Gigawatt to Petawatt

1.21 GW is very real — it's about the output of a large nuclear reactor. Doc Brown needed it for the flux capacitor, but a single lightning bolt actually delivers far more instantaneous power (up to 1,000 GW) for a few microseconds. The movie got the pronunciation slightly off: Christopher Lloyd famously said "jigawatts," which is technically an acceptable older pronunciation but not the standard one.

It varies enormously. The UK peaks at about 50 GW; Germany around 80 GW; the US about 750 GW; China over 2,000 GW of installed capacity. But installed capacity and actual consumption differ: the US averages about 450 GW of actual demand. Developing nations can operate on strikingly little — some small African nations manage on under 0.5 GW for millions of people.

The Three Gorges Dam in China holds the record at 22.5 GW of installed hydroelectric capacity — enough to power a country the size of Switzerland. It has 32 main turbines each rated at 700 MW. Its annual output of ~100 TWh makes it the world's most productive power plant, though the Itaipu Dam on the Brazil-Paraguay border occasionally produces more in a given year due to higher capacity factor.

The world added roughly 420 GW of new solar capacity in 2023 alone — more than doubling the pace from just two years earlier. Total global solar capacity surpassed 1,600 GW by end of 2024. China installed over 200 GW in a single year, which is more than the entire US solar fleet accumulated over decades. At current trajectory, solar will exceed 5,000 GW globally by 2030.

A category 5 hurricane dissipates about 600,000 GW of heat energy through cloud formation alone — dwarfing human power infrastructure. A major volcanic eruption releases energy equivalent to thousands of GW sustained over hours. The Gulf Stream carries about 1.4 million GW of thermal power northward. Even a modest thunderstorm generates 10–100 GW. Nature operates on power scales that make our entire grid look like a nightlight.

It's a time trick. A petawatt laser concentrates a modest amount of energy (maybe 100–500 joules) into a pulse lasting 10–100 femtoseconds. Dividing a few hundred joules by 10⁻¹⁴ seconds gives you 10¹⁵–10¹⁶ watts — surpassing the Sun's 3.8 × 10²⁶ W is still far off, but these lasers do exceed total human power consumption by 100,000×. The catch: the total energy delivered is only enough to heat a cup of coffee.

Primarily for nuclear fusion research (compressing fuel pellets), particle acceleration (laser wakefield acceleration can produce electron beams rivalling billion-dollar synchrotrons), medical isotope production, and probing extreme states of matter found in stellar cores. The ELI (Extreme Light Infrastructure) project in Europe uses petawatt lasers to recreate conditions found in supernovae, helping astrophysicists study cosmic explosions in a lab.

Solar flares can briefly release 10–100 PW of electromagnetic radiation. The Chicxulub asteroid impact (the one that killed the dinosaurs) delivered roughly 4 × 10²³ watts during the few seconds of impact — about 100 million petawatts. Gamma-ray bursts top everything at 10²⁵–10²⁶ PW, briefly outshining the entire observable universe. Even supernovae "only" sustain about 10³⁶ PW for a few seconds at peak.

Building one costs $50–500 million. Operating costs are surprisingly modest per shot — each pulse uses only a few hundred joules (less than lifting an apple one meter), but the capacitor banks and cooling systems draw megawatts of continuous power. The NIF facility costs about $350 million per year to operate. Individual shots are "cheap" in energy terms but the infrastructure to achieve them is staggering.

In theory yes, but in practice current petawatt lasers are terrible weapons. They fire one pulse every few minutes to hours, require warehouse-sized buildings of equipment, and deliver total energy equivalent to a firecracker. Military-grade laser weapons focus on sustained power (100–300 kW continuous beams), not ultrashort pulses. A petawatt laser is a precision scientific scalpel, not a blunt instrument — brilliant for physics, useless for destruction.