Can 100% renewable energy power the world

能100%靠可再生能源供给全世界嘛

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Every year, the world uses 35 billion barrels of oil.

This massive scale of fossil fuel  dependence pollutes the Earth

and it won't last forever.

Scientists estimate that we've consumed about 40% of the world's oil.

According to present estimates,

at this rate, we'll run out of oil and gas in 50 years or so,

and in about a century for coal.

每年，全世界会用掉 350 亿桶油。

这种对化石燃料的大规模依赖 会污染我们的地球，

而且不会永远持续下去。

科学家估计我们已经使用了大约世界总油量的百分之四十。

根据目前的估计，

以这个速度进行下去，我们将在大约 50 年后用光总有的油和气，

在一个世纪后用尽所有的煤炭。

On the flip side, we have abundant sun, water, and wind.

These are renewable energy sources,

meaning that we won't use them up over time.

What if we could exchange  our fossil fuel dependence

for an existence based  solely on renewables?

另一方面，我们拥有 充足的阳光、水和风。

这些是可再生能源，

意思是无论多久， 我们都不会用尽这些资源。

如果我们可以把对化石燃料的依赖

换成仅靠可再生能源 的存在方式会是什么样呢？

We've pondered that question for decades,

and yet, renewable energy still only provides about 30% of our needs.

That's because reaching 100% requires renewable energy that's inexpensive

and accessible.

This represents a huge challenge,

even if we ignore the politics involved and focus on the science and engineering.

几十年来，我们一直在思考那个问题，

然而，可再生能源仍只能满足 我们对能源需求的大约百分之十三。

那是因为，要达到百分之百的利用率， 可再生能源需要更廉价，

而且要容易得到。

这是项强大的挑战，

即使我们忽略政治的参与，集中在科学和工程上面。

We can better understand the problem by understanding how we use energy.

Global energy use is a diverse  and complex system,

and the different elements  require their own solutions.

But for now, we'll focus on two of the most familiar in everyday life:

electricity and liquid fuels.

Electricity powers blast furnaces,  elevators, computers,

and all manner of things in homes, businesses, and manufacturing.

Meanwhile, liquid fuels  play a crucial role

in almost all forms of transportation.

我们可以通过我们如何 使用能源来理解这个问题。

全球能源使用是 一个多样而且复杂的系统，

并且不同的元素需要 个性化的解决方式。

但是现在，我们将集中于每日生活中最熟悉的两项：

电能和液体燃料。

电能为高炉、电梯、电脑，

还有所有家里、企业和制造业需要 的各个方面提供能量。

同时，液体燃料起到了关键的作用，

主宰差不多所有方式的交通。

Let's consider the electrical  portion first.

The great news is that our technology is already advanced enough

to capture all that energy  from renewables,

and there's an ample supply.

The sun continuously radiates

about 173 quadrillion watts  of solar energy at the Earth,

which is almost 10,000 times our present needs.

It's been estimated that a surface that spans several hundred thousand kilometers

would be needed to power humanity at our present usage levels.

让我们先来考虑电的部分。

好消息是，我们的技术已经发展到了

可以捕获从可再生资源那里得到的能量，

而且这种供给资源十分充足。

太阳持续放射

大约 173 万亿瓦特太阳能到地球，

这是大约我们目前需要的 1 万倍。

据估计，几十万公里长的表面

应该足够提供我们人类 目前使用水平的能量。

So why don't we build that?

Because there are other  hurdles in the way,

like efficiency

and energy transportation.

To maximize efficiency,

solar plants must be located in areas  with lots of sunshine year round,

like deserts.

But those are far away  from densely populated regions

where energy demand is high.

There are other forms of renewable energy we could draw from,

such as hydroelectric,

geothermal,

and biomasses,

but they also have limits based on availability and location.

那为什么我们不去建造呢？

因为有其他阻碍，

例如效率

和能源运输。

为了把效率最大化，

太阳能工厂必须建在 长年有充足阳光的地区，

例如沙漠。

但是那些地区离能量需求很高

的人口密集地区很远。

我们还有其他可再生资源可以考虑，

例如水力电气，

地热

和生物质，

但是它们也有可获取性和地域的限制。

In principle, a connected electrical energy network

with power lines crisscrossing the globe

would enable us to transport power from where it's generated

to where it's needed.

But building a system on this scale faces an astronomical price tag.

We could lower the cost by developing advanced technologies

to capture energy more efficiently.

The infrastructure for transporting energy would also have to change drastically.

原则上讲，一个相连的电能网络

通过在全球纵横交错的电线连接

可以让我们把电从发电地

运输到用电的地方。

但是建造这种规模的系统需要 配备的价格标签却是个天文数字。

我们可以通过发展高科技来降低成本，

以更有效率地捕获能源。

运输能源需要的基础设施也 不得不发生巨大的改变。

Present-day power lines lose about 6-8% of the energy they carry

because wire material dissipates energy through resistance.

Longer power lines would mean more energy loss.

Superconductors could be one solution.

Such materials can transport electricity without dissipation.

Unfortunately, they only work if cooled to low temperatures,

which requires energy  and defeats the purpose.

To benefit from that technology,

we'd need to discover  new superconducting materials

that operate at room temperature.

当今的电线会损失 百分之六到八的运输电能，

是因为电线材料会通过电阻耗散能量。

电线越长意味着丢失的能量越多。

超导体可以是一种解决方式。

这种材料可以在没有能量耗散 的情况下运电。

不幸的是，它们只在低温环境下工作，

这就需要额外的能量来 控制温度，结果适得其反。

为了在这个技术上获益，

我们将需要发现可以在室温下工作

的新型超导体材料。

And what about the all-important, oil-derived liquid fuels?

The scientific challenge there is to store renewable energy

in an easily transportable form.

Recently, we've gotten better at producing lithium ion batteries,

which are lightweight  and have high-energy density.

But even the best of these store about 2.5 megajoules per kilogram.

That's about 20 times less than the energy in one kilogram of gasoline.

To be truly competitive, car batteries would have to store much more energy

without adding cost.

那基于石油的重要液体燃料怎么样呢？

它的科学挑战是把可再生能源

以容易运输的方式储存。

近来，我们已经在生产 锂离子电池方面大有进步，

它很轻而且拥有高能量密度。

但即使是最好的锂离子电池 储存的能量，每千克也只有2.5兆焦耳。

比一千克的石油提供的能量 低大约 20 倍。

要真正有竞争力，车用电池 需要储存更多的能量，

而且不增加成本。

The challenges only increase  for bigger vessels, like ships and planes.

To power a cross-Atlantic  flight for a jet,

we'd need a battery weighing about 1,000 tons.

This, too, demands a technological leap towards new materials,

higher energy density,

and better storage.

One promising solution would be to find efficient ways

to convert solar into chemical energy.

This is already happening in labs,

but the efficiency is still too low to allow it to reach the market.

随着载体变大，挑战也就越大， 例如：船只和飞机。

给一架喷气式飞机提供 横跨大西洋飞行的能量，

我们需要一个重约 1000 吨的电池。

这个问题也需要技术上 的创新来发展新材料，

拥有更高的能量密度

和更好的储存方式。

一个很有前景的解决方式 也许是想办法高效地

把太阳能转换成化学能。

这已经正在实验室里发生了，

但效率仍然太低，远不能满足市场需求。

To find novel solutions, we'll need lots of creativity,

innovation,

and powerful incentives.

The transition towards all-renewable  energies is a complex problem

involving technology,  economics, and politics.

Priorities on how to tackle this challenge depend on the specific assumptions

we have to make when trying to solve such a multifaceted problem.

But there's ample reason to be optimistic that we'll get there.

Top scientific minds around the world are working on these problems

and making breakthroughs all the time.

And many governments and businesses are investing in technologies

that harness the energy all around us.

要找到更新颖的解决方式， 我们将需要很多创新，

革新，

和强大的激励政策。

向全部可再生资源转移 是一个复杂的问题，

它涉及到技术，经济和政治。

应对这一挑战的优先次序取决于

我们在试图解决这一多面问题时 必须做出的具体假设。

可是诸多理由让我们乐观地 相信我们可以做到。

世界顶级科学家们正在寻找 解决这些问题的方式，

而且一直在取得突破。

许多政府和企业也正在投资技术，

为我们创造源源不断的能量。

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