April 27 2016
April 27 2016 GEO 100
Popular in Physical Geology
Popular in Geology
This 6 page Class Notes was uploaded by samantha Flavell on Saturday April 30, 2016. The Class Notes belongs to GEO 100 at State University of New York at Oswego taught by Rachel Lee (P) in Fall 2015. Since its upload, it has received 17 views. For similar materials see Physical Geology in Geology at State University of New York at Oswego.
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Date Created: 04/30/16
April 27, 2016 Geo 100800 Prof. Nandini Kar More US Energy Perspective: Hydro *We are the #2 world producer (consumer) of hydropower. Remember that hydro represents <5% of our national energy use. Wind Energy *Wind farms are enjoying a second renaissance Wind turns turbines to produce electricity Turbine blades kill birds Turbines are expensive to maintain Some wind farms were abandoned because of maintenance costs US Average Wind Speeds *In general 4 m/sec (9mph) winds are needed for costeffectiveness on small scales *The DOE’s goal is for 5% of US electricity to be generated by wind power by 2020 **The US recently became #1 in the world in wind production Solar Power *The most abundant energy source at Earth’s surface *Solar energy availability>> hydrocarbon availability *Challenges to wider use: Solar energy is diffuse Must be collected and converted *produces no CO2 Hydrogen Fuel Cells *Produce electricity via chemical reactions *Hydrocarbon (h2) and oxygen are reacted to yield electricity, heat and water in “fuel cells” *Fuel cells may be usable as engines for motor vehicles *Technological problems cost effective mass production of H2 Distributing hydrogen for widespread use Biofuels *Biofuel: processing plant and animal matter *Early humans used biomass (wood, charcoal dung) *biofuel has most inert material removed before use *To be widely useful, biofuel must be grown quickly *Ethanolalcohol derived from corn, cellulose, algae, etc. Burned as a motor fuel Used as a fuel oxygenate *Biofuel often produces CO2 Bioenergy *Biomass: plantderived fuel, whether directly from plants or indirectly from plantderived industrial commercial or urban wastes, or agricultural and forestry residues *Preferable to burning fossil fuels because of little release of harmful gasses *used for direct power generation of in fuels (transportation, heating) *Few barriers to widespread use (infrastructure, familiarity, technology) *Ethanol and “biodiesel” are cleanburning liquid fuels produced by biomass distillation *Burning biofuels yields virtually no CO, hydrocarbons, sulfur gases or heavy metals. CO2 is taken by biofuel plants, so the net CO2 production is virtually nil. *Current biomass power plants rely mainly on waste (agricultural, forest, industry, urban) *currently biomass burning yields 11% of the worlds energy. Although it provides only ~3% of the total in the US (just ahead of hydropower for electricity generation) *Fossil fuels are being displaced in cofiring plants in which coal is blended with cleaner biomass Environmental Issues *Fossil Fuel production and use damage the environment Oil Spills: Deep Water Horizon Spill; Gulf of Mexico Coal: Strip mining and acid drainage Shale Gas: Groundwater contamination from fracking” Nuclear Power: Radiation releases and destruction of Fukushima and Chernobyl stations Fossil Fuel Burning and the Atmosphere *Coal burning involves not only Co2 a key greenhouse gas, but SO2 from the high sulfur content of coal. Sulfur and Nitrogen gases are major causes of acid rain *Coal burning produces material called fly ash which is environmentally reactive and rich in toxic metals (i.e. mercury) *Technology provides means of ‘scrubbing’ emissions from fossil fuel burning to reduce the particle release, but these are costly and not in widespread use, especially in developing nations *Even if removed from emissions, fly ash still has to be safely disposed of Acid Rain *If you live in Atlantic Canada, your acidic precipitation by US industries (dominantly power generation) that burn coal Coal Mine Waste *Finely crushed coal constitutes a great hazard for generating acidic runoff Coal and Acid Mine Draining *As we know from chemical weather, the finer the grainsize you reduce a mass of rock, the larger equivalent surface area for which chemical reactions may take place *Sulfur is a common element in organic material. When the organic material is squeezed into coal, the sulfur forms sulfide minerals. When sulfides weather, they release sulfuric acid, which enters ground and surface waters Energy Problems *Global energy use has increased dramatically due to Industrialization Population Growth *Oil: the dominant energy source is dwindling *Many countries import oil to meet demands World Energy Consumption over Time *Energy demand, especially for oil and gas skyrocketed after World War 2 *The 1970’s energy crisis slowed consumption Energy Problems *The oil Crunch Oil extinction will occur by 20502150 Future historians will see the oil age a 200 year era We are near the peak of global oil production Humanity faces many changes as oil runs out Groundwater *Humble groundwater is among our most precious natural resources *The main points in this lecture are the behavior of water under the Earth’s surface, and how we deal with its perturbation by natural and unnatural means. **Is groundwater important? According to US estimates Groundwater provides: 34% of Agriculture use (mostly for irrigation) 40% of the Public Water supply withdrawals 53% of all drinking water for the total population 97% of drinking water for rural population Global Water Budget *Although groundwater is not very globally significant in volume, it is a critical source of domestic water, because it represents ~25% of all fresh (nonsaline) water. *It can be viewed as a nonrenewable resource: it is possible to withdraw it faster than nature replenishes it. The Hydrolic Cycle *<5% of Earth’s water is fresh water of this, 74% is tied up in glacial ice. Hence, groundwater is a precious commodity Porosity and Permeability *Porosity: Volume proportion made up of voids *Permeability: Connectedness of voids, dictating capacity to transmit flow Porosity Structure of the Crust *Naturally, porosity will decrease as load pressure increases, but it is not simply a function of depth, as no stratigraphic column is homogenous. Nevertheless, the rocks that dominate the mid lower crust (metamorphic and intrusive igneous rocks) all tend to have low porosity. Aquifers and Aquitards *Aquifers and Aquitards are commonly interlayered A: Aquifer: sediment or rock that transmits water easily B: Aquitard: Sediment or rock that hinders water flow *Unconfined: An Aquifer that intersects surface In contact with the atmosphere Easily contaminated *Confined: An Aquifer beneath an aquitard Isolated from the surface Less susceptible to pollution The Water Table *Material saturated with water lies below the water table Above the water table, pores are mostly filled with air Below the water table, pores are filled with water *Hydrofactoid: one inch of rain on one acre of ground results in 27, 192 gallons of water.
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