By 2030 the physicist expects that we will have hot fusion reactors.

Question 4a: What future energy source will solve our energy crisis? (Submitted by Davis Tan)

Michio Kaku: Well, Davis, there are hundreds of proposals to solve the energy crisis, a lot of them bogus, but some of them actually have validity. When you talk about, for example, fusion, hot fusion, we're talking about the year 2019, when the international experimental fusion reactor gets turned online in France. It turns out that the European Union, the United States, Japan, Korea and Russia are pooling their resources to build the world's largest fusion reactor in southern France in order to show that you can in fact have breakeven, that is generate as much power as you put into it. After that the next generation will be called the demo reactor, which will actually generate net power. So if all goes well, this means that perhaps by 2030, maybe by 2040, we could have commercial fusion reactors. Not small portable things that you can put into a car, these are going to be gigantic objects that consume tremendous amounts of seawater, purify the seawater by extracting certain chemicals from the seawater, fusing the tritium deuterium to create electricity and the electricity than goes in to your fuel cell, goes into your electric battery to energize modern society. So this is the hot fusion approach.

Now some people have advocated, cold fusion, most physicists do not believe that cold fusion works. I keep an open mind about it; however, the bottom line is things have to be reproducible on demand. People who claim to have attained, cold fusion in their laboratory, fusion in a glass of water, their results cannot be duplicated by other laboratories. It wants to buy a car when you turn on the ignition and it sometimes works and sometimes doesn't work? That's not a viable commercial technology. So until we can have reproducible, testable, falsifiable cold fusion, physicists are naturally going to be a little bit skeptical.

Now, some people say, what about energy from nothing? That is, free energy; energy from the ether. Well it turns out that the vacuum does have some energy. This is called dark energy; it has caused a sensation in the world of physics. We now know that empty space… empty space has a calculable amount of energy associated with it. However, and this is a huge however, it is extremely small. Over large cosmological distances, that energy is anti-gravitational, yet actually is pushing the galaxies apart. And that's why the universe is expanding. The universe is expanding because the energy of nothing, dark energy, is pushing the galaxies apart. There is dark energy in this room, there is dark energy inside your body, but it's extremely small, so small that it cannot be harvested for ordinary use.