How to Build a Solar-Powered Lawn Mower and More from TreeHugger

This week on TreeHugger, spectacular robots made from broken computers, high-tech concepts for cleaning up space junk, trash bins that text, a bike-horn-turned-iPhone speaker, and more!

1. 20 Top Tech Stories From April
We saw loads of interesting stories this past month, but here are 20 of the best that you don't want to miss.

2. How to Build a Solar-Powered Lawn Mower
Have the geekiest mower on the block, and power it for free.

3. High Tech DIY Sensors Could Help Keep Billions of Gallons of Raw Sewage Out of NYC Harbor
An entrepreneurial design student may have found an intuitive, relatively simple way to keep 27 billion gallons of raw sewage from being dumped in New York City's harbor every year.

4. 9 Concepts for Cleaning up Space Junk
Litter isn't just a problem for terra firma, it's a very real problem in space as well. The effort to clean up space junk might take a variety of different methods, and here's a look at some of those concepts being considered.

5. Build a Micro-Hydropower Generator from CDs and Repurposed Printer Parts
Think you need to be an engineer and spend a bundle to create a mini-hydropower generator? Think again.

6. Bike Horn iPhone Speaker, A Great Low-Tech DIY Gadget for Cyclists
We love this project that transforms an old-school bike horn into an electricity-free iPhone speaker.

7. Gorgeous Time-Lapse of Our Solar System Using NASA Probe Photos
Yay for space technology! Watch and be mesmerized by our solar system's movement captured in black and white images from two NASA missions.

8. Broken Computers Come Alive as Robotic Animals
Artist turns old typewriters, cameras, modern printers and computers into birds, goats, squid, dinosaurs and more.

9. Smart, Solar-Powered Kiosks for Recycling and Composting Send Text When They're Full
The University of Washington has installed smart, waste-collecting kiosks that are solar-powered and communicate wirelessly when they're full.

10. Free Photos for your Smart Phone Background or Facebook Timeline
The Ocean Conservancy has put up a gallery of wonderful — and free — images of ocean life for you to load on your cell phone or your Facebook profile.