those are really broad parameters. it seems odd that you would refer to at as an opinion essay on WHY human nature is good, the real opinion would be IF human nature is good. however based on your question i would find by searching online random acts of kindness by people. i truely believe the most truest form of good human nature is helping someone else and getting nothing in return, sincere generosity without gain. i remember around christmas hearing of a man somewhere in the midwest i think just walking down the street and handing random people hundred dollar bills to help them for christmas.i think he gave away over 20,000 dollars and had been doing it for years. that is a true random act of kindness, i think with some searching you could find alot of people just like this person, documents the person place and time that will make your essay supported. if i can think of any others i will edit. hope this helps get you started.

i found some websites to give more supported situations

http://www.intouchmag.com/33kindnessstories2.html

http://www.jamesshuggins.com/h/mot1/random_acts_of_kindness.htm

Biofuels <--- Made from stuff like animal crap and leaves. Produces much less greenhouse gases than fossil fuels but in addition produces much less power. Renewable for the reason that there's a equipped provide of them, notably the previous. Carbonaceous (or fossil) fuels <--- Made from the stays of prehistoric animals (oil and average gasoline) and crops (coal). Produce plenty of CO2 etc however are the primary supply of power on this planet at present. Non-renewable for the reason that they take thousands of years to sort.