kEnergy Basic Concepts Potential energy kinetic energy decreases with each bounce and ball heats up eventually stops as a hot ball that loses that heat to the surroundings Greek derivation work within Ability to do work energy Work force acting though a distance ball had potential energy which then became kinetic energy gravity acted on the ball Heat energy changes affecting molecular motion and temperature changes o Ex explosion energy evolved as HEAT and WORK Work air is suddenly expanding air molecules are doing work and fast Heat and Work are mans to exchange energy with surroundings Energy is flowing through ecosystems unlike nutrients which cycle First Law of Thermodynamics Energy is not created or destroyed it is conserved Transformed between forms in ordinary processes Among different forms of energy Mechanical Electrical Light Chemical Heat Second Law of Thermodynamics relates to direction of spontaneous change spontaneous changes increase entropy of the universe o relates to how mch energy is dispersed and how widely it is spread out o also related to disorder or randomness loss of heat and increasing disorder are natural essential processes energy needs to be put in to create order people need to eat in order to maintain order Inplications of Second Law for Life Spontaneous energy change not 100 efficient o Waste heat usually produced energy dispersed life is unnatural in high state of internal order low entropy o done via pumping out disorder spreading energy out put in high utility energy food or light without enery transfers no life of ecosystems possible human life and civilizations remarkable natural systems dependent on continuous flow of energy sunlight to heat agricultural industrial revolutions changed energy from mostly muscles fires changed to fossil fuels coal natural gas Quantify energy flow ratio of respiration to biomass R B rhythm and blues o atp becomes cellular currency o similar to mpg for a car related to maintenance to structure of system o eating multiple times a day R B approximations per day Chart What he is saying o one coke wouldn t be enough calories o plants related to photosynthesis and respiration o phytoplankton o humans we are more efficient than these other organisms one of the reasons we are successful on earth there are times when we don t eat GPP via photosynthesis another measure of energy flow Marine ecosystem chart What he is saying o come in toward coast energy intensity doubles because of nutrient input sediment input human impact o upwelling zone nutrient rich water flow up to surface high intensity o estuaries and reefs BAY important place in terms of energy flow per We want to preserve them not because of energy sq meter flows TROPHIC STRUCTURE ILLUSTRATES THAT ENERGY IS FLOWING THROUGH THE SYSTEM Human Energy Use systems Depletable vs Renewable Depletable use replenishment o Coal oil natural gas Renewable repleacable or not depletable o Water power and plant biomass replaceable part of hydrologic and c cycles Water has potential energy is changed to kinetic energy and then electric current Solar and wind power not depleteable flow through not Pre industrial revolution 1760s in northern England tapping cycles renewables used o Muscles biomass solar wind Human NRG Use Systems Conventional since 18th century o Depletable o Coal oil natural gas nuclear Situation today Human Uses 89 of US energy use from fossil fuels 80 of world energy from fuels Peak Oil Etc etc etc blah blah blah A Nuclear Power Plant is a Boiler Uranium fuel has to be mined October 10 2011 Second law of Thermodynamics Entropy increases First law Energy transformed Nuclear Power Located near water o They need water to cool excess heats water absorbs heat cooling towers so that water doesn t overheat river o There is no combustion or carbon being burned no Nuclear Power Attributes CO2 other ghg No carbon dioxide other ghg No air or water pollution some heat Wastes and plant radioactive 1000s of years no definitely safe solutions Yucca mtn NV Potential for accidents a concern Production of bomb grade fissionable material nuclear o Current issues with n korea and iran Volume of waste per year from a big plant would fit under ur weapons dining room table Uranium ore supplies widely dispersed in the world but might only last a few decades especially if nuclear energy expands Reprocessing wastes recovers unspent U and newly produced Pu many questions arise Alternative Human Energy Systems SEEE CHAPTER 20 IN C C Replaceale o Hydropower o Biomass Non depleteable o Wind o Geothermal o Tidal and wave o Solar Hydrogen and fuel Cells o First a counterpoint on wood energy Fuelwood Crisis dimensions Primary energy for 2 billion people Mostly in developing nations Principally women and children 10 300 days a year collecting wood Urban woodsheds like watersheds urban people require firewood and landscape is being cute water quality is changing 1700 million tons harvested 500 million shortage Consequences of Fuelwood Crisis Deforestation o Habitat loss o Soil erosion o Carbon dioxide release Use of animal maure for fuel o Decrease in soil organic matter o Decrease in soil fertility Gender issues and family disruption Indoor air pollution Science and Policy Responses Reforestation Community woodlots Efficient cleaner burning stoves Agroforestry o Interplanting food crops with trees o May enhance soil fertility if trees are legumes Erosion control Fuelwood cheaptest available fuel unit of heat Tree Legumes rapid growth 50 of fuelwood trees can coppice repeatedly cut down high calorific value burns without toxic smoke or sparks cleaner Tree Legumes Fix N2 Long lived and low maintenance Forage for livestock most ntritients in seeds Leaves and pods grazed by animals Erosion control Source of N for soil Revegetate saline and arid sites Fruit and vegetable production for humans OCTOBER 13 2011 Why is a nuclear power plant like a tea kettle It uses uranimun to boil water electricity is being created DC to AC generating heat but not from combustion of carbon HYDROGEN as a fuel lightest element H H e 30 of mass of sun source of sun s energy most easily burned oxidized loses its e convertedx to water when oxidized by oxygen h2 O2 H20 has to be produced H is naturally combined with other elements eg CH4 H20 Ways to produce H2 from natural gas o produces c02 in process o natual gas will run out eventually electrolysis of water o splits water to hydrogen and oxygen gases h20 H2 02 use wind