(September 11, 2021 at 11:36 am)Jehanne Wrote:

(September 11, 2021 at 10:05 am)Spongebob Wrote: We KNOW that EVs use electricity produced in a power plant.  We KNOW that most of that power includes fossil fuels.  We don't claim otherwise.  We also know that the EVs themselves produce zero emissions and any emissions arising from the electricity they use comes from a facility that is far better at cleaning its emissions than any ICE vehicle.  We are also generally advocates of moving away from fossil fuels to cleaner forms of energy.  So there's absolutely no hypocrisy in the position of promoting EV's.  So just stop with this bullshit argument.  You're just embarrassing yourself.

Please correct me if I am wrong, but, I have read that if the United States would harvest every photon of light from the Sun that such energy (in Joules) would only meet 50% of that which we consume.

I don’t think that’s correct. To meet all US energy needs would require about 21 000 square miles of solar panels (less, if the technology improves). This is tiny.

Boru

(September 11, 2021 at 11:52 am)BrianSoddingBoru4 Wrote:

(September 11, 2021 at 11:36 am)Jehanne Wrote: Please correct me if I am wrong, but, I have read that if the United States would harvest every photon of light from the Sun that such energy (in Joules) would only meet 50% of that which we consume.

I don’t think that’s correct. To meet all US energy needs would require about 21 000 square miles of solar panels (less, if the technology improves). This is tiny.

Boru

We use 93 quadrillion BTUs annually; one BTU is 1055.06 joules; a quadrillion is 10^15, and so, the US uses approximately 10^20 joules per annum:

EIA -- US energy

The Sun gives us 1360 watts per square meter.

NASA Earth Observatory

The US has 3.797 million square miles, and so,

3,797,000 square miles * (2,590,000 square meters / 1 square mile) = 9,834,230,000,000 square meters in the US, or 9.8 * 10^12 square meters.

Taking 10^20 joules / (365*24*3600 seconds) = 3.17 * 10^12 watts

Taking 3.17 * 10^12 watts / 1360 watts per square meter = 2.33 * 10^9 square meters of solar panels.

And, so, we need a few hundred million square meters of solar panels, a 100,000 km by 10,000 km array.  Not enough land, or so it appears.

(September 11, 2021 at 11:36 am)Jehanne Wrote:

(September 11, 2021 at 10:05 am)Spongebob Wrote: We KNOW that EVs use electricity produced in a power plant.  We KNOW that most of that power includes fossil fuels.  We don't claim otherwise.  We also know that the EVs themselves produce zero emissions and any emissions arising from the electricity they use comes from a facility that is far better at cleaning its emissions than any ICE vehicle.  We are also generally advocates of moving away from fossil fuels to cleaner forms of energy.  So there's absolutely no hypocrisy in the position of promoting EV's.  So just stop with this bullshit argument.  You're just embarrassing yourself.

Please correct me if I am wrong, but, I have read that if the United States would harvest every photon of light from the Sun that such energy (in Joules) would only meet 50% of that which we consume.

It's wrong. Energy usage of the US is about 93 quadrillion BTUs a year, which amounts to just less than 10^20 Joules per year. The solar constant is 1.361*10^3 Joules per square meter per second. That gives about 4*10^10 Joules per square meter per year. Dividing the two, we see that (capturing *every* photon) would take about 2.5*10^9 square meters, which is a square that is 50 kilometers on a side.

Now, efficiency and hours of daylight increase this, but it is still a long way from the total area of the US.

(September 11, 2021 at 11:36 am)Jehanne Wrote: Please correct me if I am wrong, but, I have read that if the United States would harvest every photon of light from the Sun that such energy (in Joules) would only meet 50% of that which we consume.

This is easily refuted.  In general terms, the sun bathes the earth in more energy in one hour than humans consume in an entire year.  Read sources below for details.  Of course we would never be able to capture all of those photons, nor would we want to.  But the point is, there's plenty of sunlight.  What you probably read had something to do with the limitations of solar panels to collect/capture photons and store them as electrical energy.  Of course there's also the possibility of collecting solar energy from space in the future, which would be orders of magnitude more efficient.  We just don't have any extension cords long enough.

sources:
https://www.businessinsider.com/this-is-...wer-2015-9
https://www.need.org/Files/curriculum/gu...tGuide.pdf
https://old-www.sandia.gov/~jytsao/Solar%20FAQs.pdf

(September 11, 2021 at 12:16 pm)Jehanne Wrote:

(September 11, 2021 at 11:52 am)BrianSoddingBoru4 Wrote: I don’t think that’s correct. To meet all US energy needs would require about 21 000 square miles of solar panels (less, if the technology improves). This is tiny.

Boru

We use 93 quadrillion BTUs annually; one BTU is 1055.06 joules; a quadrillion is 10^15, and so, the US uses approximately 10^20 joules per annum:

EIA -- US energy

The Sun gives us 1360 watts per square meter.

NASA Earth Observatory

The US has 3.797 million square miles, and so,

3,797,000 square miles * (2,590,000 square meters / 1 square mile) = 9,834,230,000,000 square meters in the US, or 9.8 * 10^12 square meters.

Taking 10^20 joules / (365*24*3600 seconds) = 3.17 * 10^12 watts

Taking 3.17 * 10^12 watts / 1360 watts per square meter = 2.33 * 10^9 square meters of solar panels.

And, so, we need a few hundred million square meters of solar panels, a 100,000 km by 10,000 km array.  Not enough land, or so it appears.

Nope. that is in square *meters*, not square kilometers. So, a 50km by 50km area would do it.

(September 11, 2021 at 12:16 pm)polymath257 Wrote:

(September 11, 2021 at 11:36 am)Jehanne Wrote: Please correct me if I am wrong, but, I have read that if the United States would harvest every photon of light from the Sun that such energy (in Joules) would only meet 50% of that which we consume.

It's wrong. Energy usage of the US is about 93 quadrillion BTUs a year, which amounts to just less than 10^20 Joules per year. The solar constant is 1.361*10^3 Joules per square meter per second. That gives about 4*10^10 Joules per square meter per year. Dividing the two, we see that (capturing *every* photon) would take about 2.5*10^9 square meters, which is a square that is 50 kilometers on a side.

Now, efficiency and hours of daylight increase this, but it is still a long way from the total area of the US.

We use a trillion watts on average, right?

---

(September 11, 2021 at 12:25 pm)polymath257 Wrote:

(September 11, 2021 at 12:16 pm)Jehanne Wrote: We use 93 quadrillion BTUs annually; one BTU is 1055.06 joules; a quadrillion is 10^15, and so, the US uses approximately 10^20 joules per annum:

EIA -- US energy

The Sun gives us 1360 watts per square meter.

NASA Earth Observatory

The US has 3.797 million square miles, and so,

3,797,000 square miles * (2,590,000 square meters / 1 square mile) = 9,834,230,000,000 square meters in the US, or 9.8 * 10^12 square meters.

Taking 10^20 joules / (365*24*3600 seconds) = 3.17 * 10^12 watts

Taking 3.17 * 10^12 watts / 1360 watts per square meter = 2.33 * 10^9 square meters of solar panels.

And, so, we need a few hundred million square meters of solar panels, a 100,000 km by 10,000 km array.  Not enough land, or so it appears.

Nope. that is in square *meters*, not square kilometers. So, a 50km by 50km area would do it.

Yep, I messed up.

---

And, so, a 50 km by 50 km array is completely doable!

(September 11, 2021 at 12:25 pm)Jehanne Wrote:

(September 11, 2021 at 12:16 pm)polymath257 Wrote: It's wrong. Energy usage of the US is about 93 quadrillion BTUs a year, which amounts to just less than 10^20 Joules per year. The solar constant is 1.361*10^3 Joules per square meter per second. That gives about 4*10^10 Joules per square meter per year. Dividing the two, we see that (capturing *every* photon) would take about 2.5*10^9 square meters, which is a square that is 50 kilometers on a side.

Now, efficiency and hours of daylight increase this, but it is still a long way from the total area of the US.

We use a trillion watts on average, right?

---

(September 11, 2021 at 12:25 pm)polymath257 Wrote: Nope. that is in square *meters*, not square kilometers. So, a 50km by 50km area would do it.

Yep, I messed up.

---

And, so, a 50 km by 50 km array is completely doable!

Because of efficiency and the fact that the sun isn't always up (so we don't get the full solar constant all the time), it would be more than that. But it is still a LOT less than the total area of even one medium sized state.

(September 11, 2021 at 12:31 pm)polymath257 Wrote: Because of efficiency and the fact that the sun isn't always up (so we don't get the full solar constant all the time), it would be more than that. But it is still a LOT less than the total area of even one medium sized state.

Um, the sun is always "up" somewhere on earth.

(September 11, 2021 at 12:33 pm)Spongebob Wrote:

(September 11, 2021 at 12:31 pm)polymath257 Wrote: Because of efficiency and the fact that the sun isn't always up (so we don't get the full solar constant all the time), it would be more than that. But it is still a LOT less than the total area of even one medium sized state.

Um, the sun is always "up" somewhere on earth.

Greetings, comrade.

I suppose this is what OLB would like everyone to be driving...