One mode of futurism is estimating the limits of a technology, without regard to what's currently feasible.
Whether this is of any relevance to your own generation is another question.
Let's consider solar power.
Ignoring current technology, it's easy to put a number on the maximum power output.
The solar power at the Earth's distance from the sun is called the solar constant.
It is 1.36 kW/m².
The power on a square meter of the ground is less than that, because of the angle of incidence as well as the atmosphere.
The solar constant hasn't changed and technology has, so it's interesting to see how people have reacted to the same number throughout the history of technology.
In this post I'll quote both Nikola Tesla and Elon Musk.
We'll see that Tesla correctly recognized solar power as a long-term possibility, as well as why it was impractical in the short term.
From Musk all I really have is a Twitter thread where he does the arithmetic.
But it's interesting to consider what has changed since Nikola Tesla's time, and how someone in Musk's generation may have recognized that it was the time to act on these calculations.
Nature has provided an abundant supply of energy in various forms which might be economically utilized if proper means and ways can be devised. The sun's rays falling upon the earth's surface represent a quantity of energy so enormous that but a small part of it could meet all our demands. By normal incidence the rate is mechanically equivalent to about 95 foot pounds per square foot per second, or nearly 7300 horse power per acre of ground. In the equatorial regions the mean annual rate is approximately 2326 and in our latitudes 1737 horse power for the same area. By using the heat to generate steam and operating a turbine under high vacuum probably 200 horsepower per acre could be obtained as net useful power in these parts. This would be very satisfactory were it not for the cost of the apparatus which is greatly increased by the necessity of employing a storage plant sufficient to carry the load almost three-quarters of the time.
Although Tesla is thinking of using sunlight as a source of heat for a steam engine, he goes on to note that we could instead use "photo-electric cells which may become, on this account, of practical importance in the future."
Now we use photovoltaic cells, so that's one thing that has changed since his time.
The other is that with modern batteries, we can construct a "storage plant", as Tesla called it.
If you keep reading the Tesla article, he seems to think storage would be unnecessary in the long term; apparently he thought his ideas for wireless power transmission would work across continents.
But another scientist and futurist, J. B. S. Haldane, correctly identified storage as the key issue when discussing wind power in his 1924 book, where he wrote:
Even to-morrow a cheap, foolproof, and durable storage battery may be invented, which will enable us to transform the intermittent energy of the wind into continuous electric power.
Well, it took longer than that, with lithium-ion batteries becoming widespread in the '90s.
Once you understand Kardashev Scale, it becomes utterly obvious that essentially all energy generation will be solar.
Also, just do the math on solar on Earth and you soon figure out that a relatively small corner of Texas or New Mexico can easily serve all US electricity.
One square mile on the surface receives ~2.5 Gigawatts of solar energy. That’s Gigawatts with a “G”. It’s ~30% higher in space. The Starlink global satellite network is entirely solar/battery powered.
Factoring in solar panel efficiency (25%), packing density (80%) and usable daylight hours (~6), a reasonable rule of thumb is 3GWh of energy per square mile per day. Easy math, but almost no one does these basic calculations.
The solar constant appears here as Musk's value in space (approximately; probably he meant that his ground value is 30% lower, which gives a closer match).
2024 is late, but Musk was early to solar power.
In 2006, when the only Tesla car was the Roadster, he wrote that "the overarching purpose of Tesla Motors (and the reason I am funding the company) is to help expedite the move from a mine-and-burn hydrocarbon economy towards a solar electric economy".
This was timely not just because solar panels were getting cheap, but because of lithium-ion batteries.
And not just for cars: Tesla (the company) was way ahead on stationary batteries for the electric grid.
But that's a story for another post.
One mode of futurism is estimating the limits of a technology, without regard to what's currently feasible. Whether this is of any relevance to your own generation is another question.
Let's consider solar power. Ignoring current technology, it's easy to put a number on the maximum power output. The solar power at the Earth's distance from the sun is called the solar constant. It is 1.36 kW/m². The power on a square meter of the ground is less than that, because of the angle of incidence as well as the atmosphere.
The solar constant hasn't changed and technology has, so it's interesting to see how people have reacted to the same number throughout the history of technology. In this post I'll quote both Nikola Tesla and Elon Musk. We'll see that Tesla correctly recognized solar power as a long-term possibility, as well as why it was impractical in the short term.
From Musk all I really have is a Twitter thread where he does the arithmetic. But it's interesting to consider what has changed since Nikola Tesla's time, and how someone in Musk's generation may have recognized that it was the time to act on these calculations.
Nikola Tesla on the solar future
The Tesla quote is from a 1931 article called "Our Future Motive Power", which discusses solar power as one of many options.
Tesla's number of 7300 horsepower per acre is approximately the solar constant.
Although Tesla is thinking of using sunlight as a source of heat for a steam engine, he goes on to note that we could instead use "photo-electric cells which may become, on this account, of practical importance in the future." Now we use photovoltaic cells, so that's one thing that has changed since his time.
The other is that with modern batteries, we can construct a "storage plant", as Tesla called it. If you keep reading the Tesla article, he seems to think storage would be unnecessary in the long term; apparently he thought his ideas for wireless power transmission would work across continents. But another scientist and futurist, J. B. S. Haldane, correctly identified storage as the key issue when discussing wind power in his 1924 book, where he wrote:
Well, it took longer than that, with lithium-ion batteries becoming widespread in the '90s.
Elon Musk on the solar present
A 2024 Twitter thread:
The solar constant appears here as Musk's value in space (approximately; probably he meant that his ground value is 30% lower, which gives a closer match).
2024 is late, but Musk was early to solar power. In 2006, when the only Tesla car was the Roadster, he wrote that "the overarching purpose of Tesla Motors (and the reason I am funding the company) is to help expedite the move from a mine-and-burn hydrocarbon economy towards a solar electric economy".
This was timely not just because solar panels were getting cheap, but because of lithium-ion batteries. And not just for cars: Tesla (the company) was way ahead on stationary batteries for the electric grid. But that's a story for another post.