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Exergy Sustainability Exergy Sustainability Rush Robinett III Deputy Director Energy, Infrastructure, and Knowledge Systems Center Sandia National Laboratories Introduction: My Filters/Biases • Aerospace engineer by training ¾ Dynamics, Controls, and Optimization ¾ Path dependent • Looking for a driving/dominant input for a controller design (stability; single point failure) • Applying it to self-organizing, complex adaptive systems Fundamental Driver for Survival • Exergy is the elixir of life. ¾ Exergy – that portion of energy available to do work (i.e.,ordered energy that is out of equilibrium with its environment; Hydro- power). ¾ Elixir – a substance held capable of prolonging life indefinitely (i.e., sustainable; fountain of youth). Fundamentals of Thermodynamics • Insights from the Laws of Thermodynamics ¾ The energy of the Universe is constant. ¾ The entropy of the Universe tends to a maximum. Fundamentals of Thermodynamics (Cont.) • Said another way: I. “Energy” can be neither created nor destroyed, only changed from one form to another. II. In using any form of Energy, it is not all “Available” to perform useful “Work”. A portion of it is “Unavailable” and must be discarded, usually in the form of “Heat”. III. All processes and activities involve Energy changes and hence must obey Laws I and II. These changes always result in the degradation of some Available Energy into Unavailable Energy. Fundamentals of Thermodynamics (Cont.) • These insights have been likened to being in a one- sided poker game with Mother Nature, where the stakes are Exergy. I. You can’t win. (You cannot get more out than you put in.) II. You can never break even. (The “House” always takes a percentage of the stakes.) III. You can’t even get out of the game. (All of existence involves Exergy.) Confusing Energy and Exergy • Economics: Looking for a scarce resource ¾ Energy is conserved; not a scarce resource ¾ Exergy is consumed/degraded; Exergy is a scarce resource. WHY?? Confusing Energy and Exergy (Cont.) • Efficiency: 2nd Law versus 1st Law ¾ A second law efficiency is the ratio of the minimum amount of available work required to do a particular job to the amount of available work used to do the job. ¾ Contrast this with a first law efficiency which is the ratio of energy out to energy in. • Decision-making via an optimization process Energy Surety • The survival of your lifestyle. Energy Surety (Cont.) • The survival of your lifestyle. ¾ Cheap fossil fuel ( i.e., coal, oil) IS the elixir that has enabled your lifestyle. Replacement??? ¾ Present infrastructures are designed for fossil fuel. ¾ Goal: Long-term predictable business plan ¾ Path: Plug ‘n’ Play Power from All Exergy Sources via a Flexible, Adaptive Infrastructure. Survival: Sustainability and Exergy Parasite • From an engineering point of view, a person is an exergy parasite in the biosphere host that is trying to order the world around him/her. Autonomous Mars Rover Lifestyle Available 12 Volts Required Power In 1 Amp Power Out Solar Super Capacitor Robot (Storage) 12 Volts Mobility 3 Amp PV Solar Cells Autonomous Man on Earth Available Lifestyle Power In Required Power Out Fossil Fuel End Solar Earth (Storage) Uses *NOTE: Required Power Out > Available Power In; Impedance/Capacity Mismatch What is Surety? • It’s about doing a job and serving a mission… – Under constraints (e.g., legal or procedural) – And with limited resources (e.g., budget/schedule) • And being successful – Providing required functionality – Being efficient – Other requirements (e.g., aesthetics) • But at the same time avoiding catastrophic loss – Safety/security (inadvertent/intentional) – System poses acceptable residual risk • In the context of the long-term. Surety and Decision-Making: Fundamental Dichotomy of Life • First need: Create order to find and harness exergy. • Second need: Degrade (consume) exergy; create entropy (disorder) to survive. • Dichotomy: How do I create order and disorder at the same time in an optimal way? ¾ The “Tyranny of the OR” versus the“Genius of the AND”. ¾ Dialectic synthesis; Transcendence of dichotomies ¾ Learn fundamental patterns of “Order and Disorder” (i.e., farming; water cycle) Multi-Criteria Optimization • Requirement: Need at least two competing criteria for interesting decision-making and learning. • Short-term value: Economics of cost/profit • Long-term value: Sustainability • Goal: Survival and Predictability of the Future given all of the Uncertainty. • Dialectic synthesis: “Live for today while planning for the future”. Our Systems Approach to Energy Surety Involves Looking at Several “Indicators of Value” Case A Cost Case B 8 6 Environmental Unsustainability Impact 4 2 Infrastructure Safety & Health Vulnerability 0 Impact Science & Energy Technology Needs Dependence Policy & Market Needs What Do You Value? Optimization is in the eye of the beholder! Transition Plan for Lifestyle Support System • Fossil fuel to synfuel to H2 to ?? • Plug ‘n’ play all power sources via a flexible, adaptive infrastructure. Persistent Energy Sources END USE Residential Agriculture Hydrocarbon Industrial Electric Intermediary Waste (Production & Storage) Transportation Fossil Fuel Hydrogen & Plants Carbon Sources Synfuel Production Options Replace with heat Coal Petroleum Natural Gas BioMass source and H 2 O/ CO2 Clean Up Jet Fuel ? JP-8 Air Enrichment Conversion to Syngas Air Steam (O Separation) (CO + H ) 2 2 Dimethyl Carbonate (CH3)2CO3 Agriculture Ammonia Hydrogen Conditioning Methanol Dimethyl Ether NH3 H2 (CO + H2) CH3OH CH3O and Waste Dimethyl Ether Hydrogen CH O H Management 3 2 Transportation Fisher Tropsch MTO / MTP MTG / MOGD (Syncrude) Olefins Gasoline Upgrading / Refining Propylene Distillates LPG Diesel Isosynthesis Electricity Jet Fuel Isobutane Jet Fuel Naphtha JP-8 i-C4H10 JP-8 Heating and Power Petrochemical The Road To A Sustainable Future Requires New Technological Insight Today: Open Near-Term: Mid-Term: Closed Cycle Closed Reversible Sustainable Far-Term: Fusion Systems Cycles Cycles 2005 2015 2025 2050? Example: Fossil Examples: H2 Production, Example: Hydropower Vision: Bring Sun to the Fuel Hybrid Vehicles Earth (and Deep Plant Space) Rain • Heat Engine H2 Clouds • Combustion By- River Products Exhausted to Solar ∫ dS=0 Fuel Atmosphere Cell Solar Dam/Lake • Biosphere Closes H O Ocean the Loop 2 H2O • Use closed cycles • Irreversible entropy productions (i.e., sediment) are to improve efficient compensated for by persistent availability Stored Desired use of current • Store excess availability for adaptability/self-organize Exergy available resources • Sustainable living energy infrastructure Actual • Equilibrium • Non-equilibrium / irreversible thermodynamics Thermodynamics Time Possibility Desired Stored Exergy Actual Time More Details Impedance/Capacity Mismatch Entropy Subsidies – Ragone Plot 6 10 Pneumatic ) g 5 k 10 / s t Elastic Element t Flywheel a 4 10 W ( r Internal Combustion e 3 w 10 o P c i 2 f i 10 c e p Photovoltaic S Fuel Cell Batteries 10 1 234 0.1 1110 01010 Specific Energy (Watt-hrs/kg) Sustainability: A Group Focus • Bruntland Commission: A form of sustainable development which meets the needs of the present without compromising the ability of future generations to meet their own needs. • Technical Definition: To provide continuous compensation of irreversible entropy production in an open system (to meet needs) with an impedance and capacity – matched persistent exergy source. • Survive!; Exergy Parasite: New insights (not from classical thermo.) Exergy Consumption Rate = To * d(SI)/dt • Ideal Situation: d SI + d SE < O Possibility Desired d SE Stored Exergy d SI Actual Time • Example #1: Subsistence Farming • Example #2: Hydroelectric Power Life, War, and Economics • Goal: Competition – “Order/Disorder Sequence and Rate” ¾ Create an Impedance Mismatch with your competitor that is Sustainable For You!!!! • Find Exergy Source (i.e., business gradient) • Accelerate the Duty-Cycle (i.e., product cycle) • Optimize Exergy Consumption Rate to order your business • Maximize Entropy Production Rate for your competitor.
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