Iceland's secret power - Jean-Baptiste P. Koehl

譯者: Lilian Chiu 審譯者: Amanda Zhu

While the weather in Iceland is often cold, wet, and windy,

儘管冰島的天氣通常 都是又冷、又濕，又多風，

a nearly endless supply of heat bubbles away below the surface.

地表下卻有著近乎 無窮盡的熱源不斷沸騰著。

In fact, almost every building in the country is heated by geothermal energy,

事實上，在冰島，幾乎所有建築物的 熱能來源都是地熱，

in a process with virtually no carbon emissions.

且過程幾乎不會排放出任何碳。

So how exactly does this renewable energy work?

所以，這種再生能源 究竟是怎麼運作的呢？

Between the Earth’s core and its crust is a mixed layer

在地核和地殼之間，

是固態和部分熔化的岩石組成的混層，

of solid and partially molten rock called the mantle.

叫做地函。

Temperatures here range from 1,000 to 3,500 degrees Celsius.

這裡的溫度

在攝氏一千到三千五百度之間。

Some of this heat comes from the radioactive decay of metals.

這些熱能有部分來自 金屬的放射性衰變。

But much of it comes from Earth’s core,

但大部分都來自於地核，

which has been radiating energy since the planet formed

從四十億年前地球形成之後，

地核便不停地輻射出能量。

over four billion years ago.

While the mantle moves slowly,

雖然地函移動緩慢，

circulating roughly 40 kilometers below the Earth’s crust,

在地殼下約四十公里深處循環，

there are places where it surges closer to the surface.

它在某些地方會特別高漲， 更接近地面。

Here, the magma forms pockets and veins in the ground,

在這些地方，岩漿會在地面下 形成岩漿庫和岩脈，

heating underground rivers and pools to temperatures reaching 300 degrees.

將地底河流與水池加溫到

攝氏三百度之高。

Controlling heated water is at the heart of harnessing geothermal energy,

若要利用地熱能源， 關鍵在於控制這些熱水，

and there are two primary models for how to do it.

要做到這一點，有兩個 主要的模型可以使用。

One is to build a geothermal power plant

第一，建造地熱發電廠，

which uses these hot, deep pools to produce electricity.

電廠能利用地下深處的 熱水池來發電。

First, engineers drill a well several kilometers into permeable rock

首先，工程師們會先向下 鑽數公里深的井，

會選擇可滲透岩來鑽鑿， 如砂岩或玄武岩。

like sandstone or basalt.

As the hot, highly pressurized groundwater flows into the well,

當高溫、增壓的地下水流入井中，

the rapid change in pressure and temperature

壓力與溫度的快速改變

produces huge amounts of steam.

會產生大量蒸氣。

This steam then turns the blades of a turbine to generate electricity.

這些蒸氣能讓渦輪機的 葉片轉動，產生電力。

Finally, the remaining cooled water and condensed steam

最後，剩下的冷水與冷凝水蒸氣

are injected back into the ground to create an open loop

會再被重新注入地下，

創造一個開放式迴路，

that provides electricity without losing water.

能提供電力，又不會把水流失掉。

However, we don't have to drill this deep to take advantage of the planet's heat.

然而，我們不必鑽這麼深

就可以利用地球的熱能。

Thanks to solar radiation,

由於太陽輻射，

dirt just 1.5 meters deep can reach temperatures over 20 degrees Celsius.

僅一點五公尺深的泥土

就可以達到攝氏二十度以上的溫度。

Geothermal heat pumps pipe water or antifreeze liquid

地熱的熱泵會以管道輸送水或防凍液，

through this layer of earth to siphon its energy.

穿過地裡的這一層，以吸收其能量。

These liquids are then pumped through local infrastructure,

這些液體接著再被幫浦輸送 至當地的基礎建設，

dispersing their heat before moving back through the ground

釋放其熱能，然後再次返回地底，

to absorb more energy.

以吸收更多能量。

While external electricity is needed to operate the pumps,

雖然需要外部電力 才能操作這些幫浦，

the energy provided is far greater than the energy used,

所供應能源遠比消耗掉的多，

meaning this process is also a sustainable loop.

意味著這個過程也是個永續的迴路。

In fact, geothermal heat pumps are both cheaper to operate

事實上，地熱的熱泵不僅用起來實惠，

and at least two times more energy efficient than fossil fuel equivalents.

其能源效率至少也是化石燃料的兩倍。

Whether geothermal energy is radiating just below our feet,

無論地熱能是在我們腳下釋放，

or heating water several kilometers deep,

還是加熱地下幾公里深的水，

the planet is constantly radiating heat.

地球都不斷在輻射出熱能。

Averaged across one year,

平均每年，

Earth gives off roughly three times more energy than humanity consumes.

地球釋放的能源

約是人類所消耗的三倍以上。

So why does geothermal only account for 0.2% of humanity’s energy production?

那麼，為什麼人類製造的能源中

只有 0.2% 是地熱 ?

The answer has to do with heat, location, and cost.

答案與熱能、地點，及成本有關。

Since geothermal heat pumps rely on the consistent heat

由於地熱的熱泵

仰賴的是地表淺層的持續熱能，

found in shallow earth,

they can be implemented almost anywhere.

幾乎任何地方都可以裝設。

But geothermal power plants require tapping into

但地熱發電廠

需要利用高溫地熱田；

high-temperature geothermal fields;

regions hotter than 180 degrees and typically several kilometres underground.

這些區域的溫度超過一百八十度，

且通常位於地下數公里處。

These high temperature zones are hard to find,

這類高溫地帶很不好找，

and drilling this deep for just one of the several wells a plant will need

且電廠需要數口這麼深的井，

光是鑽一口井成本就要兩千萬美金。

can cost up to $20 million.

There are regions with shallower geothermal fields.

有些地方的地熱田比較淺。

Iceland and Japan are near active volcanoes and tectonic plate boundaries,

冰島和日本很靠近活火山

及地表板塊交界處，

where magma rises up through the crust.

在這些地方，岩漿會上升穿過地殼。

But these same factors also make those regions prone to earthquakes,

但這些地方也因為這些因素 而很容易受地震影響，

which can also be triggered by intensive drilling.

密集鑽井也有可能引發地震。

Furthermore, while geothermal energy is clean and renewable,

此外，雖然地熱是 乾淨的再生的能源,

it’s not entirely harmless.

但也不是完全無害。

Drilling can release vapors containing pollutants

鑽井會釋放水汽，水汽含有污染物，

like methane and hydrogen sulfide.

如甲烷和硫化氫。

And drilling tools that use pressurized water can contaminate groundwater.

使用加壓水的鑽井工具

也可能會污染地下水。

Fortunately, new technologies are emerging to meet these challenges.

幸運的是，已經有新科技出現，

可以處理這些難題。

Emission control systems can capture pollutants,

排放控制系統可以捕捉污染物，

and electromagnetic monitoring can help detect seismic risks.

電磁監測可以協助偵測地震風險。

We're also uncovering entirely new sources of geothermal energy,

我們也不斷發現全新的地熱能來源，

like pockets of magma in mid-ocean volcanoes.

如散布在中洋火山孔穴內的岩漿。

So if we can safely and responsibly tap into the heat sustaining our planet,

若我們能以安全、負責的方式

利用這種能永續供應地球的熱能，

we might be able to sustain humanity as well.

那麼，我們或許也能夠 維持人類的生存。