Fusion Drawbacks

Fusion energy perpetually recedes 50 years into the future. However, I wonder if we ever get there, if fusion will be quite the panacea advertised. Sea water contains deuterium in microscopic amounts, yet the deuterium in a gallon of sea water is equivalent to 300 gallons of gasoline. However, you can’t use raw sea water in a reactor. You must extract and purify the deuterium aka heavy hydrogen. Heavy water D₂O and water H₂O behave the identically chemically, so you must use a process that takes advantage of the fact deuterium is slightly heavier that hydrogen, like repeated distillation or repeated electrolysis of water. This takes huge amounts of energy. You may have to invest so much energy preparing the fuel that the energy return is not worth the candle.

~ Roedy (born:1948-02-04 age:68)