Two technology entrepreneurs harness the power of solar energy to solve two different problems: water contamination in Ghana and jungle preservation in South America.
Two pioneers in electric power both aim to develop technologies that reduce carbon emissions - both using electric motors and batteries in aviation and speedboats.
Scientists around the world are working on projects dealing with space and space travel - extraterrestrial life, colonising Mars, the Big Bang and rocket development.
Engineers are working on streamlining vehicles to improve fuel consumption and speed. Plus, a solar-powered car competes in an endurance race.