Small scale fusion power.

Research challenges: How to get hydrogen to fuse into helium using only 500kg of machinery and less energy than will be produced.

Urgent Tasks: (In-)Validate the results of the fusor people, scale up / down as neccessary.

Reasons: Enormous amounts of energy goes into everything. If energy costs drop significantly, I expect sustained, fast and profound economic growth, in this case without too much ecological impact. Also, a lot of high-energy technology will become way more feasible, e.g. space missions.