Topic: Solar ChemicalChemicals that use solar lightArtificial photosynthesisCO2 + H2O + Sun  CHO (any carbohydrate)Hydrogen Gas2H2O 2H2 + O2electrolysistoo expensive to use electricity to create usable hydrogen gasWater has to be boiled at ridiculously high temperatures to effectively split water molecules (around 3000 degrees C)Eo=Go/-nFN: number of electrons involved in reactionF=Faraday’s constant,96.5 kJ/(V*mole)E= Eo –(RT/nF)*ln(Q)R= Gas constant= 8.3 J/moleKT= “k”Half Reactions When Splitting WaterCathode: 2H20  O2 + 4H+ + 4e-Anode: 4H+ + 4e-  2H2TiO2SemiconductorPhotocatalystSelf-cleaningPhotocatalytic property-excited electrons/holes can oxidize/reduce organic dirt into CO2 and H2OAntimicrobial property- prevent microbial growth on surfaceHydrophilic property- prevents adsorption of dirtHydropower (6% electricity production)P=ρQHgP = powerp=densityQ= Water flowrate (m^3/s)H=water headg=gravity (9.8 m/s^2)80,000MW hydroelectric generating plants in US30,000MW potential for underutilized hydroelectric powerOver half of the hydroelectric power is in California, Oregon and New York VERIFYAdvantagesClean EnergyRenewable SourceMay offer other benefits: flood control, water supply, recreational opportunitiesCheapest technologyDisadvantagesEnvironmental challenges caused by habitat alterationsWind EnergyWind creates pressure difference which will rotate the turbine and ultimately create electricityAdvantagesCleanRenewableRelatively CheapDisadvantagesHigh initial costLimitation on wind sitesCompeting with other land usesEnvironmental concernsGeothermalCurrent TechnologiesGeothermal Power PlantInject water into the ground to create steam that turns a motor generating electricityGeothermal heat pump (GHPs)Used for HVAC purposes (temperature differences allow for this)Use a coil buried underground to get a heating or cooling functionGround water has a relatively constant temperature, can be used to heat or cool a buildingDirect usage of hot water near earth’s surfaceAdvantagesCleanReliable and almost unlimitedDisadvantagesNeed to lower investment costNeed to be able use earth’s magmaCurrent Status of Nuclear Energy8% of US energy, 20% of electricityNuclear energy is cost-competitiveAround $.02/KWH, higher outputAtomic Structure and IsotopesProton, Neutron, electronReaction of a nucleusProton Mass-about 1amu, charge +1Neutron Mass-about 1 amu, charge 0Electron Mass- about 0, charge -1Typical Nuclear ReactionUranium, Atomic #-92, Atomic Mass-235U+neutron --> Rb+Cs+3nE=mc2C-speed of light: 3x10^8 m/sM is change in massFusionInvolves really light elementsAdvantages of Nuclear energyCost competitiveSmall quantity of fuel is neededReliableCleanNo fossil fuel burnedNo CO2 emissionDisadvantagesSafety-from chain recation, hard to stopWaste disposalTypes of Radioactive RadiationAlpha DecayBeta DecayGamma DecayProton EmissionNeutron EmissionFuel CellA device that converts chemical energy from a fuel to electricity through a chemical reactionChemicalelectricity no thermal process40%-70% efficiency typicallyBasic Fuel Cell ComponentsAnode-where oxidation reaction occursReleases electronsCathode-Reduction OccursAccepts electronsNeed a medium between the anode and cathodeElectrolyteAnode Produces protons and they are transferred to cathodeProsHigh energy efficiencyNo/little PollutionConsExpensiveNeed High-purity fuelNet-Zero Energy BuildingsBuildings consume about 40% of energy supply22% residential, 18% commercialFederal R&D Agenda Has 6 GoalsDevelop integrated, performance-based design and operationNet-Zero Energy Building Technologies and StrategiesWater use and rainwater retentionMaterial Utilization,Waste, and Life CycleEnvironmental Impacts, Occupant health and performanceOvercoming Barriers to implementationsHow to Achieve net-zero energy buildingsCut down on energy consumptionEfficiency technologies enable this, cut down consumption by about 60-70%Improve usage of energiesSolar, Geothermal, other clean energyNet-Zero energy occurs when clean energy produced=energy usedHeat Transfer in BuildingsConductionHeat transfer with direct contactq=dQ/dtk=thermal conductivity of materialsq=(-kA/d)(T2-T1) where d is the thicknessR=d/k  q=(-A/R)(T2-T1)R is the heat resistanceGiven Substances a, b, and c, R=Ra+Rb+RcConvectionq=–[cm(T2–T1)]/tc–specific heatm–Mass=ρVNρ=density, V=Volume, N=Number of air changes per unit timeq=-cρVN(T2-T1)RadiationQ=ϵ*σ[(T2^4)-(T1^4)]Aϵ=emmissivity coefficientσ=5.67*10^-8 W/m^2(K^4)Energy Systems in BuildingsActive systems-utilize energyPV panelSolar Hot waterSolar Space HeatingsGeothermal cooling/heatingPassive systems- minimize consumptionGreen roofReflective roof/windowLEEDLeadership in Energy and Environmental DesignRating SystemsSustainable Sites-26 pointsWater Efficiency-10 pointsEnergy and Atmosphere-35 pointsMaterials and Resources-14 pointsIndoor Environmental Quality-15 pointsInnovation, Regional Priority-10 pointsFour Categories of CertificationCertified- 40-49 pointsSilver- 50-59 pointsGold – 60-79 pointsPlatinum- 80-110 pointsLEED buildings containConstructed WetlandsBuildings Materials (recycled/recycling in general)Green RoofHealth and ProductivityNatural VentilationENCE 215 Exam 2 Study Guide 04/07/2012Topic: Solar ChemicalChemicals that use solar light- Artificial photosynthesiso CO2 + H2O + Sun  CHO (any carbohydrate)- Hydrogen Gaso 2H2O 2H2 + O2 electrolysis too expensive to use electricity to create usable hydrogen gas Water has to be boiled at ridiculously high temperaturesto effectively split water molecules (around 3000 degrees C)o Eo=Go/-nF N: number of electrons involved in reaction F=Faraday’s constant,96.5 kJ/(V*mole)o E= Eo –(RT/nF)*ln(Q) R= Gas constant= 8.3 J/moleK T= “k”- Half Reactions When Splitting Watero Cathode: 2H20  O2 + 4H+ + 4e-o Anode: 4H+ + 4e-  2H2- TiO2o Semiconductoro Photocatalysto Self-cleaning Photocatalytic property-excited electrons/holes can oxidize/reduce organic dirt into CO2 and H2O Antimicrobial property- prevent microbial growth on surface Hydrophilic property- prevents adsorption of dirt04/07/2012Hydropower (6% electricity production)- P=ρQHgo P = powero p=densityo Q= Water flowrate (m^3/s)o H=water heado g=gravity (9.8 m/s^2)- 80,000MW hydroelectric generating plants in US- 30,000MW potential for underutilized hydroelectric power-Over half of the hydroelectric power is in California, Oregon and New York