Presentation on theme: "BIOLOGY 157: LIFE SCIENCE: AN ENVIRONMENTAL APPROACH (Energy needs: Fuel)"— Presentation transcript:
BIOLOGY 157: LIFE SCIENCE: AN ENVIRONMENTAL APPROACH (Energy needs: Fuel)
ENERGY Energy is the ability to do work Humans use energy of two types Internal (= food) External or Auxiliary (= fuels, etc.)
EXTERNAL (= AUXILLARY) ENERGY This includes all those energy sources we do not use directly to fuel our bodies. On the average during the 20th century population doubled every 37 years (about 1.9% per year). HOWEVER, on the average, External Energy use doubled every 20 years during the 20 th century. This amounts to a 3.5% increase per year. Why the difference?
STATUS OF FOSSIL FUELS (I) OIL Estimated total -------- 2 trillion barrels (of recoverable oil) (2,000,000,000,000) used to date ------------- 0.465 trillion proven reserves -------- 1.15 trillion anticipated reserves --- 0.530 billion AT CURRENT RATE OF USE: proven reserves will last 40 years anticipated reserves will last 19 years
STATUS OF FOSSIL FUELS (II) NATURAL GAS Estimated recoverable total ---- 10,000 trillion ft 3 used to date ------------- 2,500 trillion proven reserves -------- 6,200 trillion anticipated reserves --- 1,300 trillion AT CURRENT RATE OF USE: proven reserves will last 60 years anticipated reserves will last 16 years
STATUS OF FOSSIL FUELS (III) COAL Estimated total -------- 10,000 billion tons (= 10 trillion) used to date ------------- 1,000 billion proven reserves -------- 1,200 billion anticipated reserves --- 7,800 billion (IF all is recoverable) AT CURRENT RATE OF USE: proven reserves will last 200 years anticipated reserves will last 1,300 years
STATUS OF FISSIONABLE NUCLEAR FUELS U 235 and Pu 239 Current rate of use ----- 100 to 200 years Extended by Breeder Reactors ----- by 10x ???????????????????
HOW A NUCLEAR REACTOR WORKS (I) A ‘controlled’ atomic bomb most reactors use the fissionable U 235 fission - the splitting of atoms splitting of atoms releases energy the released energy is normally used to heat water (or some other liquid) and this heated liquid can be used to heat water to steam to run turbines to generate electricity
HOW A NUCLEAR REACTOR WORKS (II) small pellets of the fuel (U 235 ) are embedded in fuel rods fuel rods are bundled in clusters between each cluster are damper rods (usually of boron or cadmium) which absorb neutrons the reaction rate is controlled by how far the damper rods are inserted between the fuel rod assemblies
NEW AND / OR ALTERNATIVE FUELS (I) * = renewable or potentially renewable # = not renewable and reasonably limited @ = not renewable but extremely abundant = does not produce CO 2 # TAR SANDS AND OIL SHALE * GEOTHERMAL ENERGY * WIND ENERGY * TIDE ENERGY * SOLAR ENERGY PASSIVE, ACTIVE, PHOTOVOLTAIC
NEW AND / OR ALTERNATIVE FUELS (II) * HYDROGEN * WOOD & other BIOMASS MATERIALS * METHANE and ALCOHOL (from organic materials) = ‘Biofuels’ * HYDROCARBONS (‘OIL’) FROM PLANT SAP NUCLEAR # Fission @ Fusion
CONSERVING ENERGY (I) It costs only 1/4 to 1/3 as much to ‘save’ a unit of energy as to mine, extract, produce, etc. a ‘new’ unit. 1) EDUCATION to be less wasteful, to do things differently & more efficiently 2) More AND / OR better insulation in buildings 3) Less lighting AND / OR more efficient lighting 4) Less heating-cooling AND / OR more efficient heating-cooling
CONSERVING ENERGY (II) 5) More efficient gas and electric appliances, motors, engines 6) More efficient transportation systems (mass transit & shipping; carpooling) 7) More efficient production and transmission of energy 8) Restructuring of population centers (layout and size) 9) Better (longer lasting) products (cars, appliances, furniture, etc.)
SOME QUESTIONS FROM CHAPTER 12 In what country do the people use the most energy per capita? Is this surprising? What is the most efficient (in use of fuel) way to transport freight: truck or train?