Name: 月からクリーンエネルギーを得る3つの方法 (3 Ways We Could Get Clean Energy from the Moon)
Uploaded: 2021-01-14T10:28:00.000Z
Duration: 5 min 37 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

Climate change is happening, and some of its effects are already here.

If we want to avoid the worst of them in the future,

we're going to need to stop pumping greenhouse gasses into our atmosphere.

Within the next couple of decades, our energy will have to be 100% clean.

We've got lots of renewable energy sources here on Earth,

but at this point,  we need to consider every possible option.

According to some research, it could offer solutions to our power problems that are literally out of this world.

One way the Moon could give us a hand is by helping us make use of the virtually unlimited free energy pouring out of the Sun.

Every square meter of space at the Earth's orbit receives about 1.36 kilowatts of energy.

Harnessing that power would give us all the electricity we need,

but it's not quite as simple as it sounds.

By the time it filters through our atmosphere and strikes the Earth's surface,

On top of that, most solar panels available today convert less than 20% of that remaining 340 watts into electricity.

And, of course, all this only works during the day.

A lot of these problems could be solved by putting the panels in space,

where they could receive 100% sunlight, 100% of the time.

But even with reusable rockets, it's not cost-effective to lift so much mass into orbit.

Each point on the Moon is in darkness for half the month,

so putting solar panels on the Moon isn't the best idea.

But some researchers have proposed that we could send a robotic solar-panel factory there instead.

It could harvest the resources needed to build solar panels from things like the lunar regolith.

Then, we could launch the panels into space from the Moon, where gravity is a lot weaker,

which would be way cheaper than launching from Earth.

The power could be beamed back home using microwaves,

Then again, it's safe to say that self-assembling, robotic, laser-shooting solar panels

Thankfully, the Sun doesn't just have to be our source of power.

It can also be the model for how we make power.

At its core, the Sun is powered by nuclear fusion,

the process of building larger elements from smaller ones.

For many atoms, this act releases a tremendous amount of power.

Building fusion reactors here on Earth offers the promise of nearly limitless clean energy,

“We're probably just a couple decades away from getting it to work,”

is what scientists have been saying since the 1950s.

Fusion is a simple concept that has proven incredibly hard to actually put into practice.

We've made controlled fusion reactions before,

but it takes more energy to start and control them than the fusion itself provides.

And an energy source that needs more energy than it produces is… not ideal.

But if we ever do get it working, we'll need fuel for the reactors.

In principle, any light element can be used, but one scientists are especially interested in  is helium-3,

a type of helium with one fewer neutron than normal.

When it's combined with deuterium, a kind of hydrogen,

it forms a reactor fuel with one very attractive property:

While deuterium can be mined from ocean water, helium-3 is much harder to get.

Whether you're on Earth or the Moon, once helium reaches the surface,

it's eventually lost to space forever, because it's too light for our gravity to hold on to it.

On Earth, that makes it a depleting resource.

That's because the Sun's solar wind, the stream of particles coming from our star,

Earth's magnetic field shields us from most of the solar wind,

but since the Moon lacks a magnetic field, that wind constantly strikes its surface.

In effect, that deposits atoms of helium-3 underground.

So, if we mine the lunar surface, voila, reactor fuel!

To get one just one gram of helium-3, you'd need to mine 150 million metric tons of lunar soil.

Maybe that's easier than self-replicating solar panels, but I wouldn't call it easy.

The good news is, there's one way the Moon is already helping us generate power.

In fact, if you're by the ocean, you might be seeing it right now: the tides!

For something that seems like it should be really simple, the tides are weirdly complicated,

but the basic idea is that the Moon's gravity feels stronger when we're facing it and weaker when we're not.

That makes the water levels rise and fall.

And since the oceans weigh a lot, their motion contains a vast supply of energy.

Engineers have come up with two pretty clever ways to use this motion to generate electricity.

One is the tidal barrage, which is basically a gate that traps the rising tide inside.

Then, when the tide falls, the water rushes out through holes in the gate

and drives a turbine along the way to create electricity.

Some designs even drive the turbine as the trap is filling, too.

Tidal barrages are already being used in Canada, China, France, Russia, and South Korea,

Another method builds on something you might have seen out in the country: wind turbines.

These tidal turbines are much more expensive to build than their land-based cousins,

but can also generate more power because moving water carries more energy than moving air.

Test projects have been built in Scotland and South Korea, with one in development for New York City.

On their own, they won't solve our energy problem, but the reality is that no one method will.

We'll need to generate electricity in all sorts of ways,

and some of that could be powered by the Moon.

Just in case you need another reason to love our little satellite.

Thanks for watching this episode of SciShow Space!

We think the universe is fascinating, and that by understanding how it works and our place in it,

we can learn a little about ourselves along the way.

If you'd like to keep up with our latest videos,

you can go to  youtube.com/scishowspace and subscribe.