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Mi ss i o n o f t h i s Lecture. Take a minute review previous lecture by Dr. Bean What’s the emerging p icture in context of sustainability. Design and Analysis of Solar PV E nergy Systems in detail. 2. Solar PV Energy – A Systems Perspective. Carl Elks ENGR 1559 Lecture 6.
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MissionofthisLecture • Take a minute review previous lecture by Dr. Bean • What’s the emerging picture in context of sustainability. • Design and Analysis of Solar PV Energy Systems in detail 2
Solar PV Energy – A Systems Perspective Carl Elks ENGR 1559 Lecture 6
Dr. Bean’s Previous Lecture • Solar Power (Sept 30th) • How Photovoltaics work • What are the emerging trends in PV • What are the challenges • Solar Concentration methods • Carbon Based Fuels (October 7th) • How to burn “stuff” to make energy • Can we do better? • Can we make it cleaner? • Can we make it carbon neutral ?
Recap of Solar PV • Direct conversion of sunlight into electricity • Visible Light produces electricity (Infrared does not, UV breaks e bonds – not good). • The efficiency of single crystalline solar PV cells driven by the underlying material physical limits interacting with photons (about 33%). • Methods and workarounds to improvement efficiency focus on multi-junction, concentrated PV, quantum dots, etc.. • In general, cost and manufacturing complexity goes up as we look for higher efficiencies in PV cells.
Recap of Solar PV • Another tact, don’t worry too much about efficiency, focus on cost, durability, and manufacturability. • Organic Solar cells (dirt cheap is our motto) • Thin-film (bend it like beckham) • Concentrated Solar PV – Use Fresnel lens to concentrate light on cells (10- 1000x). • Improve efficiencies near the Shockley limit for single material cells. • two-junction (near 40%) • Heat dissipation is a big problem –active or passive cooling needed • Lens can be costly • Works best in high irradiation areas (lots of clean sunlight) Why?
Fossil and Carbon Based fuels • We have studied Wind, Solar, Hydro, and Fossil. • Most recent topic, Fossil fuels - dense energy forms. • Advantages: • You can extract and store them for latter use – Portable Energy. • This relative ease of storage and transport means the fuel can be excavated where it lies, processed at a separate location and transported to wherever you need power. • Dense energy form, lot of energy in a compact volume or mass. • Disadvantage: • Release hydrocarbons that mix with the atmosphere and produce greenhouse gases like carbon dioxide or pollution, including sulphurdioxide – Polluting • Removing the fossil fuel can prove detrimental, even disastrous to the environment, from strip mining operations to oil spills – Environmental Impacts • Pollution control cost money, and eats into profits - Sensitive to regulation . • deposits are unevenly distributed worldwide, frequently in less politically stable nations – Instability of Service and Cost
What’s the Emerging Picture? • No matter the drawbacks of renewable energy or benefits of fossil fuels, one aspect ultimately trumps the argument: fossil fuels are FINITE and NON-RENEWABLE. • WE WILL EVENTUALLY RUN-OUT. • Issues with CO2 and GHG emissions associated with climate change are supremely Imperative …But we can’t rely on this argument to win the day (at least right now). • We can’t do a one-to-one replacement for all of that dense fossil fuel energy with a single renewable energy source. • Fossil and renewable energies are fundamentally different processes for producing energy.
What’s the Emerging Picture? • The BIG TAKE AWAY: The renewables (Wind, Solar, Hydro, Biomass, Biofuels) are like Silver BB’s, not like Silver bullets. • We can’t rely on any one energy source to slay the GHGmonster we have created. • We need to view the problems through the Lens of Sustainability and Service. • Each renewable energy source will have a role, it will need to consistently perform on the cheap, and must have no effect on the energy services we consume from it. • These over-arching requirements require us to think from two perspectives: • Sustainability Lens • a service oriented engineering perspective • For today we look at Solar PV from these perspectives
The Shift to the Sustainability Lens UN Summit on Climate Change – September 2014 • Energy policy and environmental policy are increasingly interconnected. • Environmental policies are changing energy markets. • Energy and other resource policies are becoming more interconnected • The recent People’s Climate March in New York City was a remarkable show of force on many levels. It was notable for its sheer size, some 300,000 demonstrators Highlighted where the political will must come from: the grass roots.
ModernEnergyConversion Sequences • Heatingof Buildings: • Gas,oil,biomass → heat • Solar→ heat ElectricityGeneration: • Coal,gas, nuclear→ heat→ mechanical→ electricity • Hydro→ mechanical→ electricity • Wind → mechanical→ electricity • Solar→ Electricity Transportation: • Oil→ gasoline,diesel,jetfuel → heat→ mechanical • Biomass → ethanol→ heat→ mechanical • Fuelcellcars:Gas → hydrogen→ electricity→ mechanical • Hybridcars:Gasoline→ mechanical→ electricity→ • battery→ electricity→ mechanical • 5
Our Energy System Model Conversions Take place here..
OrderofMagnitudeofEnergyResources 10 Source:http://www.worldenergy.org/publications/
Important Metrics Related to Energy and Power • Energy density -is simply the amount of energy per unit weight (gravimetric energy density) or per unit volume (volumetric energy density). With energy expressed in joules. • Energy density is often expressed as joules per gram (J/g) or joules per cubic centimeter (J/cm3) or, more commonly, mega-joules per kilogram (MJ/kg) and mega-joules per liter (MJ/L) or gigajoules per ton (GJ/t) and gigajoules per cubic meter (GJ/m3). • Power density – Not so simple. But for now, we will define as W/m2 of horizontal area of land or water surface or a square area. 12 SustainableEnergy– Fall2010– Conversion
TypicalEnergy Density Values Bituminouscoal 310 13 Channiwala,etal. 2002andNISTChemistryWebBook
KeyMetric:ConversionEfficiency Conversion Process EnergyInput UsefulEnergyOutput Energy Loss • When producingwork(mechanicalorelectricity): • = WorkOutput/ EnergyInput • When producing energycarriers(diesel,hydrogen): • = EnergyContentofProduct/ EnergyInput
ConversionEfficiencies Source:SustainableEnergy 17
ExamplesofEnergyConversionReactions Fuelcombustion C8H12+11 O2=8 CO2+6 H2O– gasoline C6H12O6+6O2=6 CO2+6H2O– cellulosicbiomass CH4+2O2= CO2+2 H2O–naturalgas Hydrogenfuelcell H2+½O2= H2O+ electricity+heat Theseoverallreactionsoccurthrough multiplesteps.. Can be represented by the Heat Transfer and/or Heat Engine model..
Pounds of CO2 emitted per million Btu of energy for various fuels: