.
冰岛和日本临近活火山和地壳板块的边缘，在那里岩浆从地壳中上升。
But these same factors also make those regions prone to earthquakes, which can also be triggered by intensive drilling.
但这也导致这些地区容易发生地震，而密集的钻井也会引发地震。
Furthermore, while geothermal energy is clean and renewable, it's not entirely harmless.
此外，尽管地热能是干净、可再生的，它并不是完全无害的。
Drilling can release vapors containing pollutants like methane and hydrogen sulfide.
钻井会释放出含有污染物的蒸汽，例如甲烷和硫化氢。
And drilling tools that use pressurized water can contaminate groundwater. Fortunately, new technologies are emerging to meet these challenges.
使用高压水的钻井工具也会污染地下水。幸运的是，新技术的出现能够战胜这些挑战。
Emission control systems can capture pollutants, and electromagnetic monitoring can help detect seismic risks.
排放控制系统可以捕获污染物，电磁检测可以帮助检测地震风险。
We're also uncovering entirely new sources of geothermal energy, like pockets of magma in mid-ocean volcanoes.
我们也在发现全新的地热能来源，比如海洋中火山的岩浆区。
So if we can safely and responsibly tap into the heat sustaining our planet, we might be able to sustain humanity as well.
因此，如果我们能够安全、负责任地利用地球的热量，我们或许能够维持人类的生存。
