It’s Sunday…. and it’s time for “Just for Fun”. We’ll be trying to publish a posting in “Just for Fun” category every Sunday.

Last week, Bill Gates gave speech at TED. His topic this time is about zero-emission energy sources. He mentioned that we needs break-through technology.

What’s his idea? He’s talking about Terrapower, another type of nuclear reactor. Instead of burning uranium-235, which makes less than 1% of natural uranium, this reactor burns uranium-238, which makes 99% of natural uranium. He also said that we can use all the leftover waste from today’s reactors as fuel.

According to Wikipedia, one kilogram of uranium-235 can produce about 80 trillion joules of energy, which is as much energy as 3000 tonnes of coal. What is more interesting, Bill showed a photo of depleted waste uranium in steel cylinders in Kentucky. This waste, which is full of uranium-238, can be “re-used” by Terrapower as source of energy. It should be able to supply the US energy needs for 200 years. Wow….

I’m not an expert on nuclear engineering, but it sounds really cool to me. What I don’t understand is why our current reactor doesn’t use Uranium-238 yet. Nuclear power plant has been around for more than 5 decades. Weren’t there any scientists or engineers thinking about the idea?