For the fourth and last part of my nuclear series and after reviewing 10 reasons to support nuclear, the past and present of this energy source and a review of the main fission future solutions we are finishing with fusion.
Contrary to future fission solutions, fusion won’t happen before mid-century as it is the exact opposite of current fission reactors. Instead of breaking large atoms, fusion aggregates small atoms to create larger ones.
This is what happens in any star like our sun. As this endeavor is very complex and costly, I believe we shouldn’t think of fusion to solve our current climate and energy problems.
Nonetheless, fusion is most interesting as it could enable Mankind to cover all its energy needs for millenia without any greenhouse gases emissions or pollution.
There are two main possibilities and here is how they work :
The DT reaction
DT is preferred over DD, because the DT reaction yields more energy and be cause it requires a temperature of “only” 100 million °C to get it going, whereas the DD reaction requires 300 million °C. (The maximum temper ature in the sun is 15 million °C.) Let’s fantasize, and assume that the ITER project is successful.
What sustainable power could fusion then deliver? Power stations using the DT reaction, fuelled by lithium, will run out of juice when the lithium runs out. Before that time, hopefully the second installment of the fantasy will have arrived: fusion reactors using deuterium alone.
The DD reaction
Fuses deuterium with deuterium. As MacKay notes :
If we imagine that scientists and engineers crack the problem of getting the DD reaction going, we have some very good news. There’s 33 g of deuterium in every ton of water, and the energy that would be released from fusing just one gram of deuterium is a mind-boggling 100 000 kWh.
Bearing in mind that the mass of the oceans is 230 million tons per person, we can deduce that there’s enough deuterium to supply every person in a ten-fold increased world population with a power of 30 000 kWh per day (that’s more than 100 times the average American consumption) for 1 million years (figure 24.17).