Biology 2485B Lecture : Biology 2485B - Lec 14.docx
17 Apr 2014
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It takes energy to make energy: eroi = energy returned/energy invested, net energy = energy returned invested, ecologically retrievable if eroi greater than one (>1, ecological threshold need more energy outputted than inputted, economic threshold with tech you have, be able to retrieve it for less than it is being sold for. Surface mining: coal is buried beneath a layer of earth, overburden requires mountain top removal, habitat destruction, coal << 100, need to separate coal and purify it, surface mining impacts (cid:224) are from storage of chemical waste form extracting the coal product, usually stored behind dams, dams can fail causing environmental disasters, sulfide = sulfuric acid. Oil and gas formation: generally from remains of animals that are deep underground, marine life (cid:224) stagnant bottom w/o decay (cid:224) heat and pressure, petroleum mixture of long chain hydrocarbons, natural gas methane, thermogeneic/biogenic gas ch4 methane, dependent upon temperature and pressure.
