August 8, 2023


The nuclear fusion era has arrived, if we choose it (Ethan Siegel, 8/08/23, Big Think)

[T]he ultimate goal is to create virtually unlimited amounts of energy via the process of nuclear fusion, enabling humanity's transition to a clean-energy economy. This would be an economy free from:

the pollutive effects of fossil fuels,
the need to mine and extract rare raw materials,
the risk of a nuclear power plant melting down or exploding,
and the fickle, unsteady supply arising from current green energy sources like wind, hydroelectric, or solar power.

We're all well aware of the pollutive effects of energy generation, as well as the effects that rising carbon dioxide levels are having on global temperatures, water availability, ocean acidification, and many other ecological aspects of our world. We're also keenly aware of the need for a safe, reliable, but extremely productive source of energy in order to power the modern lives of more than 8 billion (and rising) humans on planet Earth. [...]

But in order to get there, it isn't simply enough to generate these nuclear fusion reactions: something we've been capable of doing for more than 70 years. The hydrogen bomb, masterminded by Edward Teller, is a spectacular example of nuclear fusion here on Earth. However, that energy can't be readily converted into usable electrical power, as it's far too great in magnitude -- too much of an "all at once" phenomenon -- to harness.

Instead, we need to generate nuclear fusion reactions in a controlled, repeatable fashion. That fusion energy must be emitted in small doses, either continuously or in bursts, where that energy can then be used to do things like boil water, turn a turbine, or perform mechanical work that can then be extracted and transformed into usable electrical energy, just like conventional power plants.

Then, there will be engineering and efficiency concerns, like:

how can we maximize the net energy gain,
how can we minimize the energy required to initiate the fusion reactions,
how can we generate the needed energy in an on-demand fashion,
how can we transport this fusion-generated energy over long distances,
how can we successfully maintain the equipment used for generating these reactions,
and how do we successfully absorb any stray neutrons emitted in the fusion process, and prevent any radioactive materials generated from these reactions from contaminating our environment?

But in order to get there, we first need to pass the breakeven point: the point at which more energy is generated from fusion reactions than is required to initiate those reactions in the first place.

At the National Ignition Facility, omnidirectional high-powered lasers heat a pellet of material to sufficient conditions to initiate nuclear fusion. The NIF can produce greater temperatures than even the center of the Sun, and in late 2022, the breakeven point was passed for the first time from the perspective of laser energy incident on the hydrogen target relative to the energy liberated from the triggered fusion reactions.

This was a big deal when the National Ignition Facility first announced it in December of 2022, and it's a big deal that they did it again (proving reproducibility) at the end of July 2023: they have demonstrated that they have passed the breakeven point in a fusion reaction. They have achieved a net energy gain, where if you look at the amount of energy that goes into creating the fusion reaction -- the amount of energy incident on the target -- and compare it to the amount of energy that gets generated via fusion in the ensuing reaction, the energy generated is greater than the energy that went into it.

Posted by at August 8, 2023 12:00 AM