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  • 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,

  • of solid and partially molten rock called the mantle.

    是固態和部分熔化的岩石組成的混層,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,

  • over four billion years ago.

    這些熱能有部分來自 金屬的放射性衰變。

  • While the mantle moves slowly,

    但大部分都來自於地核,

  • circulating roughly 40 kilometers below the Earth's crust,

    從四十億年前地球形成之後,

  • there are places where it surges closer to the surface.

    地核便不停地輻射出能量。

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

    雖然地函移動緩慢,

  • heating underground rivers and pools to temperatures reaching 300 degrees.

    在地殼下約四十公里深處循環,

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

    它在某些地方會特別高漲, 更接近地面。

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

    在這些地方,岩漿會在地面下 形成岩漿庫和岩脈,

  • One is to build a geothermal power plant

    將地底河流與水池加溫到

  • which uses these hot, deep pools to produce electricity.

    攝氏三百度之高。

  • First, engineers drill a well several kilometers into permeable rock

    若要利用地熱能源, 關鍵在於控制這些熱水,

  • like sandstone or basalt.

    要做到這一點,有兩個 主要的模型可以使用。

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

    第一,建造地熱發電廠,

  • the rapid change in pressure and temperature

    電廠能利用地下深處的 熱水池來發電。

  • produces huge amounts of steam.

    首先,工程師們會先向下 鑽數公里深的井,

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

    會選擇可滲透岩來鑽鑿, 如砂岩或玄武岩。

  • Finally, the remaining cooled water and condensed steam

    當高溫、增壓的地下水流入井中,

  • are injected back into the ground to create an open loop

    壓力與溫度的快速改變

  • that provides electricity without losing water.

    會產生大量蒸氣。

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

    這些蒸氣能讓渦輪機的 葉片轉動,產生電力。

  • Thanks to solar radiation,

    最後,剩下的冷水與冷凝水蒸氣

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

    會再被重新注入地下,

  • Geothermal heat pumps pipe water or antifreeze liquid

    創造一個開放式迴路,

  • through this layer of earth to siphon its energy.

    能提供電力,又不會把水流失掉。

  • These liquids are then pumped through local infrastructure,

    然而,我們不必鑽這麼深

  • dispersing their heat before moving back through the ground

    就可以利用地球的熱能。

  • to absorb more energy.

    由於太陽輻射,

  • While external electricity is needed to operate the pumps,

    僅一點五公尺深的泥土

  • the energy provided is far greater than the energy used,

    就可以達到攝氏二十度以上的溫度。

  • meaning this process is also a sustainable loop.

    地熱的熱泵會以管道輸送水或防凍液,

  • In fact, geothermal heat pumps are both cheaper to operate

    穿過地裡的這一層,以吸收其能量。

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

    這些液體接著再被幫浦輸送 至當地的基礎建設,

  • Whether geothermal energy is radiating just below our feet,

    釋放其熱能,然後再次返回地底,

  • or heating water several kilometers deep,

    以吸收更多能量。

  • the planet is constantly radiating heat.

    雖然需要外部電力 才能操作這些幫浦,

  • Averaged across one year,

    所供應能源遠比消耗掉的多,

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

    意味著這個過程也是個永續的迴路。

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

    事實上,地熱的熱泵不僅用起來實惠,

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

    其能源效率至少也是化石燃料的兩倍。

  • Since geothermal heat pumps rely on the consistent heat

    無論地熱能是在我們腳下釋放,

  • found in shallow earth,

    還是加熱地下幾公里深的水,

  • they can be implemented almost anywhere.

    地球都不斷在輻射出熱能。

  • But geothermal power plants require tapping into

    平均每年,

  • high-temperature geothermal fields;

    地球釋放的能源

  • regions hotter than 180 degrees and typically several kilometres underground.

    約是人類所消耗的三倍以上。

  • These high temperature zones are hard to find,

    那麼,為什麼人類製造的能源中

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

    只有 0.2% 是地熱 ?

  • can cost up to $20 million.

    答案與熱能、地點,及成本有關。

  • There are regions with shallower geothermal fields.

    由於地熱的熱泵

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

    仰賴的是地表淺層的持續熱能,

  • where magma rises up through the crust.

    幾乎任何地方都可以裝設。

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

    但地熱發電廠

  • which can also be triggered by intensive drilling.

    需要利用高溫地熱田;

  • Furthermore, while geothermal energy is clean and renewable,

    這些區域的溫度超過一百八十度,

  • it's not entirely harmless.

    且通常位於地下數公里處。

  • Drilling can release vapors containing pollutants

    這類高溫地帶很不好找,

  • like methane and hydrogen sulfide.

    且電廠需要數口這麼深的井,

  • And drilling tools that use pressurized water can contaminate groundwater.

    光是鑽一口井成本就要兩千萬美金。

  • Fortunately, new technologies are emerging to meet these challenges.

    有些地方的地熱田比較淺。

  • Emission control systems can capture pollutants,

    冰島和日本很靠近活火山

  • and electromagnetic monitoring can help detect seismic risks.

    及地表板塊交界處,

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

    在這些地方,岩漿會上升穿過地殼。

  • like pockets of magma in mid-ocean volcanoes.

    但這些地方也因為這些因素 而很容易受地震影響,

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

    密集鑽井也有可能引發地震。

  • we might be able to sustain humanity as well.

    此外,雖然地熱是 乾淨的再生的能源,

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,

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