Since launching SpaceX and Tesla, Elon Musk has been consistent on two key beliefs. First, he believes that humanity needs to colonize Mars in order to become a multi-planetary species. Second, he’s convinced that all human activity could be powered exclusively by solar energy.
Musk recently reaffirmed the second conviction in a post on X, stating that it would be obvious to people if they understood the calculations:
“Once you understand [the] 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 U.S. electricity.”
Russian astrophysicist Nikolai Kardashev proposed the Kardashev scale in 1964. It measures a civilization’s technological development level based on the amount of energy it can use. Humanity, the only civilization we know of, hasn’t even reached the first level on this scale.
There are three types of civilizations in the Kardashev scale:
- Type I: Planetary Civilizations. They can efficiently manage and take advantage of all the energy available on their planet of origin.
- Type II: Stellar Civilizations. They can use and store all the energy of their host star. It refers to civilizations that could have built real megastructures around their star to capture most solar power, such as the hypothetical Dyson Sphere.
- Type III: Galactic Civilizations. They can control and capture the energy of millions of stars within their galaxy.
The Kardashev scale is more popular in the search for extraterrestrial life than in the energy sector. However, Musk uses this method to highlight how under-utilized the Sun is. According to his calculations, an area of just one square mile on Earth receives 2.5 GW of solar energy. Beyond the magnetic shield of the atmosphere in outer space, 30% more solar energy is available.
“Factoring in solar panel efficiency (25%), packing density (80%), and usable daylight hours (~6), a reasonable rule of thumb is 3 GWh of energy per square mile per day,” Musk said, adding, “Easy math, but almost no one does these basic calculations.”
It’s Not That Easy
Musk’s calculations are accurate but overlook the technical and economic challenges faced by the solar power industry.
Solar power capacity increased by 73% last year, reaching a total of 3,870 GW globally. It’s the fastest-growing energy source, surpassing even the growth rate of nuclear power at its peak. However, even in countries that lead in solar panel installations, such as the U.S., China, and Spain, there’s still reliance on non-renewable energy sources like fossil fuels.
The main challenge isn’t the capacity of solar power but its intermittency. Due to limitations in electronics, the power generated by solar panels decreases on cloudy or very hot days. These fluctuations would pose practical challenges for the power grid without the presence of power plants capable of generating electricity on demand, such as gas-fired or nuclear power plants. As such, the power grid needs to be flexible.
In other words, the issue at hand is essentially a storage problem. Solar energy’s intermittency wouldn’t threaten grid supply if there were tens of GWh in storage capacity. This could be achieved through various means such as green hydrogen and reservoirs. Overall, the main solution is battery farms. However, the challenge lies in the fact that the growth of battery installations hasn’t kept pace with that of solar panels. This is due to their high cost and the lack of sufficient incentives for storage.
In China, several provinces have made installing batteries compulsory for every new solar installation. Nonetheless, these batteries are seldom utilized. What’s more, electricity prices are already low, and storing it isn’t always profitable. Similarly, in Europe, the proliferation of renewables has frequently driven the price of energy down to zero or even negative, making storage economically unviable.
Our society is working toward resolving these issues by making necessary changes in the electricity market to align it with current times. However, we’re still in a transitional stage. Since Type I civilizations can efficiently utilize all the energy available on their planet of origin, we can’t be classified as one yet.
Image | Steve Jurvetson
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