Yay, something I'm pretty knowledgeable about, but there's not that much to write about it. Well, "nuculear" (as Bush likes to say, still rofl) energy tends to apply to nuclear fission, but I'll mention fusion as well.
Nuclear fission is a good idea, theoretically. Large amounts of many forms of energy are released during nuclear fission. However, humans have only been able to harness only a microscopic amount of the thermal form of energy released. I've seen the whole system of how a nuclear fission reaction works, and it basically uses a controlled, maintained fission chain reaction to generate heat, which is used to heat water, producing steam that goes through an electric turbine and then into the atmosphere. To put it simply, a nuclear reactor plant, along with coal power plants, uses steam power--something that was around since ancient Greece(B.C., used for various mechanical tricks in churches and presents for leaders, etc.).
I personally think it's really primitive and very outdated, not to mention unbelievably inefficient, wasteful, and even polluting. You really think all that steam doesn't contain any radioactive "residue" of sorts when it returns to the atmosphere. Also, the radioactive effects on the immediate area, particularly when something goes wrong (I don't think I need to mention any examples...). Humans need to find ways to harness much more of the energy released during nuclear fission. There's lots of research going on to improve the efficiency of modern nuclear power plants, including recycling radioactive material, harnessing more heat energy by various techniques and reducing the radioactive material needed, and even floating nuclear power plants (as they need lots of water to run properly; planned by Russia and other countries). But, there needs to be much more research in how to harness more types of energy.
It has been brought to my attention, in light of the USA satellite that crashed to earth recently, that there have been intensive studies to harness more of the energy released by nuclear fission. The satellite was supposedly using a radioisotope thermoelectric generator. From the looks of it, it seems to have great potential and looks interesting. Here's it from Wiki if you're interested:
Code:
http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator
Nuclear fusion reactions, on the other hand, are much less developed. There are several fusion reactors already built, but they're only used for research. They're trying to find out everything they can about it and how to harness enough energy from the fuel needed to produce the reaction, cost-benefit analysis, maintaining the reaction, etc. But, it doesn't look like anything practical will be put into use for perhaps 50 years or more...