One of the projects that seem interesting when it comes to energy is the one that the Japanese Space Agency (JAXA) and Osaka University are working on. It’s about a device that converts sunlight to laser light, and it does it four times better then any previous attempts. This laser light is then sent to Earth where it is converted to electricity. It works by storing the sunlight energy into plates made of special metals, which when hit by a low intensity laser light it amplifies it and increases its strength by a factor of four. One of the tests saw a 0.5 watt laser amplified to 180 watts. The laser would then transfer the energy to Earth. The bad part is that it will be ready to launch on a satellite only in 2030.
I can see quite a number of uses for a powerful space based laser and I can also see quite a few bad parts. The technology to shoot down any asteroids that might come close to Earth is one of the good ones, the thought that those space based lasers might be hijacked by terrorists, hackers or used in military conflicts is one of the bad ones.