Spodaj je zelo dobra razlaga razlik v energetski gostoti različnih virov energije – primerjava med sončnimi paneli, jedrskimi, plinskimi in premogovnimi elektrarnami. Energetska gostota energije iz sončnih panelov na kvadratni meter je pač za okrog 50-krat (1 proti 50) manjša od enegetske gostote električne energije iz jedrskih elektrarn. In to v pogojih, da bi sonce ves čas sijalo. Ker pa v naših krajih sonce sije samo eno osmino časa v letu, so potrebne ogromne baterije in ogromno nadomestnih energetskih kapacitet (iz fosilnih virov), da bi zagotovili enake količine električne energije kot iz jedrskih elektrarn na kvadratni meter.  Kar pomeni, da se to razmerje pridobljene elektrike iz sonca in jedrskih elektrarn na kvadratni meter iz okrog 1 proti 50 spremeni v približno 1 proti 500. Vsak fizik, vsak elektro inženir in vsak energetik to ve.

Avtor spodnjega teksta se sprašuje, kdo bo to razložil Elonu Musku. Jaz sem dodal še našega premierja Roberta Goloba. Toda to (naslovno) vprašanje je povsem napačno. Oba – Musk in Golob – vse to, kar ve vsak fizik, vsak elektro inženir in vsak energetik, tudi sama dobro vesta. Vprašanje bi se moralo glasiti – zakaj se delata, da tega ne vesta. Odgovor se skriva v komercialnem interesu. Tako kot so nekateri politiki, uradniki, strokovnjaki in novinarji plačani za to, da ne razumejo, imata Musk in Golob komercialni interes, da “ne razumeta”. Musk prodaja baterijske sisteme za sončne elektrarne, Golob pa je vodil podjetje, ki se ukvarja s prodajo električne energije (s fokusom na solarni energiji) in sončnih elektrarn.

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Someone needs to explain the concept of energy density to @ElonMusk.

The sun does provide us with a near-infinite supply of energy. At first glance, it seems like a no-brainer that we should harness it and use technology to convert it into useable electricity.

But, when Musk claims that “People don’t get it,” he is dismissing some very legitimate criticisms of the drawbacks to solar photovoltaic (PV) technology that people (like me) bring up.

The issue isn’t that the sun provides a constant supply of energy (and a lot of it at that). The glaring issue is that capturing that energy and being able to 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡𝑙𝑦 convert it into enough electricity to power modern civilization is a lot more challenging.

This is for two reasons:

1. While the sun is always shining, sunlight does not always reach the ground. Electricity can only be generated by PV can during the day and the amount during the day is contingent on latitude (more efficient in the lower mid-latitudes and tropics) and sky cover, which fluctuates with weather.
2. The laws of physics mandate that PV technologies cannot physically be made much denser than they are in their current form. As a result, solar PV has a rather large land footprint in comparison to nuclear fission or fossil fuels (coal and natural gas).

On a sunny day at noon, about 1,000 watts (Joules per second) of solar radiation impinge the surface covering an area measuring one square meter (m²). But, because it is diffuse, being able to concentrate all of it into a smaller area is practically impossible and the fact that once you consider correction factors for latitude; day and night; seasonal effects; and cloud cover, that figure is a lot smaller.

Let’s do some math.

The areal power density (Pd) can be calculated with the equation:

Pd = [rated capacity (in watts, W) × capacity factor] / land area (in m²)

For a fair apples to apples comparison, let’s assume that each type of power plant and solar farm have a rated capacity of 1,000 megawatts (MW) [equivalent to 1 BILLION watts).

Solar PV requires between 5 and 10 acres of land per MW of capacity. So, a 1,000-MW solar PV farm would require 5,000 to 10,000 acres of land. By contrast, nuclear reactors require 0.3-1 acre per MW capacity, natural gas plants require 0.2-0.8 acres per MW, and coal plants require 1-4 acres per MW.

🔗https://thundersaidenergy.com/downloads/is-there-enough-land-for-an-energy-transition/

Solar PV also has a capacity factor (a measure of just how efficient an energy source is, including factors like weather conditions or downtime for maintenance) of 23.4% as of 2024, according to the U.S. Department of Energy (DOE). It is worth nothing here that solar [by far] has the lowest capacity factor of any electricity generation source.

By comparison, nuclear fission, natural gas (combined cycle) and coal have capacity factors of 92.3%, 59.9% and 42.6%, respectively.

🔗https://energy.gov/ne/articles/what-generation-capacity

Using the formula above, we find that solar has by far the lowest power density:

⚛️ Nuclear fission: 228.0 – 760.0 W/m²

🔥 Natural gas: 185.0 – 740.0 W/m²

🏭 Coal: 26.3 – 105.2 W/m²

☀️ Solar PV: 5.8 – 11.6 W/m²

𝐒𝐨𝐥𝐚𝐫 (at its best) 𝐢𝐬 𝐨𝐯𝐞𝐫 𝐚𝐧 𝐨𝐫𝐝𝐞𝐫 𝐨𝐟 𝐦𝐚𝐠𝐧𝐢𝐭𝐮𝐝𝐞 𝐋𝐄𝐒𝐒 𝐩𝐨𝐰𝐞𝐫 𝐝𝐞𝐧𝐬𝐞 𝐭𝐡𝐚𝐧 𝐧𝐮𝐜𝐥𝐞𝐚𝐫 (at its worst).

This means solar PV takes up a lot more land than gas or nuclear, yet powers far fewer homes. And, because solar is intermittent, it requires even more land for the battery and fossil fuel backup.

Rooftop solar has its place (and a very bright future). It is marketable. But, clearing tens of thousands of acres of land to build solar arrays is not only environmentally destructive climate virtue signaling, but it is inefficient from an energy and economic standpoint. It would be more suitable to use just a tiny fraction of that land to build a 1,000-MW nuclear power plant.

Consumers understand this.

Although solar PV capacity has grown exponentially in recent years, especially in China, it still makes up less than 3% of the global energy mix [as of 2023]. This is because when solar is added to the electric grid, it just increases overall electricity consumption as opposed to displacing fossil fuels.

🔗https://ourworldindata.org/energy-mix

This is documented in the peer-reviewed literature (e.g., Mahalik, 2023).

🔗https://link.springer.com/article/10.1007/s10098-023-02689-8

Solar PV isn’t inherently bad, but physics renders it an infeasible solution to our energy needs and environmental problems.

For what it’s worth, I respect Elon a lot. He’s done amazing things whether it is his involvement with Tesla, SpaceX or restoring freedom of speech to social media through his acquisition of Twitter. But, I’m not sure why he doesn’t (seem to) understand this about energy.

Vir: Chris Martz