Question: How doable are fusion reactors on earth, and if they are, when will we be able to use them.

Luke Humphrey answered on 22 Jun 2023:

Great question. In short, fusion reactors do work and we’re already doing fusion on earth! However, it will probably be 2040-2050 (at least!) that we see fusion power plants putting electricity on the grid.

The remaining work before we’re able to use them for electricity is in designing fusion energy power plants. For a power plant to be effective, we need to generate enough power to pay the energy costs of the plant and still have enough left over for the electricity we generate to be affordable. Designing such a power plant means you need to make the reaction and the engineering as efficient as possible, so we are doing a lot of experiments at the moment to gain the data required to make informed decisions. Fusion is still so new and exotic that there just isn’t much data yet!

In the UK, we are designing a fusion power plant called STEP which is targeting 2040. Many countries around the world are also designing similar prototypes. Once energy companies have a prototype power plant, they can invest in a fleet of such plants to generate electricity on a national scale. One way this might be accelerated is if the government subsidises the cost of low-carbon electricity, which would incentivise energy companies to build more low carbon power plants. Another barrier is public opinion. Many people hear the word “nuclear” and get scared, so we have a lot of work to do educating people about fusion and why it is a desirable energy source.

The first fusion reactors on earth date back to around the 1950s, and it was only a few decades earlier in the 1920s that scientists began to understand fusion and how it powers the sun. That might seem like a long time ago, but considering the burning of coal predates the age of electricity, it’s actually quite recent in energy science terms!

Further reading: https://euro-fusion.org/fusion/history-of-fusion/