Total area of solar panels needed to power world

[Nealithi]

A little tangent on the topic. But what was the deal with the argument that solar energy wasn't 'dense' enough to even power small motors? So solar power was all just a show?
I caught this line like nine years ago and my father parroted it. And it sounds wrong some how. Maybe a misquote?

[TGLS]

That kinda falls apart on the face of it. What about all the solar cars? I mean, it might not necessarily be practical, but you can get enough voltage to drive a small motor.

[Darth Wedgius]

A little tangent on the topic. But what was the deal with the argument that solar energy wasn't 'dense' enough to even power small motors? So solar power was all just a show?
I caught this line like nine years ago and my father parroted it. And it sounds wrong some how. Maybe a misquote?

Photovoltaic efficiency has increased significantly in my lifetime. Maybe it used to be true?

[Nealithi]

A little tangent on the topic. But what was the deal with the argument that solar energy wasn't 'dense' enough to even power small motors? So solar power was all just a show?
I caught this line like nine years ago and my father parroted it. And it sounds wrong some how. Maybe a misquote?

Photovoltaic efficiency has increased significantly in my lifetime. Maybe it used to be true?

I don't know. It came up when they began putting small solar panels on the poles. But back in the late eighties there was this fad for little panels to run motors on stick figure sculptures. In the window the guy would pedal his bicycle or other display items. Or if you turned on the lights in the room. But the way the counter to the ones on the pole went, you would think something from twenty years prior hadn't actually worked? Like I said I don't get the argument.

[LittleRaven]

But what was the deal with the argument that solar energy wasn't 'dense' enough to even power small motors? So solar power was all just a show?

Uh....I have no idea. Energy itself doesn't have density. That's a mass thing.

Now, that said, there are certainly limits to how much energy one can extract from solar per unit of area. There's a theoretical maximum efficiency, which I think the eggheads calculated at somewhere around 87%, but we don't get anywhere near that in practice. The most efficient solar cells that I've heard of supposedly get somewhere around 50% efficiency under ideal conditions, but I think somewhere around 20% is much more realistic for most cells you see around today. That sounds bad, but when I was a kid you were lucky to get 5% out of a photocell, so we've made tremendous gains. Exactly how much energy you get out of a solar panel is going to vary wildly, because it depends not only on the efficiency of your cell but where on the planet you are. The farther north or south you go from the equator, the less energy you're going to get. And then there's cloud cover, which is a whole 'nother ball of wax.

I suspect the argument your dad was trying to make is that solar power could never replace fossil fuels as we use them in say, cars, because you can't put enough solar cells on a car to match the energy you can get out of a tank of gas. And that's not even wrong...it's just a stupid argument, because it assumes that we have to generate the energy in real time as we use it. We can't do that with solar, but we don't do that with fossil fuels either. The energy in gasoline was generated a long, long time ago...we're merely releasing it when we burn it in our cars. There's no reason we can't do the same with solar energy.

[Madner Kami]

Uh....I have no idea. Energy itself doesn't have density. That's a mass thing.

Actually, energy density is a thing. The word, however, describes more or less how much energy is contained in a given mass, so in the context of solar panels it's pretty nonsensical. Energy density is relevant in terms of how much energy you can store in a battery for example or how much energy you can extract from different kinds of coal or nuclear fuels.

[Antiboyscout]

Uh....I have no idea. Energy itself doesn't have density. That's a mass thing.

Actually, energy density is a thing. The word, however, describes more or less how much energy is contained in a given mass, so in the context of solar panels it's pretty nonsensical. Energy density is relevant in terms of how much energy you can store in a battery for example or how much energy you can extract from different kinds of coal or nuclear fuels.

when it comes to powerplants it means production per square ft.

[FaxModem1]

Keep in mind that we are improving in this regard, and the more people have independent renewables such as wind and solar for their homes or businesses, the less strain is needed on a hypothetical world-wide solar panel farm.

We're also seeing some experimentation with better batteries, as Tesla working it out with Australia: link

I'm not sure in terms of energy, how many watts are needed, but in various parts of the world, we are working on the problem: Bloomberg

For instance, there's work on becoming fully renewable in Japan, India, Greece, Germany,above mentioned Australia and US states like Hawaii, California, and as mentioned above, my home state of Texas.

So, even if building one worldwide grid in the middle of the Sahara Desert isn't happening, and wouldn't help everyone, at least a lot of countries and US states the size of countries are getting with the program and doing what they can to improve things.

[Riedquat]

I've usually heard of energy density in terms of the amount of energy stored in a given mass. That's part of the battle with electric cars - the amount of energy in a given mass of petrol or diesel is much greater than in the same mass of battery, although it's countered to a degree by electric motors being more efficient, and not needing a complex powertrain. It's proving hard to get away from existing fuels because they contain a lot of energy and are relatively easy to handle and sometimes store (you can leave coal piled up in a heap outside).

[Madner Kami]

Uh....I have no idea. Energy itself doesn't have density. That's a mass thing.

Actually, energy density is a thing. The word, however, describes more or less how much energy is contained in a given mass, so in the context of solar panels it's pretty nonsensical. Energy density is relevant in terms of how much energy you can store in a battery for example or how much energy you can extract from different kinds of coal or nuclear fuels.

when it comes to powerplants it means production per square ft.

Never seen it used in that context.