@Andercot - The oceans contain enough fusion fuel to power our current

The oceans contain enough fusion fuel to power our current civilization for 65 billion years. If we assume compounding growth of 2%, how long will it last? Fusion: 1060 years Solar: 460 years Let's dig into the physics of our energy economy. (warning: math ahead). Nuclear fusion is how the sun produces energy, taking light elements like hydrogen and fusing them into heavier elements like helium. This releases the energy we receive as sunshine. Every water molecule has two hydrogen atoms. About one in every 6420 hydrogen atoms has an extra neutron attached, this isotope of hydrogen is called deuterium. Burning one gram of deuterium via fusion releases the same energy as burning 83,300 gallons of gasoline. The energy-per-mass of nuclear fuels is astounding, and is millions of times greater than carbon fuels. Gasoline: 45x10^6 J/kg Deuterium: 8.5x10^14 J/kg Total fusion energy stored in the worlds oceans: Let's go through the numbers together to see how much fusion fuel we have on the planet, using joules for energy and kilograms for mass. Mass of all the earth's oceans: 1.4x10^21 kg Mass of water in the oceans: 1.3x10^21 kg (we remove the 35g/L of salt) Each water molecule has two hydrogen atoms, but hydrogen is a lot lighter than oxygen. So, water by-mass is only 11% hydrogen (H). Mass of H in the oceans: 1.43x10^20 kg Mass of deuterium in that H: 4.46x10^16 kg Fusion-energy stored in oceans: 3.8x10^31 Joules That's about 500 times the kinetic energy of the moon, or seven million billion Minute Man ICBM's, if each one carried a 1.2 megaton W57 bomb. How long will it last us? In 2022 the world used 160,000 tera-watt hours of energy. Worldwide energy consumption: 5.76x10^20 J If our energy consumption remains the same, our ocean-water fusion fuel will last us 65 billion years. However, over time our energy use grows at 1-2% per year. If we assume a growth rate of 2% per year, we can add up the years of energy consumption to see when it will equal our fusion energy reserves. Assuming a constant growth rate of 2%, our ocean-water fusion-fuel will last us ~ 1060 years. At that time the annual energy consumption of our civilization will be about 11 seconds worth of the Sun's total energy output. So, fusion energy buys us 1000 years of compounding energy usage. How long could solar take us, assuming the same growth rate? Annual solar energy reaching Earth: 5.5x10^24 J Current use *(1 + growth rate)^periods = future use 5.76x10^20*(1.02)^n = 5.5x10^24 n=462 Solar energy gets us 460 years of compounding energy growth until our annual consumption equals the total solar power reaching the planets surface. This means 100% of the Earth's surface is covered with 100% efficient solar panels. If we only covered the land-area of Earth with panels that were 50% efficient, Solar gets us 360 years. If we could only extract half the deuterium in the ocean, because of process efficiency and etc, Fusion still gets us 1026 years of compounding growth. Notably we would also still have land to live on. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Today, solar energy is cheap, abundant, and extremely competitive. It will take immense amounts of land and material resources to reach our civilizational-scale needs for energy if we keep growing our economy and energy needs. Fusion is seen as difficult, expensive, and slow to mature. Why bother? If you want humanity to last more than 360 years and still have land to live on, you need fusion. And the far future? The outer solar system is abundant in hydrogen and deuterium, and deficient in solar energy which becomes weaker with the square of the distance from the sun. Fusion energy can power our civilization into a space-faring future among the outer planets, and take us to the stars.