If you have a computer or an Android phone, help in the search for a cure for HIV/AIDS by joining the World Community Grid.

Its very easy just:
1/ download BOINC from here https://boinc.berkeley.edu/download_all.php or for Android from the PlayStore.
2/ join the World Community Grid here https://www.worldcommunitygrid.org/discover.action

Its it safe? Yes very, I have been running BOINC for over 10 years with no issues, it will not slow down or harm your devices.

You can do research for many other humanitarian/scientific causes.

Finally if you are concerned about electricity cost, you can join team Gridcoin here https://gridcoin.us/ and earn some digital currency for the help you provide.