MIT22_081JF10_lec04a

MIT22_081JF10_lec04a - Recitation: Discussion of...

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Unformatted text preview: Recitation: Discussion of Sustainability Issues Dr. John C. Wright MIT - PSFC 21 SEP 2010 Introduction Outline O UTLINE 1 Another definition of sustainability - not running out of things. e.g. land Energy footprint Environmental footprint Ecological footprint Carbon footprint The Three Dimensions of Sustainabilty Finance/ Economy Social Development Trade-Offs & Equity/ Synergies Ecology/ Environment 2 3 Drivers of Change Opportunities and Barriers; timing issues Derived from the World Bank (1996) Derived from World Bank (1996) 2 Sustainability Recitation Footprints Motivation W E ARE NOT IN STEADY STATE Population and standards of living. 1990 data. Pop 5,278,639,789 (1990) 1 0.8 HDI 0.6 0.4 0.2 0 0 0.5 1 1.5 kWh/percapita 2 104 Sustainability Recitation Africa Asia Europe North America South America Oceania 3 Footprints Motivation W E ARE NOT IN STEADY STATE Population and standards of living are increasing. 2005 data. Pop 6,486,882,848 (2005) 1 0.8 HDI 0.6 0.4 0.2 0 0 0.5 1 1.5 kWh/percapita 2 104 Sustainability Recitation Africa Asia Europe North America South America Oceania Along the way, we need to make informed choices. 3 Footprints Motivation H OW DO HUMANS IMPACT THE ENVIRONMENT ? Need to include direct consumption and also externalities in the supply chain - life cycle analysis. Resource depletion (water, energy, food, manufactured materials, fertile land, habitats, etc.) Waste product pollution Interference in environmental balances. Need a metric to apply across technologies and consumption. How do I compare an egg to a light bulb? Energy used - convert all energy requirements into a common unit like TOE (tonnes of oil equivalent). Need to convert all usage to primary energy (e.g., including the inefficiency of electricity production from primary energy). CO2 emitted - Here the energy footprint is weighted for the carbon intensity of the primary energy sources. (may not even be zero for nuclear or renewables) Land area used - a computation of land needed to collect water, to grow food, to produce various resources, to convert fossil energy to land to produce equivalent biomass energy, etc. for our individual use. 4 Sustainability Recitation Footprints Motivation C ARBON EMISSION FACTORS FROM ENERGY USE The Kaya equation relates CO2 emissions to other quality factors: CO2 = Pop Standard of living Energy Intensity Carbon intensity Pop represents global population Standard of living is in GDP/pop Energy intensity is energy used to produce in BTU/GDP Carbon intensity is efficiency of fuel and how much CO2 emitted in CO2 /BTU 5 Sustainability Recitation Footprints Motivation K AYA DATA Average Annual Percent Change 1980-1999 Region Africa Australia Brazil China East Asia E. Europe India Japan Middle East OECD OECD-Eur. United States World Population 2.54% 1.36% 1.61% 1.37% 1.78% 0.44% 2.04% 0.41% 2.98% 0.68% 0.53% 0.96% 1.60% Standard of Living - 0.58% 1.98% 0.76% 8.54% 5.00% - 1.91% 3.54% 2.62% 0.04% 1.73% 1.74% 2.15% 1.28% Energy Intensity 0.82% - 0.37% 1.83% - 5.22% 0.92% - 0.14% 0.27% - 0.57% 2.45% - 0.88% - 1.00% - 1.64% - 1.12% 6 Carbon Intensity - 0.01% 0.00% - 0.80% - 0.26% - 0.70% - 0.61% 0.03% - 0.96% - 1.14% - 0.58% - 1.06% - 0.21% - 0.45% Carbon Emissions 2.77% 2.98% 3.43% 4.00% 7.10% - 2.21% 5.97% 1.47% 4.34% 0.94% 0.18% 1.23% 1.30% Sustainability Recitation Footprints Motivation W HY DOES ECOLOGICAL FOOTPRINT MATTER Footprints are about measuring how much of a finite resource you are using. Carrying capacity of earth? Sustainable economies, societal institutions, and the environment Ecological footprints for modest European lifestyle are 2.6 hectares or about 6.5 acres per person US average = 24 acres per person (8.8 hectares) UK average = 5.3 hectares per person (13.3 acres) Above modest European lifestyle applied to China suggests it could support a sustainable population of 333 million! [Optimum Population Trust, UK, 1993] Area of US is similar to China - so US can support its population at European lifestyle levels! - but we are ~3 that level. 7 Sustainability Recitation Footprints Motivation D ISCUSSION How much does our location globally have to do with our footprint? Solutions? Equity? Consequences? 8 Sustainability Recitation Footprints Motivation E NERGY F OOTPRINT Land used to generate energy Land needed to absorb CO2 emissions from energy generation Energy used in an activity or production of an item 9 Sustainability Recitation Footprints Case Studies S OLAR , HOW DO WE GET FROM 1300 W/ M2 TO 4? Solar insolation is 1300 W/m2 at the top of the atmosphere. => 1GW plant needs 877 m 877 m Clear air attenuates to 1000 W/m2 => 1000 m squared Only half the Earth is illuminated 500 W/m2 => 1400 m squared The sun rises and sets sin = 1 250 W/m2 => 2000 m sq 2 Cloud cover can cost 25%-50% , but we'll be generous and as sume we use deserts. Efficiency of solar cells. Take 20%. 50 W/m2 => 4472 m squared Packing efficiency. Solar plants typi cally only cover 25% with cells or mir rors. e.g. Solarpark Lieberose has 50 ha of cell area on 163 ha of land used by the plant (300 ha overall leased). 25 W/m2 => 9000 m squared 10 Sustainability Recitation Footprints Case Studies E COLOGICAL FOOTPRINT See http://www.earthday.net/footprint What is your footprint? My own footprint is not great: Food Mobility Shelter Goods Services Total 3.0 acres 7.0 acres 3.2 acres 3.0 acres 8.7 acres 24.9 acres (about US average) Worldwide there are 4.5 biologically productive acres per person. Is there enough to go around? 11 Sustainability Recitation Footprints Case Studies S HOULD I FLY, TAKE THE TRAIN , OR DRIVE TO P RINCETON ? They all take 6 hours. They all cost the same $ (at least for one person). It's 600 miles round trip. Flying A full Boeing 747-400 with 240 000 liters of fuel and 416 passengers can travel 8 800 miles (14 200 km) Jet fuel has 10 kWh/liter of heat energy. 10kWh/liter 12000kWh per passenger Pro rate this for my trip: 300/8800 400kWh 12 Sustainability Recitation 2240000liter 416passengers Footprints Case Studies S HOULD I FLY, TAKE THE TRAIN , OR DRIVE TO P RINCETON ? They all take 6 hours. They all cost the same $ (at least for one person). It's 600 miles round trip. The train A regional train uses 5-15 kWh per 100 seat-mi Take the middle range and assume the train is full 6 10 kWh per 100 seat-mi = 600 kWh 12 Sustainability Recitation Footprints Case Studies S HOULD I FLY, TAKE THE TRAIN , OR DRIVE TO P RINCETON ? They all take 6 hours. They all cost the same $ (at least for one person). It's 600 miles round trip. Driving A single passenger in a non-hybrid getting 30 mi/gallon. Gasoline has about 44 kWh per gallon. 880kWh 600mi 30mi per gallon 44kWh/gallon 12 Sustainability Recitation Footprints Case Studies D ISCUSSION It is said the Gobi desert could supply the world's power if covered in photovoltaic cells. Is this true? The Gobi desert is approximately 1 280 000 square kilometers. What about snow? Practical issues? How much can we reasonably reduce our footprints? When you are a working professional, do you hope to have a larger footprint? Do you care? What other choices did I have for short trips? What other considerations? 13 Sustainability Recitation Drivers of Change D RIVERS OF C HANGE - FOR DISCUSSION Technological innovation Will it enable painless transition to sustainable lifestyles. eg Firelight -> Lightbulb -> CFL -> LED What are you willing to give up? Does life style = quality of life? Zipcar, hybrids, public transport Desktop(300W) -> laptop(60W) -> Smartphone (5W) Substitution of alternatives Policy and regulatory requirements. Is regulation the way to go? What about personal freedoms? Will the market decide/respond? Recycling, incandescent bulbs (2012 efficiency standards 14->45 lumens/W) Related closely to adoption and development of technologies. Refrigerators as a historical example resisted by industry. Changes in people's preferences. Social pressure. What have you observed compared to say 20 yrs ago? greening of industries? Why? 14 Sustainability Recitation Drivers of Change O PPORTUNITIES AND BARRIERS ; TIMING Technologies Market barriers - costs. Maybe subsidies are required? eg solar and wind. Inertia - infrastructure investment payout, consumer preferences Policy - Stimulus fund, cash-for-clunkers, grid and other infrastructure upgrades. Creating jobs, but opportunity to adopt new more efficient infrastructure. 15 Sustainability Recitation Drivers of Change S OME RESOURCES Sustainable Energy; Tester et al. Sustainable Energy, Without the hot air; MacKay at http://www.withouthotair.com/ Earthday footprint analysis at http://www.earthday.net/footprint Carbonfund Carbon footprint calculator at http://www.carbonfund.org/site/pages/calculator/ 16 Sustainability Recitation MIT OpenCourseWare http://ocw.mit.edu 22.081J / 2.650J / 10.291J / 1.818J / 2.65J / 10.391J / 11.371J / 22.811J / ESD.166J Introduction to Sustainable Energy Fall 2010 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms. ...
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This note was uploaded on 02/24/2012 for the course MECHANICAL 2.650J taught by Professor Johnc.wright during the Fall '10 term at MIT.

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