How scientists turn lakes into giant batteries

譯者: Helen Chang 審譯者: Zoe Walmsley

As of 2020, the world’s biggest lithium-ion battery

截至 2020 年， 全球最大的鋰離子電池

is hooked up to the Southern California power grid

位於南加州電網上，

and can provide 250 million watts of power,

它能提供 2.5 億瓦的電力,

or enough to power about 250,000 homes.

相當於 25 萬戶的家庭用電。

But it’s actually not the biggest battery in the world:

可是它並不是世界上最大的電池：

these lakes are.

這些湖泊才是。

Wait— how can a pair of lakes be a battery?

等等——兩座湖泊怎麼會是電池?

To answer that question, it helps to define a battery:

回答這個問題前， 讓我們先看一下電池的定義：

it’s simply something that stores energy and releases it on demand.

電池是用來儲存、 並在需要時釋出能量的容器。

The lithium-ion batteries that power our phones, laptops, and cars

我們的手機、筆記型電腦， 及汽車所用的鋰離子電池

are just one type.

只是其中一種。

They store energy in lithium ions.

電力儲存在鋰離子中。

To release the energy, the ions are separated from their electrons,

發電時，鋰離子從電子分離出來，

then rejoined at the other end of the battery

跑到電池的另一頭再重新結合，

as a new molecule with lower energy.

形成一個帶電量較低的分子。

How do the two lakes store and release energy?

那兩座湖泊如何儲存及放電?

First, one is 300 meters higher than the other.

首先，兩座湖泊標高差距三百公尺。

Electricity powers pumps that move billions of liters of water

利用電力加壓幫浦把數十億升的水

from the lower lake to the higher one.

從下面的湖吸到上面的湖中。

This stores the energy by giving the water extra gravitational potential energy.

水分子多出了額外的重力位能， 完成充電的動作。

Then, when there’s high demand for electricity,

然後，在電力需求上升時，

valves open, releasing the stored energy by letting water flow downhill

打開閥門放水， 同時釋放儲存的能量，

to power 6 giant turbines that can generate 3 billion watts of power

驅動六個巨型渦輪， 發電量高達 30 億瓦，

for 10 hours.

持續 10 小時。

We’re going to need more and more giant batteries.

我們會需要越來越多巨型的電池。

That’s because right now, generating enough electricity to power the world

因為目前全世界使用的發電方式

produces an unsustainable amount of greenhouse gas:

產生太多溫室氣體：

14 billion tons per year.

每年 140 億噸。

We’ll need to get that number down to net-zero.

我們必須把那個數字降到零。

But many clean energy sources can’t produce electricity 24/7.

然而很多潔淨能源並非全天候發電。

So to make the switch, we need a way to store the electricity until it's needed.

所以要如何轉換， 把電力儲存到需要的時候，

That means we need grid-scale batteries:

意味著我們需要電網規模大小的電池：

batteries big enough to power multiple cities.

大到能供應多座城市所需的巨型電池。

Unfortunately, neither of the giant batteries we’ve talked about so far

可惜，前面所說的這兩種巨型電池

can solve this problem.

都無法解決這個問題。

The two lakes setup requires specific geography, takes up a lot of land,

兩座湖的發電設計 需要特定地理位置，佔地太廣，

and has high upfront costs to build.

且前期的建設成本很高。

The giant lithium-ion battery in California, meanwhile,

位於加州的巨大鋰離子電池

can power about 250,000 homes, yes, but only for an hour.

雖然可以供應 25 萬戶的家庭所需， 但僅能持續一個小時。

Lithium-ion batteries are great for things that don’t use a lot of power.

鋰離子電池對於 耗電量小的東西非常理想。

But to store a lot of energy, they have to be huge and heavy.

但隨著儲存量上升， 電池的體積重量也隨之變大變重。

That’s why electric planes aren’t a thing:

這就是電動飛機仍不成氣候的原因：

the best electric plane can only carry two people

目前最好的電動飛機只能載兩個人，

for about 1,000 kilometers on one charge,

充一次電可飛大約一千公里，

or its batteries would be too heavy to fly.

電池太重就會飛不起來。

A typical commercial jet can carry 300 people over 14,000 km

典型的商用飛機能載 300 人， 飛行超過 14,000 公里，

before refueling.

才需再加油。

Lithium-ion batteries also require certain heavy metals to make.

製造鋰離子電池還需要某些重金屬。

These resources are limited, and mining them often causes environmental damage.

這些資源有限， 礦產的開採往往會破壞環境。

Inventors all over the world are rising to the challenge

全世界的發明家奮起面對挑戰，

of making batteries that can meet our needs—

要做出能滿足人類需求的電池,

many of them even weirder than the two lakes.

其中有許多甚至比兩座湖還更奇怪。

One company is building a skyscraper battery.

有家公司專做摩天樓電池。

When the sun is shining, a crane powered by solar energy

白天，太陽照耀時， 太陽能驅動的起重機

piles blocks on top of each other in a tower.

將重力方塊拉上塔井堆疊。

At night, the cranes let gravity pull the blocks down

到了晚上，起重機則讓地心引力 把重力方塊拉下去，

and use the resulting power to spin generators.

利用藉此產生的力量驅動發電機。

Though there have been some early setbacks,

另一個雖在初期遭遇挫折,

another promising approach involves heating up salts until they melt.

卻相當有希望的發電方法 是將鹽加熱熔融，

The molten salt can be stored until there’s a high demand for electricity,

儲存下來，等電力需求急速上升時，

then used to boil water.

使用熔融鹽將水加熱，

The steam can power turbines that generate electricity.

所產生的蒸汽能驅動渦輪機發電。

Another idea: bio-batteries made from paper, powered by bacteria,

還有紙做的生物電池， 用細菌發電，

and activated by spit.

用唾液啟動。

Bacteria release energy in the form of electrons when they metabolize glucose,

細菌代謝葡萄糖時 以電子的形態釋放能量，

and at least one species of bacteria can transfer those electrons

至少有一種細菌能夠把這些電子

outside its cells, completing a circuit.

轉移到細胞外，形成完整的電路。

While these batteries won’t power a city, or even a house,

儘管這些新電池無法 供應一個城市或一棟房子所需，

they don't have the waste and cost concerns of traditional batteries.

它們少了傳統電池 產生廢棄物及成本考量的問題。

From vast mountain lakes to microscopic bacteria,

從巨大的山湖到微小的細菌,

from seawater batteries that bypass the need for heavy metals

從不使用重金屬的海水電池，

to nuclear batteries that power deep space missions,

到深太空任務所使用的核電池，

we're constantly rethinking what a battery can be.

人類不斷反覆思考電池的未來。

The next unlikely battery could be hiding in plain sight—

下一個意想不到的電池 可能正藏在光天化日之下——

just waiting to be discovered and help us achieve a sustainable future.

等著被發現，幫我們 實現一個永續發展的未來。