How about solving world hunger?
The main cause: many people in the world still do not have sufficient income to purchase (or land to grow) enough food. However, other cited causes include: harmful economic systems, armed conflict, environmental overload, discrimination, and powerlessness.
The 1996 World Food Summit set a target to halve the number of undernourished people by 2015 from their number in 1990-92. However, while the number of hungry people in developing regions has fallen by over 200 million (from 991 million to 790.7 million), the goal was 497 million, which means that the target was not reached.
One Israeli inventor has developed a technology that can extend the shelf life of produce by 1,500% while also preventing disease and fungus, useful in countries where the transportation systems are slow and refrigeration is hard to come by. If all food was grown with his technology, he argues about a third of the food grown today which is typically lost to spoilage and disease would actually make it to market. Thus, farmers in poor countries could earn more on all produce they grow and have more to offer to those in their community, or small farms could have extra to sell and earn income.
One organization names many other solutions to world hunger: sustainable food, access to credit, food donations, access to education, urban farming, government intervention, and birth control education.
I’m certainly no expert, but there is a plethora of research out there. World hunger is an immense issue with no single solution yet. Still, I’m sure with your expertise, you can brainstorm several inventions (that alter food itself, involve an inexpensive farm-in-a-box for anyone to grow their own food, use unique drones to carry food from one region to the next with regular deliveries, etc.) that will curb this problem and help us reach the World Food Summit goal of at least halving the number of undernourished people in the world.
But hey, if not, then how about a computer that is recharged through each push of a key on the keyboard? Then I wouldn’t have needed to locate and plug in my charger, and use electricity, during this post.