Nuclear energy is released during fission and fusion.

WSJ: The New Nuclear Revolution

The good news is that the big names in nuclear energy -- like Areva, Hitachi, General Electric and Toshiba -- have recently been joined by a bevy of high-tech start-ups seeking to develop advanced nuclear-reactor designs for both fission and fusion energy production.

WSJ: The New Nuclear Revolution

So far, there are five fission and two fusion start-ups, among them Hyperion, NuScale and Tri Alpha.

WSJ: The New Nuclear Revolution

This helps address the drawbacks of both fusion and fission.

FORBES: A Nuclear Hybrid

However, while mining helium-3 from the moon will be one challenge, extracting energy from it is another, as it relies on nuclear fusion, rather than fission used in today's nuclear reactors.

CNN: Mining the moon for a nuclear future

Today, most alternative energy technologies that are discussed--wind, solar, tides, waves, clean coal, nuclear fission and, perhaps one day, fusion--are useful only for making electricity.

FORBES: Magazine Article

This is why the idea of nuclear fusion is cool as opposed to fission, if this is possible.

FORBES: Executive Profiles: Disruptive Tech Leaders In Social Business -- Parker Harris, Salesforce.com

Few believe in fusion now, though uranium-powered fission reactors may be coming back into fashion.

ECONOMIST: A fundamental change is coming sooner than you might think

Fusion produces no greenhouse gases, and, unlike nuclear fission, it does not produce long-lived radioactive waste.

FORBES: A Challenge to America: Develop Fusion Power Within a Decade

The Earth is warmed naturally by its own nuclear fission reactors within and also by the sun, that big nuclear fusion reactor.

WSJ: The New Nuclear Revolution

The experimental fusion reactors, he suggests, could be used to clean up the waste generated by the fission reactors.

ECONOMIST: Nuclear waste